Initial System Set-Up; Brake Cabinet Port Identification - Komatsu 930E-2 Shop Manual

INITIAL SYSTEM SET-UP

Prior to checking the brake system, the hydraulic
steering system must be operating properly, have
correct accumulator precharge and be up to normal
operating temperatures. Refer to Section L, "Hydraulic
System", for steering system operation troubleshoot-
ing procedures and specifications.
Be certain brakes have been properly bled to remove
trapped air. Refer to "Wet Disc Brake Bleeding Proce-
dure" in this Section. Also, prior to checking the brake
system, make certain the parking brake is functioning
properly. Refer to parking brake this section.
1. Apply the parking brake, put selector switch in
NEUTRAL, place the Rest switch in the ON posi-
tion, turn the key switch OFF to shut down the
engine, and allow approximately 90 seconds for
the steering accumulators to bleed down. Confirm
the steering pressure is released by turning the
steering wheel - no movement should occur.
Block the truck wheels.
NOTE: Leave Rest switch in the ON position and the
GF Cutout Switch in the CUTOUT position throughout
brake tests. (See Figure 3-1, page E3-2, Propulsion
System, for GF switch location.)
2. Open each brake accumulator bleeddown valve
and precharge both brake manifold accumulators
(1 & 3, Figure 4-1) to 1400 psi (9,652 kPa). Move
the charging kit to the frame mounted accumula-
tors (behind right front tire) and precharge both
accumulators to 1400 psi (9,652 kPa). Allow gas
temperature to approach ambient temperature
before completing precharge process.
* Record on data sheet.
NOTE: For best performance, charge accumulators in
the ambient conditions in which the machine will be
operating.
3. Close both accumulator bleeddown valves.
4. Install pressure gauges at:
a) Front brake test port "B2" (in brake cabinet) -
3000 psi (20,685 kPa) gauge.
b) Rear brake test port "B1" (in brake cabinet) -
3000 psi (20,685 kPa) gauge.
c) Park brake release pressure "PK2" (9, Figure
4-1). (in brake cabinet) - 3000 psi (20,685 kPa)
gauge.
d) Low accumulator pressure test port "LAP1"
(front side of brake manifold) - 5000 psi (34,475
kPa) gauge.
J4-4
FIGURE 4-3. BRAKE CABINET PORT
(Viewed from Bottom of Cabinet)
1. AR1: Rear Brake Oil Supply to Brake Valve
2. AA: Automatic Apply Oil Supply to Brake
Valve
3. AF1: Front Brake Oil Supply to Brake Valve
4. PK1: Oil Supply to Park Brake
5. T1: Oil Return to Hydraulic Tank
6. SP1: Brake System Oil Supply from
Bleeddown Manifold and filter
7. To "B1" Port on Brake Valve
5. Set park brake. Release brake lock.
6. Start engine. Observe rising brake pressures as
system charges.
Brakes should release at approximately 1650 psi
(11,375 kPa) both front and rear.
7. Actuate brake lock. Turn parking brake switch
OFF. Rear brake pressure should not exceed
2000 ±100 psi (13,788 ±690 kPa).
Release brake lock.
* Record on data sheet.
8. Slowly depress brake pedal and note brake valve
pressures. If the rear brake circuit exceeds 2400
psi (16,545 kPa) at the "B1" test port or front brake
circuit exceeds 2400 psi (16,545 kPa) at the "B2"
test port, correct the problem before proceeding.
This brake valve may require adjustment or a dual
relay valve may be malfunctioning.
Refer to repair procedures, this section.
* Record on data sheet.
Brake Circuit Checkout
IDENTIFICATION
J04025