GB183172A - Improvements in or relating to hydraulically operated variable speed gears - Google Patents

Abstract

183,172. Smith, M. M. Feb. 21, 1921. Clutches and' speed-varying mechanism.-An hydraulic variable-speed and reversing gear comprises pumps A, a of the axially-sliding vane or other type in which the working spaces enlarge and diminish circumferentially, Fig. 2, mounted on the driving-shaft B and a normally stationary sleeve C respectively, and a driven casing which may be connected to a shaft E. In the first form the pump members are provided with circumferential grooves A<1>, A<2>, A<3>, a', a<2>, a3 into which project fixed abutments, the vanes A<5>, a<5> are operated by cam-surfaces on the ends of the casing and on a central cam-block H, and a sleeve fixed to the casing is provided with ports for each pump member. Surrounding the sleeve is a valve G, axially adjustable to produce speed variations and reverse drive, and provided with longitudinal slots L, Fig. 1, and passages L<1>, L<2>, L<3>, L<4>, L<8>, L<9>, L<10>. When the valve is in the position shown in Fig. 1, the inlet and outlet ports of the pump A are open to the slots L, and a direct drive is obtained, the sleeve C carrying the pump a being allowed to rotate. By moving the valve to the left, the whole of the ports of the pump A are first connected to the first series of ports of the pump a through the slots J, and thereafter the number of ports of the pump A open to the slots J decreases, while the number of ports of the pump a communicating with them increases, a progressive reduction in speed being thus obtained. When none of the pump A ports are open to the slots J, no drive is transmitted, the inlet and outlet ports of this pump being put into communication with each other past the end of the valve sleeve or through the passages L<1>, L<4>. The reverse drive is obtained by moving the valve still farther to the left, until a -projection F<8> on a stationary block engages a recess G<2> in the valve, the pump outlet ports J<1> being then put into communication with ports j<1>, j<2>, j<3> through passages L<1>, L<2>, F<7>. L<3>, recesses F<9> and slots L. The valve is provided with longitudinal passageways, through which liquid can pass from one end of the casing to the other as the valve is moved and from which liquid can pass to the slots L under the control of automatic non-return valves. In a modification, the valve is divided into two parts M, m, Fig. 6, separated by two pairs of half-rings N, O. Longitudinal and transverse slots M<1>, M<2>, m<1>, m<2> are provided, passages M<3>, m<3> connecting each transverse slot with a longitudinal one, and passages M<4>, m<4> leading from each transverse slot up to the rings N, 0, which are each provided with a series of perforations. For all forward drive positions, the longitudinal slots M<1>, m<1> are in communication with each other through registering perforations in the rings, while communication between the passages M<4>, m<4> is interrupted. In order to obtain a reverse drive, the rings N, O are moved in opposite directions to interrupt communication between the slots M<1>, m<1> and establish it between the passages M<4>, m<4>. The valve is moved axially to secure speed variations by rods P and a yoke P<8>, mounted on a collar on a shaft Q which is held against rotation by rods Q<3> engaging grooves Q<4>, and slid endwise by means of a lever Q<6>, and a sleeve Q<5> having internal helical splines engaging helical grooves on the shaft Q. The rings N, O are operated by projections P<6>, P<7> on rods P<4> connected to a yoke mounted on a sleeve R, which is prevented from rotation by rods R<4> engaging guides and has internal helical splines engaging grooves on a shaft R<2>, which is rotated by a lever R<6> and squared shaft R'. In a further modification, the casing is formed of concentric parts D<4>, D<5>, Fig. 10, the pump members are adjacent to the casing, and enclose a liner F, inside which is a valve surrounding the driving- shaft B. The valve comprises portions S<1>, T<1>, carried by sleeves S, T and provided with slots V<1>, V<2>, v<1>, v<2>, Fig. 13, and discs U provided with slots V. Speed variations are obtained by moving the valve axially, and the reverse by rotating the sleeve T through a right angle relatively to the sleeve S, so as to bring the slots V into the echelon formation shown in Fig. 13, by means of bars U<1> passing through the discs. The brake drum C<1> which normally prevents the sleeve C from rotating may be utilized as an oil reservoir; or an oil reservoir may be mounted on the shaft B. A pendulum ring C<2> weighted at C<3> carries tubes C<4>, C<5>, the tube C<4> serving as an oil inlet to the gear and the tube C<5> as an outlet. Oil passes through the tube C<4> to an annular chamber C<6>, and through passages C<7> to a chamber x, where it is available to replenish leakage through passages Z<4> controlled by ball valves Z<3>. Passages for lubricating lead from the chamber C<6> to hollows in the cam-surfaces d<2>, from which lead ducts x<3>, x<4>, X<4>, X<3>, the last of which communicates with a chamber X. Surplus oil returns to the reservoir through a clearance between the shaft B and the sleeve S, holes Y', Y<2> and the tube C<5>. Air present in the gear also passes to the reservoir and escapes at C<9>.