TANDEM OPERATIONS

4-33. Using graders in tandem expedites such operations as leveling, mixing, spreading, and haul-road maintenance.

PRODUCTION ESTIMATES

4-34. Use the following formula to prepare estimates of the total time (in hours or minutes) required to complete a grader operation.

Total time PD ---= × SE×

where—

P = number of passes required

D = distance traveled in each pass, in miles or feet

S = speed of grader, in mph or fpm (multiply mph by 88 to convert to fpm)

E = efficiency factor

• Number of passes. Estimate the number of passes (based on the project requirements) before construction begins.

• Distance traveled. Determine the required travel distance per pass before construction begins.

• Speed of the grader. Speed is the most difficult factor in the formula to estimate accurately. As work progresses, conditions may require

that speed estimates be increased or decreased. Compute the work output for each rate of speed used in an operation. The speed depends largely on the skill of the operator and the material type.

• Efficiency factor. For grader operations the efficiency factor is usually no better than 60 percent.

EXAMPLE

Time estimate based on the number of miles of construction.

Maintenance of a 5-mile gravel road requires cleaning the ditches and leveling and reshaping the road. Use a CAT 130G grader and a 0.6 efficiency factor.

Cleaning the ditches requires two passes in first gear, leveling the road requires two passes in second gear, and final shaping of the road requires three passes in fourth gear.

Speeds (from Table 4-2, page 4-13):

First gear = 2.3 mph Second gear = 3.7 mph Fourth gear = 9.7 mph

× × ×

Time estimate based on the number of feet of construction.

A 1,500-foot gravel road requires leveling and reshaping. Use a CAT 130G grader with a 0.6 efficiency factor. The work requires two passes in second gear and three passes in third gear.

Speeds (from Table 4-2):

Second gear = 3.7 mph Third gear = 5.9 mph

× ×

Total time 21,500--- 31,500

---+ 15.4 14.4 + 29.8 minutes

=

== ()0.688 3.7× × ()0.688 5.9× ×

SAFETY

4-35. Listed below are specific safety rules for grader o perators:

• Always display a red flag or a flashing light on a staff at least 6 feet above the left rear wheel when operating a grader slowly on a highway

or roadway.

• Never allow other personnel to ride on the blade or rear of the grader.

• Always engage the clutch gently, especially when going uphill or pulling out of a ditch.

• Always reduce speed before making a turn or applying the brakes.

• Always keep the grader in low gear when going down steep slopes.

• Always take extra care when working on hillsides to drive slowly and

to be observant of holes or ditches.

• Never use graders to pull stumps or other heavy loads.

• Always keep the blade angled well under the machine whe n it is not in use.

• Never allow more than one person on a grader while it is in operation.

If it has a buddy seat, ensure that no more than two people are on the machine while it is in operation.

Loaders

Loaders are used extensively in construction operations to handle and transport material, to load haul units, to excavate, and to charge aggregate bins at both asphalt and concrete plants. The loader is a versatile piece of equipmen t designed to excavate at or above wheel or track level. The hydraulic-activated lifting system exerts maximum breakout force with an upward motion of the bucket. Large rubber tires on wheel models provide good traction and low ground-bearing pressure. A wheel loader can attain high speeds, which permits it to travel from one job site to another under its own power.

DESCRIP TION

5-1. Military loaders are diesel-driven, rubber-tired machines (Figure 5-1, page 5-2). They are available in varied sizes and capacities. A power-shift transmission with a torque converter gives the loaders fast-movement

capability in both forward and reverse, with a minimum of shock. This lets the machines maintain a high production rate. The hydraulic system gives the operator positive control of mounted attachments and assists with steering.

Most loaders have pintles or towing hooks for towing small trailers or light loads.

ATTACHMENTS

5-2. The most common loader attachments are a shovel-type bucket or a forklift (Figure 5-2, page 5-3). The loader’s hydraulic sys tem provides the power necessary for operating these attachments. Hooks (designed for lifting and moving sling loads) and snowplows are other available attachments.

BUCKET

5-3. Buckets may be general-purpose (one-piece, conventional) or multipurpose (two-piece, hinged-jaw) (Figure 5-2). The bucket attaches to the tractor unit by

lift arms. Buckets are made of heavy-duty, all-welded steel and vary in size from 2.5 to 5 cubic yards. The bucket teeth are bolted or welded onto replaceable cutting edges. Bolt-on, replaceable teeth are prov ided for excavation of medium-t ype materials. The multipurpose bucket provides the capability to use the loader as a dozer and to grab material.

FORKLIFT

5-4. A forklift can be attache d to the tractor unit in place of a bucket. Designed for material handling, the fork attachment is made of steel with two movable tines.

Cab (ROPS)

Multipurpose bucket

Figure 5-1. Wheel Loader

Multipurpose bucket

General-purpose bucket

Forklift

Figure 5-2. Loader Attachments

USE

5-5. Typical uses for a loader are loading trucks; stockpiling materials; digging basements or gun emplacements; backfilling ditches; lifting and moving construction materials; and, when equipped with rock-type-tread tires, operating in and around rock quarries. They may also be used for many miscellaneous construction tasks. These include stripping overburden, charging hoppers and skips, lifting and moving forms for concrete work, moving large concrete and steel pipes, assisting with plant erection and maintenance, and towing small trailers and light loads.

SELECTION

5-6. Two critical factors to consider in selecting a loader are the type and volume of material being handled. Loaders are excellent machines for excavating soft to medium-hard material. Loader production rates decrease rapidly when excavatin g medium to h ard mate rial. Another factor to consider is how high the material must be raised. To be of value in lo ading trucks, the loader must be able to dump over the side of the truck’s dump bed. A loader attains its highest production rate when working on a flat, smooth surface with enough space to maneuver. In poor underfoot conditions or when there is a lack of space to operate efficiently, other equipment may be more effective.

OPERATION