Disc brake piston installation tool

DETAILED DESCRIPTION The above and other objects are achieved in accordance with the present invention, which provides a pneumatically operated piston installation tool for use with disc brake caliper assemblies having a piston movably disposed in a piston bore at one side of a caliper housing and an outer support bracket at the opposite side.
The piston installation tool comprises: a first plate, positionable within the disc brake caliper housing in contact with an outer edge of an extended piston; a second plate in alignment with, and spaced apart from, the first plate and positionable against an inside surface of the outer support bracket; a piston shaft attached at one end to the first plate at a central point thereof and extending perpendicularly therefrom passing slidably through a central opening in the second plate into a surrounding cylinder attached to the second plate; and pneumatic means for moving the piston shaft out of the cylinder and pushing the first plate against the outer edge of the piston in a direction away from the second plate, forcing the piston to retract into the piston bore.
Compressed air for the operation of hand-held pneumatic tools is generally available in garages and maintenance shops where repair work on disc brake assemblies is commonly carried out.
The piston installation tool of the present invention includes a hose that can be plugged into the compressed air system in the same manner as other common pneumatic tools, such as pneumatic drills, impact guns, and the like to supply pneumatic pressure to the cylinder.
In a preferred embodiment, the piston installation tool of this invention includes a pressure gauge that displays the pressure being applied.
By observing the pressure gauge, the amount of pressure necessary to move the piston can be determined.
Thus, the gauge can be used to determine the resistance of the piston to retraction and also can be used as an indicator of a frozen piston.
Furthermore, the resistance of a piston to retraction can be compared with the resistance of a piston in the disc brake assembly on the opposite wheel and thus determine whether the brakes are stopping evenly or not