Control Piston Group - Komatsu 930E-2 Shop Manual

DISASSEMBLY
When disassembling or assembling pump, choose
a work area where no traces of dust, sand or other
abrasive particles which could damage the unit are
in the air. Do not work near welding, sand-blasting,
grinding benches and the like. Place all parts on a
CLEAN surface. To clean parts which have been
disassembled, it is important CLEAN solvents are
used. All tools and gauges should be clean prior
to working with these units and new, CLEAN and
threadless rags used to handle and dry parts.
1. Drain off excess hydraulic oil from pump inlet and
discharge ports. It may be necessary to loosen the
four valve plate capscrews (8, Figure 6-15) pull
back on valve plate to allow fluid to seep out of the
case.
2. Thoroughly clean and dry the outside surface of
the pump housing.
NOTE: Depending upon what part or parts are to be
inspected, it may not be necessary to completely
disassemble all components.

Control Piston Group

3. Remove the two large plugs (24, Figure 6-13) with
O-rings (25) from both sides of pump.
4. Control piston (11, Figure 6-14) must be in the
"neutral" position. Control link pin (16) should be
centered in the plug opening.
5. Using appropriate snap ring pliers, remove retain-
ing rings (14) from both sides of the pin and
remove control link washers (15).
6. For handling purposes, insert a 1/4-20 UNC cap-
screw into the threaded end of the control link pin
(16).
7. Using a brass rod and hammer, tap on end oppo-
site the capscrew to remove control link pin.
L6-14
Stroke adjuster assembly (items 12, 13, 14, 15 and
16, Figure 6-13) MUST be removed BEFORE further
disassembly of control piston.
8. Without disturbing jam nut (16), unscrew gland
(15) and remove stroke adjuster as a complete
assembly.
9. Back out capscrews (1, Figure 6-15), then remove
cap (4).
10. Remove bias control spring (1, Figure 6-14).
Valve Plate Group
NOTE: Valve plate (11, Figure 6-15) is a slight press
fit in the pump housing.
11. Support valve plate (11) from an overhead hoist
(lifting lug holes are provided) and remove four
capscrews (8) from valve plate.
12. Remove valve plate from pump housing by tapping
away from the housing with a mallet until valve
plate pilot diameter disengages from the case 0.25
in (6.35 mm).
13. With the weight of the valve plate still suspended
from the overhead hoist, slide valve plate back
until it disengages from driveshaft and set valve
plate aside. Care must be taken not to damage the
"wear face" of the valve plate.
14. To further disassemble control piston assembly,
move control piston (11, Figure 6-14) into sleeve
(4) until control piston maximum stop pin (8) con-
tacts the sleeve. Use a large mallet to drive piston
and sleeve assembly outward from the valve
plate.
15. When all sleeve seals (5, 6, & 7, Figure 6-14) are
clear of the valve plate, re-extend control piston.
While tipping the assembly enough to clear the
hole, pull the assembly from the valve plate.
16. Remove pin (18) from control piston by pressing
or tapping it out through the hole on opposite side.
Control stop pin (8) can be removed and control
piston (11) slipped out of sleeve (4).
17. Remove capscrews (12, Figure 6-16) and remove
compensator block (10).
18. Remove capscrews (7, Figure 6-15) and cover
plate (9).
Steering Circuit Component Repair L06021