Abstract: A vacuum booster device having a diaphragm the inner peripheral portion of which is rigidly clamped between the outer peripheral portion of a valve body and the central portion of a piston plate, wherein a rigid annular ring is attached to the diaphragm for preventing the radial outward movement of the material of the inner peripheral portion of the diaphragm when the diaphragm is compressed axially between the valve body and the piston plate.

Abstract: A vacuum augmentation device for use with a vehicle braking system and of the type having a body, a diaphragm-piston mechanism providing a pair of fluid chambers in the body, valving for isolating or communicating the chambers, a push rod actuated plunger assembly for operating the valving, an output rod shiftably mounted in the body and carrying a fulcrum plate, and a number of reaction levers for effecting a lever type coupling between the diaphragm-piston mechanism, the shiftable plunger assembly and the fulcrum plate on the output rod is provided with improved structure for coupling the reaction levers with the diaphragm-piston mechanism, which structure employs a mounting plate member engaged with the mechanism and carrying on the opposite side thereof an elongate fulcrum pin for each reaction lever which is longitudinally engageable with the latter in line contacting relationship to provide a radially fixed fulcrum for each of the reaction levers.

Abstract: A vacuum degree augmentation device for use in brake apparatus is provided in which a diaphragm-piston divides the body of a valve mechanism into two air-tight chambers, the valve mechanism is shiftable in response to the operation of a plunger which in turn operates in response to the operation of an input rod, the operation of the valve normally maintains the chambers in communication with each other under low pressure, but, during braking, one chamber is placed in communication with the open air to produce a differential pressure between the chambers so as to operate the piston, with the force operating the piston being transferred through a reaction lever, a fulcrum plate and an output rod to a master cylinder.

Abstract: In a power piston for use in a booster which includes a piston plate coupled with a diaphragm for receiving differential pressure acting thereacross, a valve body one end of which being secured to the center portion of the piston plate and a valve mechanism disposed in the valve body, the improvement resides in that there are provided a head portion and a hole respectively on one end of the valve body and in the center portion of the piston plate which have complementary configurations such that the hole can receive the head portion only when they are at specific angular positions, and there is provided a neck portion continuous with the head portion of the valve body and having an axial length sufficient to receive the piston plate thereon, the inner circumferential portion of the diaphragm is clamped by means of the piston plate and thus secured to the valve body.