GB225384A - Improvements in change speed gear - Google Patents

Abstract

225,384. Rowledge, A. J. Dec. 4, 1923. Controlling variable-speed gearing.-A two speed gear used with an internal-combustion engine is operated by hydraulic means under manual control, and using "scavenger" oil, speed change being possible only when the engine throttle, is closed or nearly so, the whole being specially adapted for aircraft. In Fig. 1. d is the hydraulic cylinder which operates the two-speed gear inside casing b alongside, crank case a<1>. Valve e controlled by lever p admits oil to the cylinder from pump g unless valve f connected to the throttle a<2> allows the oil to pass freely by pipe g<3> to tank g<1>. When the throttle is closed, oil from the pump can be directed into the cylinder by movement of the lever p. Thus bv turning valve e, Fig. 2, oil from pipe g<2> passing the valve f by conduit d<8> is directed to either end of the cylinder d by conduits d<3>, d<6> while the other end is connected by conduit d<5> or d<4> and aperture e<3> to exhaust, that is to the tank via pipe g<3>. When the throttle is open, barrel valve f allows the oil to pass freely by conduit d<11> to pipe g<3>. The valve e is shaped as shown in Fig. 4, the lower opening e<4> distributing pressure oil to either end port. the upper opening e<3> allowing exhausted oil to pass away over the end of the valve. The speed is' changed by imparting a part turn to a spindle c, Fig. 2, to which is secured a bell-crank lever c<2>. One arm of the lever c<2> engages the end of the piston rod d<131>, the other arm forming part of spring toggle c<9>. which toggle ensures completion of the motion to fully engage a plate clutch forming part of the speed gear, not shown.