PS S5.0 5000
001 OE35
Version noT-code
F-code Section C-code
Electrical System with TX and TT Card
138
Service Manual 1997-10-23
4.2. Current Limit
This circuit monitors motor current by utilizing a sensor in
series with the armature. The information detected across the
sensor is fed back to the card so current may be limited to a
pre-set value. If heavy load currents are detected, this circuit
overrides the oscillator and limits the average current to a
value set by function 4 of the handset. The C/L setting is
based on the maximum thermal rating of 1REC and the peak
voltage on the capacitor. Because of the flyback current
through 3REC, the motor current usually runs 2 to 3 times
battery current. See current limit curves for available current
and adjustment range.
4.3. Plugging
Slow down is accomplished when reversing by providing a
small amount of retarding torque for deceleration. If the
vehicle is moving and the directional lever is moved from one
direction to the other, the motor field is reversed. The plug
signal is initiated by the fact that the directional switch has
moved from one direction to the other. The motor armature,
driven by the inertia of the vehicle, acts as generator. This
generated current passes through 4REC and the sensor. The
oscillator circuit regulates at a plug current limit level as set by
the handset. This controls the pulse rate of 1REC to regulate
the generated motor current and bring the truck to a smooth
stop and reversal. With the accelerator potentiometer is at
minimum resistance, function 5 will enable adjustment of
plugging current from max to min current level for plug current
limit.
4.4. Pedal Position Plug
This feature will allow for plugging distance based on pedal
position. Pedal position will reduce the plugging current to the
current value set by this function as the accelerator is
returned to the creep speed position. Maximum plug current
is obtained with the accelerator in the top speed position. This
feature is adjustable by using function 16 on the handset.
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