INDUSTRIAL
APPLICATION and
INSTALLATION GUIDE
TABLE OF CONTENTS
Page
Introduction . . . 3
Engine Selection . . . 5
Engine Installation Considerations: Power Transmissions . . . 19
Mounting and Alignment . . . 37
Air Intake . . . 69
Exhaust . . . 75
Cooling . . . 79
Lubrication . . . 93
Fuel Governing and Control . . . 99
Starting . . . 111
Instrumentation, Monitoring, and Shutoff . . . 121
Application and Installation Audit Forms . . . 125
Start-Up Checklist . . . 133
Maintenance and Records . . . 145
Conversion Tables and Rules of Thumb . . . 149
INTRODUCTION
Reliability of machinery is a major factor affecting satis-factory performance. Engines must be properly installed in an acceptable environment if reliability of each engine system and the total installation are to be achieved. The objective of this guide is to outline application and installation requirements of Caterpillar Diesel Engines applied in material handling and agricultural applications and to provide the installer with data needed to com-plete an installation with satisfactory results.
A layout for engine installation should include space for connections to functional systems, including ventilation, and working space or access allowing performance of repair and scheduled maintenance.
Current technical information for all engines other than the 3000 Family can be found on-line using the Technical Marketing Information (TMI) program (https://tmiweb.cat.com). 3000 Family information is on CD and can be ordered through the Media Logistics System asking for LERH9330.
View specification sheets, Product News bulletins, the 3400 Performance and Drawing Book (LEBH9181), and other industrial engine information including this book on the Electronic Media Center (EMC). The URL address is http://emc.cat.com
A complete library of installation drawings for all Caterpillar Engines is available on CD by ordering LERQ2015. Subscribers to this library will automatically receive up-dates four times a year.
The goal of each engine sale should be a good installation in an appropriate application.
ENGINE SELECTION
Page
General . . . 6
Power Requirements . . . 6
Comparison with Experience . . . 6
Horsepower, Torque, and Machine Productivity . . . 6
Calculated Horsepower Demand . . . 6
Dynamometer Measured Horsepower Demand . . . 7
Engine Measured Horsepower Demand. . . 7
Torque Rise Effect on Performance . . . 7
Response Effect on Performance . . . 8
Adequate Machine Performance . . . 8
Tolerances . . . 8
Fuel Heating Value . . . 8
Auxiliary Loads . . . 8
SAE Standard Conditions . . . 8
Determining Total Power Needs . . . 8
Simulating Performance of a Smaller Engine . . . 9
Life Related to Load Factor . . . 9
Engine Ratings and Configurations . . . 9
Engine Capability Determines Ratings . . . 9
Power Setting Determines Maximum Fuel Rate . . . 9
Factors Involved in Establishing a Rating. . . 9
Engine Usage Determines Rating Validity . . . 9
Engines are Developed for Specific Rating Levels . . . 10
Rating Curves . . . 10
Continuous Rating Defined . . . 10
Intermittent Rating Defined . . . 10
Maximum Rating Discussed . . . 10
Application Ratings . . . 10
Special Ratings . . . 11
Altitude Derating . . . 11
Regulatory Requirements . . . 11
Homologation . . . 11
Actual Power Output Derives From Load Demand . . . 11
Laboratory Testing . . . 11
Engine Configuration Variations Provide Rating Range . . . 12
Aftercooling Variations. . . 12
Aftercooling Configurations Versus Ratings . . . 13
Wiring . . . 13
Mechanically Governed Engines . . . 13
GENERAL
The purpose of this section is to discuss power demand, engine ratings, and engine selection to result in satisfactory machine performance and engine life.
POWER REQUIREMENTS
Comparison with Past Experience
Before selecting an engine model and rating, power demand must be analyzed. This task is simplified if experience is available with a similar machine powered by an engine of known rating and fuel rate performance. This experience provides a basis for deciding whether the machine was under powered, correctly powered, or over powered.
Horsepower, Torque, and Machine Productivity
To better understand torque and horse-power, consider that a very small engine can provide sufficient torque for a very large machine, if there is enough speed reduction. But, although the machine could have sufficient torque, it would operate at such a slow speed as to be unproductive. Productivity of most machines is approxi-mately proportional to horsepower input.
Horsepower is the time rate of doing work. Or restated, horsepower is proportional to the product of torque times rpm. Some basic relationships are: T x N bhp = _____ 5252 5252 bhp T = ________ N 33,000 ft-lb 1 hp = _________ min Where: T = Torque, ft-lb N = rpm
Calculated Horsepower Demand
An estimate of machine load demand can be made mathematically, when no actual machine experience is available to serve as a baseline of comparison. Using basic engineering principles on work and energy and data on the type of task to be accom-plished, it is possible to convert all func-tions of a machine to ft-lb per minute and then convert to horsepower demand. Mathe-matical calculation may be the only way available to estimate power requirements at the start of a new machine design. Of course, this approach is accurate only to the extent that all factors are considered and assumptions are correct. For certain applications such as pumps or other con-tinuous loads, where demand is known quite well, calculated values are quite accu-rate. In other applications, actual demand can be significantly different than calculated levels.
Dynamometer Measured Horsepower Demand
Actual load demand measurement by powered dynamometer is the most accu-rate way to determine power demand of components or of a total machine. It is rec-ommended that a manufacturer do this to more accurately determine where power is being consumed. This can identify a device or system which is using more power than it should and is in need of redesign for improved efficiency. For example, this occa-sionally happens with hydraulic systems. However, a dynamometer normally mea-sures only the steady-state power demand. More sophisticated instrumentation is required to measure load demand under dynamic, transient conditions. If this type of measuring apparatus is available, the dyno-driven load must accurately simulate the real machine operation to yield accurate data. Estimated h.p. loss due to: 1) torque con-verter, 2) transmissions, 3) generators, 4) belt drives, 5) gear reducers.
Engine Measured Horsepower Demand Usually, the most practical way to assess power demand, and capability of an engine to perform adequately, is to make a logical selection based on calculation or compari-son with past experience and test it. There is no substitute for a rigorous evaluation of an engine in the machine or application. This provides the final proof of machine performance acceptability, or it will identify shortcomings in need of correction.
Torque Rise Effect on Performance For machines which are capable of lugging the engine (i.e., applying sufficient load to pull the engine speed down below rated speed, at full throttle), it is important to con-sider two other characteristics of engine performance. These are torque rise and response to sudden load change.
Torque Rise % =
(Peak Torque) – (Rated Torque)
__________________________ x 100 Rated Torque
Cat Diesel Engines typically provide high torque rise to perform well in a wide variety of applications.
A torque curve is the graphical representa-tion of torque versus speed.
Some modification to a torque curve is possible in those cases where this is required to achieve satisfactory machine performance. Consult your engine supplier if this need exits.
If torque rise is higher than necessary, those parts of the machine driveline ahead of the transmission may be subjected to torque levels which may shorten the life of gearing and bearings. For this reason it is sometimes desirable to let the machine operator shift to a lower gear to increase engine speed, instead of always lugging the engine without a gear change. So, the decision to use an extra high torque rise engine must also consider driveline capa-bility. By contrast, an engine with insuffi-cient torque rise will seem weak and may even stop running before the operator has time to make a shift change. This is not acceptable either. The best compromise is to use enough torque rise to satisfy machine performance requirements, but not so much that driveline life becomes unacceptable.
Devices such as blowers, pumps, and pro-pellers cannot lug an engine because power demand drops off much more quick-ly than engine capability as speed is reduced. The amount of torque rise avail-able in these applications is generally meaningless because torque rise is not required, except as it may contribute to the ability to accelerate the load.
Response Effect on Performance
A naturally aspirated engine has the fastest response to sudden load increase because required combustion air is immediately available.
A turbocharged engine will not respond quite as fast because it takes a moment for the turbo to accelerate upon sudden load increase. Steady progress in turbocharger development has produced smaller, faster responding turbochargers and, therefore, turbocharged engines which respond quick-ly to sudden load increase. In a steady load and speed situation, turbo response is of no consequence. Air/fuel ratio controllers, also called smoke limiters, momentarily limit fuel delivery until sufficient air is avail-able for combustion. They respond to inlet manifold boost pressure. The air/fuel ratio setting is a compromise between machine responsiveness and acceptable level of transient smoke for a particular application. Adequate Machine Performance
Manufacturers and customers develop their own ideas of what constitutes ade-quate machine performance. Insufficient power causes low productivity and user dissatisfaction. Excessive power costs more to purchase, requires heavier drive-line components, and may reduce machine life if the operator is careless. The ideal machine is responsive, productive, and durable, satisfying the owner’s need for performance and overall value.
Tolerances
Actual engine horsepower output may vary by up to ±3% from nameplate value on a new engine. Similarly, where load demand of some work-producing device is pub-lished, the manufacturer’s tolerance should be added to demand horsepower if power needs are to be met in all cases.
Fuel Heating Value
Heating value of the fuel affects power out-put because fuel is delivered to the engine on a volumetric basis. Allowance should be made for a fuel with lower heat content (higher API than standard) where the power level is critical. Caterpillar Diesel ratings are based on use of 35 API fuel with HHV of 19,590 Btu/lb (45570 kJ/kg) or 138,000 Btu/gal.
Auxiliary Loads
In addition to the main load carried by the engine, allowance must also be made for all other engine-driven auxiliary loads. Extra loads imposed by a cooling fan, alternator, steering pump, air compressor, and hydraulic pump may represent a significant propor-tion of total engine power available.
SAE Standard Conditions
Engine ratings express actual usable power available under standard SAE (Society of Automotive Engineers) specified condi-tions of 29.38 in Hg (99.2 kPa) barometer, 85°F (30°C). Devices, such as the oil pump, fuel pump, and jacket water pump, which are part of a runnable engine, do not sub-tract from rated power.
Determining Total Power Needs
After establishing main load power demand and adding all auxiliary power demands, some additional power should be allowed for peak loads (such as grades and rough terrain) and reserve for acceleration.
Simulating Performance of a Smaller Engine
If a machine is thought to be overpowered and a change to a smaller engine is being considered, it is possible to simulate a lower horsepower engine by resetting the fuel system on the larger engine to some lower horsepower. Then, an experienced operator can fully evaluate machine perfor-mance at the lower horsepower. Although performance will not be exactly the same, because of greater rotational inertia and displacement (which both improve ability to handle sudden load changes), this will roughly simulate performance to be expect-ed with a smaller engine. This may demon-strate that a smaller engine is a viable pos-sibility which should be tested further. Or, such testing may show that the lower power level cannot meet the peak demands sat-isfactory; that the larger engine will deliver sufficient performance advantage to justify its cost.
Life Related to Load Factor
Use of an oversized engine contributes to longer engine life because it runs at a lower overall load factor. It also provides quicker response to sudden load changes. Load factor is the ratio of average fuel rate to the maximum fuel rate the engine can deliver when set at a rating appropriate for a par-ticular application, expressed as a percent. Fuel usage is a better indicator of engine life than engine hours.
ENGINE RATINGS AND CONFIGURATIONS
A major concern in applying engines is the proper application of engine horsepower to obtain desired performance, economic oper-ation, and satisfactory engine life. Successful application of engines requires an under-standing of how they are rated and how to properly select and use these ratings.
Engine Capability Determines Ratings Horsepower rating capability is determined by engine design. Combined capability and durability of all engine components deter-mine how much horsepower can be pro-duced successfully in a particular application. Power Setting Determines Maximum Fuel Rate
The horsepower output of a basic engine model can be varied within its design range by changing the engine fuel setting or speed setting. Both of these settings affect the engine’s maximum fuel rate and, therefore, the power output capability. Thermal and mechanical design limits will not be exceeded, if an appropriate engine and rating is selected.
Factors Involved in Establishing a Rating
Some of the application conditions consid-ered by a manufacturer in determining a rat-ing for an application are: load factor, duty cycle, annual operating hours, and histori-cal experience at a particular rating level. Engine Usage Determines Rating Validity A properly maintained engine in actual use will determine whether or not a particular rating level is appropriate. Ratings which are validated by acceptable field experi-ence are retained. Continuing engine development results in on-going engine improvement, and some increases in rat-ings result from this process.
Engines are Developed for Specific Rating Levels
Engines are designed and developed to produce specific power levels for particular applications. Subsequent lab and field experience confirms the validity of these ratings. Increasing the engine horsepower beyond approved levels by increasing the fuel rate, to compensate for excessive load, is not an acceptable practice. Excessive engine wear or damage can result and could invalidate the warranty. Published ratings express engine power and speed capability under specified loading condi-tions or for specific applicacondi-tions.
Rating Curves
Consult TMI for Industrial Engine rating curves which show available ratings at var-ious speeds for each model and configura-tion. Specification sheets also carry some of this information, for preliminary sizing purposes.
Continuous Rating Defined
The CONTINUOUS rating is the power and speed capability of the engine, which can be used without interruption or load cycling. Few industrial or agricultural appli-cations require a rating as low as the con-tinuous rating because load and speed fluctuation is usually present. However, the continuous rating will extend engine life and reliability in any application.
Intermittent Rating Defined
The INTERMITTENT rating is the power and speed capability of the engine which can be utilized for about one hour followed by an hour of operation at or below the continuous rating. Any rating with the horsepower or engine speed above the continuous rating is also considered an intermittent rating. An intermittent rating, when properly applied, provides excellent engine life in a broad
range of applications characterized by the fluctuating load and speed. The majority of material handling and agricultural applica-tions are in this category.
Maximum Rating Discussed
Maximum rating developed when only nat-urally aspirated engines were available. Although this was never intended as a usable rating, it was used by some as a point of reference. The actual rating was sometimes compared with the maximum, and the difference was somewhat erro-neously considered to be a power reserve or an indication of degree of conservatism of the rating.
Today, with turbocharged engines, a maxi-mum rating has even less significance. An engine can often produce power levels well beyond approved application ratings; but, unless the effect of these ratings on engine life in a particular application is known, there is no basis for judging conser-vatism of ratings. Use of maximum ratings was also encouraged, unfortunately, by competitive pressures between manufac-tures trying to extend the apparent capa-bility of their engines. Appropriate Caterpillar ratings are established for each application or type of duty. Rely upon these remendations rather than attempts at com-parison with almost meaningless maxi-mum ratings.
Application Ratings
Ratings other than continuous and inter-mittent are approved for certain specific applications. Examples of these application ratings are irrigation pumping continuous, off-highway truck, and locomotive.
Special Ratings
Most engine applications are well under-stood and utilize one of the above existing published ratings which have been con-firmed by thousands of hours of successful experience. However, occasionally, a unique application merits special rating considera-tion because of unusually low load factor or unusually short life requirements. In this case, consult dealer. Factory application engineers will require that a special rating request data sheet be submitted for review before a special rating can be considered for approval.
Altitude Derating
Each model and rating has established maximum altitude capabilities for lug and for nonlug applications. For higher altitude operation, power settings must be reduced approximately 3% per 1000 ft (305 m) above the altitude limit for that rating. Diesel engines do not self-derate enough so that the fuel setting can be left unchanged. If they are not reset to appropriate power lev-els, naturally aspirated engines may smoke badly and turbocharged engines may suffer excessive thermal and mechanical loading, resulting in internal damage, without giving external indication of distress.
Regulatory Requirements
Regulatory requirements often dictate the use of specific regulatory agency-approved rating levels, as required in underground mining and in mobile industrial equipment designed to be self-propelled on-highway. Caterpillar works with certain of these agen-cies (for example, Mine Safety and Health Administration [MSHA] and Environmental Protection Agency [EPA]) to provide preap-proved ratings. Compliance with these regu-lations can make it difficult to get special rat-ings or to derate the engine.
Homologation
Machine manufacturers who plan to export product to other countries should investigate the need for homologation (approval) in that country. This may affect acceptability of engines, ratings, and other machine features. Ultimately the end user is responsible to make sure his engine complies with all regulations. Actual Power Output Derives
from Load Demand
Regardless of engine rating (power and speed setting), the actual power devel-oped by an engine derives from the load imposed by driven equipment. For exam-ple, an engine set to produce 500 hp (373 kW) will actually produce only 40 hp (30 kW), if the driven load demands only 40 hp (30 kW). For this reason, average fuel consumption is an indicator of average load demand. Average fuel consumption is also used as an indicator of load severity on the engine by comparing it with maximum fuel rate associated with the approved rating for that application. When this ratio is expressed as a percent, it is called load factor.
Laboratory Testing
Engine ratings are set at levels which pro-vide both satisfactory performance and engine life. This requires consideration of many operating variables used to assess severity of operation on internal engine parts. To provide data for this purpose, all engine models are run in the laboratory to acquire part load data. It shows how each of the significant operating parameters varies with load and speed. Measured parame-ters include turbo speed, exhaust temper-ature before and after turbocharger, fuel consumption, boost, smoke level, and fuel limit setting position. To assure good per-formance and long life, limits on each of these parameters are established. These are run under controlled reference condi-tions so that valid comparison with other data and with other ambient conditions can be made.
Engine Configuration Variations Provide Rating Range
On a given engine model, a horsepower range capability is created by providing different engine configurations such as naturally aspirated, turbocharged, and tur-bocharged-aftercooled. Internally, these engines may differ significantly.
Also, Caterpillar offers both direct injected (DI) and prechamber injected (PC) engines to provide a more complete product offer-ing. Each system has its own advantage. Increasing horsepower output by injecting more fuel requires additional air for com-plete combustion and internal cooling. This requires additional mechanical strength of internal components and additional design features, such as oil jet cooling for pistons. In an engine, the mass flow of air supplied to each cylinder determines the amount of fuel which can be efficiently burned. But, the entire engine must be designed for strength and durability at approved power levels. The limit on a naturally aspirated engine horsepower rating is usually the amount of air available for combustion, because of exhaust temperature and smoke levels. Turbocharging, using energy from waste exhaust gas, provides an efficient means to increase air flow. Compression of the air by the turbocharger increases the air tem-perature. The horsepower rating of a tur-bocharged engine is usually limited by the internal temperatures, turbocharger speed, and structural limits.
An aftercooler between the turbocharger and the engine intake manifold cools the hot compressed air. Cooling the air increases its density and allows more air to be packed into the cylinder and more fuel to be burned. The rating is typically limited by internal temperature limits, turbocharged speed, and structural limits.
Because the effect of turbochargers and aftercoolers is to provide more air to the engine, and fuel rate can usually be increased to use this extra combustion air, engine component loading or turbo speed become the limit on rating. Caterpillar Diesel Engines do not utilize turbos or aftercoolers as add-ons. Rather, engines are designed and developed in all aspects for these higher loading levels. Then they are tested thoroughly to assure long life and satisfac-tory performance.
Aftercooling Variations
Engine jacket water is usually used in the aftercooler to cool the turbocharger-com-pressed air. This jacket water aftercooled (JWAC) configuration includes the after-cooler and piping required to flow engine jacket water through the aftercooler. This is the most reliable aftercooling system because it is an integral part of the engine jacket water circuit and a separate water pump is not required.
Lower aftercooler water temperatures per-mit higher engine ratings because cooler, denser air allows the burning of more fuel without exceeding exhaust temperature limits. The use of a separate circuit after-cooled (SCAC) engine configuration requires a separate source of lower tem-perature aftercooler water. This is not practical in most material handling and ag applications.
Aftercooling Configurations Versus Ratings
Depending upon the type of engine config-uration, a variety of ratings is available. Naturally aspirated (NA) engines have the lowest ratings. Turbocharged (T) configu-rations are next, and ratings are higher with various types of turbocharged after-cooled (TA) engines. The jacket water aftercooled (JWAC) system is based on 175°F (80°C) average temperature water to the aftercooler, while a higher rating is possible by the use of separate circuit water to the aftercooler. For example, a rating designated SCAC 85°F (30°C) would require 85°F (30°C) water at appro-priate flow required for a particular model. (See TIF for flow requirements.)
WIRING
Mechanically Governed Engines
Because of the variety of attachments and starter/alternator combinations available, it is difficult to generalize, other than to refer to wiring schematics and installation guides for any given attachments. One word of caution would be to consider ambient tem-perature, engine size, and primary battery cable length recommendations given in Application and Installation manuals when specing starting circuit components. Cable recommendations are as follows:
Electronically Governed Engines
In addition to the same starter and alter-nator considerations for mechanical gov-erned engines, electronically govgov-erned engines have additional electronic/electri-cal considerations. These additional con-siderations involve electrical/control, dis-play, sensors external to the engine, power supply to the engine/display electronics, grounding, and finally customer parameter programming via service tool. Considering the following will help prevent potential wiring/electrical installation problems.
1. Electronic capability, equipment, and features change rapidly, so consult the most recent engine wiring schematics and installation guides avail-able before engine installa-tion.
2. Do NOT modify or splice into the on-engine wiring harness that comes with the engine from the factory. Communi-cate with the engine only through the 40-pin customer connector (usually identified on wiring schematics as J3/P3).
3. Switching circuits and grounds for electronic components (engine ECM, displays) are very critical. An AWG 4 ground wire from the engine ground stud (located on the customer con-nector mounting bracket) to the bat-tery negative buss must be installed. Ground paths through machine frames are NOT permitted
Battery Recommendations
System Cold Cranking Amperes ¤ –18°C Engine Voltage 0°C & Up –18 — –1°C –32 — –19°C
3406 12 1740 1800 2000 24 800 870 1000 30/32 800 870 870 3408/3412 24 870 1000 1260 30/32 870 870 1260
Total Cable Length Cable Size awg 12V – m 24-32V – m 0 1.22 4.57 00 1.52 5.49 000 1.83 6.40 0000 2.29 8.24
4. Other battery positive and negative control wiring should be with AWG 14 wire.
5. All other engine, display, sensor, and data link wiring can be accommodated by AWG 16.
6. All circuits for engine related power, control and displays must be dedicated to engine functions (isolated from other machine electrical/electronic functions) to minimize the risk of introducing electrical noise into engine related circuits. For example do not operate a machine control solenoid from power or ground wires also serving engine electronics.
7. All wire insulation outside diameter must be 2.2 to 3.4 mm to facilitate adequate environmental sealing when used with Deutsch connectors.
8. Any unused Deutsch connector wire location MUST have an 8T-8737 seal-ing plug installed for environmental sealing.
9. Any wire bundle exiting a Deutsch connector must have at least twice the bundle diameter as a bend radius if a bend is necessary. This is to avoid excessive stress on the back-side Deutsch connector environmental seals. A minimum straight length of 25 mm is recommended for wires exiting a Deutsch connector.
10. Do not paint Deutsch connectors. Paint will wick into the mating con-nector components and prevent easy future disassembly if required.
11. The recommended master disconnect switch is between the engine ECM power/start switch and the unswitched power connection to the engine ECM.
12. J1587 (ATA) and CAT Data Link (CDL) positive and negative leads must be unshielded twisted pairs (1 twist per 25 mm) within each data link (not combined). These leads must NOT be installed in a metal conduit, because the conduit acts as a shield.
13. The J1939 (CAN) data link MUST be shielded and its positive and negative leads must be twisted (1 twist per 25 mm). Consult the engine’s wiring schematic for proper routing of the wire shield. Extended wire end Deutsch pins and sockets are available to facilitate shield routing through Deutsch con-nectors (133-0967 & 133-0969). 14. All wire bundles must be adequately
protected from accidental damage (stepping, dropping hard objects, pinch points, or grabbing).
15. The only electrical connections (not considering the starter circuit) required to allow an electronic engine to start and achieve low idle are all positive and negative battery connections to the engine ECM. It may be advanta-geous for the initial start-up of a new machine powered by an electronic engine to start with the basic positive and negative battery circuits for the initial start, then connect one circuit at a time to the customer connector to validate each circuit (one at a time). 16. Caterpillar electronic engines leave the
factory with all customer programm-able parameters/features programmed to default values. Consult the most cur-rent version of the Electronic Application and Installation Guide (SENR1025) for default and parameter/feature ranges/ options. To change any customer parameter, an electronic engine ser-vice tool is required. Currently the Electronic Technician (ET) and the Electronic Computer Analyzer Pro-grammer (ECAP) are the only two
industrial electronic engine service tools supported by Caterpillar. All Caterpillar industrial engines have a service tool con-nection as part of the on-engine wire har-ness. The service tool connector is located on the customer interface connector (J3/P3) mounting bracket.
17. A Caterpillar electronic engine instal-lation audit checklist is included in this manual on page 137.
18. Caterpillar also provides detailed electronic troubleshooting manuals. Contact your servicing CAT dealer or Factory contact for this appropriate electronic engine manual. This manu-al MUST be used in any electronic diagnostic troubleshooting journey for a comprehensive orderly diagnostic journey.
19. Caterpillar currently has an industrial electronic engine display attachment. This display is referred to as an Electronic Monitoring System (EMS). The EMS consists of three separate units: a main unit (warning lamps and scrollable parameter window), a tacho-meter unit (engine speed), and a quad gauge unit (oil pressure, water tem-perature, battery voltage, and fuel transfer pump pressure). If any of the display units are used, the main unit must be used (it decodes the CDL data link information for itself and the other two units). The tachometer and quad gauge units are optional. Multiple display units can be used, and a max-imum total wire length of 33 meters is suggested. Refer to the engine wiring schematics or EMS wiring schematic (148-5625) for proper wiring and fea-ture implementation. The EMS requires 24V for operation even though the engine ECM may operate on 12V power. A 12V to 24V converter is available (127-8853). Caterpillar has available an EMS interconnect har-ness (160-1050) if more than the main unit is utilized.
20. The most up-to-date indications of electronic features available can be found by referring to the customer connector (J3/P3) pin-out descrip-tions given on the industrial engine wiring schematic. Please note that customer connector pin-outs HAVE minor differences between industrial inline six cylinder and vee engines, and possibly major differences between on-highway truck, marine, machine and EPG applications. So, while an electronic capability might be similar to another non-industrial application, the capability probably will NOT be identical (e.g. cruise control for on-highway vs. PTO mode for industrial — cruise control operates on vehicle ground speed, PTO operates on engine speed). Please refer to the most current version of SENR1025 for the latest industrial electronic descrip-tions.
21. Please be aware that the service tool will not allow anyone the capability of damaging the engine by features acti-vated or operational limits selected. The OEM has the ability to select any rating available (A – E tier) contained within the personality flash file with-out factory passwords for any given family of industrial iron. It IS the respon-sibility of the OEM or engine selling dealer to make sure the appropriate tier rating for the application is select-ed. If an OEM or customer arbitrarily selects a higher rating, drive train damage or reduced engine time to overhaul could result. If drive train damage occurs because of misap-plied rating, Caterpillar is NOT respon-sible for drive train damage. OEM’s have the option of locking out critical parameters to prevent tampering — e.g. rating. If a parameter is locked out, factory passwords are required to unlock the parameter.
Safety
Every machine manufacturer is concerned about the safety of those who will own, operate, or be near any machine. The following suggestions/considerations
may help minimize the risk of injury: ✓Acknowledge
1. Guard or shield all rotating exposed components ____ (e.g. fans, belt drives, drive shafts).
2. Locate the fuel filler where it is convenient for service and will not allow ____ spilling of fuel on the engine, even by a careless operator. Make sure the
fuel tank is vented and contains enough expansion volume to allow fuel expansion as it warms.
3. Route, enclose, and clip all electrical wires to avoid wearing through ____ the insulation and causing an electrical short. Also route wiring away
from hot components.
4. Guard hot parts (exhaust manifold, water lines, air lines from the turbocharger ____ (air-to-air aftercooling systems)) to help prevent contact by the operator unless
the component is adequately surrounded by machine features to prevent accidental contact.
5. Route, clip, and guard hydraulic/fuel lines and hoses away from sharp ____ edges, hot engine components, and pinch points to avoid damage.
Supplementary shielding may be necessary.
6. Install a fire extinguisher on the machine for quick access in the case of ____ an emergency.
7. Provide instruction and warning labels where needed to inform the ____ operator against improper actions.
8. Factory supplied engine operation and maintenance literature must be ____ available to the owner/operator of the machine.
9. Consider means for locking open inspection doors, shields, and guards. ____ to avoid accidental closure.
10. Consider non-slip steps and grab handles for routine inspections, ____ especially for radiator coolant level/fill checks.
Application/Engine: Industrial — S/N Prefixes:
2AW1 — UP ...3176C 1DW1 — UP ...3196 6BR1 — UP ...3406E 3LW1 — UP ...3456 7PR1 — UP ...3408E 4CR1 — UP ...3412E General Wiring Considerations: (Ref. SENR1025) — read before audit
Special note: pg. 17 voltage thresholds; pg. 32 sensor return; pg. 25 welding
(SENR1025-03; Jun 98) ✓Acknowledge
1. Caterpillar does not accept warranty responsibilities for customer wiring. ____ 2. An AWG 4 wire must be installed between the ground lug on the J3/P3 ____
mounting bracket and the battery negative buss. Using a frame member as a ground conductor is not acceptable for engine electronics.
3. A maximum of three terminal lugs per any single electrical lug recommended. ____ 4. Wire insulation outside diameter is 2.2 — 3.4 mm when used with Deutsch ____
connectors. This assures proper environmental sealing.
5. Allen head bolt lock torque on Deutsch connectors = 2.26 N•m. ____ 6. 8T-8737 sealing plugs must be installed in every unused Deutsch connector ____
pin location.
7. Every wire exiting a Deutsch connector must withstand a 45 N pull test. ____ 8. Wire bundle exiting Deutsch connectors should have a minimum bend radius ____
of 2X bundle diameter, and 25 mm straight before bend starts.
9. Deutsch connector back seals are not stressed allowing moisture entry. ____ 10. All wires — bundled, secured, and protected from accidental damage ____
(stepping, dropping hard objects, pinch points, grabbing).
11. All electronic features utilized by the customer have been demonstrated. ____ 12. Deutsch connectors are not painted. Paint will wick and impair serviceability. ____ 13. Logged faults caused by installation audit activity cleared, and any other logged ____
faults corrected and cleared.
14. Customer instructed on how operational and configuration checks can be ____ made before shipment to end user, so consistent engine operation is insured
for a given application.
15. No modifications to on-engine wire harness permitted. ____ 16. Suggested battery master disconnect is between engine pwr/start switch and ____
ECM unswitched positive battery junction. If master disconnect is located in the battery negative cable, the last hour of ECM job data will be lost (sw opened).
17. The J1587 data link (143-5018) must be unshielded twisted pair (1 twist/25 mm). ____ 18. The CDL data link (143-5018) must be unshielded twisted pair (1 twist/25 mm). ____ 19. The J1939 data link (153-2707) must be shielded twisted pair (1 twist/25 mm). ____
Application/Engine: Industrial — All Engines with Cat Data Link
Engine Monitoring System (EMS) Considerations: ✓Acknowledge 1. Reference EMS wiring schematic 148-5625 for wiring instruction. ____ 2. If display option is utilized, EMS main unit must be used. Other two units of ____
EMS display (quad gauge, tach) are optional.
3. Caterpillar interconnect harness between EMS units is available (160-1050) – used? ____ 4. If auxiliary temperature and pressure sensors are utilized, trip points must be ____
programmed via, ET for enunciation on the main EMS unit.
5. EMS requires 24V supply. If 12V electric’s are utilized, install a 127-8853 converter. ____ Is a jumper wire across the negative battery in and out terminals on the converter
in place?
6. Caterpillar does not supply engine to EMS wire harness. ____ 7. Wire size for EMS = (+) & (–) BAT.14AWG; ALL OTHER 16AWG dedicated to ____
CAT electronics only (other machine functions not permitted).
8. Battery positive supply must be 5A circuit breaker protected (single unit). ____ 9. Multiple EMS display stations are permitted. Ref. page 59 in SENR1025-03 or ____
LEXH6427 (Product News) for details (NON-shielded data link wire required).
10. Total length of CAT data link cable should not exceed 33 m. ____ 11. Cat data link cable must be a twisted pair (1/25 mm) non-shielded. ____
REF. SENR1025 (change level 03 dated June 98) Electronic A&I Guide SENR1073 (change level 01 dated February 98) 6 Cyl Troubleshooting SENR1065 (change level 01 dated March 98) 8 & 12 Cyl Troubleshooting LEXH7530 (change level 00 dated 1997) EMS Operators Guide
LEXH6427 (dated Nov. 1996) Engine Monitoring System (EMS) for Caterpillar Industrial Engines
POWER TRANSMISSIONS
Page
General Considerations . . . 20
Clutches . . . 20
General Description and Selection Considerations . . . 20
Engine-Mounted Enclosed Clutches . . . 21
Light-Duty (LD) . . . 21
Normal-Duty (ND) . . . 21
Heavy-Duty (HD) . . . 21
Extra Heavy-Duty (EHD) . . . 22
Typical Light-Duty (LD) Clutch Applications . . . 22
Typical Normal-Duty (ND) Clutch Applications . . . 22
Typical Heavy-Duty (HD) Clutch Applications. . . 22
Typical Extra Heavy-Duty (EHD) Clutch Applications . . . 22
Automotive-Type Clutches . . . 23
Air Clutches. . . 24
Centrifugal Clutches . . . 25
Transmissions . . . 25
Mechanical Transmission . . . 26
Automatic, Semiautomatic, and Preselector-Type Transmissions . . . 26
Speed Increasers/Reducers. . . 28
Compounds. . . 28
Stub Shafts . . . 29
Hydraulic Drives . . . 30
Fluid (Hydraulic) Couplings . . . 30
Torque Converters . . . 30
Single-Stage Torque Converters . . . 32
Multistage Torque Converters . . . 32
Special Considerations . . . 32
Side Loading. . . 32
Overhung Power Transmission Equipment . . . 33
Wet Flywheel Housings . . . 34
Couplings . . . 34 Misalignment Capability . . . 35 Stiffness . . . 35 Serviceability . . . 35 Coupling Selection . . . 36 Auxiliary Drives . . . 36 Gear Drives. . . 36 Belt Drives . . . 36 Crankshaft Pulleys . . . 36
GENERAL CONSIDERATIONS
The first decision in designing an engine installation is selection of the coupling and drive method to connect the engine to the driven equipment.
The coupling and drive selection con-nections are closely related to the proper selection of engine support and mount-ing. This ensures a successful trouble-free installation from the standpoint of both the engine and driven equipment, as well as the power transmission com-ponents. (Refer to Mounting and Alignment section.)
A rigid precision-type mounting system must be provided for both the engine and driven equipment if a solid or nearly solid driveline is utilized.
Drive components which utilize universal joints, drive shafts or belts, and chain-type drives permit slightly greater align-ment deviations.
When selecting the power transmission system, the possible need for a com-plete torsional analysis must be consid-ered. System incompatibility will result in premature and/or avoidable failures. (Refer to Mounting and Alignment sec-tion, Page 33, Torsional.)
CLUTCHES
General Description and Selection Considerations
Engine starting capability is normally limit-ed and the direct connection of large mass driven equipment makes starting difficult or impossible, therefore, a type of clutch or disconnect device may not only be desir-able but necessary.
Exceptions, if properly sized to the engine starting capability, may be centrifugal pumps, fans or propellers, and generators which provide a direct connected load with a low starting torque requirement. Certain compressors which utilize a starting “unload-ing device” may also be direct connected. Piston-type pumps, most compressors, belt- and chain-driven equipment, and all mobile vehicles will require an engine dis-connect system.
The engine disconnect feature provides an important safety and service function. It per-mits rotating the engine for service and adjustment, as well as servicing the driven equipment without disconnecting the drive-train. It also permits engine warm up before applying load — an accepted requirement for extended engine life. On multiple engine installations driving into a common compound or driven machine, it permits operating at less than full power level if desired, as well as at partial power should one engine be down for routine service or because of failure.
Numerous devices are available for con-nection or engagement of the engine to the driven machine. The device selection will depend on the desired engagement function; however, several general consid-erations must be made regardless of the device selected.
The selected device must have adequate capacity to transmit the maximum engine torque to the driven equipment. With the exception of “dog-type” clutches, which are generally not acceptable on material han-dling equipment, clutches rely on friction for power transmission.
(Dog-type clutches provide a direct mechan-ical connection and cannot be engaged during operation nor do they have any modulating [slipping] capability.)
Engine-Mounted Enclosed Clutches Caterpillar offers, as price list attachments, a wide selection of “power takeoff” -type enclosed clutches suitable for most indus-trial-type applications.
These clutches (power takeoffs) will be cov-ered in greater detail under the following classifications (clutch rating definitions), as well as the specific selection considerations for the type of clutch and application.
Figure 1
ENGINE MOUNTED ENCLOSED CLUTCH
Enclosed clutch selection for either rear or front engine mounting must be made in accordance with the “Horsepower Absorption Capability”.
The following rating definitions are applic-able to clutch arrangements offered by Caterpillar.
Light-Duty (LD)
A light-duty clutch is used primarily to dis-connect and pick up light inertia loads, but does more work during engagement than “cut-off” duty.
A light-duty clutch should engage within two seconds, start the load less than six times per hour, and never heat the pres-sure plate outer surface above hand hold-ing temperature.
Example: Disconnect clutch between engine and hydraulic torque converter with engine above low idle when engaging clutch, as in power shovel master clutch, generator, or similar drives.
Normal-Duty (ND)
A normal-duty clutch is used to start inertia loads with frequencies up to 30 engage-ments per hour. More important is that the clutch can start the heaviest inertia load within three seconds, and that the product of seconds of clutch slip per engagement times number of engagements per hour be under 90.
A normal-duty application may raise the outer clutch surface temperature to under 100°F (37.8°C) rise above ambient air temperature.
Example: Power takeoff starting average inertia loads where starting load is 40% of the running load.
Heavy-Duty (HD)
A heavy-duty clutch is used to start inertia loads with frequencies up to 60 engage-ments per hour. More important is that the clutch can start the heaviest inertia loads within four seconds, and that the product of seconds of clutch slip per engagement times number of engagements per hour be under 180.
Heavy-duty applications may raise the clutch outer surface temperature to a max-imum of 150°F (65.6°C ) rise above ambi-ent air temperature.
Example: Power takeoff starting average inertia loads whose starting load is 80% of the running load. Also, rock crusher appli-cations where the clutch is not used to “break loose” jammed loads.
Extra Heavy-Duty (EHD)
An extra heavy-duty clutch is used to start inertia loads requiring over four seconds to start the heaviest load, with longest slip peri-od per engagement not exceeding 10 sec-onds. Also, when the product of seconds of clutch slip per engagement times number of engagements per hour exceeds 180, it is beyond extra heavy-duty. Contact your Caterpillar dealer for application approval of extra heavy-duty-type service.
Example: Power takeoff starting inertia loads whose starting load approaches or exceeds the running load.
Typical Light-Duty (LD) Clutch Applications
A. Agitators — pure liquids. B. Cookers — cereal.
C. Elevators, bucket — uniform loads, all types.
D. Feeders — disc-type. E. Kettle — brew.
F. Line shafts — light-duty.
G. Machines, general — all types with uniform loads, nonreversing.
H. Pumps — centrifugal.
Typical Normal-Duty (ND) Clutch Applications
A. Agitators — solid or semisolids. B. Batchers — textile.
C. Blowers and fans — centrifugal and lobe.
D. Bottling machines.
E. Compressors — all centrifugal and lobe-type.
F. Elevators, bucket — uniformly loaded or fed.
G. Feeders — apron, belt, screw, or vane. H. Filling machine — can type.
I. Mixers — continuous.
J. Pumps — three or more cylinders; gear- or rotary-type.
K. Conveyor — uniform load. Typical Heavy-Duty (HD) Clutch Applications
A. Cranes and hoist — working clutch. B. Crushers — ore and stone.
C. Drums — braking.
D. Compressors — lobe rotary plus three or more cylinder reciprocating-type. E. Haulers — car puller and barge-type. F. Mills — ball-type.
G. Paper mill machinery — except calenders and driers.
H. Presses — brick and clay.
I. Pumps — one- and two-cylinder reciprocating-type.
J. Mud pumps — one- and two-cylinder reciprocating-type.
Typical Extra Heavy-Duty (EHD) Clutch Applications
A. Compressors — one- and two-cylin-der reciprocating-type.
B. Calenders and driers — paper mill. C. Mills — hammer-type.
Once all machine parameters have been established, contact your Caterpillar dealer for selection assistance.
Automotive-Type Clutches
Also known as diaphram or spring-loaded-type clutches, this category is generally a light-duty classification; it is normally used in strictly mobile applications, such as on-highway trucks or higher speed mobile machines, which utilize a multispeed trans-mission. The automotive-type clutch is normally foot-operated for disengagement or is engaged with the friction being gener-ated by spring force acting on an engine-driven plate.
Although this type of clutch is not a Caterpillar price list attachment, on the smaller engine families, there is offered a selection of flywheels to accommodate the more common commercial models offered by a number of manufacturers.
If the machine design requires this type of clutch, the package designer and installer should work very closely with the clutch manufacturer to ensure proper selection. CAUTION: THIS TYPE OF CLUTCH, DUE TO ITS INHERENT TORQUE CAPACITY LIMITATIONS, SHOULD NOT BE USED WITH THE LARGER 3500 FAMILY CATERPILLAR ENGINES.
Figure 2
Air Clutches
Air-type clutches are commercially avail-able in sizes to fit the entire Caterpillar Diesel Engine line. Basically, engagement friction is maintained by air pressure. This feature is particularly advantageous when remote control of the engagement/disen-gagement functions is required.
Air clutches utilize an expanding air blad-der for the clutch element. (See Figure 3.) Air clutches do not normally have side load capability, so if such capability is required,
the output shaft must be supported by two support bearings. These bearings must be mounted on a common base with the engine package. Air pressure to operate the clutch is supplied by an air connection through the drilled passage in the output shaft. Clutch alignment tolerances are reduced as air pressure to the clutch increases.
Caterpillar does not offer air clutches on an attachment basis. When selecting an air clutch, the package designer/installer must work closely with the clutch manufacturer.
Figure 3
Centrifugal Clutches
Centrifugal clutches are commercially avail-able in sizes to fit the entire Caterpillar Diesel Engine line. The centrifugal clutch accomplishes the engagement/disengage-ment functions by centrifugal force which is generated by the engine operating speed. It provides a power engagement/disengage-ment function controlled strictly by the engine governor speed control (throttle). Centrifugal clutches offer smooth automat-ic engagement of load without complautomat-icated controls. Typically, a diesel engine with a full load operating speed of 1800 rpm will be fitted with a centrifugal clutch which effects engagement at a speed of about 1000 engine rpm. Once engaged, most clutches of this type will remain engaged even if the engine speed is pulled down due to load — as low as the engagement speed (i.e., 1000 rpm) or lower (e.g., dis-engagement at 800 rpm). If the load is such that engine stall speed is approached, the clutch will disengage. Centrifugal clutches are not offered by Caterpillar as standard price list attach-ments. As with the air-type clutches, they have limited or no side load capability and for other than in-line drive loads, a sepa-rately supported output shaft with two sup-port bearings must be provided and must be mounted on a common base with the engine package.
When selecting a centrifugal clutch, the pack-age designer/installer must work closely with the clutch manufacturer.
TRANSMISSIONS
Over the years rapid technological ad-vances have enabled numerous commercial manufacturers to offer a broad range of transmissions with nearly unlimited fea-tures and options.
For this discussion transmissions will be divided into three broad classifications all of which transmit power through sets of mechanical gears, either spur or helical types, or planetary designs. Where multi-speed capability is provided, it is accom-plished either mechanically or automatical-ly (hydraulicalautomatical-ly, pneumaticalautomatical-ly, etc.).
Due to the large number of transmissions commercially available and the fact that Caterpillar does not offer transmissions (with the exception of marine transmissions — single speed — forward/reverse functions) as price list attachments, the transmission discussion will be restricted to general oper-ating principles and considerations.
When selecting a transmission, the pack-age designer must work closely with the transmission manufacturer.
CAUTION: REGARDLESS OF THE TYPE OR BRAND OF TRANSMISSION SELECT-ED, THE DESIGNER MUST ENSURE THAT IT HAS THE CORRECT HORSE-POWER, TORQUE, AND SPEED CAPA-BILITY TO MATCH THE DIESEL ENGINE PERFORMANCE CHARACTERISTICS.
Mechanical Transmission
The mechanical transmission provides the lowest cost method of providing multiple output speeds when the driven equipment input speed range or torque requirements exceed the operating capability of the diesel engine. Mechanical transmissions are usu-ally equipped with some type of clutch assembly to facilitate not only engine start-ing but also to change gear ratios.
Figure 4 MECHANICAL TRANSMISSION
This type of transmission is applicable to both semimobile and mobile installations where the momentary loss of power to the driven equipment when gear changes are effected does not pose operating problems. Generally, the mechanical transmission is employed when the gear speed change requirements are not a constant require-ment and the speed shifts do not have to be executed rapidly.
Today’s modern mechanical transmission, when properly matched to the engine-dri-ven equipment, will provide reliable trou-ble-free service. Frequent gear changes, however, will accelerate clutch wear and maintenance costs.
Installation is simplified since mechanical transmissions do not normally require oil cooling systems as do the automatic type.
Automatic, Semiautomatic, and Preselector-Type Transmissions
As the names imply, these transmission types effect the gear changes either com-pletely automatically or as predetermined by the machine operator.
Engine power engagement/disengagement clutching is normally fully automatic and does not require the machine operator to physically move a clutch pedal or lever. For disengagement the operator need only move the selector lever to a neutral position. As with the mechanical transmission, the automatic type must be carefully matched to the engine operating horsepower, torque, and speed characteristics. However, with the automatic types, additional match con-sideration may be required since they nor-mally utilize a torque converter, hydraulic coupling, or other type of nonmechanical engagement device for the power engage-ment/disengagement function. This is near-ly always accomplished hydraulicalnear-ly.
The automatic-type transmissions provide operator ease of machine operation, as well as a nearly constant power flow to the driven equipment during gear changes. A number of commercial manufacturers offer a wide range of automatic-type trans-mission. The package designer/installer must work closely with the transmission supplier to ensure the transmission prop-erly matches the machine application and provides the desired operating features. Some automatic transmission designs uti-lize a lockup feature. This device, in effect, turns the transmission into a direct mechanical drive to eliminate the inherent inefficiencies of the hydraulic clutching device.
Figure 5 AUTOMATIC TRANSMISSIONS
Generally, the higher cost of an automatic transmission can be justified with a machine requiring high productivity and frequent load cycle changes.
When using automatic-type transmissions, other installation considerations are required since most types require a system to cool the transmission oil. Caterpillar offers jack-et water connections to supply cooling water to customer or transmission manu-facturer-supplied heat exchangers.
Also offered are complete heat exchanger packages, but care must be exercised to ensure that the Caterpillar system is capa-ble of handling the transmission heat rejec-tion. The cooling system capacity of the sys-tems offered by Caterpillar can be obtained from your Caterpillar dealer and is in the Owner’s Maintenance Manual.
Speed Increasers/Reducers
These power transmission devices resem-ble a mechanical transmission in that power is normally transmitted through a mechanical gear set of spur or helical gears. They are used when the engine speed range is not compatible with the dri-ven equipment input speed requirements and when the installation is best suited to an in-line drive arrangement rather than the offset belt of chain drive systems.
Figure 6 SPEED REDUCER
Speed increasers/reducers generally uti-lize a mechanical cutoff clutch for engine starting and are usually of a single-speed, nonreversing design, although exceptions to the above do exist. They seldom exceed two speed ratios.
Speed increasers/reducers are available for either direct engine mounting or for remote mounting. The remote-mounted type should be on a rigid common base with the engine for ease of alignment.
Caterpillar does not offer speed increasers/ reducers as price list attachments. The pack-age designer/installer must work closely with the commercial gear supplier to ensure proper selection and installation.
Compounds
Although infrequently found in material han-dling/agriculture applications, specific de-signs may require an engine compound. Basically, a compound is an enclosed gear or chain device which permits several engines to provide input power with the power out-put coming from one or more shafts. Compounds providing a single engine input and multiple outputs is most common. An example would be a hydrostatic machine where a single engine provides power to multiple hydraulic pumps when separate pumps are used for the various functional drives of the machine.
Figure 7 MULTIPLE PUMP DRIVE
Multiple engine compounds can be used in applications where less than the installed horsepower capability is occasionally called upon for part load operation of the driven machine.
When part load operation is adequate, the excess capability can be removed by declutching engines, reducing overall operating costs and maintenance.
Caterpillar does not offer compounds as standard price list attachments, however, a number of commercial manufacturers offer a variety of different compounds.
The package designer/installer must work closely with the compound manufacturer to ensure proper selection and installation.
Figure 8 MULTIPLE ENGINE COMPOUND DRIVE
Stub Shafts
Where the application permits, a stub shaft will provide a low cost, simple method of direct power transmission.
Figure 9 FRONT MOUNTED STUB SHAFT
Caterpillar offers, as standard price list attachments, stub shafts for mounting on both the front and rear of the engine crank-shaft.
Stub shaft drives must not be used when the starting load of the driven equipment is sufficient to impair engine starting unless a declutching or unloading device is utilized. Stub shafts also have limited side load capability.
Complete details on the physical size, as well as the power transmission and side load capability of the Caterpillar-supplied stub shafts, are available from your Caterpillar dealer.
Hydraulic Drives
Hydraulic drive devices generally fall into two major classifications: fluid or hydraulic couplings and torque converters.
The theory involved is similar in all types of hydraulic drives although the internal design may vary. Basically, the engine out-put is absorbed by a turbine-type pump. The oil or fluid in the pump housing is accel-erated outward, and the engine power is transmitted to the outer edge of the pump as kinetic energy in the form of high veloc-ity fluid. This energy is then transferred back towards the center of the output shaft. This is where the differences occur between a hydraulic or fluid coupling and a torque converter.
Fluid (Hydraulic) Couplings
In the fluid couplings, the high velocity fluid is directed into a matching turbine located very close to the turbine-type pump which is engine driven. The matching turbine absorbs the energy as the fluid is directed back toward the center of the coupling and the energy is delivered to the output shaft.
Figure 10 HYDRAULIC COUPLING
The output torque will always equal the input torque less internal friction losses which will be observed as a lower output speed (rpm) than the input speed (engine rpm).
The primary advantage of a hydraulic cou-pling is the total lack of a mechanical con-nection between the driving engine and the driven equipment.
This isolates or greatly reduces the transfer of mechanical shocks, vibration, and unde-sirable torsional effects between the driven load and the engine.
A hydraulic coupling will prevent engine stall under load; however, the engine can be pulled down in speed by varying degrees depending on the hydraulic coupling fluid cooling capacity. It also permits starting high inertia-driven loads without the use of a cut-off clutch.
The main disadvantages of a hydraulic cou-pling are the reduced efficiency over a mechanically coupled drive and its inability to generate a torque multiplication as is possible with a torque converter.
Normally, hydraulic couplings are best suit-ed to applications which are constant spesuit-ed applications where the slip capability is desirable to compensate for shock loads, overloads, high inertia load startups, and assist in torsional vibration reduction. Torque Converters
As with hydraulic couplings, torque convert-ers differ considerably in internal construc-tion and refinement but can generally be placed in two classifications: single-stage and multistage. These differences will be expanded later in this section.
The torque converter differs from the hydraulic coupling in that one or more third members, called stators or turbine reactors, are utilized in addition to the input pump and the output turbine. These stators or reactor members are imposed in the fluid flow path
in such a manner as to produce a multipli-cation of the input torque to the output shaft at reduced output speeds (rpm).
Figure 11 TORQUE CONVERTER
The maximum torque is transmitted to the output shaft (driven equipment) at stall con-dition (output shaft is not rotating) when it will equal from 1.6 to more than 6.0 times the converter input torque (engine output torque) value. When operating at full rated engine speed, with the imposed load at a level which permits the output speed to be close to the engine speed, the torque converter acts in principle like a hydraulic coupling.
The necessity of matching a torque con-verter to the engine cannot be overempha-sized. An improperly sized converter, one with the wrong blading or one which oper-ates in a highly inefficient speed range, will prove unsatisfactory. An improperly matched torque converter can result in engine over-load, high inefficiency, high fuel consump-tion, poor engine response, and other undesirable results.
The torque converter manufacturer gener-ally has computer programs which, when coupled to the performance characteristics of the engine, can ensure a correct “match” for any installation/application. Most con-verter manufacturers have performance data on the Caterpillar Diesel Engine mod-els or data can be obtained from your Caterpillar dealer. This data is covered in the Caterpillar Technical Information File (TIF). Performance data for nonstandard ratings is also available from your Caterpillar dealer.
Additionally, cooling of the torque convert-er fluid is required. Torque convconvert-ertconvert-er cool-ing must be provided for the equivalent of at least 30% of the total engine heat rejec-tion when using a precombusrejec-tion cham-ber-type engine. When using a direct injec-tion-type engine, torque converter cooling must be provided for the equivalent of at least 50% of the total engine heat rejection. Caterpillar offers, as price list attachments, either jacket water connections for heat exchanger-type coolers or, on the 3200, 3300, and 3400 Series Engines, complete heat exchanger cooling packages.
It is imperative that the cooling package be of adequate capacity. The capacity of Caterpillar-supplied cooling systems can be obtained from your Caterpillar dealer. Most commercially available converters are also offered with attachment cooling packages.
If the engine cooling system is used to cool the torque converter, adequate reserve radiator capacity must be provided. (Refer to Cooling section.)
Single-Stage Torque Converters
This type of converter is normally selected for light-duty applications. It has a decreas-ing torque absorption curve as the output speed approaches stall condition and will not pull down the engine input speed (lug the engine).
Multistage Torque Converters
Most applications will utilize a multistage converter. They provide a broader usable range and higher torque multiplication value than single-stage converters.
Torque converter manufacturers provide excellent manuals and assistance in the selection of the correct converter for a spe-cific application. Consequently, rather than elaborating on selection guidelines in this publication, it is suggested that the pack-age designer/installer counsel with the con-verter manufacturer for expert advice. In addition to offering the same benefits as a hydraulic drive, the torque converter also offers a torque multiplication benefit as well as, if properly matched, higher power transmission efficiency. The multistage converter is particularly preferred for vari-able output speed applications.
As standard price list attachments, Caterpillar offers flywheels to couple to most commercial torque converters and hydraulic drives.
Special Considerations
With the selection of any of the above methods of power transmission, several general areas must also be given special consideration to ensure a successful installation.
Side Loading
Excessive side loading is one of the most commonly encountered problems in the transmission of engine power.
It is impossible to overemphasize the need for accurate evaluation of side load imposi-tion on all types of power transmission devices.
For Caterpillar-supplied attachment power takeoffs, the Caterpillar Industrial Engine Price List LEKI8162 provides complete instructions and capacity data for side load evaluation.
For power transmission devices supplied by others, the manufacturer must be consulted for a capability analysis of his equipment. Overhung Power Transmission
Equipment
Power transmission equipment, which is directly mounted to the engine flywheel housing, must be evaluated to ensure that the overhung weight is within the tolerable limits of the engine. If not, adequate addi-tional support must be provided to avoid damage.
CAUTION: CERTAIN APPLICATIONS, SUCH AS AGRICULTURE MACHINES, DRILLS, OFF-HIGHWAY TRUCK, ETC., REQUIRE CONSIDERATION OF THE EFFECTS OF THE DYNAMIC BENDING MOMENT IMPOSED DURING NORMAL MACHINE MOVEMENT OR ABRUPT STARTING AND STOPPING.
The dynamic load limits and the maximum bending moment that can be tolerated by the flywheel housing can be obtained from your Caterpillar dealer.
For determination of the bending moment of overhung power transmission equipment installations, see Figure 13.
Figure 13 DETERMINATION OF BENDING MOMENT FOR OVERHUNG
To compensate for power transmission systems which create a high bending moment due to overhung load, a third mount is required. Proper design of the support is essential. Forces and deflec-tions of all components of the mounting system must be resolved. If the third mount is in the form of a spring, with a ver-tical rate considerably lower than verver-tical rate of the rear engine support, the effect of the mount is in a proper direction to reduce bending forces on the flywheel housing due to downward gravity forces, but the overall effect may be minor at high gravity force levels. The use of supports with a vertical rate higher than the engine rear mount is not recommended since frame bending deflections can subject the engine power transmission equipment structure to high forces. Another precau-tion is to design the support so that it pro-vides as little resistance as possible to engine roll. This also helps to isolate the engine/transmission structure from mount-ing frame or base deflection.
Wet Flywheel Housings
Certain types of power transmission equip-ment require a “wet” flywheel housing. Wet housing equipment requires that the flywheel housing be able to accommodate a degree of flooding by the fluid medium of the power transmission equipment. The stan-dard Caterpillar Diesel Engine does not:
A. Contain sufficient provisions for seal-ing in the area of the rear crankshaft seal to prevent the transfer of the power transmission fluid into the engine lubricating oil reservoir (pan).
B. Have the capability of evacuating the transmission fluid from the flywheel housing back to the transmission reservoir to prevent engine crank-shaft seal flooding.
These provisions can be provided on Caterpillar Engines but additional cost will normally be incurred.
COUPLINGS
Unless a belt, chain, or universal joint-type drive is taken directly from the output shaft of the engine-driven power transmission device, the use of some type of mechani-cal coupling device is recommended. The coupling must be installed between the power transmission output shaft and the input drive shaft of the driven machine. On close-coupled driven equipment, the use of a coupling can be avoided if two basic criteria are met:
A. Is the torsional compatibility of the driven machine compatible with the engine to the point that lack of a cou-pling will not cause either engine or driven machine problems?
B. Is the package base sufficiently rigid to avoid any distortion during operation? Does it contain sufficient alignment control features to successfully retain alignment during operation to preclude the need for the misalignment toler-ance capability of a coupling?
Seldom can both of these questions be answered affirmatively.
A large number of commercial coupling designs, are available to the package designer/installer.
CAUTION: THE COUPLING MUST BE TORSIONALLY COMPATIBLE.