From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Description of a self-energising brake system (Patent Pending) by Harold B. Mead.
| Identifier | ExFiles\Box 85\1\ scan0371 | |
| Date | 12th November 1937 guessed | |
| SELF-ENERGISING BRAKE. HAROLD B. MEAD. (Patent Pending). The brake is of the normal expanding shoes type, the shoes and expanding cam assembly being mounted upon an anchor-plate. The plate, however, instead of being rigid, is allowed to rotate through a limited arc against spring resistance co-axially to a second anchor-plate which is rigidly fixed in the usual manner. A secondary cam is connected through its shaft by a lever and link to the fixed anchor-plate. Upon application of the first cam, which is foot-pedal operated, the shoes connect the brake-drum with the intermediate (rocking) anchor-plate, the torque being transmitted to the fixed anchor-plate via the springs which are then overcome owing to the tendency of the rocking plate to follow the revolving drum. As the rocking-plate rotates, the secondary or "servo" cam automatically alters its angularity in relation to its anchorage upon the fixed plate and in so doing assumes the angle of the primary cam and tends to exceed it. It thus relieves the primary cam which then merely acts as a control, taking up any additional expansion created by the servo cam. Owing to the urge of the servo cam to revert to the "Off" position by reason of the rocking-plate springs aided by the shoe return springs, it is always under the control of the primary cam and cannot remain "On" after the primary cam has been released. It will be seen that the initial brake torque is taken by spring giving smooth action. The actual servo action does not come into operation until these springs are to a degree overcome, resulting in a progressive braking effort. At low speed/loads the servo action would not therefore operate unless a violent application be made as in an emergency. (Forward. | ||