Hydraulic actuators

Claim 2

A disc brake comprising a stationary housing of substantial mass, a radial braking surface in the housing, a rotatable shaft within the housing, at least two rotatable friction discs mounted on the shaft, a static disc located between adjacent rotatable friction discs, and fluid pressure means for urging the disc assembly against said radial braking surface, wherein said fluid pressure means comprises co-operating annular cylinder and piston elements, one of which is movable to apply axial pressure to the discs, and a thin metal shell of channel section fixed to the housing and forming a surface which, together with said movable element, constitutes said fluid pressure means, said movable element and said static disc being keyed to the shell against circumferential movement relative thereto whereby torque taken by said movable element and said static disc is transmitted through the shell to the housing.

Claim 3

A disc brake adapted to be fitted within a rigid casing and incorporating at least one stationary friction surface and one rotatable disc, axial pressure against said disc being provided by a hydrauilc actuator comprising a pair of co-operating annular cylinder and piston members, one of said members being movable by hydraulic pressure against said rotatable disc to take braking torque upon application of said brake and the second of said members being fixed to the casing, the co-operating surface between said one and second members being formed by a thin metal shell, a sliding seal being provided between the second member and the shell, means fixing said one member and said shell against relative circumferential movement so that the braking torque taken by said one member is transmitted directly to said shell, and means fixing said shell and said second member against relative circumferential movement so that said braking torque is transmitted by said shell directly to said second member and said casing.

Claim 4

A disc brake adapted to be fitted within a rigid casing and incorporating at least one stationary friction surface and one rotatable disc, axial pressure against said disc being provided by a hydrauilc actuator comprising a pair of co-operating annular cylinder and piston members, one of said members being movable by hydraulic pressure against said rotatable disc to take braking torque upon application of said brake and the second of said members being fixed to the casing, the co-operating surface between said one and second members being formed by a thin metal shell, a sliding seal being provided between the second member and the shell, means fixing said one member and said shell against relative circumferential movement so that the braking torque taken by said one member is transmitted directly to said shell, and means fixing said shell and said second member against relative circumferential movement so that said braking torque is transmitted by said shell directly to said second member and said casing.

Claim 5

A disc brake as in claim 2 wherein the member having its co-operating surface formed by a metal shell comprises an annular piston fixed to the casing, the outer member comprising an annular cylinder.

Claim 6

A disc brake comprising a stationary housing of substantial mass, a radial braking surface in the housing, a rotatable shaft within the housing, a rotatable friction disc mounted on the shaft, and fluid-pressure means for applying axial pressure to the friction disc to force it into engagement with said radial braking surface, wherein said fluid pressure means comprises co-operating annular cylinder and piston elements, and a sliding seal between said elements, one of said elements being movable to apply said axial pressure to said friction disc and to take torque upon application of said brake, and the other of said elements comprising a thin metal shell of channel section fixed to the housing, and means keying said movable element directly to the shell so as to prevent circumferential movement of said movable element relative to said shell so that the torque taken by said element on application of the brake is transmitted directly through the shell to the housing.

Claim 7

A disc brake comprising a stationary housing of substantial mass, a radial braking surface in the housing, a rotatable shaft within the housing, a rotatable friction disc mounted on the shaft, and fluid-pressure means for applying axial pressure to the friction disc to force it into engagement with said radial braking surface, wherein said fluid pressure means comprises co-operating annular cylinder and piston elements, and a sliding seal between said elements, one of said elements being movable to apply said axial pressure to said friction disc and to take torque upon application of said brake, and the other of said elements comprising a thin metal shell of channel section fixed to the housing, and means keying said movable element directly to the shell so as to prevent circumferential movement of said movable element relative to said shell so that the torque taken by said element on application of the brake is transmitted directly through the shell to the housing.

Claim 8

A disc brake as in claim 4 wherein the annular piston is defined by an annular projection on the housing and the thin metal shell fits closely over the projection, the movable element comprising an annular cylinder axially movable over the shell, said sliding seal being disposed between said cylinder and said shell.

Claim 9

A disc brake as in claim 4 wherein the annular movable element engages directly with the rotatable friction disc.

Claim 10

A disc brake as in claim 6 where the movable element is an annular piston.