AUTOMATIC REAR HUB BRAKES.
The old hand brake, common on the tricycle, was even used on the rear-driving bicycle, the [Columbia] and New Mail having once been made with it. The latest type, however, is the “automatic,” placed on the hub of the driving wheel, and put into action by back-pedalling. Of this type are the Doolittle, the [New Departure], the [Willits], and others. In back-pedalling, the sprockets and chain never actually run backward, but the forward movement is resisted, and thus there is a “tendency” for them to move a little more slowly than the wheel. This tendency is employed in this type of brake, and the principle is that the rear sprocket, being so mounted as to allow a very slight backward slip with relation to its axle (which is what occurs as soon as attempt is made to stop the sprocket by backing on the pedal) slips just enough to put the brake “on,” the friction being between either a cam disk or a split ring and a brake shoe which is held immovable by the frame. The first attempt to back-pedal sets the brake, its pressure depending on the force applied to the pedal. The brake remains set of itself until pressure forward comes on the pedal again, when it automatically releases. Under proper operation, as intended, the rider is hardly aware of this brake, noticing only that his back-pedalling is very effective.