Signal indicator for railway vehicles having disc brakes

Claim 1

In an indicator which generates a signal when predetermined wear occurs in the brake lining of disc brakes in a vehicle, the combination of a control valve comprising a pair of valves with valve members therein moveable in opposite directions and a compression spring therebetween, a pair of holders mounted on said vehicle and supporting brake linings on opposed sides of a brake disc, actuation stems on said valve members extending outwardly of said control valve in opposite directions, first means on said control valve for connecting to a source of pressure and second means thereon for connecting to a signal indicator, said control valve having a first opening to the atmosphere associated with said first connection means and a second opening to the atmosphere associated with said second connection means, said first and second connecting means and said first and second openings defining a pressurized circuit interconnecting said valve and a signal indicator, said valves controlling said first and second connecting means and said first and second openings so that actuation of at least one valve disconnects said second means from said source of pressure and connects said second means to the atmosphere, and sensor device means engageable with said valve actuation stems and actuated by a said holder when predetermined brake lining wear occurs for actuating said valves to vary the state of pressure in said circuit whereby a signal is generated by the signal indicator.