657 TRACTOR-SCRAPER Operating Techniques Caterpillar

Operating Techniques
1.1. Loading
2.1. Push Loading
3.1. Push-Pull Loading
4.1. Hauling
5.1. Dumping and Spreading


1. Reduce travel speed to 2nd, push hitch control to LOCKDOWN and check to see if ejector is to rear of bowl.

2. Open apron approximately 15 inches (1/2 m) and lower bowl to desired depth when entering cut.

3. Regulate apron opening to keep material from piling in front of lip or falling out of bowl.

4. Decrease depth of cut if engines lug below operating range. When finishing cut, close apron then raise bowl.

Raise and lower bowl rapidly to pump in loose material. When finishing in loose material, raise bowl slightly, close apron partially, then raise bowl.

Push Loading

1. Keep moving while pusher is making contact. Keep tractor-scraper in line with pusher. Cut deep as possible without stalling machines.

2. Raise bowl as soon as it is full. Allow pusher to help machine out of cut area. Maintain smooth cut area when practical.

Push-Pull Loading

1. Position first machine in cut to allow room for second machine to line up in the rear. Start loading front machine.

2. With bail raised, bring rear machine's push block in contact with front machine's push block. Keep machines in line.

Hitch control must be in LOCKDOWN.

3. Lower bail of rear machine while loading front machine. Regulate speed of rear machine to work as a pusher unit.

4. Raise bowl of front machine as soon as loaded. Lower rear scraper bowl to loading depth. Regulate speed of front machine to work as pulling unit.

5. Pull bail control up while loading rear machine. Hook on front unit will keep bail from raising.

6. When rear machine is loaded, ease ahead to disengage hook. Bail will automatically raise clear of hook.

Operate machines in normal independent manner through haul, dump and return cycles.


Pull hitch lever to engage CUSHION RIDE. Do not engage CUSHION RIDE on side slopes or in sharp turns.

Carry bowl as low as possible and still clear obstructions. Accelerate tractor and scraper engines equally to highest practical travel speed.

When shifting back and forth between two highest gears, use the lower gear unless cycle time can be reduced in higher gear.

Reduce travel speed and downshift when approaching downgrade. Use retarder and service brakes as necessary to control speed. Keep engine RPM below 2100 and retarder temperature below 275°F (135°C).

In poor footing conditions engage differential lock. Reduce speed to permit lock to engage if one wheel is spinning.

To maneuver out of soft spots apply tractor individual wheel brakes. Do not apply brakes when differential lock is engaged.


Watch for and obey flagmen in traveled areas.

Dumping and Spreading

1. Dump and spread material at highest practical travel speed, considering fill and traffic conditions. Approach fill in line with dump area. Lower bowl to desired spread height.

For better control of spreading, push hitch lever to LOCKDOWN.

2. Pull apron lever at start of dump area. Push and pull apron lever to loosen sticky material before moving ejector.

3. Pull ejector control lever after material has fallen from back of apron.

4. Push apron lever when bowl is empty. Pull bowl lever and raise bowl slowly to leave fill area smooth.

5. Push control lever to return ejector to rear. Pull hitch lever for CUSHION RIDE (if not engaged) for return to cut.