FITTING AS 1952037 - Caterpillar

The ProAct? control system functions by receiving a position command signal from a Woodward electronic governor. The system then sends a pulse width modulated current (-12 A to +12 A) signal to the actuator, modified by signals from a position feedback, velocity, and current sensor from the actuator (Figure 4-1).
Figure 4-1. ProAct II Functional Block DiagramElectronic Circuits
All circuits in the ProAct driver are solid state and are not serviceable in the field. The printed circuit board is manufactured by Woodward to provide maximum tolerance to temperature and vibration.Four potentiometers, accessible when the cover of the driver box is removed, provide all adjustments to the driver system.A 25-turn pot (Position Command Gain) adjusts how far the actuator travels when the speed control signal varies from minimum to maximum.A 25-turn pot (Position Command Offset) adjusts the offset of the actuator travel when the speed control signal varies from minimum to maximum.A 25-turn pot (System Position Feedback Gain) adjusts the system position feedback gain as the actuator varies from minimum to maximum.A 25-turn pot (System Position Feedback Offset) adjusts the system position feedback offset as the actuator varies from minimum to maximum.Actuator Position Signal
The feedback device is located on the closed shaft of the actuator. The device is a rotary transducer which changes resistance proportional to the location of the shaft. The device is a non-contacting unit, thereby eliminating most wear problems.Actuator
The rotary design of the ProAct actuators gives 75 degrees of shaft rotation to position fuel controls. The actuators apply torque in both directions. Torque is proportional to the current supplied to the actuator by the driver. The actuator uses sealed bearings, eliminating the need for maintenance. The feedback mechanism attaches to the end of the rotor not being used to control the engine. The device is enclosed in a Ryton housing and is sealed against the elements. Avoid pressure washing the actuator.An inertia disc is installed on the actuator output shaft. The disc is necessary for stable actuator operation with light, low-friction linkages. Do not remove the disc (see Figure 1-3).