All 4QD’s controllers work on an input voltage, which is usually derived from a potentiometer.
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.
Simpler controllers which do not include this must be used with the correct value of potentiometer and will normally be supplied correctly set – if we know what throttle device you propose to use!
Full speed is typically given for about 4v input. Gain adjustment usually increases this voltage, to allow for instance 0-12v or 0 to 24v input to be used.
Full Speed adjustment
Sometimes it is useful to have a switch which restricts pot operation to, for instance, half full speed. An example of this might be an mobility aid which is 8mph full speed for road use but must have a switch to restrict the top speed to 4mph for pavement use. This is easily achieved and details are given in the 4QD series manual and in the Pro-120series manual as these are the controllers usually used for such vehicles.