BRACKET 5291936 - Caterpillar

Hydraulic Schematic (Reverse at High Speed with Traction Control)
Illustration 3 g01197726
When the machine is traveling in reverse, the top envelope of the pressure control pilot valve is active. The position of the pressure control pilot valve is determined by the duty cycle of the signal that is sent from the propel ECM. The propel ECM analyzes the input signals in order to determine the magnitude of the output signal that is sent to the pressure control pilot valve.Charge oil flows through the orifice and to the EDC metering spool. Charge oil is then metered across the EDC metering spool to the reverse servo piston. The charge oil causes the reverse servo piston to shift. This shift changes the angle of the swashplate in the pump, and the pump generates flow in the reverse circuit.While the machine is traveling in reverse, the reverse multifunction valve limits system pressure. Oil from the forward circuit flows through the flushing relief valve. The makeup valve in the forward multifunction valve allows charge oil to flow into the forward circuit.When the shift switch is in the HIGH SPEED position, the front motor shift solenoid is energized. When the front motor shift solenoid is energized, reduced pressure oil from the auxiliary pump flows into the high side of the servo piston chamber. The pressure of this oil is 4820 kPa (700 psi). Oil from the low pressure side of the propel loop is directed into the low side of the servo piston chamber. The pressure differential between the two sides of the servo piston causes the swashplate in the motor to move to the minimum angle. In this case, the motor operates in the high speed range.The traction control system for the front propel system engages an electric solenoid. This solenoid engages a flow divider. Normal operating conditions allow differential wheel rotation and tire slippage based on underfoot conditions. Under normal operating conditions oil flows through the flow divider shuttle spools and around the flow divider valve. When the front flow divider solenoid is energized, the solenoid causes charge pressure oil to pass to the pilot circuit of the flow divider shuttle spools. The flow divider spools move out. In this case, an equal volume of oil is sent to the left propel motor and to the right propel motor, regardless of the pressure demand of the individual front wheels.Hydraulic Schematic (Forward with Traction Control)
Illustration 4 g01197732
Machines equipped with optional rear wheel assist have a rear propel hydraulic circuit. The rear propel hydraulic circuit consists of a closed loop hydrostatic drive circuit with one pump, two motors and a freewheel manifold with open loop electrical control. The rear propel pump and control solenoid EDC are identical to the front propel pump and control solenoid EDC. When the engine is running, the rear propel and rear charge pumps rotate along with the front propel, front charge, and auxiliary pumps. The machine ECM controls the front propel system and the rear propel system in parallel. Forward, reverse, and