Bogie Frame Can be of steel plate or cast steel. In this case, it is a modern design of welded steel box format where the structure is formed into hollow sections of the required shape. An air brake cylinder is provided for each wheel. A cylinder can operate tread or disc brakes. Some designs incorporate parking brakes as well.
Some bogies have two brake cylinders per wheel for heavy duty braking requirements.
Each wheel is provided with a brake disc on each side and a brake pad actuated by the brake cylinder. A pair of pads is hung from the bogie frame and activated by links attached to the piston in the brake cylinder. When air is admitted into the brake cylinder, the internal piston moves these links and causes the brake pads to press against the discs. A brake hanger support bracket carries the brake hanger s , from which the pads are hung. A steel coil spring, two of which are fitted to each axlebox in this design.