Komatsu 830E Shop Manual page 366

30. Depress the brake pedal very slowly until the
brake differential pressure switch activates the
low brake pressure lamp and buzzer.
Verify fault indicators are activated at:
Refer to Table I Pressures.
· Record Pressure on data sheet.
Table 1. - Differential Pressure Switch Adjustment
Pressure - Switch Contacts Closing
Spring Color
"B1" Valve Spool
Red 250 ± 30 psi
(1 724 ± 207 kPa)
Green 600 ± 50 psi
(4 137 ± 345 kPa)
! WARNING ! DO NOT attempt to adjust a "red"
spring to the higher "green" spring pressures.
This will cause the spring to "bottom out" and
the warning switch will not function properly.
For more specific details regarding Table I,
refer to previous chapter: BRAKE CIRCUIT
COMPONENT SERVICE, BRAKE VALVE, "Dif-
ferential Pressure Switch Adjustment".
· Record on data sheet.
31. Turn key switch off and bleed down both brake
accumulators by opening the manual bleed
down valves on the brake manifold.
32. Outside the brake cabinet, reconnect the hose
that connects the front brake accumulator (port
AF1)to the brake pedal in the cab. Disconnect
the hose that supplies oil from the rear brake
accumulator to the brake pedal in the cab for
the rear brakes (port AR1) and plug the tube
end at the cabinet. Be sure to leave end of hose
vented to atmosphere.
33. Slowly depress brake pedal. Differential switch
must actuate the low brake pressure buzzer
and lamp at 375 ± 50 psi (2586 ± 345 kPa) front
brake pressure. Adjust if necessary.
· Record on data sheet.
J4-6
"B2" Valve Spool
375 ± 50 psi
(2 585 ± 345 kPa)
1000 ± 75 psi
(6 895 ± 517 kPa)
Brake Circuit Check-Out Procedure
34. Turn key switch off and bleed down both brake
accumulators by opening the manual bleed
down valves on the brake manifold.
35. Outside the brake cabinet, reconnect the hose
that supplies oil from the rear brake accumula-
tor to the brake pedal in the cab.
36. Install a jumper wire between circuits #33 and
#33W at the brake warning timer. Install another
jumper wire between circuits #33W and #33T
on the brake warning relay. Both circuits are in
the brake cabinet.
37. Start engine and build accumulator pressures.
NOTE: With engine running, and service and brake
lock released, the low brake pressure warning
system should be activated.
38. Slowly depress the service brake pedal until the
low brake pressure warnings are deactivated.
39. Slowly release pedal, the low brake pressure
warning should activate when the rear brake
pressure reaches 1000 ± 25 psi (6895 ± 172
kPa). (Checks brake lock degradation pressure
switch.)
40. Remove jumper between circuits #33W and #33.
41. Disconnect one end of the jumper between #33T
and #33W.
NOTE: With engine running, there should be no
warnings.
42. Reattach jumper between #33T and #33W. The
low brake pressure warning should actuate
approximately 1.0 second after reconnecting
jumper. (Checks delay of timer).
· Record on data sheet.
43. Remove all jumper wires, and gauges. This con-
cludes the brake check out.
J04031