All About Bogie Frame Types
Summary- Railway bogies are hardly noticed by the average passenger but they are an essential part of the the train, its drive system and its guidance mechanism. A standard railway vehicle will have two bogies, generally located near the vehicles ends. Each bogie is a 4-wheeled or 6-wheeled truck that provides the support for the vehicle body and which is used to provide its traction and braking. Bogies (Trucks)Steerable Bogies.
Picture Courtesy-Jupiter Wagons
Bogies (Trucks)
Bogies may be powered, either by electric motors of some type of mechanical drive connected to a motor of diesel engine. They may also just provide the carrying function - so-called trailer bogies. Both motor and trailer bogies are normally braked, under the control of the train braking system.
A pair of train wheels is rigidly fixed to an axle to form a wheelset. The wheels are pressed on to the axle so that they both rotate together. As we’ve seen above, normally two wheelsets are mounted in a bogie, so the bogie is simply a 4-wheeled truck – the Americans call it a truck – mounted under a railway carriage in order to support and guide the carriage along the track.
Traditionally, springs were steel, either coil or flat. Nowadays they are often rubber or compressed air bags or some sort of combination.
Steerable Bogies
A conventional bogie frame is turned into the curve by the leading wheelset as it is guided by the rails. However, there is a degree of slip and a lot of force required to allow the change of direction. The bogie frame type is, after all, carrying about half the weight of the vehicle it supports. It is also guiding the vehicle, sometimes at high speed, into a curve against its natural tendency to travel in a straight line.
