HYDRAULIC SYSTEM
YARDMASTER®
HR45-25, HR45-27, HR45-31, HR45-40S,
HR45-36L, HR45-40LS, HR45-45LSX,
MAINTENANCE AND REPAIR
• When lifting parts or assemblies, make sure all slings, chains, or cables are correctly fastened, and that the load being lifted is balanced. Make sure the crane, cables, and chains have the capacity to support the weight of the load.
• Do not lift heavy parts by hand, use a lifting mechanism. • Wear safety glasses.
• DISCONNECT THE BATTERY CONNECTOR before doing any maintenance or repair on electric lift trucks. Disconnect the battery ground cable on internal combustion lift trucks.
• Always use correct blocks to prevent the unit from rolling or falling. See HOW TO PUT THE LIFT TRUCK ON BLOCKS in the Operating Manual or the Periodic Mainte-nance section.
• Keep the unit clean and the working area clean and orderly. • Use the correct tools for the job.
• Keep the tools clean and in good condition.
• Always use HYSTER APPROVED parts when making repairs. Replacement parts must meet or exceed the specifications of the original equipment manufacturer.
• Make sure all nuts, bolts, snap rings, and other fastening devices are removed before using force to remove parts.
• Always fasten a DO NOT OPERATE tag to the controls of the unit when making repairs, or if the unit needs repairs.
• Be sure to follow the WARNING and CAUTION notes in the instructions.
• Gasoline, Liquid Petroleum Gas (LPG), Compressed Natural Gas (CNG), and Diesel fuel are flammable. Be sure to follow the necessary safety precautions when handling these fuels and when working on these fuel systems.
• Batteries generate flammable gas when they are being charged. Keep fire and sparks away from the area. Make sure the area is well ventilated.
NOTE: The following symbols and words indicate safety information in this manual:
WARNING
Indicates a condition that can cause immediate death or injury!
CAUTION
Hydraulic System YardMaster® Table of Contents
TABLE OF CONTENTS
Description ... 1
Main Hydraulic Tank ... 2
Main Hydraulic Pump ... 2
Description ... 2
Load Sensing Pressure ... 2
Main Pump Controller... 3
LS Servo... 4
LS Control Valve... 4
Power Servo ... 4
Adjust ... 5
Load Sensing Pressure LS1 ... 5
Load Sensing Pressure LS2 ... 6
Standby Pressure ... 6
Power Control Valve... 6
Main Control Valve ... 7
Description ... 7 Adjustment... 8 Relief Pressures... 8 Main ... 8 Derricking Up... 8 Derricking Down ... 8 Telescoping Out ... 9 Telescoping In... 9 Spreader Supply... 9 Spreader Standby... 9 Steering Supply... 9 Derricking Cylinder ... 9
Flow Control Settings ... 9
Derricking Down Speed ... 9
Derricking Up Speed ... 10 Telescoping Speeds ... 10 Steering ... 10 HR45-25, HR45-27, HR45-31, and HR40S... 10 Description... 10 Adjust ... 10 HR45-36L, HR45-40LS, and HR45-45LSX ... 11 Description... 11 Pilot System ... 11 Pilot Pump ... 11
Telescoping Retract Control Valve... 11
Manipulator Pressure Valve ... 11
Description ... 11
Operation... 12
Adjust... 13
Engine Cooling System ... 13
Adjust (Standby Pressure)... 14
Adjust (Maximum Pump Pressure)... 14
Hydraulic Cooling System ... 14
Description ... 14
TABLE OF CONTENTS (Continued)
Adjust ... 16
100 Bar Relief Valve ... 16
Service Brakes... 17
Description ... 17
Parking Brake ... 19
Description ... 19 This section is for the following models:
HR45-25, HR45-27, HR45-31, HR45-40S, HR45-36L, HR45-40LS, HR45-45LSX, HR45H [B227]
1900 SRM 1107 Description
Description
This section describes the hydraulic system at the frame side of the Laden Yardmaster. A location overview of the hydraulic system components is shown in Figure 1.
Related items for the hydraulic system can be found in the following:
• Electrical System 2200 SRM 1106 • Diagrams 8000 SRM 1084
• Boom 4500 SRM 787
• Extendable Container Attachment, PPM 5000 SRM 1063
NOTE: Information on the Elme spreaders can be found in Extendable Container Attachment 5000 SRM 776.
1. PUMP COOLING SYSTEM
2. SERVICE BRAKE AND PILOT PUMP 3. FUEL TANK
4. PARK BRAKE SOLENOID VALVE 5. MAIN HYDRAULIC PUMP 6. MAIN HYDRAULIC OIL TANK 7. AIR CONDITIONING CONDENSER 8. BRAKE OIL TANK
9. 5H 9’6" RETRACT TELESCOPING CONTROL VALVE
10. 170 bar (2466 psi) LOAD SENSING SWITCH 11. 210 bar (3046 psi) LOAD SENSING SWITCH 12. SPREADER AND BOOM CONTROL SOLENOIDS 13. OPTIONAL DEAD MAN SOLENOID
14. OPTIONAL WINCH CONTROL VALVE
15. JOYSTICK PRESSURE VALVE
16. 4H 9’6" RETRACT TELESCOPING CONTROL VALVE
17. AIR/COOLANT/TRANSMISSION OIL COOLER 18. BRAKE ACCUMULATOR
19. HYDRAULIC AND BRAKE SYSTEM OIL COOLER 20. HYDRAULIC SYSTEM FILTER
21. BRAKE SYSTEM FILTER
22. BRAKE COOLING PRESSURE REGULATOR 23. BRAKE COOLING SOLENOID VALVE
24. HYDRAULIC AND BRAKE SYSTEM COOLING PUMP
25. TRANSMISSION OIL FILTERS 26. ENGINE AIR FILTER
MAIN HYDRAULIC TANK
The hydraulic tank is located at the RH side of the frame. At the side of the truck, a sight glass indi-cates the hydraulic oil level. When the running board cover above the tank is open, the breather and the general oil return are accessible. The breather also serves as the fill plug. The general oil return bracket
incorporates the oil return screen, which is accessi-ble after the bracket is removed.
Just in front of the cover is the suction shutoff, which allows replacement of pump suction hoses without having to empty the entire tank. Verify the suction valve is open before starting the engine.
Main Hydraulic Pump
DESCRIPTION
The main hydraulic pump provides oil pressure to the steering system, boom, and spreader functions. All other hydraulic functions use separate oil pumps. The main hydraulic pump is a variable displacement pump with two identical sections. See Figure 2. Figure 2 shows only one section of the pump. Each section consists of a housing with nine pump plungers. The housing, with the plungers, rotates and is driven by the pump shaft. The plungers are connected with a disc by joints. The position of the plunger in the housing depends on the position of the disc.
The disc rotates in a cutaway of the swash plate. When the swash plate is at an angle, the disc will rotate at the same angle. The joints in the disc will follow the induced axial movement, forcing the plungers in the housing to make the same stroke at each revolution. When the swash plate is level, the plungers will not make a stroke. The angle of the swash plate determines the volume displaced by the plungers which relates directly to pump supply volume. See Main Pump Controller.
LOAD SENSING PRESSURE
Oil leaves the pump via a variable metering orifice in the pump control valve. Independently of the flow,
the variable metering orifice causes a pressure drop between 22 and 25 bar (319 and 363 psi). The vari-able metering orifice is adjusted by regulators LS1 and LS2 on the pump control valve. This implies that delivered pump oil pressure is always 22 bar (319 psi) lower than the pressure at the pump plungers. See Figure 3.
The pressure measured immediately after the meter-ing orifice is called Load Sense (LS) Pressure. LS pressure tends to get lower at increasing flow and tends to get higher at decreasing flow. The absolute LS pressure varies almost according to pump pres-sure.
To properly detect variations in load sense pressure, the LS pressure line is separately connected with the LS controller. The LS pressure line and LS controller are also connected with the priority valves in the main control valve with the steering system. To ob-tain one signal for both pump sections, the LS1 and LS2 ports are interconnected at the main pump and at the main control valve.
When flow demand increases, the initially higher LS pressure will escape via the priority valves to the function being operated. The resulting pressure drop in the LS pressure line is signalled by the LS con-troller in the pump control system.
1900 SRM 1107 Main Hydraulic Pump
1. LOAD SENSING SERVO 2. PLUNGER 3. PLUNGER HOUSING 4. SWASH PLATE 5. POWER SERVO 6. PUMP SHAFT 7. SPRING 8. DISC 9. JOINT 10. PRESSURE PORT 11. SUCTION PORT
Figure 2. Main Hydraulic Pump
MAIN PUMP CONTROLLER
The pump controller contains servos and the LS con-trol valve, which manipulate the angle of the swash plate. The pump controller consists of the bigger LS servo, LS control valve, and the smaller power servo. When there is no oil pressure, the spring will move the swash plate towards maximum supply. When
there is high oil pressure, the bigger LS servo will overcome forces of both the spring and the smaller power servo and moves the swash plate toward min-imum supply.
The position of the swash plate is primarily deter-mined by the pressure in the LS servo, which is reg-ulated by the LS control valve.
1. LOAD SENSING LINE 2. LS CONTROL VALVE 3. POWER SERVO 4. LS SERVO 5. PUMP 6. SWASH PLATE
7. VARIABLE METERING ORIFICE
Figure 3. Main Pump Controller
LS Servo
The LS servo is directly connected with the swash plate. The piston side of the LS servo receives pres-sure from the LS control valve. The rod side is di-rectly pressurized by pump pressure. Apart from a spring that moves the LS servo toward maximum supply, the pressure difference between the pump and the LS control valve determines the position of the LS servo.
LS Control Valve
The LS control valve controls pressure at the piston side of the LS servo by comparing pump pressure with load sense (LS) pressure. At higher pressure differences, when LS pressure is relatively low, pres-sure for the LS servo is drained to tank. The LS servo will move the swash plate toward maximum supply.
At relatively higher LS pressures, when there is less oil demand, the spool supplies pump pressure to the LS servo, which will move the swash plate to mini-mum supply.
The LS controller cannot be adjusted separately, but its function relates to the pressure settings of LS1 and LS2. See Adjust.
Power Servo
Maximum supply flow of the pump is 420 liter (111 gal) per minute at 2350 rpm. This supply flow would overload the engine at higher pressures. When demanded oil flow and pressure represent a higher engine power than the available engine power, the power servo reduces supply flow by pres-surizing the LS servo. See Figure 4.
1900 SRM 1107 Main Hydraulic Pump
A. PRESSURE B. FLOW
1. MAIN RELIEF VALVE PRESSURE 2. POWER REGULATION
3. MAXIMUM SUPPLY
Figure 4. Power Regulation
The pressure at which the power servo starts pres-surizing the LS servo depends on the absolute pump pressure and the momentary force of the power servo spring. The momentary force of the power servo spring depends on the position of the swash plate (equal to pump supply). The power servo spring is less compressed at maximum pump supply, allowing the power servo to be opened more easily. At decreasing oil supply, it takes a higher pump pres-sure until the power servo opens to pressurize the LS servo. When pump supply volume has decreased to a third of maximum supply, the power servo will no longer open. This is because the maximum system pressure has been reached, which is determined by the main relief valve.
The power servos are adjusted regulators X1 and X2 for each of the pump sections. See Adjust.
To cover for low power at idle engine speeds or just above, oil supply is reduced by the manipulator valve. See Manipulator Pressure Valve.
ADJUST
NOTE: Adjustments must be made with engine tem-perature 60 to 80 C (140 to 176 F) and with hydraulic oil temperature between 45 to 65 C (113 to 149 F). The engine must be running at full speed, spreader fitted, no load.
Load Sensing Pressure LS1
NOTE:To set pressure at the load sense line, regula-tors LS1 and LS2 have to be isolated, and pressures have to be set independently. See Figure 5.
1. Disconnect the LS2 connection from the pump and plug the open connections. See Figure 6. 2. Install a pressure gauge of 600 bar (8702 psi) at
port M on the main control valve. See Figure 7.
1. X1 TEST PORT 2. X1 POWER REGULATOR 3. X2 POWER REGULATOR 4. X2 TEST PORT 5. LS2 REGULATOR 6. LS1 REGULATOR 7. DUMMY 8. LS2 PORT 9. PUMP CONTROLLER
A. LS1 PRESSURE SETTING B. LS2 PRESSURE SETTING 1. LS1 PORT 2. LS1 REGULATOR 3. LS2 REGULATOR 4. LS2 PORT 5. PLUG 6. CONTROLLER
Figure 6. LS1 and LS2 Pressure Settings
3. Install a pressure gauge of 600 bar (8702 psi) at the load sensing pressure line.
4. Run engine at 1200 rpm.
5. Operate sideshift function left to right and adjust pressure regulator LS1 between 22 to 25 bar (319 to 363 psi) during operation of the sideshift func-tion.
6. Remove the plugs and reconnect the LS2 load sensing line.
Load Sensing Pressure LS2
Pressure setting for LS2 is similar for LS1. To set LS2 pressure, isolate LS1 from the LS line. See De-scription and Figure 6.
To avoid interference at the load sense controllers, pressures at LS1 and LS2 may NOT be identical. Maintain a difference of about 2 bar (29 psi). The pump produces a noise when the difference in pres-sure is too small.
Standby Pressure
NOTE: To verify the minimum available pressure, measure the pump pressure at the main valve bank at port M. See Figure 7.
1. Run engine at idle with no functions operating. NOTE: Standby pressure must be 30 to 35 bar (435 to 508 psi).
2. Adjust LS1 and LS2 accordingly.
Power Control Valve
1. Install a pressure gauge of 600 bar (8702 psi) on following points:
• Port M on the main control valve
• Pressure plugs X1 and X2 on the main pump 2. At the main control valve, temporarily set the
pressure at 180 bar (2611 psi) at full throttle for following relief valves:
• Boom derricking up relief valves B3 and B4 • The two main relief valves (at M and at port
P1)
NOTE:For a smooth transition to the power regulat-ing mode, set X1 and X2 at a pressure difference of about 3 bar (44 psi).
3. Adjust power regulators X1 and X2 at full throt-tle to 80 bar (1160 psi) ±10 bar (145 psi).
4. Adjust the main relief valves to 420 bar (6092 psi) and the derricking up relief valves to 350 bar (5076 psi).
1900 SRM 1107 Main Control Valve
Main Control Valve
DESCRIPTION
The main control valve consists of six sections, which are held together with tie rods. The two outer sec-tions serve as a hydraulic connection for the four in-ner sections. Openings in the sections interconnect with pump supply, load sense line, and tank return. The steering priority valves block hydraulic flow to the four inner functions when load sense pressure at the steering side is lower than load sense pressure at the inner sections. See Figure 7 and Figure 8. The RH outer, P1 section has a bolted-on steering priority valve and an integrated main relief valve, which is normally set to 420 bar (6092 psi).
The LH outer section has, in addition to the 420 bar (6092 psi) main relief valve, a 220 bar (3191 psi) steering relief valve, a steering priority valve and the bolted-on 25 bar (363 psi) standby pressure valve for the spreader.
The four inner sections are for the spreader, telescop-ing, and derricking functions. Each inner section has a spool that opens proportionally with pilot pressure at the ZA and ZB ports. Flow rate of the spools is ad-justed by reducing or extending the maximum spool stroke with an adjustment bolt.
The location of the flow control valves is at the A side of the main valve. Relief valves for A ports are lo-cated at the A side of the valve. Relief valves for B ports are located at the B side of the valve. For the location of the various ports, see Figure 7 and Fig-ure 8.
Control valve sections cannot be repaired, except for replacing relief valves or exchanging seal kits. If the control spool is being removed, the mounting bolts must be secured with oil resistant Loctite®.
Table 1. Main Control Valve Torque Specifications
Item Specification
Tie rod nuts 100 ±10 N•m (74 ±7 lbf ft) Tie rod lock nut 60 ±10 N•m (44 ±7 lbf ft) Relief valves 85 ±10 N•m (63 ±7 lbf ft) Flow valves 100 ±10 N•m (74 ±7 lbf ft) Pilot ports 17 ±5 N•m (13 ±4 lbf ft) Load sense plug 17 ±5 N•m (13 ±4 lbf ft)
1. MAIN SECTION 2. SPREADER SECTION 3. TELESCOPING SECTION 4. DERRICKING SECTION 5. STEERING PRIORITY VALVE
6. SPREADER STANDBY RELIEF VALVE 7. STEERING RELIEF VALVE, P2
A PORT RELIEF VALVES B1 PORT P1 PORT
A2 PORT B2 PORT R2 PORT
A4 PORT B3 PORT ZA PILOT PORTS
B PORT RELIEF VALVES B4 PORT ZB PILOT PORTS
1. STEERING/MAIN VALVE SECTION 2. SPREADER VALVE SECTION 3. TELESCOPING VALVE SECTION 4. DERRICKING VALVE SECTION
5. DERRICKING VALVE SECTION 6. MAIN RELIEF VALVE SECTION 7. FLOW CONTROL VALVES
Figure 8. Main Control Valve Ports, Alternate View
ADJUSTMENT
NOTE: Adjustments must be made with engine tem-perature 60 to 80 C (140 to 176 F) and with hydraulic oil temperature between 45 to 65 C (113 to 149 F). The engine must be running at full speed, spreader fitted, no load.
Relief Pressures
Main
1. Attach a pressure gauge of 600 bar (8702 psi) at port M. See Figure 7.
2. Temporarily increase the pressure of the derrick-ing up relief valves, B3 and B4, to over 420 bar (6092 psi).
3. Fully raise the boom and keep the joystick in der-ricking position.
4. Adjust the two main relief valves to 420 bar (6092 psi) with the engine at full throttle. 5. With the boom still raised, reset the derricking
up relief valves, B3 and B4, to 350 bar (5076 psi). Derricking Up
1. Attach a pressure gauge of 600 bar (8702 psi) at port M.
2. Fully raise the boom and keep the joystick in der-ricking position.
3. With the engine at full throttle, set the derricking up relief valves, B3 and B4, to 350 bar (5076 psi). Derricking Down
1. Attach a pressure gauge of 600 bar (8702 psi) at port M.
1900 SRM 1107 Main Control Valve
2. Fully lower the boom and keep the joystick in derricking down position.
3. With the engine at full throttle, set the derricking down relief valve A4 to 110 bar (1595 psi). Telescoping Out
1. Attach a pressure gauge of 600 bar (8702 psi) at port M.
2. Fully extend the boom and keep the joystick in the extending position.
3. With the engine at full throttle, set extension re-lief valve A2 to 350 bar (5076 psi).
Telescoping In
1. Attach a pressure gauge of 600 bar (8702 psi) at port M.
2. Fully retract the boom and keep the joystick in retraction position.
3. With the engine at full throttle, set retraction relief valve B2 to 190 bar (2756 psi).
Spreader Supply
1. Attach a pressure gauge of 600 bar (8702 psi) at port M.
2. Disconnect solenoids E16 and E17 at the spreader control valve.
3. Operate and hold the sideshift lever.
4. With the engine at full throttle, set spreader sup-ply relief valve B1 to 200 bar (2901 psi).
5. Reconnect solenoids E16 and E17. Spreader Standby
1. Remove and plug the hose from port Z. 2. Attach a pressure gauge at port Z. 3. Remove the plug from the relief valve.
4. Run the engine at elevated idle and set the spreader standby relief valve to 25 bar (363 psi). 5. Replace the plug, remove the gauge, and
recon-nect the hose to port Z.
Steering Supply
1. Attach a pressure gauge of 600 bar (8702 psi) at port M.
2. Operate the steering wheel at full stroke. 3. With the engine at full throttle, set steering
sup-ply relief valve P2 to 220 bar (3191 psi). Derricking Cylinder
Maximum occurring pressure at the derricking cylin-der is set at the holding valve. See Boom 4500 SRM 787 for adjustment procedure.
For adjustment of the spreader functions see Ex-tendable Container Attachment, PPM 5000 SRM 1063 and for boom functions see Boom 4500 SRM 787.
Flow Control Settings
Hydraulic oil flow is checked by measuring the time required to complete a specific movement. To speed up, increase flow by loosening the socket head screw at the flow control valve. To slow down, restrict flow by tightening the socket head screw.
Derricking Down Speed
Derricking down speed is set at the holding valves on the derricking cylinders, if flow control valve A4 provides sufficient flow.
Establish the correct setting of the flow control valve at A4 as follows:
NOTE:Time required to fully lower the boom at full throttle is 30 to 32 seconds.
1. Measure actual derricking down speed.
2. Adjust the holding valves as necessary. See Boom 4500 SRM 787.
3. Tighten the flow control valve at A4 until derrick-ing down speed is reduced.
4. Release the socket head screw until flow restric-tion is again influenced by the holding valves.
Derricking Up Speed
NOTE: First adjust derricking down speed before ad-justing derricking up speed.
Derricking up speed is set by the flow control valves at A3 and A4. The total resulting flow of ports B3 and B4 determines the derricking up speed. Try to keep the setting of B3 and B4 at an equal value by keep-ing the socket head screws equally tightened. When derricking up speed has to be reduced, tighten flow control valve A3. Do not tighten A4, because this will
affect derricking down speed as well. Time to derrick up completely at full throttle is 22 to 23 seconds.
Telescoping Speeds
Both telescoping retraction and extension speeds are restricted by the flow control valve at A2. This im-plies that a compromise must be found between both speeds. The time required to fully extend the tele-scoping cylinder is 28 to 30 seconds. The time re-quired to fully retract is 25 to 28 seconds.
Steering
HR45-25, HR45-27, HR45-31, AND HR40S
Description
The supply oil to the steering control unit comes from port P2 in the main control valve. Pressure of port P2 is controlled by the steering relief valve, which is set at 220 bar (3191 psi). See Figure 7.
The relief pressure of the steering control unit must be set a little higher to prevent an almost continuous flow over the relief. The 20 bar (290 psi) pressure difference is to absorb shocks caused by objects or bumps in the road.
Depending on the rotation of the steering wheel, the steering control unit pressurizes and relieves oil at the desired side of the steering cylinder.
Flow demand is monitored by the LS (Load Sense) line. When the steering wheel is turned, the in-creased flow demand will drop pressure in the LS line, which results into an increased supply by the main pump. A pressure drop in the LS line also ac-tuates the steering priority valves 1 and 2 at either side of the main valve, blocking off oil flow to other functions. See Figure 9.
When the engine is not running, a check valve in the line between P2 and the steering control unit closes and permits the steering control unit to operate as a hydraulic motor. The vehicle is difficult to steer without sufficient oil supply, but steering is possible.
Figure 9. Steering Schematic
Adjust
NOTE:Maximum supply pressure is set by the steer-ing relief valve on the main control valve.
1. Install a pressure gauge of 600 bar (8702 psi) at main pressure port M on the main control valve. 2. With the engine at full throttle and the steering cylinder at full stroke, adjust the relief valve P2 to obtain 220 bar (3191 psi).
1900 SRM 1107 Pilot System
HR45-36L, HR45-40LS, AND HR45-45LSX
Description
The supply oil to the steering amplifier comes from port P2 in the main control valve. Pressure of port P2 is controlled by the steering relief valve on the main control valve, which is set at 220 bar (3191 psi). See Figure 7.
Oil from the main control valve enters the flow am-plifier at port HP, where the priority valve either di-rects oil to the steering system or to the relief valve, which is set at 210 bar (3046 psi). Relieved oil drains to the tank via port HT.
The directional valve spool is moved by oil from the steering control unit. This allows oil flow to the am-plifier valve and to open connections between the steering cylinder and amplifier valve.
Oil from the steering control unit to the amplifier valve, opens the connection between port HP and the directional valve. A poppet valve prevents pump
pressure to enter the line of the steering control unit. The steering cylinder is now pressurized by oil from the main control valve until the amplifier valve is closed by oil pressure of the steering control unit. Flow demand is monitored by the LS (Load Sense) line. When the steering wheel is turned, the in-creased flow demand will drop pressure in the LS line, which results into increased supply by the main pump. A pressure drop in the LS line also actuates the steering priority valves 1 and 2 at either side of the main valve, blocking off oil flow to other func-tions.
The cushion and suction valves reduce pressure peaks in the steering cylinder and avoid cavitation when there is force on the steering wheels.
NOTE:Steering the lift truck manually can be diffi-cult.
When the engine is OFF, it is possible to steer the vehicle by rotating the steering wheel manually.
Pilot System
PILOT PUMP
The pilot pump is bolted on the service brake pump at the right rear side of the engine.
The pilot pump provides oil pressure to the following systems:
• Telescoping retract valve • Manipulator pressure valve • Joystick
• Optional sliding cab system
Telescoping Retract Control Valve
Pilot pump oil pressure is controlled by an 80 bar (1160 psi) relief valve, located close to the manipu-lator pressure valve. When the pressure from joy-stick port 2 has exceeded 7 bar (102 psi), the telescop-ing retract valve is opened. The telescoptelescop-ing retract valve is located near port F of the steering section of the main control valve. The opened retract valve causes pilot pump pressure to be transferred to the holding valve of the telescoping cylinder, which will be opened. Main pump oil flow causes the telescop-ing cylinder to retract. See Boom 4500 SRM 787.
Manipulator Pressure Valve
Description
The manipulator pressure valve reduces pilot pump pressure to maximum 26 bar (377 psi) and transfers oil to the joystick and to the throttle pedal.
Depending on the pressure in the LS line, solenoids E9, E10, and E11 are opened or closed. Each sole-noid resets to its own set pressure, as long as all pilot pump supply can escape through the 3 mm (0.12 in.) restriction behind the relief valve. The lowest pos-sible relief pressure at lowest pilot pump supply (at engine idle) is 13 bar (189 psi). At increasing engine speed, the 3 mm (0.12 in.) restriction will not be able to relieve all excess oil. Pressure will rise gradually until the 26 bar (377 psi) relief valve opens.
Pressure at the joystick pressure port is identical to the output pressure of the manipulator valve. If pres-sure at the joystick is at a lower level, 13 to 17 bar (189 to 247 psi), then the proportional control spool in the main valve can open only partially. The reduced control spool movement limits oil demand from the main pump.
Reducing the joystick pressure results in the follow-ing:
• Preventing engine stalls at low speed and high sys-tem pressure.
• Smoothing operation of the joystick at high system pressure.
Operation
When ordering a replacement LS pressure switch, the switch-on setting has to be adjusted. The red setscrew at the top allows setting the switch-on pres-sure to the required 170 or 210 bar (2466 of 3046 psi). By turning the red setscrew clockwise, switching oc-curs at higher pressures. By turning counterclock-wise, switching occurs at lower pressures. Deter-mine switch-on setting by connecting a voltmeter on solenoid E9 for 170 bar (2466 psi) pressure, and on solenoid E11 for 210 bar (3046 psi) pressure. Max-imum torque for the hydraulic connection fitting is 70 N•m (52 lbf ft).
1. PRESSURE SWITCH 170 bar (2466 psi) 2. LOAD SENSING PRESSURE SWITCH PLUG 3. PRESSURE SWITCH 210 bar (3046 psi)
Figure 10. Load Sensing Pressure Switches
The manipulator valve reduces joystick pressure, depending on the pressure in the load sense line. Pressure in the LS line is measured by the 170 bar (2466 psi) and 210 bar (3046 psi) LS pressure switches. Depending on the pressures measured, solenoids E9, E10, and E11 of the manipulator valve are opened or closed. When E10 and E11 are en-ergized, the related spools are opened. When E9 is energized, the related spool blocks oil flow. See Figure 10, Figure 11, and Table 2.
1. FROM 8CC PILOT PUMP 2. TO JOYSTICK
Figure 11. Manipulator Pressure Valve Schematic
1900 SRM 1107 Pilot System
Table 2. Pressures in Relation to the Position of Solenoids and Spools
Pressure at LS Line E9 Solenoid Spool E10 Solenoid Spool E11 Solenoid Spool Regulated Control Pressure Below 170 bar (2466 psi) De-energized Open De-energized Blocked De-energized Blocked 17 to 26 bar (247 to 377 psi) 170 to 210 bar (2466 to 3046 psi) Energized Blocked Energized Open De-energized Blocked 15 to 26 bar (218 to 377 psi) Above 210 bar (3046 psi) Energized Blocked De-energized Blocked Energized Open 13 to 26 bar (189 to 377 psi) Adjust
NOTE:On the hydraulic schematic, the pressure plug is connected with port U.
1. Attach a gauge of 60 bar (870 psi) at the pressure plug of the manipulator pressure valve. See Fig-ure 12.
1. SOLENOID (E9) 2. SOLENOID (E10) 3. SOLENOID (E11)
4. RELIEF VALVE 13 bar (189 psi) 5. RELIEF VALVE 15 bar (218 psi) 6. RELIEF VALVE 17 bar (247 psi) 7. RELIEF VALVE 26 bar (377 psi) 8. 3 mm (0.12 in.) RESTRICTION 9. 0.85 mm (0.033 in.) RESTRICTION 10. PRESSURE PLUG
Figure 12. Manipulator Pressure Valve
2. Adjust the 26 bar (377 psi) relief valve with the engine at full throttle and without operating the joystick.
3. Adjust the 17 bar (247 psi) relief valve at E9 with the engine at idle and the joystick at full stroke
4. Adjust the 15 bar (218 psi) relief valve at E10 with the engine at idle, solenoids E9 and E10, and the joystick at full stroke in the derricking up position.
5. Adjust the 13 bar (189 psi) relief valve at E11 with the engine at idle, solenoids E9 and E11 ac-tivated, and the joystick at full stroke in the der-ricking up position.
Engine Cooling System
A 28 cc variable displacement pump, which is fitted at the transmission, provides oil flow to the engine radiator fan motor. Oil flow provided depends on the speed of the engine and the momentary displacement of the pump, which depends on the pressure in the LS line. For functioning and description of the pump, see Main Hydraulic Pump.
The LS line of the pump is draining to the tank through a restriction and two thermostat valves. When there is no flow, the resulting high LS line pressure governs the pump to minimum supply. At minimum pump supply, the fan motor rotates at a slow speed ratio compared with engine speed. The thermostatic valves are located in the radiators for coolant and transmission oil. Thermostats begin opening when fluid temperature in the radiators has reached 87 C (189 F) and are completely open at 97 C (207 F). The LS line of the 28 cc cooling pump starts draining when any of the two thermostats be-gin to open. The resulting LS pressure drop causes pump displacement to increase, resulting in higher fan motor speed. In case of malfunction of the ther-mostat(s), it is possible to drain the LS line to the tank by opening the manual shutoff valve located at the coolant side of the radiator. When the manual valve is opened, the fan will rotate continuously.
Adjust (Standby Pressure)
1. Attach a 250 bar (3626 psi) pressure gauge at the pressure gauge fitting. See Figure 13.
2. Verify that the thermostats are closed, tempera-ture well below 87 C (189 F).
3. Run engine at idle speed.
4. Adjust the standby pressure of the pump be-tween 20 and 22 bar (290 and 319 psi), by turning the upper screw marked X. The cooling fan should rotate between 790 and 810 rpm. Adjust (Maximum Pump Pressure)
1. Open the manual shutoff valve. 2. Run the engine at full throttle.
3. Adjust pump pressure between 135 to 140 bar (1958 to 2031 psi), by turning the lower adjust-ment screw. The cooling fan should rotate
be-tween 2200 and 2250 rpm. 1. STANDBY PRESSURE ADJUSTMENT
2. MAXIMUM PUMP PRESSURE ADJUSTMENT 3. PRESSURE GAUGE FITTING
Figure 13. Cooling Pump
Hydraulic Cooling System
DESCRIPTION
NOTE: There are no adjustments for the hydraulic cooling system. In case of malfunction, individual components have to be checked or replaced.
The hydraulic cooling system also serves as the by-pass filtering system of the main hydraulic system. The hydraulic oil cooling pump, which is fitted at the LH front of the engine, provides a continuous oil flow from the tank, through the radiator and oil filter, and then back to the tank. See Figure 14.
The radiator is protected by a relief valve, which opens when fluid resistance exceeds 5 bar (73 psi). When the temperature of the radiator has reached 45 C (113 F), the temperature sensor switches ON solenoid E13, causing the oil cooler fan to turn. The temperature sensor switches OFF when tempera-ture has come down to 34 C (93 F). See Brake Oil Cooling System.
The oil filter clogging sensor is set slightly lower than the 3.5 bar (51 psi) of the filter relief pressure. After it is filtered, oil returns to the main tank.
1900 SRM 1107 Hydraulic Cooling System
1. COLD OIL BYPASS 2. BRAKE OIL COOLER 3. HYDRAULIC OIL COOLER 4. COLD OIL BYPASS
5. BRAKE COOLING SOLENOID
6. HYDRAULIC SYSTEM COOLING PUMP 7. BRAKE SYSTEM COOLING PUMP 8. MAIN HYDRAULIC TANK
9. BREATHER
10. BRAKE COOLING OIL TANK 11. HYDRAULIC SYSTEM FILTER 12. SERVICE BRAKE
13. BRAKE SYSTEM OIL FILTER 14. FAN MOTOR
15. TEMPERATURE SENSOR
Brake Oil Cooling System
DESCRIPTION
Cooling system for the brakes is separated from the rest of the hydraulic system and has a separate 30 liter (8 gal) oil tank at the RH side of the truck. The brake oil pump provides a continuous oil flow from the tank, through the radiators and the service brakes, and then back to the tank.
When oil is cold, brake cooling solenoid E13 bypasses oil flow past the fan motor. As a consequence, the fan motor will not turn. See Figure 15.
1. CHECK VALVE 2. MANIFOLD
3. SOLENOID VALVE 4. RELIEF VALVE
Figure 15. Oil Cooler Solenoid Valve
Solenoid E13 is controlled by the temperature sen-sors in the radiators for the brake system and in the radiator for the main hydraulic system. When ei-ther of these sensors has reached 45 C (113 F), so-lenoid E13 is activated, which forces brake cooling oil to pass through the fan motor. The temperature sensors switch OFF when temperature is at or below 34 C (93 F).
When solenoid E13 is activated during higher en-gine speeds, the inertia of the cooling motor and fan causes a pressure peak. This pressure peak is cush-ioned by the 100 bar (1450 psi) relief valve.
The radiators are protected by a relief valve, which opens when fluid resistance exceeds 10 bar (145 psi). Before entering the service brakes, oil is filtered. The filter clogging sensor is set slightly lower than the 3.5 bar (51 psi) of the filter relief pressure.
At each end of the drive axle, three hoses are fitted. The top hose is for cooling oil supply and the middle hose is for cooling oil return. The bottom hose con-nects with the service brake system. After having cooled the brakes, oil is driven back into the brake tank.
ADJUST
100 Bar Relief Valve
NOTE: Maximum pressure will occur directly after bypassing the temperature switch. Once the fan mo-tor and fan have reached speed, the pressure mea-sured will drop. To obtain proper circumstances for a next measurement, the bypass has to be discon-nected and the fan has to be stopped. Repeat the pressure check at least once, after the relief valve has been set to 100 bar (1450 psi).
1. Loosen the relief valve. See Figure 15.
2. Attach a 250 bar (3626 psi) pressure gauge at the brake cooling pump. See Figure 16.
3. Run the engine at full throttle.
4. Bypass one of the temperature switches at the radiators to activate solenoid E13.
5. Adjust the relief valve to 100 bar (1450 psi). 6. Remove the pressure gauge and bypass at the
1900 SRM 1107 Service Brakes
Figure 16. Oil Cooling Pumps
Legend for Figure 16
1. PRESSURE PLUG 2. BRAKE COOLING PUMP
3. HYDRAULIC SYSTEM COOLING PUMP
Service Brakes
DESCRIPTION
NOTE: For further information, see Service Brake 1800 SRM 1038.
The brake oil pump is fitted at the RH side of the en-gine and provides oil pressure to the brake control valve. When the brake pedal is applied, the brake pistons in the drive axle push against the friction discs for braking action. Releasing the pedal relieves pressure from the brake pistons. See Figure 17. The pressure regulator maintains pressure at 160 bar (2321 psi) for the brake pedal valve, park brake cylinder, and accumulator. Excess oil is re-turned to the tank.
The brake control valve has two pressure switches. The 105 bar (1523 psi) switch activates the brake warning light, when regulated brake pressure is be-low 105 bar (1523 psi). The 5 bar (73 psi) switch acti-vates the brake lights, when the brakes are applied. The accumulator has the capability to provide a lim-ited supply of oil when the brake pump has stopped. As oil pressure is being used up, the lights for park brake and low brake pressure will go ON, the APC 100 will switch the transmission into neutral, and the springs in the park brake caliper will overcome residual pressure and gradually apply the park brake.
1900 SRM 1107 Parking Brake
Legend for Figure 17
1. BRAKE PEDAL 2. ACCUMULATOR
3. BRAKE CONTROL VALVE
4. LOW BRAKE PRESSURE SWITCH 5. PRESSURE REGULATOR
6. FROM SERVICE BRAKE PUMP
7. PARKING BRAKE SWITCH 8. BRAKE COOLING LINE 9. SERVICE BRAKE
10. BRAKE LIGHT PRESSURE SWITCH 11. PARKING BRAKE SOLENOID
Parking Brake
DESCRIPTION
The parking brake system uses a disc brake that is installed at the rear of the differential. Spring force applies the disc brake. When applying oil pressure to the piston, spring pressure is overcome, which re-leases the parking brake.
Oil pressure from the brake control valve is admit-ted to the disc brake by energizing parking brake solenoid E227. When pressure has reached 105 bar (1523 psi), the two pressure switches will open. One is for the Park Brake Warning Light to go OFF and the second switch is for the APC 100 system to allow a gear to be selected. See Figure 18.
1. SOLENOID VALVE 2. MANIFOLD
3. PRESSURE SWITCH 4. PARKING BRAKE SWITCH 5. PLUG
