621 TRACTOR-SCRAPER Every 2000 Service Hours Or 1 Year Caterpillar

(27)Steering Gear Sector Housing And Shaft Lower Bearing

1. Remove fill plug. Maintain oil level to plug opening. Clean and install plug.

2. Remove plug. Lubricate with 2 or 3 squirts of oil. Clean and install plug.

(28)Steering Column Shaft Upper Bearing

Lubricate 1 fitting.

(29)Transmission Control Lever

Lubricate 1 fitting.

(30)Seat Suspension

Lubricate 3 fittings.

(31)Tractor Brake Camshaft Bearings

Lubricate 1 fitting by each wheel. Total of 2 fittings.

(32)Scraper Brake Camshaft Inner and Outer Bearings

Lubricate 2 fittings by each wheel 2 strokes. Total of 4 fittings.

(33)Scraper Wheel Bearings

1. Park tractor-scraper on level ground. Stop engine. Raise and securely block rear of scraper.

2. Remove wheel.

3. Remove axle and wash parts in clean solvent.

4. Inspect all parts for wear.

5. Repack bearings and install axle and wheel.

6. Fasten a rope to wheel at least one full wrap around outside circumference of tire. Attach spring scale to free end of rope.

7. Tighten nut while turning wheel. Wheel bearings are properly adjusted when a pull of 6 to 12 lbs. (2,7 to 5,4 kg) on scale is required to turn wheel through one revolution. Slightly less pounds (kg) pull is required if worn seals are used.

8. Adjust brakes. See item 18.

9. Repeat procedure for opposite wheel.

10. Remove blocks and lower scraper.

If Equipped With Grease Fitting

1. Remove lower plug.

2. Apply lubricant through fitting until a steady flow of grease appears at the lower plug opening.

3. Install lower plug.

4. Lubricate the bearings for the other wheel in the same manner.

(34)Ejector Carrier Rollers

1. Raise ejector and block to remove weight from carrier roller.

2. Remove cover.

3. Remove cotter pin, nut and washer.

4. Remove carrier roller. Wash shaft and carrier parts in clean solvent. Inspect parts for wear.

5. Apply grease to inner bearing. Install carrier roller and fill with grease.

6. Install outer bearing, washer and nut.

7. Tighten nut until roller locks. Back off 1/6 turn. (Roller must turn freely by hand.)

8. Install cotter pin, pack in grease and install cover.

9. Remove jack and blocking.

10. Repeat procedure for other carrier roller.

11. See item 42 for roller adjustment.

(35)Ejector Guide Rollers

1. Remove cover.

2. Flatten lock. Remove nut, lock and washer.

3. Loosen and remove clamp bolt.

4. Drive shaft down.

5. Remove guide roller. Wash shaft and roller parts in clean solvent. Inspect for wear.

6. Apply grease to lower bearing. Install guide roller and drive shaft up. Tighten adjusting bolt.

7. Fill guide roller with grease. Install upper bearing, washer, lock and nut.

8. Install clamp bolt.

9. Tighten nut until roller locks. Back nut off 1/6 turn. (Roller must turn freely by hand.)

10. Crimp lock so nut will not turn.

11. Pack in grease and install cover.

12. See item 42 for roller adjustment. Tighten clamp bolt.

13. Repeat procedure for other guide roller.

(36)Hydraulic System

1. Lower bowl and apron and retract ejector. Stop the engine. Move all scraper controls to relieve pressure.

2. Remove filler cap slowly to relieve pressure.

3. Remove hydraulic tank drain plug.

4. Open drain valve and drain oil.

5. Change filter elements. See item 19.

6. Close drain valve.

7. Clean and install drain plug.

8. Remove snap ring and filler strainer. Wash strainer in clean solvent. Install strainer.

9. Fill hydraulic tank to bottom of filler strainer. (See Refill Capacities.)

10. Check oil level with engine stopped and oil cool. Maintain oil level between ADD and FULL marks in sight gauge or above LOW mark on dipstick.

11. Check filler cap gasket. Use new gasket if necessary. Install and tighten cap.

(37)Differential And Final Drives

1. Position final drive drain plugs down.

2. Remove final drive drain plug.

3. Remove differential drain plug.

4. Clean and install drain plugs.

5. Remove final drive fill plugs.

6. Fill final drives to level of fill plug opening. Clean and install fill plugs.

7. Remove differential fill cap. Fill differential to FULL mark on plunger gauge. (See Refill Capacities.)

8. Clean and install fill cap.

9. Wash breather. (See item 25.)

10. Start engine and operate tractor-scraper on level ground a few minutes.

11. Check oil level. Oil should be to FULL mark on plunger gauge. Add oil if necessary.

(38)Diesel Engine Valve Lash

Valve Numbering Guide

1. Check and adjust valves with engine stopped. Do not use starting motor to rotate flywheel.

2. Remove camshaft covers.

3. Remove timing bolt and inspection cover.

4. Turn flywheel or crankshaft in the direction of normal engine rotation until left bank timing mark becomes visible.

5. Remove dowels from storage holes from both banks.

6. Install dowels in timing holes one in each bank.

7. Continue to turn the crankshaft slowly until dowels drop into matching holes in the camshafts as the timing mark becomes aligned. If both don't drop see your AVSpare dealer.

8. Timing mark "TC1-7" on the flywheel will be directly beneath "TC1-7" timing hole in flywheel housing. Install timing bolt.

9. The valves for No. 1 cylinder are closed at this point.

10. Adjust lash for No. 1, No. 4, No. 5 and No. 8 exhaust valves.

11. Turn adjusting screw clockwise to obtain zero lash. There should be no free rocker movement or adjusting screw button lateral movement.

Show/hide table

NOTICE
The adjusting screw button can still be rotated by finger pressure even when it is in contact with valve stem and clearance is zero. Turning the adjusting screw clockwise beyond this point will force the valve off its seat, and final lash setting will be incorrect.

12. Turn adjusting screw counterclockwise specified number of clicks on detent (see page 25).

13. Adjust lash for No. 1, No. 3, No. 6 and No. 8 inlet valves.

14. Remove timing bolt.

15. Remove dowels from timing holes and insert in storage holes.

16. Turn flywheel 360° and align flywheel timing mark "TC1-7" with the timing pointer.

17. Install timing bolt in flywheel.

NOTE: The camshaft will rotate only 180° during 360° crankshaft rotation. The camshaft timing mark should not be visible at this time.

18. The valves for No. 7 cylinder are closed at this point.

19. Adjust lash for No. 2, No. 3, No. 6 and No. 7 exhaust valves.

20. Adjust lash for No. 2, No. 4, No. 5 and No. 7 inlet valves.

21. Remove bolt from flywheel.

22. Install inspection cover and timing bolt.

23. Install camshaft covers.