Pdf Place.

Just downoad PDF files from our collection and be peased with it..


Comments Off


Tread Brake Unit. Wabtec westinghouse air brake Transit Car Products Tread Brake Unit. A mechanism which pushes the brake shoe to tread of wheels driven. GENERAL. It is proposed to provide Tread Brake Units (TBU) with and without parking brakes instead of conventional brake rigging on HHP. TBU (Tread brake unit) is a pneumatic- mechanical unit for brake application on wheel. It can be permanently fixed on to bogie frame or freely mounted (floating.


Author: Mr. Adolfo Schmidt
Country: Denmark
Language: English
Genre: Education
Published: 20 April 2017
Pages: 771
PDF File Size: 1.97 Mb
ePub File Size: 30.90 Mb
ISBN: 390-4-28408-998-2
Downloads: 26113
Price: Free
Uploader: Mr. Adolfo Schmidt


Tread Brake Unit | Wabtec Corporation

Goods and mineral vehicles were provided with hand brakes by which the brakes could be applied by a hand tread brake unit operated by staff on the ground. These hand brakes were used where necessary when vehicles were parked but also when these trains needed to descend a steep gradient; the train then stopped before descending and the guard tread brake unit forward to pin down the handles of sufficient brakes to give adequate braking effort.

  • Navigation menu

Early goods vehicles had brake handles on one side only and random alignment of the vehicles gave the guard sufficient braking but, from aboutso-called "either-side" brake handles were provided. These trains, not fitted tread brake unit continuous brakes were described as "unfitted" trains and they survived in British practice until about However, from aboutsemi-fitted trains were introduced, in which some goods vehicles were fitted with continuous brakes and a proportion of such vehicles marshalled next to the locomotive gave sufficient brake power to run at somewhat higher speeds than unfitted trains.

The brake tender was low, so that the driver could still see the line and signals ahead if the brake tender was propelled pushed ahead of the locomotive, which was often the case.

By there were over patents in various countries for braking systems, most of which were obviously stillborn.

Railway brake

In the late 19th century, significantly better continuous brakes started to appear. The tread brake unit type of continuous brake was the chain brake [15] which used a chain, running the length of the train, to operate brakes on all vehicles simultaneously.

The chain brake was soon superseded by air operated or vacuum operated brakes. These brakes used hoses connecting all the wagons of a train, so the driver could apply or release the brakes with a single valve in the locomotive. These continuous brakes can be simple or automatic, the essential difference being what happens tread brake unit the train break in two.

With simple brakes, pressure is needed to apply the brakes, and all braking power is lost if the continuous hose is broken for any reason. Simple non-automatic brakes are thus useless when things really go wrong, as is shown with the Armagh rail disaster.

Railway brake - Wikipedia

Automatic brakes are thus largely " fail safe ", though faulty closure of hose taps can lead to accidents such as tread brake unit Gare tread brake unit Lyon accident. The standard Westinghouse Air Brake has the additional enhancement of a triple valve, and local reservoirs on each wagon that enable the brakes to be applied fully with only a slight reduction in air pressure, reducing the time that it takes to release the brakes as not all pressure is voided to the atmosphere.

Non-automatic brakes still have tread brake unit role on engines and first few wagons, as they can be used to control the whole train without having to apply the automatic brakes. Types[ edit ] Air versus tread brake unit brakes[ edit ] Driver's duplex air brake gauge; left needle shows main reservoir pipe supplying the train, right needle shows the brake cylinder pressure In the early part of the 20th century, many British railways employed vacuum brakes rather than the air brakes used in much of the rest of the world.

The main advantage of vacuum was that the vacuum can be created by a steam ejector with no moving tread brake unit and which could be powered by the steam of a steam locomotivewhereas an air brake system requires a noisy and complicated compressor.

However, air brakes can be made much more effective than vacuum brakes for a given size of brake cylinder.


With a vacuum system, the maximum pressure differential is atmospheric pressure Therefore, an air brake tread brake unit can use a much smaller brake cylinder than a vacuum system to generate the same braking force. This advantage of air brakes increases at high altitude, e.

Tread Brake Unit

Peru and Switzerland where today vacuum brakes are used by secondary railways. The much higher effectiveness of air brakes and the demise of the steam tread brake unit have seen the air brake become ubiquitous; however, vacuum braking is still in use in India, Argentina and South Africa, but this will be declining in near future.


Tread brake unit air pressure can also be used to operate loading and unloading doors on wheat wagons and coal and ballast wagons. On passenger coachesthe main reservoir pipe is also used to supply air to operate doors and air suspension.

Four-step brake handle on a UK Class Electric Multiple Unit The higher performing EP brake uses a "main reservoir pipe" feeding air to all the brake reservoirs on the train, with the brake valves controlled electrically with a three-wire control circuit.

This provides between four and seven braking levels, depending on the class of train.

It also allows for faster brake application, as the electrical control signal is propagated effectively instantly to all vehicles in the train, whereas the change in air pressure which activates the brakes in a conventional system can take several seconds or tens of seconds to propagate tread brake unit to the rear of the train.

This system is not however used on freight trains due to cost.


Electronically controlled pneumatic brakes Electronically controlled pneumatic brakes ECP are a development of the late 20th Century tread brake unit deal with very long and heavy freight trains, and are a development of the EP brake with even higher level of control.