Abstract: A apparatus for forming a brake actuator that includes a flange case defining a peripheral groove circumscribing a push rod movable axially in relation to the flange case whereby the push rod presents a push rod guide bushing on the bearing surfaces of the push rod guide bushing being in contact with a seal. An automatic manipulator of the apparatus moves in multi-axial directions relative the flange case. A tucking tool of the automatic manipulator holds the seal. The tool includes at least two members movable relative to one another. First member rotates around the axis of the tucking tool and presents a tucking surface for forcing the seal into the peripheral groove of the flange case. Second member gradually injects the seal into the peripheral groove and pushed the seal into the back wall of the peripheral groove.