Twin leading drum brake
Encyclopedia
The twin-leading-shoe brake (2LS) is a type of drum brake
that has two leading shoes, rather than the single leading shoe and a single trailing shoe of a single-leading shoe (SLS) drum brake. A leading shoe has a self-servo effect, so an advantage of a 2LS is that it provides the maximum retardation in its intended direction of travel, i.e. forwards. 2LS brakes are fitted on the front axle of automobile
s, or the front wheel of a motorcycle
. A 2LS brake is more powerful than an SLS
design.
The self-servo effect arises because the leading shoe are dragged into the friction surface of the brake
drum, and thus achieving maximum braking force.. A "trailing" shoe would move against the direction of rotation, being thrown off the friction surface of the drum and would not retard the drum so effectively.
When the vehicle is moving in reverse, or if it is stationary but facing uphill, the role of the leading and trailing shoes is reversed. A twin-leading design thus becomes twin-trailing, with the rotation of the drum working against the brake shoes, trying to throw them off the drum. The exact opposite of the self-applying effect. A 2LS brake is virtually useless when working in the opposite direction. For this reason, it is more usual to have a leading/trailing drum brake
design on the rear of a the vehicle
, so that there is sufficient braking when travelling in reverse or when parked on a slope..
Drum brake
A drum brake is a brake in which the friction is caused by a set of shoes or pads that press against a rotating drum-shaped part called a brake drum....
that has two leading shoes, rather than the single leading shoe and a single trailing shoe of a single-leading shoe (SLS) drum brake. A leading shoe has a self-servo effect, so an advantage of a 2LS is that it provides the maximum retardation in its intended direction of travel, i.e. forwards. 2LS brakes are fitted on the front axle of automobile
Automobile
An automobile, autocar, motor car or car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor...
s, or the front wheel of a motorcycle
Motorcycle
A motorcycle is a single-track, two-wheeled motor vehicle. Motorcycles vary considerably depending on the task for which they are designed, such as long distance travel, navigating congested urban traffic, cruising, sport and racing, or off-road conditions.Motorcycles are one of the most...
. A 2LS brake is more powerful than an SLS
Leading/trailing drum brake
The leading/trailing drum brake is a type of drum brake design. It is typically found on the rear of automobiles, though it has appeared on the front of some older models such as the Bedford CA. Its advantage is that is equally effective whether the vehicle is travelling forwards or in reverse...
design.
The self-servo effect arises because the leading shoe are dragged into the friction surface of the brake
Brake
A brake is a mechanical device which inhibits motion. Its opposite component is a clutch. The rest of this article is dedicated to various types of vehicular brakes....
drum, and thus achieving maximum braking force.. A "trailing" shoe would move against the direction of rotation, being thrown off the friction surface of the drum and would not retard the drum so effectively.
When the vehicle is moving in reverse, or if it is stationary but facing uphill, the role of the leading and trailing shoes is reversed. A twin-leading design thus becomes twin-trailing, with the rotation of the drum working against the brake shoes, trying to throw them off the drum. The exact opposite of the self-applying effect. A 2LS brake is virtually useless when working in the opposite direction. For this reason, it is more usual to have a leading/trailing drum brake
Leading/trailing drum brake
The leading/trailing drum brake is a type of drum brake design. It is typically found on the rear of automobiles, though it has appeared on the front of some older models such as the Bedford CA. Its advantage is that is equally effective whether the vehicle is travelling forwards or in reverse...
design on the rear of a the vehicle
Vehicle
A vehicle is a device that is designed or used to transport people or cargo. Most often vehicles are manufactured, such as bicycles, cars, motorcycles, trains, ships, boats, and aircraft....
, so that there is sufficient braking when travelling in reverse or when parked on a slope..