General Information
Outputs pulse hydraulic pump power transistors, the shunt field; and they control the pump contactor coil. The power transistors pulse to control the speed of the hydraulic pump motor. To provide full speed, the logics activates the pump contactor, stops pulsing the power transistors and turns OFF the pump shunt field. A failure protection circuit is also included to protect against malfunctions of the power circuit.
When the term M80D is used, it refers to the M80D family of lift trucks (M70D, M80D, M100D and M120D). The MicroCommand panel is the control center of the M80D family of lift trucks. The Logic Unit (logics) is the decision making part of the MicroCommand Control System (MCS). The logics provide a selfcontained Battery Discharge Indicator (BDI) with lift interrupt and built-in diagnostics capability. The battery charge state and built-in diagnostics are monitored by the logics and displayed by the Central Vehicle Monitoring System (CVMS) located on the steer console.
The speed and direction of the drive motor is controlled by voltage inputs to and outputs from the logics. Inputs to the logics are generated by the accelerator control and direction switch. Outputs from the logics control contactor coils, drive transistor pulsing and drive shunt field. The drive circuit pulses transistors to provide travel speed control up to 90% of full speed, after which the bypass contactor closes and the drive shunt field turns OFF to provide full speed. The drive circuit includes a failure protection circuit that detects malfunctions of the drive power circuit, a regenerative braking and plugging circuit to provide electrical braking, and a current limit circuit to prevent excessively high currents during transistor pulsing.
NOTICE The motors and control panels are either 36/48 or 72/80 volt units and must be operated at their designed voltages. The voltages cannot be changed without changing motors and control panel. Damage to all motors and control panels will result.
The M80D truck also has a bypass dropout feature. With this feature the bypass contactor will deactivate when the drive motor draws over 1100 amps on 36/48V trucks and 800 amps on 72/80V trucks for more than two seconds.
Four jumpers located on the MicroCommand logic card are used to select the appropriate battery voltage: J1 = 36V
J2 = 48V
J3 = 72V
J4 = 80V Thermal protection circuits are used on the hydraulic pump motor, the drive motor and the control panel to prevent permanent damage caused by overheating.
If the wrong voltage is selected, the lift system may not operate, and travel speed will be slowed. The LED display will not monitor the battery correctly, and deep battery discharge may occur. If the truck battery voltage is changed, the appropriate jumper must also be moved to select the correct voltage. In addition, the BDI potentiometer on the logic board (P5) must be readjusted. The MCS provides operation of the drive motor and hydraulic pump motor systems on this family of lift trucks. The steering system is activated when the truck is powered up and the line contactor closes. The truck uses a combined power steering/hydraulic system where the hydraulic fluid for steering is provided by a (compound/series) hydraulic motor, pump, and priority valve. The speed of the hydraulic motor is controlled by voltage inputs to and outputs from the logics. Inputs are generated by a pressure switch (steering), a valve control card (lift, tilt, auxiliary). MicroCommand Control System
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Systems Operation
