Abstract: A tandem brake booster has a housing defined by a front shell that is joined to a rear shell to create an interior cavity. The interior cavity is divided by first and second diaphragm assemblies that are separated by a partition member to respectively isolate a first chamber from a second chamber and a third chamber from a fourth chamber. The first and third chambers are connected to fluid having a substantially constantly first pressure while the second and fourth chambers are connected to selectively receive the fluid at the first pressure or fluid at a second pressure. The partition member is characterized by a disc with a cylindrical body extending from a ledge formed on a peripheral surface of the disc and a flange located on the cylindrical body between the ledge and an end face of the cylindrical body.

Abstract: A brake booster (12) having a housing (18) with an interior separated into a front chamber (26) and a rear chamber (28) by a wall (30) retained on a peripheral surface (106) of a cylindrical body (34) of a hub (32). The cylindrical body (34) is characterized by having a radial flange (100) that extends from a first end (44), a ledge (102) located adjacent the radial flange (100), an annular shoulder (104) that extends from the peripheral surface (106) and a groove (108) located between the ledge (102) and shoulder (104). The groove (108) has a depth (d) adjacent the shoulder (104) that is approximately equal to the height (h) of the shoulder (104) above the peripheral surface (106) and a side wall (110) that transitions from the groove (108) into the ledge (102). The wall (30) is characterized by a metal disc (38) having an axial flange (202) that extends from a first end (204) into an annular slot (218) in a diaphragm (36) to define a lip (40).