Curtis PMC 1297 Manual
A-2
APPENDIX A: GLOSSARY
Bidirectional throttle
A bidirectional (wigwag) throttle allows the operator to control vehicle speed
and direction by rotating the throttle mechanism clockwise and counterclock-
wise. The Curtis ET-XXX is an example of this throttle type.
Braking rate
The braking rate is the time required for the controller to increase from 0%
braking output to 100% braking output when a new direction is selected—see
Section 3A, page 26.
Boost
The boost feature can provide a burst of extra torque when the controller detects
that the traction motor is about to stall—see Section 3
A, page 25.
Coast and pick
The coast and pick feature can be used to drive the vehicle a short distance
forward while the Pick switch is activated. When the Pick switch is released, the
vehicle coasts to a stop—see Section 2, page 18, and Section 3
A, page 26.
Creep speed
Creep speed is activated when a direction is first selected. The output maintains
creep speed until the throttle is rotated out of the throttle deadband (typically
10% of throttle). This feature helps to prevent rollback when starting uphill with
low throttle—see Section 3A, page 31.
Current limiting
Curtis PMC controllers limit the traction motor’s drive current and the pump
motor current to their programmed maximum values—see Section 3A, page 24,
and Section 3B, page 46. Current limiting protects the controller from damage
that might result if the current were limited only by motor demand. PWM
output is reduced until the motor current falls below the set limit.
In addition to protecting the controller, the current limit feature also
provides some protection to the rest of the system. By eliminating high current
surges during acceleration, stress on the motors and batteries is reduced and
their efficiency enhanced.
Current multiplication
During acceleration and during reduced speed operation, the Curtis PMC
controller allows more current to flow into the motor than flows out of the
battery. The controller acts like a dc transformer, taking in low current and high
voltage (the full battery voltage) and putting out high current and low voltage.
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