Fig. WH 111
On control piston 4th section of left valve bank.
Make reference to WARNING on first page of the TESTING AND ADJUSTING Section.
Reason for Fitting
The 4th section of each valve bank is fitted with a reinforced spring assembly (compound piston). The advantage of improved handling of the machine that this provides is offset by the forfeiture of the sensitivity of the optional hydraulic function. By fitting spring 5W4204 or 5W4205 - with the dimensions d = 7.5 mm; D = 47.4 mm; 1 = 86.1 mm; if = 5 effective turns - the original sensitivity is restored.
Thus, only exchange springs in the 4th section of the left valve bank.
Installation is necessary when:
Equipment such as swing ditching buckets, laterally displaceable hydraulic equipment etc. is attached. In the case of a hydraulic rotatable grab, fitting is not normally necessary. In especially rugged service, however, failure can occur; here fitting is advisable. Contact the local AVSpare dealer for more information when necessary.
NOTE: Absolute cleanliness and care are essential.
Removing the springs:
1. Remove 2 allenhead screws (1) on cover (2).
2. Remove spring assembly with piston from valve bank.
3. Loosen allenhead screw (3). If necessary heat to 250 to 300°C. (Hold at other end of piston).
4. Remove shim (4), spring plate (5) and springs (6) and (7).
Installing Spring 5W4204 or 5W4205:
1. Remove grease from thread M 10 in pin (9) and allenhead screw (3).
2. Place 5W4204 or 5W4205 Spring on spring plate (8) [instead of springs (6) and (7)] and on this, spring plate (5). Only one spring now.
3. Place shim (4) in spring plate (5).
4. Replace allenhead screws (3) with Loctite No. 582 (observing Loctite instructions). Tighten to 48.1 N·m. Hold at other end of piston.
5. Push piston with spring back into valve bank and close with cover (2) and allenhead screw (1).