657 TRACTOR-SCRAPER Operating Techniques Caterpillar

Loading

1. Reduce travel speed and downshift when approaching cut. Move ejector to the rear. Push cushion-hitch lever to LOCKDOWN.

2. Open apron approximately 15 inches (1/2 m). Lower bowl to desired depth of cut. Shift transmission to 1st or 2nd speed.

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. Close apron and raise bowl to finish cut.

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. Push cushion-hitch lever to LOCKDOWN. Keep moving while pusher tractor is making contact. Keep tractor-scraper in line with pusher for efficient push loading.

2. Cut deep as possible without stalling tractor-scraper and pusher.

3. Start raising bowl as soon as it is full.

4. Allow pusher to help machine out of cut area in poor underfoot conditions.

Push-Pull Loading

1. Position first machine in cut to allow room for second machine to line up at rear of scraper. Move hitch control to LOCKDOWN-BAIL UP.

2. Start loading front scraper while rear machine is maneuvering into position. Make sure machines are in line.

3. Move rear machine hitch control to LOCKDOWN-BAIL UP and approach front machine.

4. Contact front scraper push-block gently. Move rear machine hitch control to LOCKDOWN-BAIL DOWN when contact is made.

5. Load front scraper first. Regulate speed of rear machine so it will work as a pusher unit.

6. Raise bowl of front scraper as soon as loaded. Lower rear scraper bowl to loading depth.

7. Load rear scraper. Regulate engine speed of front machine so it will work as a pulling unit.

8. Raise rear scraper bowl as soon as loaded. Move bail control to UP position.

9. Ease rear machine ahead to disengage hook. Bail will automatically raise clear of hook.

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

Hauling

1. Move hitch control to CUSHION RIDE. Carry bowl just high enough to clear obstructions.

2. Travel at highest speed practical on level ground. Accelerate both engines equally.

3. Downshift on upgrade before engine speed drops below normal operating range.

4. Reduce travel speed and downshift when approaching downgrade.

5. Use retarders, if so equipped, and service brakes to control travel speed on downgrade.

6. Use low enough gear speed to keep engine speed below 2200 RPM on downgrade.

7. Engage differential lock in poor footing to apply equal power to each tractor wheel. It may be necessary to reduce speed to permit lock to engage, if one wheel is spinning.

Show/hide table

Disengage Differential Lock before turning. Turning with lock engaged can be hazardous.

8. Apply individual tractor wheel brakes to maneuver out of soft spots. Lever forward applies right wheel brake and transfers full power to left wheel. Lever back applies left brake and powers right wheel.

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. Move hitch control to LOCKDOWN.

2. Open apron at start of dump area. Raise and lower apron to loosen sticky material before moving ejector.

3. Move ejector forward after material has fallen from back of apron.

4. Close apron as soon as bowl is empty.

5. Raise bowl gradually to leave fill area smooth. Return ejector to rear.

Return to Cut

1. Move hitch control to CUSHION RIDE. Carry bowl just high enough to clear obstructions.

2. Upshift to travel speed as soon as practical.

3. Keep engine speed under 2200 RPM on downgrade.

4. Use retarders if so equipped, and proper gear speed to control travel speed.