Integrated Railmotive Systems Inc.

Excellence in Engineering


    In modern freight trains the brakes are applied whenever air pressure in the Brake Pipe (which connects all the cars in the train with the locomotive) is reduced, either by the action of the Engineer or as a result of a disconnect in the system. Actual brake effort comes from air cylinders with air supplied from storage reservoirs on each car. Cylinder pressure is under control of the Brake Pipe.  As this pressure is reduced from its fully charged value, Brake Cylinder pressure rises, until at a reduction of around 25 PSI, full service brake cylinder pressure will be reached, further reduction producing no more increase. If, however, the Brake Pipe pressure is completely vented, a 20% higher brake cylinder pressure, known as emergency pressure, will be established.
    When a train is stopped by this system. The brake cylinder pressure will remain at a high enough level to hold the train for some time, but this level always begins to fall due to leakage on the individual cars. Because of this leakage, the operating rules for all railroads require that when a train is stopped and is to be left unattended or not connected with a locomotive, the train crew must set a certain number of hand brakes to prevent movement of the train due to either grade or wind conditions, after all brake cylinder air has leaked away.

In recent times the size of train crews has been reduced, however, to the point where with one or two man crews it is difficult or impossible to set the required number of handbrakes. In order to increase safety in such cases, the brake cylinder attachments of fig 1 and fig 2 were designed by Railmotive to lock an applied brake cylinder into its fully extended condition in response to an emergency application. This would mechanically ensure against release of the brakes even if all air was to leak off on every car in the train. We also built a prototype of the system for testing. Patents were issued and assigned to WABTEC by Tom Engle.
In operation the system needs only to be connected to the Brake Pipe and to the brake cylinder line and its control (not shown in the illustration) will sense an emergency application; and after a suitable time delay, will operate the control actuator to engage the lock. Once engaged the brake cylinder piston is prevented from moving toward release thus locking in whatever brake force was produced by the cylinder.
    The device can be easily released at any time in several ways. If it is desired to release all brakes and move the train, a locomotive must recharge the brake, and  the brake pipe pressure will be sensed by the control, as well as the release of brake cylinder air pressure. The control will then force the control actuator’s internal piston to open the lock and allow the brake cylinder piston to move back, releasing the brakes.  This action will be more or less simultaneous on all cars in the train.
     If it is only desired to remove a few cars from the end of the train, these cars have their brake pipe hoses uncoupled from the rest of the train at the point where they are to be uncoupled. And the angle cock closed at that point. They can then be connected to a switch engine and their brakes released by charging only the brake pipe of the cars to be set out.
     A third alternative which is to uncouple the hoses as above, then connect a locomotive and pull the release levers on each car to be pulled off.  This will release all brakes and permit the cars to be moved without brakes as commonly done today.