Ausco Lambert disc brake
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The Ausco-Lambert disc brake is an unusual
brake A brake is a mechanical device that inhibits motion by absorbing energy from a moving system. It is used for slowing or stopping a moving vehicle, wheel, axle, or to prevent its motion, most often accomplished by means of friction. Background ...
where an axially-expanding shoe assembly is sandwiched between two linked rotating discs. It may be thought of as an "inside out"
disc brake A disc brake is a type of brake that uses the calipers to squeeze pairs of pads against a disc or a "rotor" to create friction. This action slows the rotation of a shaft, such as a vehicle axle, either to reduce its rotational speed or to hol ...
: instead of pads pinching a disc, the pads expand inside a hollow disc.


History

Ausco-Lambert brakes were introduced in late 1948 and used commercially in some
Chrysler Stellantis North America (officially FCA US and formerly Chrysler ()) is one of the " Big Three" automobile manufacturers in the United States, headquartered in Auburn Hills, Michigan. It is the American subsidiary of the multinational automoti ...
cars and some
Farmall tractor Farmall was a model name and later a brand name for tractors manufactured by International Harvester (IH), an American truck, tractor, and construction equipment company. The Farmall name was usually presented as McCormick-Deering Farmall and l ...
s. The 1950
Crosley Crosley was a small, independent American manufacturer of subcompact cars, bordering on microcars. At first called the Crosley Corporation and later Crosley Motors Incorporated, the Cincinnati, Ohio, firm was active from 1939 to 1952, interr ...
Hot Shot is often given credit for the first production
disc brakes A disc brake is a type of brake that uses the calipers to squeeze pairs of pads against a disc or a "rotor" to create friction. This action slows the rotation of a shaft, such as a vehicle axle, either to reduce its rotational speed or to hol ...
but the Chrysler Crown Imperial actually had them first as standard equipment at the beginning of the 1949 model year. The Crosley disc was a Goodyear development, a caliper type with ventilated rotor, originally designed for aircraft applications. Only the Hot Shot featured it. Lack of sufficient research caused enormous reliability problems, especially in regions requiring the use of salt on winter roads, such as sticking and corrosion. Drum brake conversion for Hot Shots was quite popular. The Chrysler 4-wheel disc brake system was more complex and expensive than Crosley's, but far more efficient and reliable. It was built by Auto Specialties Manufacturing Company (Ausco) of
St. Joseph, Michigan St. Joseph, colloquially known as St. Joe, is a city and the county seat of Berrien County, Michigan. It was incorporated as a village in 1834 and as a city in 1891. As of the 2010 census, the city population was 8,365. It lies on the shore o ...
, under patents of inventor H.L. Lambert, and was first tested on a 1939
Plymouth Plymouth () is a port city and unitary authority in South West England. It is located on the south coast of Devon, approximately south-west of Exeter and south-west of London. It is bordered by Cornwall to the west and south-west. Plymouth ...
. Unlike the caliper disc, the Ausco-Lambert utilized twin expanding discs that rubbed against the inner surface of a cast iron brake drum, which doubled as the brake housing. The discs spread apart to create friction against the inner drum surface through the action of standard
wheel cylinder A wheel cylinder is a component of a hydraulic drum brake system. It is located in each wheel and is usually positioned at the top of the wheel, above the shoes. Its function is to exert force onto the shoes so as to bring them into contact wit ...
s. Chrysler discs were "self energizing," in that some of the braking energy itself contributed to the braking effort. This was accomplished by small balls set into oval holes leading to the brake surface. When the disc made initial contact with the friction surface, the balls would be forced up the holes forcing the discs further apart and augmenting the braking energy. This made for lighter braking pressure than with calipers, avoided brake fade, promoted cooler running and provided one-third more friction surface than standard Chrysler twelve-inch drums. But because of the expense, the brakes were only standard on the Chrysler Crown Imperial through 1954 and the Town and Country Newport in 1950. They were optional, however, on other Chryslers, priced around $400, at a time when an entire Crosley Hot Shot retailed for $935. Today's owners consider the Ausco-Lambert very reliable and powerful, but admit its grabbiness and sensitivity.


Pad Expansion

The Ausco-Lambert brake has an unusual
mechanism Mechanism may refer to: * Mechanism (engineering), rigid bodies connected by joints in order to accomplish a desired force and/or motion transmission *Mechanism (biology), explaining how a feature is created *Mechanism (philosophy), a theory that ...
to expand the
brake pad Brake pads are a component of disc brakes used in automotive and other applications. Brake pads are composed of steel backing plates with friction material bound to the surface that faces the disc brake rotors. Function Brake pads convert the kin ...
s. It uses two flat rings, both with pad material on one side and
conical A cone is a three-dimensional geometric shape that tapers smoothly from a flat base (frequently, though not necessarily, circular) to a point called the apex or vertex. A cone is formed by a set of line segments, half-lines, or lines conn ...
divots on the other side. Two rings are placed together with the conical divots facing together and a ball bearing in each pair of divots. When the rings are rotated relative to each other, the balls roll up the ramp faces of the conical divots, pushing apart the two rings.


Self Energizing

The Ausco-Lambert brake is self-energizing. It holds one ring rigidly and lets the other rotate freely, without a stop. The rotation direction is arranged so the direction of free rotation is the same as the hollow brake "disc". Thus, the disc tends to pull the ring in the direction that further applies the brake. A shallower cone angle increases the amount of self-energizing effect. Self-energizing brakes are more subject to
brake fade Vehicle braking system fade, or brake fade, is the reduction in stopping power that can occur after repeated or sustained application of the brakes, especially in high load or high speed conditions. Brake fade can be a factor in any vehicle that u ...
, but it appears part of the Ausco Lambert design is to reduce the exponential gain of
drum The drum is a member of the percussion group of musical instruments. In the Hornbostel-Sachs classification system, it is a membranophone. Drums consist of at least one membrane, called a drumhead or drum skin, that is stretched over a she ...
and
band Band or BAND may refer to: Places *Bánd, a village in Hungary *Band, Iran, a village in Urmia County, West Azerbaijan Province, Iran * Band, Mureș, a commune in Romania *Band-e Majid Khan, a village in Bukan County, West Azerbaijan Province, I ...
brakes, and thus reduce grabbiness and hot fade.


Self Release

When the disc rotates the opposite direction of ring rotation, the brake tends to self-release. This is common also for drum brakes and is acceptable for uses where hard braking is in one direction.


References

{{DEFAULTSORT:Ausco Lambert Disc Brake Vehicle braking technologies