Decelostat information

{{{annotations}}} B-3 Decelostat valve at the axlebox (the end of the axle) of this railway wagon[1]

Decelostat is a wheel slide protection system developed by Westinghouse Air Brake Company that is used in railroad cars to prevent over-braking that causes wheel-slide, a condition of reduction in friction between train wheels and rails. This low wheel/rail adhesion condition reduces braking performance and causes damage to wheels (wheel spalling and wheel flat) and the rails.^[2]

When over-braking, the Decelostat will detect rapid deceleration of wheel rotation caused by creep in the wheelset, another condition preceding the wheel-slide. Once detected, the system manipulates brake valves to reduce brake pressure. This allows the affected wheels to rotate at the speeds that are more comparable to the speeds of the train to gain the wheel/rail adhesion again. When that happens, the system deactivates to allow the brake pressure to be restored to continue braking. The system may reactivate again if it detects another creep. The cycle of activation and deactivation is usually brief but it could take place repeatedly during the braking process.^[2]

Decelostat was the term used by Westinghouse Air Brake Company when it originally developed the system in the 1930s.^[3] The term had then been used by the railway industry as a generic term to refer to wheel slide protection systems during the late twentieth century.^[1] However, it was a registered trademark of Westinghouse Air Brake Company from 1943 to 2003,^[4] and the trademark was assigned to Wabtec, Westinghouse's successor, in 2004.^[5]