Brake Cylinder Tester

A brake cylinder testing tool can be constructed from a three-way ball valve, small regulator, bleed valve, whip hose, air hose quick coupler, and fabricated cylinder plate and gasket.

 
Brake Cylinder Tester inlet, regulator, ball valve, and bleed valve

The air enters from an air source via the air hose quick connector, through a regulator which sets the cylinder pressure desired. When the three way valve is in the open position, air flows from the supply to the cylinder, actuating it. When the air valve is in the closed position, air from the supply is cut off and the cylinder air bleeds off slowly through the bleed valve. If the valve is moved to an intermediate position, air entering the cylinder can be balanced against air bleeding off to cause the piston to remain in a fixed, yet intermediate position.

 
Old Brake Cylinder Pin Retainer

The plate on the end of the whip hose has a swivel to allow for attachment to the cylinder in awkward locations (e.g. while on the car) and the plate, with gasket, is drilled to allow bolting to the air cylinder. The nuts are just keepers for the bolts and gasket and are removed during use.