Model 5200 High-Level Orderpicker
Section 8. Theory of Operation Travel
Travel
turn the traction motor in the correct direction. c. Simultaneously an analog voltage, that represents and is proportional to the throttle command, is output from the Steer/Tractor Manager and sent to the traction power amplifier. This voltage (TRAVEL REQ) ranges from 0 to about +4.25VDC depending on throttle input WRT TRAVEL REF. Based on this, the TPA controls the strength of the field and armature to obtain the correct travel speed in the appropriate amount of time. The higher the voltage, the faster the TPA makes the lift truck travel.
General When the potentiometer voltage increases or decreases from the neutral deadband, the Steer/Tractor Manager sends a travel request for direction (TF/FORWARD or FF/REVERSE) and speed (TRAVEL REQ) to the traction power amplifier. The voltage from the Steer/Tractor Manager is directly related to the speed request. As the input request changes, the travel request voltage to the traction power amplifier mirrors the change. See “Modes of Operation” on page 5-24. When a change in direction is requested, the Steer/Tractor Manager changes the direction request to the traction power amplifier and changes the speed request output (TRAVEL REQ) to reflect the requested plugging strength.
Moving Directional/Speed Control NOTE: The current flowing through the traction motor armature and field windings are controlled independently of each other by the traction power amplifier. 1. When the throttle is moved to the forward position (tractor-first), the wiper in the variable resistor (VR-1) is moved so that the voltage output decreases. The Carriage Manager, sensing this decrease in voltage, sends a communication message over the transmit line to the Tractor Manager. The Tractor Manager interprets this as a request for travel in the forward direction and causes the following steps to occur: a. The TF/FORWARD line to the traction power amplifier is activated (driven to about 19VDC). This is the input to the traction power amplifier that determines the traction motor field polarity to enable travel in the forward direction.
NOTE: Travel speed is limited until the operator initializes steering and the Steer/Tractor Manager detects the request. 2. The TRAVEL REQ voltage is used by the traction power amplifier to drive the armature and field transistors to meet the throttle request. The armature transistor is, in effect, connecting terminal M- to B(in varying amounts) allowing current to flow through the traction motor armature. The traction power amplifier also drives its internal field transistors that, in turn, controls the amount and direction of flow through the traction motor field winding. When a plug is requested, the Steer/Tractor Manager changes the direction request to the traction power amplifier and changes the speed request output (TRAVEL REQ) to reflect the requested plugging strength. Current now flows from B+ through: • FU3 • Traction motor armature • M• B- (TP4) • To battery negative 3. During operation, the traction power amplifier monitors for:
b. The traction power amplifier then drives its internal field control transistors to
Publication Number: 1043922B, Revised: 2 Sept 2015
• Armature current* • Field current* • M- shorted to B-*
8-5
