STRAP AS- 4692534 - Caterpillar

Illustration 8 g01876933
Close up view of the steering valve solenoidsThe basic components of the differential steering system include the following items: a planetary and brake unit, a steering differential and brake unit, a hydraulic steering pump, a hydraulic steering motor, and the steering controls. The units transfer power from the bevel gear to the final drives in varying proportions. The input is based on the operator input from the steering control lever. Input from the steering control lever signals the steering pump to send oil to the steering motor. The steering motor acts on the steering differential and brake unit in order to vary the power to each final drive. The solenoid valves for the left steering pump and the right steering pump are outputs of the machine ECM. The machine ECM uses these solenoid valves to steer the machine. The solenoids control the direction and the amount of the pump oil displacement. Each solenoid has a connector with two contacts.One contact receives a signal from the corresponding J1-67 or J1-68 connector contact of the ECM. The other contact of each solenoid is connected to the return circuit of the solenoid at J1-54.Note: The solenoid coils are not designed for the operation of 24 VDC directly. The machine ECM sends a 24 V PWM signal at a duty cycle which provides the necessary current to the solenoid coils. Do not activate the coils with 24 VDC (+battery). This activation will cause the life of the coils to be reduced drastically. Use 12 VDC if the coils must be activated without the ECM.The solenoids are the proportional type. The ECM uses a pulse width modulated signal (PWM) in order to vary the current to the solenoid. The distance of travel of the plunger is proportional to the electrical current that is sent by the ECM. The position of the plunger controls the amount and direction of the pump displacement. A decrease in electrical current to any one solenoid causes a decrease in pump displacement in that direction.The operator selects the amount of pump displacement by pulling or pushing the direction/speed control lever. As the direction/speed control lever is pulled toward the operator, the solenoid for the right steer is activated during right forward turns and left reverse turns. Similarly, as the direction/speed control lever is pushed away from the operator, the solenoid for the left steer is activated during left forward turns and right reverse turns.Starter Motor Relay
Illustration 9 g01693254
Starter motor relayThe starter motor relay is controlled by the ECM through an on/off output driver.When the ECM receives a start input from the key start switch, the ECM will turn on the on/off output driver in order to activate the starter motor relay provided the following machine conditions are present:
The parking brake is engaged.
The transmission is in NEUTRAL.
The operator is in the seat.When the ECM activates the starter motor relay, system power is directed to the starter motor through the relay contacts.Transmission Speed Clutch Solenoids
Illustration 10 g01876905
Transmission speed and direction clutch solenoids
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