Patent GB-250913-A (GB)
Title: Improvement in power actuators or servomotors
IPC: B60T13/24
Filed: 1926-03-10
Abstract: 250,913. Bragg, C. S., and Kliesrath, V. W. April 16, 1925, [Convention date]. Fluid-pressure.-A pneumatic or hydraulic relay for operating brakes &c. comprises a doubleacting piston in a cylinder, provided with a cylindrical valve chamber having ports connecting it with the cylinder on either side of the piston, and a piston valve within the chamber, the valve having a suction chamber open to the interior of a sleeve operating the valve and cylindrical portions adapted to register with the ports, and means for admitting higher pressure fluid to both ends of the valve chamber. The operation of the valve controls the supply and exhaust of fluid to the ends of the cylinder and so actuates the piston and a part connected to it. Fig. 1 shows the piston carrying a tubular rod 7 passing through the cylinder stuffing-box and fitted with a lug 10 for attachment to a part of the brake, clutch, or other mechanism of a motor vehicle or aircraft; a pressure fluid inlet 11 is provided in the end of the rod. The piston hub is formed as a hollow valve chamber containing a valve 14 mounted on a hollow rod 20 passing through a stuffing-box in the other end of the cylinder and having a lug 30 for attachment to a brake pedal &c. The hollow rod 20 is divided by a plug 17 into a suction part open to a suction pipe 29, connected e.g. to the inlet manifold of an internalcombustion engine, and a pressure part open to the pressure, inlet 11, each of these parts having ports 18, 26. The suction ports 18 communicate with a suction chamber 23, Fig. 3a, in the valve 14, the pressure ports lead directly to one end of the valve chamber and through longitudinal passages in the valve to the other end. By operation of the valve one or other of the ports 15, 16, in the piston hub may be opened to the suction chamber 23 while the other is opened to the end of the valve chamber, and the piston is moved accordingly. A spring 31 fnr returning the. valve e.g. in the operation of brake mechanism is disposed. between the valve rod 20 and the pistonrod 7. The rod 20 has a flanged nut 37 which can be brought into contact with the end of the piston-rod by further actuation of the pedal when the brake mechanism has been automatically actuated to its fullest extent, thereby giving a further motion; foot or hand actuation in case of power failure is also rendered possible. The spring may be dispensed with, operation of the valve being effected by the operator in each direction. According to the Specification as open to inspection under Sect. 91 (3) (a), Fig. 4 (Cancelled) shows a modified apparatus, suitable for aviation control or for steering motor boats, in which the piston-rod extends at each side and wholly encloses the valve rod, connections 130, 130a. 110, 110a being provided at each end for the actuating means and the actuated parts. In a modified valve construction, Fig. 6a Cancelled), the ports 215, 216 are in the normal or off position open to vacuum. The relays may be subject to vacuum and atmospheric or super pressure, or to vacuum and super pressure on opposite sides. Fig. 7 (Cancelled) shows an hydraulic relay operated by a continuous circulation of oil from an inlet 311a to an outlet 329, the valve being constructed, as in Fig. 8a (Cancelled), to allow this free flow in the normal position. Movement of the valve closes the connection of one of the ports to the suction passage, and pressure building up on one side of the piston moves the piston and its connected part. In a further modification, independent oil inlets are provided to each end of the valve chamber, the longitudinal passages through the valve being omitted. This subject-matter does not appear in the Specification as accepted.