GB470080A - A vehicle in which means are provided for varying the tread surface of the pneumatic tyres and for varying the force of adhesion of the wheels - Google Patents

Abstract

470,080. Vehicle wheels. MICHAEL, P. Feb. 7, 1936, No. 3815. [Class 144 (ii)] A device for adjusting tyre pressures according to road conditions comprises means which in one position connect the tyres to a pressure supply, said means being movable to another position for connecting the tyres to atmosphere to lower the inflation-pressure to a predetermined minimum. Auxiliary road-gripping devices may be fitted at one or both sides of the wheels to operate when the tyres are running under low-pressure. The apparatus shown comprises a manually-operated cock 1 by which the pressure-device pipe 2 may be placed in communication with a pipe 5, directly through a branch 3 or through a reducing-valve 8 in the branch 4, the pipe 5 leading to a chamber 57 in the axle-casing. Pressure-controlled means are provided for connecting the chamber 57 with the tyres through an axle-bore 6 and conduits 37, 47, the effective tyre-pressure being controlled by the position of the cock 1. For reducing the tyre-pressure, the cock is turned to the position shown in Fig. 2 whereby air at the desired reduced pressure is fed through the core 6 and ports 14, 16, 19 to a space 22 which is normally closed at its axially-outer end by a spring-loaded valve 24 and, at its inner end, is fitted with a piston 26 carried by a valve 28. The load on the valve 24 is adjusted to prevent the valve being unseated by the low-pressure in the space 22. This pressure, however, is sufficient to lift the valve 28 against the pressure of a spring 40 fitted between the valve 28 and a valve 38. Displacement of the valve 28 opens the chamber 84 to atmosphere through ports 29, 30, space 20, and ports 31 ... 35. The high-pressure existing in the tyre then operates, through conduit 37 and space 83, to unseat the valve 38 thereby opening the tyre to atmosphere through the chamber 84. After a predetermined fall of pressure in the tyre determined by the adjustable spring-load on the valve 38, the latter is returned to its seat to shut off the tyre from the chamber 84. The cock 1 is then turned to vent the space 22 and its. communications through the passage 8, the valve 28 being reseated by the spring 40. To reinstate high-pressure in the tyre, the cock 1 is moved to place the space 22 in direct communication with the high-pressure supply. The valve 28 becomes unseated and the valve 24 moved to close the atmosphere-vent 35, the tyre being further inflated through the conduit 47 and, after unseating of the valve 38, through the conduit 37. When the desired pressure is obtained in the tyre, the cock 1 is moved to vent the space 22. As shown in Fig. 5a, a rim 65 having ground-engaging strokes 61 is fitted at the side of the wheel to function when the tyre is operating at low pressures. A rubber cushion 64 is vulcanized to the rim 65 and an inner rim 66 which is detachably secured to a carrier ring 63 on the wheel.