Fig. 23. Contracting Brake.
Fig. 24. Expanding Brake.
Running Brake.—The running brake is operated by the foot pedal, whereas the emergency brake is generally connected up with the lever at the side of the seat.
The foot pedal is on some cars connected with the clutch in such a way that when pedal is pressed to set the brake, the clutch is released. This prevents an inexperienced or confused driver from applying the brake when he forgets to release the clutch.
Double-Acting Contracting Brake.—Fig. 23 shows the manner in which a double-acting contracting brake operates. As the band A, has a tension on each end, when the rod B, is drawn forwardly, it is immaterial which way the brake drum C travels.
In Fig. 24 the drum C has a pair of oppositely-disposed shoes D, which are held in such a position that they are not revoluble, and may be moved outwardly by the lever E and links F.
These figures, of course, show merely the simple forms of the two types, and do not go into the refinements of construction which make them so effective in service.
It is obvious, however, that the power exerted through either type of brake, depends on the leverage afforded by the relative lengths of the limbs of the bell-crank lever E, to each other.
Contracting Brake.—Fig. 25 shows a well-known type of contraction brake, in which the cylinder A, has thereon two brake bands B C, hinged together at their rear ends. At their front ends they are connected with a bell-crank lever D, the forward movement of the upper end of the lever being such as to cause the bands to pinch the drum A.