TRACK GP 3969704 - Caterpillar

Illustration 2 g00572997
(4) Travel line relief valve (5) Check valve (6) Check valveThe two travel counterbalance valves (1) are located below the swing gear in the center compartment of the carbody. There is one travel counterbalance valve for the right travel circuit and one travel counterbalance valve for the left travel circuit.The travel counterbalance valves provide passages for circuit pressure that is entering the travel motors and for return oil that is returning to the tank. Each passage has a travel line relief valve which regulates the maximum pressure which can develop in the circuits.The travel counterbalance valves perform the following functions during operation:
The travel counterbalance valves stop shock loads when the travel motors are stopped.
The travel counterbalance valves function as overspeed valves in order to keep the travel motors from overspeeding by applying a partial hydraulic lock on the travel motors.
The travel counterbalance valves help to prevent cavitation in the travel motors.
Line relief valve functionOperation of the Travel Counterbalance Valve
Level Travel
Illustration 3 g00574480
Travel Counterbalance Valve During Travel (1) Travel counterbalance valve (3) Travel line relief valve (4) Travel line relief valve (5) Check valve (6) Check valve (7) Travel motors (8) Throttling slots (9) Chamber (10) Passage (11) Passage (12) Line from the travel motors (13) Passage (14) Throttling slots (15) Line to the travel motors (16) Line to the swivel (17) Outer spring (18) Inner spring (19) Line to the swivel (20) Inner spring (21) Outer spring (22) Sleeve (23) Spool (24) Passage (25) Chamber (26) Spool (27) Sleeve (28) Implement piston pumps (29) Travel, bottom dump and crossover control valveTravel counterbalance valve (1) consists of sleeve (22), sleeve (27), check valve (6), check valve (5), travel line relief valve (4), spool (23), spool (26) and travel line relief valve (3) .When the travel control levers actuate forward travel, the travel control spool in the travel, bottom dump and crossover control valve allows pump oil to enter the travel counterbalance valve through line (19). Oil at circuit pressure flows into the right end of the travel counterbalance valve (1). The pressurized oil and spring force hold spool (26) to the left. The oil flows into the upper chamber and forces check valve (5) open. When check valve (5) is open, oil flows through line (15) to the travel motors.A portion of the pump oil enters line (19) and flows through passage (24) into chamber (25). The pressurized oil in chamber (25) now pushes on spool (23) in sleeve (22). Spool (23) moves left against the force of outer spring (21) and inner spring (20). The movement of spool (23) to the left opens throttling slots (8). The motor return oil goes through passage (12), throttling slots (8), and out through line (16) to the travel spools and to the hydraulic tank.When oil pressure in passage (24) decreases, outer spring (21) and inner spring (20) forces spool (23) right. Moving spool (23) to the right closes throttling slots (8). Return oil flow from the motor is now restricted and