Handle A is accessible under the bonnet To adjust, turn it clockwise as far as it will go, then unscrew it sufficiently to bring the brakes into action (the engine being stationary) when the pedal has travelled about 1 1/2 inches forward from its off position. No other adjustment is necessary, and it is most important that none of the connecting rods in the mechanism is altered in length.

The mechanical force on the brake is applied by means of a piston contained in a cylinder that communicates with the induction pipe through a valve connected to the brake pedal. When the driver moves the brake pedal forward, the valve is opened and the suction in the induction pipe is communicated to the cylinder. This moves the piston and the force thereon augments the force applied by the driver to the pedal. The connections between the piston and the brake mechanism on the one hand, and between the pedal and the valve on the other, are, however, so arranged that the driver's foot is the fulcrum of the system of levers through which the piston acts, and the consequence is that not only is the auxiliary mechanism unable to operate independently of the driver but it cannot exert a disproportional force.