BRAKE CIRCUIT COMPONENT SERVICE
BRAKE VALVE
The brake pedal assembly combines the dynamic
retarding control with service brake control functions.
As the pedal is depressed, the first portion of pedal
travel actuates an internal potentiometer which pro-
vides an electrical signal to the propulsion system,
signalling a request by the operator for retarding. The
electrical signal is modulated by the operator as he
continues to depress the pedal, increasing the level of
retarding effort from minimum to maximum. Further
pedal depression after maximum retarding request is
achieved, results in service brake application from
minimum to maximum when the pedal is fully de-
pressed. A slight increase in pedal resistance can be
felt when service brake actuation occurs. Additionally,
indicator lights on the overhead display panel in the
cab will turn on as dynamic retarding is applied. A
second lamp will turn on when service brakes are
applied.
NOTE: The following information discusses the opera-
tion, test and repair of the hydraulic brake valve as-
sembly only. Refer to Section “E” for information
concerning the retarding control portion of the pedal.
The Brake Valve is a pressure modulating valve, actu-
ated mechanically (brake pedal) or hydraulically
through the automatic apply valve (8, Figure 3-1).
The Brake Valve controls the pressure delivered to the
front and rear service brake dual relay valves which
provide the apply pressure for the front wheel and rear
wheel disc brake assemblies. Apply pressure can be
modulated from zero to maximum braking effort by use
of the foot pedal.
Rebuild Criteria
If any one of the following conditions exist, the brake
valve should be removed and repaired:
•
Excessive cam rock in pedal actuator.
•
Any sign of external leakage.
•
Internal leakage at the tank port must be less
than 100 cc/minute with the valve in the re-
leased position and system pressure supplied
to the “P1” and “P2” inlet ports.
•
Tank port leakage must be less than 250
cc/minute with valve pilot or manual applied at
2750 psi (18,960 kPa) system pressure.
•
Failure of the pedal to return to full release po-
sition.
•
Valve holds pressure when in the neutral posi-
tion.
•
Varying output pressure with pedal fully de-
pressed.
FIGURE 3-1. BRAKE ACCUMULATOR BLEED DOWN
1. Rear Brake Accumulator
2. Charging Valve
3. Front Brake Accumulator
4. Charging Valve
5. Brake Manifold
6. Accumulator Bleed Down Valve (Front)
7. Accumulator Bleed Down Valve (Rear)
8. Automatic Apply Valve
J03019 1/99
Brake Circuit Component Service
J3-1
Summary of Contents for 930E-2
Page 1: ......
Page 2: ......
Page 4: ...NOTES ...
Page 8: ...KOMATSU MODEL 930E Dump Truck A 4 Introduction A00017 03 01 ...
Page 10: ...NOTES A1 2 Index A01001 2 94 ...
Page 12: ...930E MAJOR COMPONENTS A2 2 Major Component Description A02055 ...
Page 35: ...START HERE Walk Around Inspection A03017 General Safety and Operating Instructions A3 21 ...
Page 46: ...NOTES A3 32 General Safety and Operating Instructions A03017 ...
Page 78: ...NOTES B1 2 Index B01016 ...
Page 88: ...NOTES B3 6 Dump Body B03013 03 01 ...
Page 92: ...NOTES B4 4 Fuel Tank B04015 ...
Page 94: ...NOTES C1 2 Index C01021 03 01 ...
Page 118: ...NOTES C5 6 Air Filtration System C05013 5 98 ...
Page 126: ...NOTES D2 6 24VDC Electric Supply System D02018 ...
Page 142: ...NOTES D3 16 24VDC System Components D03019 04 01 ...
Page 146: ...FIGURE 2 1 PROPULSION SYSTEM DIAGRAM E2 2 Electrical Propulsion System Components E02014 3 01 ...
Page 196: ...NOTES E2 52 Electrical Propulsion System Components E02014 3 01 ...
Page 240: ...NOTES E3 44 AC Drive System Electrical Checkout Procedure 3 01 E03015 Release 17 Software ...
Page 242: ...NOTES G1 2 Index G01017 ...
Page 250: ...NOTES G2 8 Tires and Rims G02015 ...
Page 274: ...NOTES H1 2 Index H01013 04 01 ...
Page 282: ...NOTES H2 8 Front Suspensions H02013 2 01 ...
Page 288: ...NOTES H3 6 Rear Suspensions H03013 ...
Page 334: ...NOTES J3 32 Brake Circuit Component Service J03019 1 99 ...
Page 378: ...NOTES L2 8 Hydraulic System L02028 ...
Page 401: ...FIGURE 4 5 FLOW AMPLIFIER VALVE L04031 Steering Circuit L4 7 ...
Page 403: ...FIGURE 4 6 FLOW AMPLIFIER NO STEER L04031 Steering Circuit L4 9 ...
Page 405: ...FIGURE 4 7 FLOW AMPLIFIER LEFT STEER L04031 Steering Circuit L4 11 ...
Page 407: ...FIGURE 4 8 FLOW AMPLIFIER RIGHT STEER L04031 Steering Circuit L4 13 ...
Page 409: ...FIGURE 4 9 FLOW AMPLIFIER NO STEER EXTERNAL SHOCK LOAD L04031 Steering Circuit L4 15 ...
Page 414: ...NOTES L4 20 Steering Circuit L04031 ...
Page 422: ...NOTES L5 8 Steering Control Unit L05021 ...
Page 429: ...L06021 Steering Circuit Component Repair L6 7 ...
Page 450: ...NOTES L6 28 Steering Circuit Component Repair L06021 ...
Page 466: ...NOTES L7 16 Hoist Circuit L07023 ...
Page 492: ...NOTES L9 6 Hydraulic System Filters L09008 ...
Page 504: ...NOTES L10 12 Hydraulic Check out Procedure L10012 ...
Page 508: ...NOTES M1 2 Index M01034 03 01 ...
Page 518: ...NOTES M2 3 10 Ansul Checkfire Electric Detection and Actuation System M02003 ...
Page 524: ...NOTES M5 4 Wiggins Quick Fill Fuel System M05002 10 96 ...
Page 532: ...NOTES M8 8 Special Tools M08012 9 99 ...
Page 560: ...NOTES M9 28 Air Conditioning System M09010 6 97 for HFC 134a Refrigerant ...
Page 618: ...M20 20 Payload Meter II M20007 10 00 ...
Page 619: ...M20007 10 00 Payload Meter II M20 21 ...
Page 627: ...M20007 10 00 Payload Meter II M20 29 ...
Page 634: ...NOTES N1 2 Index N01020 03 01 ...
Page 654: ...NOTES N3 6 Cab Components N03011 7 98 ...
Page 660: ...NOTES N4 6 Operator Comfort N04020 ...
Page 686: ...NOTES N5 26 Operator Cab Controls N05044 ...
Page 688: ...NOTES P1 2 Index P01024 ...
Page 691: ...P02034 Lubrication and Service P2 3 ...
Page 722: ......
Page 723: ......
Page 724: ......
Page 725: ......
Page 726: ......
Page 727: ......
Page 728: ......
Page 729: ......
Page 730: ......
Page 731: ......
Page 732: ......
Page 733: ......
Page 734: ......
Page 735: ......
Page 736: ......
Page 737: ...NOTES R1 2 930E Schematics R01048 with Cummins QSK60 Series Engine ...
Page 738: ......
Page 739: ......