As with the Pelham, the action of the Kimblewick is dependent upon the position of the riders hands. The rein slides on the Dee shaped bit ring. If the hands are lowered prior to pressure being applied to the reins, the rein will slide about an inch and the bit will assume roughly a 45° angle in the mouth. Causing the mouthpiece to act in a downward and backward motion on the lower jaw, this is complemented by a downward pressure on the poll, giving the bit a lowering action. There are 3 rein settings which increase or decrease the pressure.
The idea behind this mouthpiece design, a soft tube which curves around the tongue applying spread tongue and bar pressure has since been further finessed with the innovation of the moulded mullen.