Abstract: A system for controlling brakes on a rail or light rail motive power unit, in which the brakes are provided with a pneumatic braking system including a pneumatic main pipe and a pneumatic brake pipe. The system includes a control unit, manually operated actuating devices, a relay valve interposed between the pneumatic main pipe and the brake pipe, an electro-pneumatic control unit operable under the control of the unit to supply a variable braking control pressure, pneumatic back-up devices operable under the control of the actuating devices to supply a pneumatic back-up pressure which can be used to control the braking, and an enabling valve which can be switched between a normal operating condition and a back-up operating condition in which it can connect a control inlet of the relay valve selectively to the outlet of the electropneumatic unit or to the back-up devices.

Abstract: The system comprises a control unit, manually operated actuating devices, a relay valve interposed between the pneumatic main pipe and the brake pipe and provided with two control inlets, an electropneumatic control unit connected to the main pipe and operable under the control of the said unit to supply a variable braking control pressure, pneumatic back-up devices connected to the main pipe and operable under the control of the actuating devices to supply at their outlet a pneumatic back-up pressure which can be used to control the braking, and an enabling valve which can be switched between a normal operating condition and a back-up operating condition in which it can connect a control inlet of the relay valve selectively to the outlet of the electropneumatic unit or to the back-up devices.