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Dual ramp reversing

If the controller is operating when the reversing switch is changed, the controller will automatically slow down at a rate determined by the decel ramp adjustment to zero speed. It will then reverse the motor (this may require the speed to be turned to zero) and accelerate to full speed, rate determined by the acceleration ramp.

Gain adjustment

This enables the top speed to be reduced, e.g. in a child’s car where the child is too young to use the full speed range. It also allows the controller to be matched to various throttle devices (e.g. foot-pedal, Bell throttle, twist-grip throttle) and supply voltages.

High pot lockout

Prevents a controller from starting up until the speed control pot is returned to the zero position.

Inhibit Function

The inhibit function acts as an emergency stop feature that allows the controller to be disabled without switching off the ignition. On re-start the high pot lockout feature is bypassed and the controller ramps back up to the speed set on the input.


A joystick (aka Wig-Wag control) is a lever operated speed and direction control. Move the lever forward to go forward, and pull it back to go backwards. The speed is controlled by how far forward (or back) you pull the lever.

Over voltage protection

Protects the controller from possible damage caused by high voltages that can be generated during regen braking.

Parking brake

Some motors have an electrically operated parking brake fitted. Some 4QD controllers have a circuit fitted that will lift the brake automatically before applying power.

Pot fault detection

A feature that disables the controller if it detects that there is a fault with the speed control potentiometer.

Powerdown state

Describes the state of the connection between the controllers motor terminals when no power is applied. This will affect the amount of regenerative braking experienced when trying to push or tow a vehicle.

Pre-select reversing

In this mode, operating the reverse switch whilst the controller is operating has no effect. If the reverse switch is operated and the speed is manually reduced to zero, then the controller will start up in the pre-selected direction.


Controls the rate at which the controller will speed up or slow down. Slow rates are useful on locos and childrens vehicles, fast rates are useful for robots and some industrial machines.

Regenerative braking

A way of providing a braking force by converting the kinetic energy of the vehicle back into electricity.

Tacho feedback

Whether the controller can accept feedback from our tacho generator board. This is used to get precise control over the speed of a motor.

Thermal overload protection

Shuts the controller down if the internal temperature exceeds a pre-set value, generally set at 90’C on most of our models.

Under voltage protection

A feature that disables the controller if the battery voltage drops below a set threshold. AKA battery discharge protection.

Water resistant coating

We can apply a water resistant coating to the circuit board of our controllers which will significantly improve their resistance to corrosion in damp environments.

If you will be using your controller in a marine application, anywhere with high humidity, or where it could get water splashed on it, then this is well worth considering to ensure long term reliability.