A contractile spring E draws back the lever when the foot releases the pedal, and the link F, between the bell-crank lever and the upper band C, has a turnbuckle arrangement to provide for taking up in case of wear.
The brake bands have means for automatically holding them clear of the wheels when not in use.
Fig. 25. Contract Mechanism.
Equalizers.—Sometimes the brake is placed on the propeller shaft; but when one of the brakes is placed on each wheel, an equalizing bar, or other means, must be used. One form of this is shown in Fig. 26, in which A is the bar, B the rod which goes to the brake lever, and C C, the rods that run back to the brakes on the wheels.
Naturally, the equalizer will not act with the same effect on both wheels, unless they are in the same condition. Frequently one of the brake cylinders will be dry and the other coated with grease, or accumulate moisture from some source. It is, therefore, a necessary part of inspection and care to keep them in serviceable condition.
Fig. 26. Equalizer Bar.
The Emergency Brake.—The emergency brake has a pawl which acts in the teeth of a segment alongside of the lever, so it may be held in any position to which the lever may be thrown. This lever has no provision whereby the clutch is disengaged when the brake is applied, for the reason that should it become necessary to stop a car going up hill, and when the emergency brake is required, the brakes would have to be released before the clutch could be thrown in, so that the car would be likely to start down hill before this could be done. On this account the emergency brake has no connection with the clutch.
