Model 4700 Maintenance Manual
Section 8. Theory of Operation
Systems Overview
Systems Overview This section is an overview of the components that make up the control systems of the truck. See “Pinout Matrix” beginning on page 8-14 for specific input, output, and voltage information.
Vehicle Manager The Vehicle Manager (VM) provides several functions. It interfaces with the travel direction switches and travel potentiometer. The VM stores the learned values for the travel and lift potentiometers. It also stores the learned values for the lift and travel potentiometers as well as default configuration values. With the standard spool valve hydraulic controls, lift/lower, sideshift, tilt, 4th, and 5th auxiliary function switch/potentiometer requests are input directly to the VM. The VM distributes 24V power to the operational and working lights on the truck. It also contains the circuits that activate the brake and tail lights based on inputs from the TPA. Refer to “Hydraulic System” on page 8-8 for specific information on the operation of standard and optional hydraulic systems.
Traction Power Amplifier Dual Traction Motor Trucks The Traction Power Amplifier (TPA) is a Dual AC Motor Controller. The TPA contains two separate controllers within a single unit with outputs for two separate AC motors. The controllers are designated as Master and Slave. The Master controls the right traction motor and the Slave controls the left traction motor. The Master and Slave communicate with each other internally as well as externally with other devices connected to the CAN-Bus. Requests for travel direction and speed are communicated from the VM via the CAN-Bus. The TPA generates an RPM request to the traction motors to comply with the travel request. It then monitors motor operation and adjusts the command voltage to the motors to maintain motor performance equal to the request. The TPA receives an input from the steer potentiometer and regulates traction motor
Publication 1160093, Issued: 20 May 2013
System Architecture direction and speed with regard to steer wheel angle. It stores the learned value for the steer potentiometer. Motor parameters such as acceleration, speed limiting, motor braking, motor current, and creep speed can be configured with FlashWare and are stored in the TPA. The TPA also stores the learned values for the steer potentiometer. The Master and Slave are capable of generating error codes. See “Codes” on page 6-4. Single Traction Motor Trucks The Traction Power Amplifier (TPA) is an AC Motor Controller. Requests for travel direction and speed are communicated from the VM via the CAN-Bus. The TPA generates a command voltage to the traction motor to comply with the travel request. It then monitors motor operation and adjusts the RPM request to the motor to maintain motor performance equal to the request. Motor parameters such as acceleration, speed limiting, motor braking, motor current, and creep speed can be configured with FlashWare and are stored in the TPA. The TPA is capable of generating error codes. See “Codes” on page 6-4.
Pump Power Amplifier The Pump Power Amplifier (PPA) is an AC motor controller that controls the motor used to provide hydraulic power for all hydraulic functions. The PPA communicates with other devices via the CAN-Bus. Requests for all hydraulic functions (including steering) are communicated to the PPA via the CAN-Bus from the VM or from the Armrest Board (fingertip control configurations). The PPA then generates an RPM request to the pump motor. Pump motor operating parameters may be different for the various hydraulic functions. Parameters such as delay, maximum speed, and maximum motor current can be configured with FlashWare and are stored in the PPA. The PPA is capable of generating error codes. See “Codes” on page 6-4.
Amplifier Fan The truck is equipped with a cooling fan for the TPA and PPA. This fan should energize within
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