Leading/trailing drum brake
- Leading/trailing drum brake
The leading/trailing drum brake design is typically found on the the rear of automobiles, though it has appeared on the front of some older models such as the Bedford CA. [Bedford CA service training manual 1959] Its advantage is that is equally effective whether the vehicle is travelling forwards or in reverse. [The AA Book of the Car 1976] It is not as powerful as a twin leading design, but that is not so important on the rear where too much braking force could cause the rear wheels to lock.
The term "leading/trailing" is used because there is one shoe that is "leading", moving with the direction of rotation of the drum and thus exhibiting a self-applying effect, i.e. being dragged into the friction surface of the drum and thus achieving greater braking force. [The AA Book of the Car 1976] The other shoe is "trailing", moving against the direction of rotation, being thrown off the friction surface of the drum and not retarding the drum quite so effectively.
When the vehicle is moving in reverse, the role of the leading and trailing shoes is reversed. What would be the leading shoe when the vehicle is travelling forwards becomes the trailing shoe, and vice-versa. [The AA Book of the Car 1976]
References
Wikimedia Foundation.
2010.
Look at other dictionaries:
double anchor drum brake — See leading/trailing drum brake … Dictionary of automotive terms
Drum brake — A drum brake with the drum removed as used on the rear wheel of a car or truck. Note that in this installation, a cable operated parking brake uses the service shoes … Wikipedia
Twin leading drum brake — The twin leading drum brake design is typically found on the front of automobiles. Its advantage is that it provides maximum possible retardation in its intended direction of travel, i.e. forwards. Everything else being equal, it is more powerful … Wikipedia
Disc brake — Close up of a disc brake on a car On automobiles, disc brakes are often located with … Wikipedia
brake shoe — That part of the brake system, located at the wheels, upon which the brake lining is attached. There are usually two shoes (curved or arc shaped pieces) in each wheel. When the wheel cylinders are actuated by hydraulic pressure they force the… … Dictionary of automotive terms
leading shoe — The British term for primary shoe, the shoe of a brake drum system which pivots outwards into the approaching drum. Compare trailing shoe … Dictionary of automotive terms
Murphy brake — The Murphy brake is a drum brake with shoes that pinch the drum via a rotating fork. In contrast, most drum brakes use either shoes that press only on the inside of the drum, or shoes that press only on the outside of the drum, like a band brake … Wikipedia
single leading brake shoe — The use of a single hydraulic plunger and a common pivot point which expands two shoes against the drum with equal pressure whether braking from forward or reverse direction. The leading brake shoe is usually called the Primary Shoe and trailing… … Dictionary of automotive terms
anchor — [1] A mounting point on the vehicle frame or unibody for a non structural but stressed component, such as a seat or seat belt. [2] The stationary portion of a leading/trailing drum brake on which the heels of the brake shoes ride. Also see belt… … Dictionary of automotive terms
anchor plate — The stationary portion of a leading/trailing drum brake on which the heels of the brake shoes ride. Also see caliper mounting bracket … Dictionary of automotive terms
