Upright TL33 - General Information

5-4
TL33 Work Platform
Troubleshooting
Section
5.2
5.2 GENERAL INFORMATION
The TL33/49 use a single DC Motor Control Unit to control the speed of the hydraulic pump electric drive motor.
The SP 37 uses two Motor Control Units. One for the hydraulic pump electric drive motor and one for the two (2) electric
traction drive motors.
The DC motor control units powers the electric motors at a speed that depends on (1) the signal from the lower or upper
controls and (2) the pre-programmed software inside the MCU. Many names are in use for these DC motor controllers,
the most common is MOS90. To separate the two we tend to call them TRACTION MOS90 (MCU1) and PUMP MOS90
(MCU2).
The name MOS90 relates to the technology behind this system of providing variable, multi-directional, control of a DC
motor. The basic principle of this system is to deal with a high current (resulting in a high temperature) in a compact and
energy efficient manner. The main component in a MOS90 is a MOSFET transistor (micro osmosis field effect
transistor). The MOSFET can deal with very high currents, quickly rid itself of high temperatures and in a very efficient
way (95%). All this despite its small physical size.
The SP37 control circuit operates at 48 Volts whilst the TL33/49 operate at 24V. Both circuits are limited to 7A by the
control fuse. The components used are relays, diodes, selector/limit switches, motor contactors, the joystick, horn and tilt
sensor.
Between the components we generally use 0.75 sq.mm (AWG 20) cable and P.C.B’s (Printed Circuit Boards). The
P.C.B. connectors are of the MOLEX type.
Terminology
The reference points used on the schematics e.g. JP1 (Junction Point #1) and Pin 1 (connection pin #1) have the
following meanings:
• JP is a cable harness connector, e.g. between P.C.B. and multi-connector
• PIN is the pin number of the P.C.B. or on the MOS90.
The software of the MOS90 is related to the various functions as follows:
• e.g. Speed 5 is the #5 internal speed setting of the Pump MOS90.
• e.g. Switch 5 (sw5) is the logical switch in the software enabling Speed 5