GB642654A - Improvements in or relating to a rotational drive for heavy apparatus - Google Patents

Abstract

642,654. Transmitting power by gases. GENERAL AMERICAN TRANSPORTA- .TION CORPORATION. Feb. 17, 1947, No. 4504. Convention date, Feb. 16, 1946. [Class 8(ii)] [Also in Groups I and XXIX] 'Four fluid-operated motors are shown, Fig. 7, spaced 90 degrees apart, each having a U-shaped pawl on the end of its piston rod so that upon a power stroke each pawl engages with an annular gear 2 to cause it to rotate. In order to obtain a balanced driving effort only diametrically opposite motors 18 are arranged to operate together and since the return stroke is quicker than the power stroke, the thrust of a pair of motors may either commence just before or as soon as the thrust of the other pair of motors has ceased. 'To control the operation of the motors 18 there is provided a synchronous electric motor 99 operating two eccentrics 93 displacing 180 degrees relative to each other to control in any desired time relationship the valves A and Bone for each diametrically opposed pair of motors 18. Each valve A B comprises a sliding valve member 82, casing 70, with main inlet 72, conduits 74 and 76 leading respectively to the front and back end of each piston of a pair of motors 18, and exhaust conduits 78 and 80 so that with valve member 82 in the left-hand position shown pressure fluid entering conduit 72 is led by conduit 74 to the front end of each piston of a pair of motors 18 whilst fluid from the other side of these pistons flows through conduit 76 to exhaust conduit 80. With the valve member 82 in the righthand position the pressure liquid travels through conduit 76 and exhausts through conduit 74. The electric motor 99 may be replaced by a clock and servo mechanism. In a modification, the annular gear is located in an inverted position and the U- shaped pawls are maintained in contact, with the annular gear by means of springs or counterweights. The return strokes of the motors may be effected by means of springs. In another modification, the valves A and B are dispensed with and the tubular body 16b, Fig. 8, has' attached to it two gear boxes 122 wth a lower gear 123 meshing with a gear ring 124 secured to the gear 2, whilst above each gear box 122 is a rotary valve 126. Each rotary valve consists of a casing and a rotor 147, the casing having a main inlet conduit 127, an exhaust conduit 143 and a conduit 128 leading to one of 'two auxiliary slide valves 130. In the rotor 147 are passages 145, 146 which, depending upon the angular position of the rotor, connect the conduit 128 to either pressure or exhaust conduits 127 or 143, respectively. A chamber behind a piston 134, Fig. 9, in the auxiliary valve 130 is connected by a conduit 136 to a constant pressure source, which may be the inlet pressure in conduit 127. The rod of each piston 134 is attached to a piston 132 of one of the main slide valves into 'the casing of each of which latter enter conduits 136, 138 connected to a pair of diametrically disposed motors 22b and, conduits 140 and 141 which may open to atmosphere or system exhaust so as to relieve the pressure at each end of the main slide valve cylinder. When pressure is admitted through conduit 138 the pistons of diametrically opposite motors 22b will be driven forward and flues from the rear of the piston of each motor will be expelled through a conduit 148. At the end of the stroke the auxiliary valve 130 is reversed by rotation of gear ring 124 and rotary valve 126 so that conduit 138 is opened to exhaust conduit 141 'thereby enabling pressure fluid to enter conduit 148 and return the pistons of the pair of motors 22b in readiness for another power stroke. The other pair of motors are similarly controlled by the other rotary auxiliary and main valves to operate with a 180 degrees displacement in respect of the first pair of motors. The speed control of the mechanism may be effected by a pump connected directly to conduits 127, 136, 140, 141 and 148 or by a throttle valve.