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A brief history of the Air Brake

The straight air brake

The first form of the air brake consisted of an air pump, a main reservoir, and an engineer’s valve on the locomotive, and of a train pipe and brake cylinder on each car. One problem with this first form of the air brake was that braking was applied to the first cars in a train much sooner than to the rear cars, resulting in shocks and damages when the rear cars bunted against the cars ahead of them. The main objection however was that it was not an automatic brake, i.e. even a minor mishap like a broken coupling left the entire train without any brake power at all.

The plain automatic air brake

In 1872, George Westinghouse invented the automatic air brake by inventing the triple valve and by equipping each car with its own air cylinder. Air pressure is maintained in the auxiliary reservoirs and in the train pipe at all times when the brakes are not applied. An equilibrium of air pressure is maintained in the train pipe and in the auxiliary air cylinders.

To apply the brakes to all of the cars at about the same time, pressure is released from the train pipe, causing the triple valve on each car to apply the brakes. To release the brakes on each car, pressure is increased in the train pipe until an excess pressure above that of the pressure in each auxiliary cylinder is reached, which throws the triple valve so as to close the inlet to the brake cylinder and open the inlet to the auxiliary reservoir from the train pipe, thus allowing the equilibrium of the two pressures to be reached.

The quick action triple valve

Although the plain automatic air brake was a great improvement over the straight air brake, in an emergency the system still applied the brakes to the last cars in a train later than to the first cars in a train. To remedy that condition, George Westinghouse invented the quick action triple valve in 1887. It automatically vents air from the brake pipe locally on each car, which applies the brakes more quickly.
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WABCO: a brief history

The air brake was invented by George Westinghouse of New York State in 1868. He moved to Pittsburgh, Pa., where he established the Westinghouse Air Brake Company (WABCO). WABCO’s direct successor companies include WABCO automotive (NYSE: WBC), a commercial vehicle air brake manufacturer, and Wabtec (NYSE: WAB), a railway equipment manufacturer, which have been owned and operated independently of each other since the mid-twentieth century.

After having manufactured equipment in Pittsburgh for a number of years, he began to construct facilities and plants eastwards of the city where homes for his employees were built, particularly at East Pittsburgh, Turtle Creek, and Wilmerding.

The Air Brake plant was obviously very prosperous and was nothing far from a gift for this small town. By 1905 over 2,000,000 freight, passenger, mail, baggage, and express cars and 89,000 locomotives were equipped with the Westinghouse Air Brakes.

The company has two 21st century successors, which are independent of each other. One, which continues to design and manufacture railway air brakes in Wilmerding, Pennsylvania, merged with locomotive manufacturer MotivePower Industries, to form Wabtec. The other, now known as WABCO Holdings Inc, designs and manufactures control systems for commercial road vehicles, including air brakes, and is headquartered in Brussels, Belgium. WABCO Holdings (NYSE: WBC) was floated in a 2007 initial public offering by American Standard, WABCO’s owners for 30 years.
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Knorr Bremse: a brief history

Knorr-Bremse is a manufacturer of braking systems for rail and commercial vehicles that has operated in the field for over 100 years. The company also produces door systems for rail vehicles and torsional dampers. In 2006, the Group’s workforce of over 13,000 achieved worldwide sales of EUR 3.1 billion.

Inventor Georg Knorr founded knorr-Bremse in 1905 in Berlin. The initial basis for the company’s commercial success was provided by an agreement with the Prussian State Railways to supply single-chamber express braking systems offering considerably enhanced safety performance compared with traditional systems. In the early twentieth century, train guards still had to operate the brakes by hand, from so-called “brake vans.” The first pneumatic brakes were of a basic design, but before long, indirect automatic systems using a control valve were developed.

The second main area of activity for Knorr-Bremse emerged in 1922, when they moved into pneumatic braking systems for commercial road vehicles. Knorr-Bremse was the first European company to develop a new pneumatic system that applied the brakes simultaneously to all four wheels of a truck as well as its trailer. The resultant reduction in braking distances made a significant contribution to improving road safety.
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Haldex: a brief history

Haldex AB, also known as Haldex Group, is a Swedish public company operating in the automotive industry. It is listed on the OMX Stockholm Stock Exchange (Mid Cap), and has an annual turnover of around 8 bn SEK.

Concentrating core activities in vehicle dynamics, the environment and safety, Haldex business operations are split into four divisions: Commercial Vehicle Systems, Garphyttan Wire, Hydraulic Systems, and probably its most-known (although smallest) division - Traction Systems - which is better known as Haldex Traction, and produces limited slip coupling.

The Haldex Commercial Vehicle Systems (CVS) division operates in the commercial vehicle sector; specifically heavy trucks, trailers, and buses. It is the largest division of the Haldex Group, with a 57% share of Haldex operations in 2007. It develops and manufactures brake systems, covering all aspects, including air brakes.
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Bosch: a brief history

Robert Bosch GmbH is a German diversified technology-based corporation which was started in 1886 by Robert Bosch in Stuttgart, Germany.

Robert Bosch GmbH is the world’s largest supplier of automobile components and has business relationships with virtually every automobile company in the world.

The Bosch Group comprises more than 275 subsidiary companies. In addition to auto-component supply business, which brings in more than 90% of its revenues, the company produces industrial machinery and hand tools. It also owns 50% of Bosch-Siemens Hausgeräte, the European appliance maker. Bosch’s Blaupunkt unit is a main manufacturer of vehicle audio equipment. The subsidiary Bosch Rexroth produces hydraulic, electric, and pneumatic machinery for applications ranging from automotive to mining.

About 50 percent of Bosch’s worldwide annual sales are produced in automotive technology. Bosch invented the magneto, a predecessor of the alternator, which sparked most of the earliest internal combustion engines. Bosch also invented the anti-lock braking system (ABS), and as time passed, Bosch became a leader in such specialized fields as traction control systems (TCS), the Electronic Stability Programme (ESP).
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Brake Calipers: a brief history

Disc-style brakes began in England in the 1890s; the first ever automobile disc brakes were patented by Frederick William Lanchester in his Birmingham factory in 1902, though it took another half century for his innovation to be widely adopted.

These brakes offer better stopping performance than comparable drum brakes, including resistance to “brake fade” caused by the overheating of brake components, and are able to recover quickly from immersion. Unlike a drum brake, the disc brake has no self-servo effect and the braking force is always proportional to the pressure placed on the braking pedal or lever.

Many early implementations for automobiles located the brakes on the inboard side of the driveshaft, near the differential, but most brakes today are located inside the wheels. (An inboard location reduces the unsprung weight and eliminates a source of heat transfer to the tires).

The brake caliper is the assembly which houses the brake pads and pistons. The pistons are usually made of aluminum or chrome-plated steel. There are two types of calipers: floating or fixed. A fixed caliper does not move relative to the disc. It uses one or more pairs of opposing pistons to clamp from each side of the disc, and is more complex and expensive than a floating caliper. A floating caliper (also called a “sliding caliper”) moves with respect to the disc, along a line parallel to the axis of rotation of the disc; a piston on one side of the disc pushes the inner brake pad until it makes contact with the braking surface, then pulls the caliper body with the outer brake pad so pressure is applied to both sides of the disc.

Floating caliper (single piston) designs are subject to failure due to sticking which can occur due to dirt or corrosion if the vehicle is not operated regularly. This can cause the pad attached to the caliper to rub on the disc when the brake is released. This can reduce fuel effiency and cause excessive wear on the affected pad. Additional heat generated by the constantly rubbing pad can also lead to warping of the disc.
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(Thanks to Wikipedia for all this information).