Patent GB-1016036-A (GB)
Title: Fluid pressure motor
IPC: F15B17/00
Filed: 1962-10-01
Abstract: 1,016,036. Fluid-pressure brakes. KELSEY-HAYES CO. Oct. 1, 1963 [Oct. 30, 1961], No. 37041/62. Heading F2F. A fluid pressure motor mechanism comprises a pressure-responsive member, an axially movable structure engaging the pressureresponsive member, a manually operable member, valve mechanism carried partly by the axially movable structure and partly by the manually operable member and being operable to move the pressure-responsive member, and means for utilizing pressure delivered to the pressure-responsive member for tending to prevent movement of the axially movable structure upon operation of the valve mechanism whereby, upon a drop of such pressure, the manually operable member may more readily move the axially movable structure to operate manually the pressure-responsive member. The fluid pressure motor 10 comprises a cylindrical casing 11 in which is a diaphragm piston 13 which in turn comprises a casting 14, slidable in the cylinder 11, a rolling type diaphragm 16 and a retaining plate 17 which clamps the inner edge of the diaphragm 16 and the periphery of a rubber bumper 25 to the casting 4. The outer edge of the diaphragm 16 is clamped between a flange 19 on the casing 11 and a flange 20 on a housing 22, which is secured to the frame of the vehicle by bolts 98 through a flange 97. In the housing 22 is a structure 55, one end of which penetrates a bearing wall 58, and in which are incorporated fluid pressure control valves for hydraulic operation and which, as a whole, can transmit pedal pressure for mechanical operation of the brake. This combination provides a chamber 28 which is always open to the atmosphere, through an air cleaner 46, and a fluid pressure chamber 29. The diaphragm piston 13 is connected by a push rod 42 to the piston 36 of the master cylinder 35 which operates the brakes. The structure 55 includes a cylindrical body 56 which is slidable in the bearing wall 58 through a seal 57 and is held in its normal position, as shown, by the restriction of its axial movement in one direction by the bumper 25 and in the other direction by a snap ring 60. The cylindrical-body 56 houses a valve member 74 and a sleeve 62, the latter, at one end, being a driving fit in a bore in the body, which bore is enlarged to provide an annular passage 63 around the outside of the sleeve. A port 83 communicates with grooves 84 in the end face of the body 56 and thence with the chamber 29. Mounted in the sleeve 62 is an axially movable member 68 with one end passing through a cap 85, threaded on the body 56, and screwed to a pedal-operated member 88. This is housed in a cover 94 fixed to the flange 97; there being grooves 99 in the adjacent flange face. A sleeve 54 surrounds the cylindrical body 56 and is seated at one end against the inside of the cover 94, where it is notched to provide apertures 101. The cap 85 carries an annular seal 86 slidable in the sleeve 54. In the normal position of the parts, as shown in the drawing, the chamber 29 is in communication with the atmosphere through grooves 84, port 83, a passage 76 through the valve member 74, a passage 77 leading to a space within an annular resilient valve 78, an axial bore 72 through the member 68, a passage 92 in the member 88, a chamber 93 inside the cover 94, the apertures 101, an annular space 100 between the cover 94 and the sleeve 54 and the grooves 99. A port 65 in the body 56 gives access from the annular passage 63 to a space within the sleeve 54 which forms a pressure reservoir 64, to which fluid under pressure is supplied through an inlet 115 va an annular space 116, between the sleeve 54 and the inside of the housing 22, and the open end of the sleeve facing the bearing wall 58. In normal brake application the cylindrical body 55 is held to the light, as seen in the drawing, by pressure in the reservoir 64 acting against the inside of the cap 85, and pedal pressure transmitted through a rod 106 moves the member 88 and 68 to the left, as shown, so closing a normally open valve 79 and blocking the communication between the chamber 29 and the atmosphere. The valve 79 is on the end of the member 74 and that therefore moves and so opens the valve 78. Pressure fluid from the reservoir 64 then flows through the port 65, annular passage 63, passages 77, 76, port 83 and grooves 84 into the chamber 29 and the piston 13 is therefore moved to apply the brake through the push rod 42. When resistance is encountered by contact of the brake shoes with the drums, back pressure raises the fluid pressure in the chamber 29 and the rise is reflected on the inner surface of a diaphragm 89, the backing plate 110 of which overcomes the force of a spring 111 and presses on a shoulder on the member 88 to give a resistance feel to the brake pedal. If there is a drop or failure in fluid pressure the cylindrical body 56 is not held back and the end of the member 68 comes into contact with the inner surface of the end wall 71 of the sleeve 62, and accordingly brake pedal operation, carried out beyond its normal short stroke, will transmit forces from the structure 55 through the bumper 25 to the diaphragm piston 13 to effect manual operation of the plunger 36.