Bogies are essentially the undercarriage of rolling stock and where you’ll find the suspension, brakes and wheels of a Railway Vehicle. They are comprised of a number of complex parts.
A chassis or framework for the undercarriage, a bogie frame can be made from either steel plate or cast steel. Quote often in modern designs they will actually be made of several smaller cast parts which will be welded together, reducing costs. Bogie Frames used to be the domain of fabrication, but now thanks to larger CNC machines they are able to be produced by precision engineers. This is advantageous due to the more precise and complex nature of bogies.
Each wheel has its own brake cylinder, and in some cases two due to the heavy duty nature of the braking involved. In order to slow the train down, each wheel will have a brake disc on either side or a brake pad actuated by a brake cylinder. Within the brake cylinder is a piston, and when air is admitted into the cylinder this piston will move a link and cause the brake pads to press against the disc, slowing the wheels. The brake pads themselves are hung from a support bracket.
In order to absorb shocks and deal with weight distribution, bogies house a number of suspension systems. One of the most simple being Suspension Coils, these are made out of steel and carry the weight of the bogie frame. Alongside this most vehicles will also have an air suspension unit. Primarily this is employed when the train is stationary to ensure the carriage remains at the same height as passengers get on and off. There are also a number of shock absorbing parts.
A wheelset is composed of an axle with bearings and a wheel at each end. Railways Wheels actually sit on the track without guidance. Next to the wheels are flanges which act as a safety feature so as to prevent the wheels from being derailed. The ‘tyre’ of a wheel is coned so as to suit the slightly curved edge of the track, different countries have different degrees of angle for their track.
Bronte Precision are sub-contract manufacturers who can produce a wide range of mechanical components for rolling stock which includes a number of brake, suspension and bogie parts. We are fully ISO accredited and based in Bradford, West Yorkshire.
Image Courtesy of Railway Technical