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Brake force, also known as Brake Power, is a measure of braking power of a vehicle.
In the case of railways, it is important that staff are aware of the brake force of a train so sufficient brake power will be available to bring the train to a halt within the required distance from a given speed. In simple terms the brake force of a train should be relative to the sum of the brake force that can be exerted by all the vehicles in the train relative to the weight of the train, excluding problems that may occur such as wheels locking and sliding under braking.
Modern freight wagons typically have brakes that can be operated from the
A simple guide to train physics
Brakes Force {{classicalmechanics-stub
Railways
In the case of railways, it is important that staff are aware of the brake force of a train so sufficient brake power will be available to bring the train to a halt within the required distance from a given speed. In simple terms the brake force of a train should be relative to the sum of the brake force that can be exerted by all the vehicles in the train relative to the weight of the train, excluding problems that may occur such as wheels locking and sliding under braking.
Modern freight wagons typically have brakes that can be operated from the locomotive
A locomotive or engine is a rail transport vehicle that provides the Power (physics), motive power for a train. If a locomotive is capable of carrying a payload, it is usually rather referred to as a multiple unit, Motor coach (rail), motor ...
, these are sometimes referred to as ''fitted'' freights. Older wagons typically were not fitted with brakes that could be operated from the locomotive, sometimes these are referred to as ''unfitted freights''. These unfitted freights would typically have brake van
Brake van and guard's van are terms used mainly in the UK, Ireland, Australia and India for a railway vehicle equipped with a hand brake which can be applied by the guard. The equivalent North American term is caboose, but a British brake van ...
s attached to provide additional braking force and operated at a reduced field.
While very early passenger trains might have had brakes that would have been applied by a brakesman riding in say every second carriage modern passenger vehicles have brakes that will be applied to all vehicles.
There are a certain of cases in modern practice where operating at higher at higher speeds can could the brake force above a certain speed would be insufficient to stop the train within the required distance. Some cases arise because the brake force to weight ratio of a locomotive of typically 80 to 120 tonnes in weight is often less than that of passenger vehicle in the 40 tonne range; and it may be that locomotives running by themselves require several coaches to be attached if the train is to run at its maximum permitted speed with a suitable brake force to weight ratio. Another issue that can arise is when a locomotive is hauling a set of coaches, typically a multiple unit
A multiple-unit train or simply multiple unit (MU) is a self-propelled train composed of one or more carriages joined together, which when coupled to another multiple unit can be controlled by a single driver, with multiple-unit train contr ...
, where it is unable to work the brakes of the unit. In this case additional braking vehicles may be attached or the train may need to run at reduced speed.
See also
*Tractive effort
As used in mechanical engineering, the term tractive force can either refer to the total traction a vehicle exerts on a surface, or the amount of the total traction that is parallel to the direction of motion.
In railway engineering, the term tr ...
*Continuous tractive effort
As used in mechanical engineering, the term tractive force can either refer to the total traction a vehicle exerts on a surface, or the amount of the total traction that is parallel to the direction of motion.
In railway engineering, the term tr ...
*Power at rail
As used in mechanical engineering, the term tractive force can either refer to the total traction a vehicle exerts on a surface, or the amount of the total traction that is parallel to the direction of motion.
In railway engineering, the term tr ...
References
External links
A simple guide to train physics
Brakes Force {{classicalmechanics-stub