MOUNT AS-SENSOR 3311991 - Caterpillar

Illustration 1 g01405806
Travel brake valve (1) Crossover relief valve (2) Spring (3) Valve (4) Passage (5) Valve (6) Passage (7) Passage (8) Passage (9) Spool (10) Valve (11) Passage (12) Spring (13) Crossover relief valve (14) Cover (15) Spring (16) Passage (17) Check valve (18) Passage (19) Passage (20) Port (21) Passage (22) Passage (23) Port (24) Passage (25) Passage (26) Check valve (27) Passage (28) Spring (29) Valve (30) Spring chamber (31) Passage (32) Counterbalance valve (33) Check valve (34) Check valve (36) Passage (37) SpoolThe travel counterbalance valve consists of counterbalance valve (32), crossover relief valve (1) and crossover relief valve (13). The travel counterbalance valve is bolted to the travel motor. The travel counterbalance valve has the following four functions.
The travel counterbalance valve prevents a shock load when travel is stopped.
The travel counterbalance valve prevents overspeed while the machine is travelling down a slope.
The travel counterbalance valve prevents cavitation.
The travel counterbalance valve routes a portion of the oil to the travel parking brake in order to release the brake.Counterbalance Valve Operation During Level Travel
Illustration 2 g01536856
Left travel motor and travel brake valve (1) Crossover relief valve for forward travel (13) Crossover relief valve for reverse travel (20) Port (23) Port (32) Counterbalance valve (35) Left travel motorCounterbalance valve (32) consists of valve (3), valve (29), check valve (17), check valve (26), spring (15) and spring (28). All of these components are located in spool (9). During forward travel on level ground, pump oil is supplied to port (23). The oil flows from port (23) through passage (24) to check valve (33). The pressure oil forces check valve (25) to open and the check valve allows the oil to flow through passage (25) to motor (35) in order to drive the motor.A portion of the oil delivery from the left pump in port (23) flows through passage (24) and passage (27). The oil proceeds to flow into spring chamber (30). The oil in spring chamber (30) pushes on the right end of spool (9). Spool (9) is now moved to the left against the force of spring (15) in order to open passage (6). As spool (9) shifts to the left, return oil from the travel motor flows through passage (18), passage (4), passage (6), passage (19) and port (20) to the hydraulic tank.When the oil flow from port (23) is blocked, the pressure in spring chamber (30) decreases. The force of spring (15) shifts spool (9) to the right. Passage (6) closes. Return oil from the travel motor is blocked and the rotation of the travel motor stops.When the direction of travel is reversed, pump oil flows to spool (9) through port (20). Spool (9) shifts to the left. The return oil flows through port (23). During reverse travel, the travel counterbalance valve operates in the same manner as the forward travel operation.Counterbalance Valve Operation During Slope Travel
When the machine travels down a slope, the travel motors rotate at a higher speed. The higher speed is due