MOUNTING GP-TURBOCHARGER 2389941 - Caterpillar

Forward Travel at Overspeed
Illustration 2 g03635976
Hydraulic schematic of the travel motor (Overspeed) (1) Travel motor (2) Displacement change valve (3) Cutoff valve (4) Port "X" - from speed shift solenoid (5) Crossover relief valve (6) Counterbalance spool (7) Shuttle valve (8) Travel brake valve (9) From main control valve (10) To main control valve (11) Makeup valve (12) Crossover relief valve (13) Actuator pistonTravel brake valve (8) blocks the return oil from the motor to the tank in the condition of overspeeding. By measuring the RPM in the transmission, the speed shift solenoid will reduce the pressure that is supplied to displacement change valve (2). This action allows displacement change valve (2) to move upward. A decrease of the oil pressure in the forward side of the travel motor will cause cutoff valve (3) to shift upward. The shift opens the head end of actuator piston (13) to the hydraulic tank. Oil is allowed to flow into the rod end of actuator piston (13). Oil flows to the rod end of actuator piston (13). Actuator piston (13) moves downward in order to upstroke the motor toward the maximum angle. Machine speed is reduced.The pressure in the return passage opens crossover relief valves (5) and (12). Makeup oil flows to the supply passage for lower pressure.Once overspeeding is reduced, the speed shift solenoid will increase the pressure that is supplied to displacement change valve (2). This action will allow oil to flow to the head end of actuator piston (13). Actuator piston (13) moves upward in order to destroke the motor toward the minimum angle. Machine speed is increased. This function is a continuous electronic process.Forward Travel at Creeper Speed
Illustration 3 g03636057
Hydraulic schematic of the travel motor (Creeper speed) (1) Travel motor (2) Displacement change valve (3) Cutoff valve (4) Port "X" - from speed shift solenoid (5) Crossover relief valve (6) Counterbalance spool (7) Shuttle valve (8) Travel brake valve (9) From main control valve (10) To main control valve (11) Makeup valve (12) Crossover relief valve (13) Actuator pistonIn Illustration 3, the pilot oil pressure from the speed shift solenoid through port "X" (4) is cut off. Displacement change valve (2) shifts upward in order to fully upstroke the motor. The pressure in the travel system is directed by displacement change valve (2) to the rod end of actuator piston (13). Actuator piston (13) moves fully downward to the maximum angle. Machine speed is reduced.Travel speed is now determined by the amount of pump flow from the travel valves through ports "B" (8) or "A" (9) .Travel on Level Surface
When the travel pedal is pushed forward, oil enters travel motor (1) through port "A" (9). Oil from speed shift solenoid through port "X" (4) flows to displacement change valve (2) and shifts downward. The oil shifts shuttle valve (7) in order to allow high-pressure oil to flow to cutoff valve (3) for travel motor (1) and to the head end of actuator piston (13). When the oil pressure