Differential Pressure Switch Adjustment - Komatsu 930E-2 Shop Manual

Differential Pressure Switch Adjustment

10. Attach an ohmmeter or continuity tester lead to
connector on differential pressure switch wire.
Attach other lead to valve body. Verify switch
contact is open.
11. Remove plug on bottom of valve body for access
to adjustment screw plug (29, Figure 3-11).
12. Open the "B1" regulated output circuit needle
valve (11) to bleed the pressure back to tank.
Adjust pilot pressure regulator for 0 psi (0 kPa) on
gauge (7).
13. Slowly adjust regulator valve to obtain 300 psi
(2,068 kPa) on the "B2" circuit pressure gauge
(9).
a. If switch contact has not closed, turn differential
pressure switch adjustment screw (29) coun-
terclockwise until switch contact just closes.
b. If switch contact closed before reaching 300 psi
(2,068 kPa), turn screw plug counterclockwise
and repeat previous step.
14. Reduce pilot pressure until switch opens.
15. Slowly increase pilot pressure and verify switch
contact closes at 300 ±30 psi (2,068 ±207 kPa).
J03019 1/99
16. Reduce pilot pressure. Close "B1" needle valve
(11) and open "B2" circuit needle valve (12).
17. Slowly increase pilot pressure and verify switch
contacts close at 300 ±30 psi (2,068 ±207 kPa)
as read on "B1" circuit gauge (10).
18. If necessary, adjust screw plug (29) and repeat
steps 12 through 17.
19. Install plug in switch adjustment port. Tighten to
90 - 100 in. lbs. (10.2 - 11.3 N.m) torque.
20. Shut down the test bench and relieve all hydraulic
pressure from the lines.
Be certain all hydraulic pressure has been re-
leased prior to disconnecting hoses and valve.
Hydraulic fluid escaping under pressure can have
sufficient force to enter a person's body by pene-
trating the skin and cause serious injury and pos-
sibly death if proper medical treatment by a
physician familiar with this injury is not received
immediately.
21. Remove hoses from valve and remove valve from
test stand.
Brake Circuit Component Service J3-21