SENDER AS 2109442 - Caterpillar

Illustration 1 g06050776
Left Side of Machine
(1) Front-wheel assist manifold
(2) Front-wheel bypass solenoid
(3) Front-wheel assist solenoidOn machines with the front-wheel assist system, front-wheel assist manifold (1) is on the left side of the machine. This manifold is near the left tow point cylinder. The left side door provides more access to this component.Front-wheel assist manifold (1) controls the operation of the front-wheel assist motors. The propel pumps provide the supply oil for the front-wheel assist system via the propel motors.Front-wheel assist solenoid (3) is on the rear face of front-wheel assist manifold (1). This solenoid controls the flow of supply oil from the propel motors to the front-wheel assist motors. When this solenoid is energized, supply oil causes the front-wheel assist motors to rotate. When this solenoid is de-energized, supply oil is blocked and the front-wheel assist motors freewheel.Front-wheel bypass solenoid (2) is on the left face of front-wheel assist manifold (1). This solenoid works with front-wheel assist solenoid (3) to activate or de-activate the front-wheel assist system. This solenoid controls the operation of the bypass valves. The bypass valves provide a return path from the propel motors to the propel pump. When the bypass solenoid is energized, the bypass valves are closed and return oil from the propel motors is directed through the front-wheel assist motors.The machine electronic control system coordinates the activation of the clutch valve with the operations of front-wheel assist manifold (1). When front-wheel assist operations are commenced, the front-wheel assist motors are enabled immediately and the clutch valve is energized after a delay of 5 seconds. When front-wheel assist operations are completed, the clutch is disengaged immediately and the front-wheel assist motors are disabled after a delay of 3 seconds.Note: When the propel lever is moved to the REVERSE range, the machine electronic control system immediately disables the front-wheel assist motors and clutch valve.Front-wheel assist manifold (1) contains two differential pressure valves, one for each front-wheel assist motor. These valves maintain the differential pressure across the front-wheel assist motors at 20000 2000 kPa (2900 290 psi). This differential pressure helps to maintain constant torque of the motors.Check valves are installed in parallel with each differential pressure valve. These check valves allow the front wheel motors to free-wheel in the forward direction.