Vacuum booster

Claim 1

A vacuum booster comprising a casing, a resilient diaphragm in said casing and having the outer periphery secured to the casing and dividing the interior thereof into two chambers, means connecting one of said chambers permanently to a source of vacuum, a power piston secured to said diaphragm, a valve mechanism incorporated in said power piston for selectively connecting the other chamber with said one chamber or a source of pressure higher than the vacuum pressure, an input rod connected to the valve mechanism for actuating the valve mechanism for generating differential pressure between said two chambers, an output rod member for receiving the force corresponding to the differential pressure from the power piston, said valve mechanism having a member on an end toward said output rod member, a pin-and-socket connection connecting the output rod member to said member of said valve mechanism, said pin-and-socket connection having a pin on one of said members and a socket on the other of said members snugly receiving the pin, said pin having an annular groove therein and a generally U-shaped resilient wire rod with two parallel arm portions engaged in said groove with an axial clearance sufficient for allowing free relative axial movement between the pin and socket corresponding to the dimension of said groove along said pin in a normal operating condition of the vacuum booster, said socket having two diametrically opposite grooves each extending along a chord of the socket and completely through the thickness of the wall of the socket in which the parallel arm portions are received for projecting into the annular groove in said pin, whereby said resilient wire rod prevents escape of said pin from said socket during assembly or repair of said vacuum booster.