Service
3 - 8
Brake Valve Pressure Check and Adjustment
All except installations with 2 speed control
Test Equipment:
•
(2) 1,000 psi (6,895 kPa) Gauges
Connect pressure gauges to test ports:
• X1
• TP-BRAKE
(or
TP-BR)
Instructions
1. With the engine shut off, connect a 1000 psi pressure
gauge to the
TP-BRAKE (or TP-BR)
pressure test
port and one 1000 psi pressure gauge to the
X1
pressure test port on the control manifold.
2. Start dozer and set to high-free idle.
3. Slowly meter the control lever into the
LINE-IN
position while monitoring both gauges.
4. TP-BRAKE
pressure will jump to full pilot supply
pressure when
X1
reaches the pilot setting of the
brake valve.
5. Check pressure as indicated in Table 3-4. The brake
valve sets the overlap between the hydraulic motor
drive and brake release.
6. A low setting on the brake release valve will release
the brake before the motor begins driving. A high
setting on the brake release valve will momentarily
drive the motor against the brake before the brake
releases.
Table 3-4 Hydraulic Pressure Readings
1000 PSI
Gauge at
TP-BRAKE
1000 PSI
Gauge at
X1
Dozer
Pressure in
PSI [kPa]
X1
BRAKE RELEASE
PRESSURE
TP-BRAKE
PILOT
PRESSURE
Komatsu
D275AX-5 (K65)
130 - 150
[896 - 1,034]
500 - 570
[3,447 - 3,930]
Komatsu
D85-15 (K50)
534 - 618
[3,682 - 4,261]
Liebherr
PR754 (L54)
290 - 350
[1,999 - 2,413]
Liebherr
PR756 (L56)
290 - 350
[1,999 - 2,413]
Liebherr
RL56 (L561)
335 - 365
[2,310 - 2,517]
CAT
D8T Tier 4 (C74)
400 - 450
[2,758 - 3,103]
John Deere
JD1050K (E75)
620 - 680
[4,275 - 4,688]
Brake Valve Adjustment
1. Slowly meter the control lever into the
LINE-IN
position.
2. Measure pressure at
TP-BRAKE
and
XI
pressure
test ports.
3. Loosen brake valve locknut. Turn adjusting capscrew
OUT to decrease pressure and IN to increase
pressure. Adjust pressures as shown in Table 3-4.
NOTICE
The values in Table 3-4 are based on
information available at time of publishing.
Refer to the service/maintenance manual
supplied with your dozer to verify the
available pilot pressure.
Figure 3-8 Test Equipment Setup
Summary of Contents for H12E
Page 8: ...vi Notes ...
Page 48: ...General 1 40 Notes ...
Page 54: ...Section 1 1 46 Figure 1 35 H12E Hydraulic Electrical Schematic Option Code B CAT D8T C74 ...
Page 55: ...Section 1 1 47 Figure 1 36 H12E Hydraulic Electrical Schematic Option Code D CAT D8T C74 ...
Page 59: ...Section 1 1 51 Figure 1 40 H12E Hydraulic Electrical Schematic Option Code D CAT D8R C59 ...
Page 63: ...Troubleshooting 2 4 Notes ...
Page 75: ...Service 3 12 Notes ...
Page 90: ...Section 4 4 15 Intentionally Blank ...
Page 102: ...Section 4 4 27 Intentionally Blank ...
Page 108: ...Section 4 4 33 Intentionally Blank ...
Page 116: ...Section 4 4 41 Intentionally Blank ...
Page 119: ...Repairs 4 44 Notes ...
Page 120: ......