Patent GB-243707-A (GB)
Title: Improvements in or relating to power transmission mechanisms
IPC: F16D3/80
Filed: 1925-11-13
Abstract: 243,707. Invernairn, (W. Beardmore), Lord, and Chorlton, A. E. L. Nov. 27, 1924, [Convention date]. Controlling clutches or variablespeed gearing.- A torque responsive coupling is adapted through the medium of a fluid pressure system to disconnect clutch or like driving mechanism when the torque is excessive. The clutch or like device connects driving and driven members A, B, Fig. 1, and it is held in engagement by means such as plungers H actuated by pressure liquid passing through a central valve K to a duct N. The torqueresponsive control coupling C, which may be of construction shown in Fig. 4, lies between a first driving-shaft A<1> and the shaft A. One member C<1> of the coupling has an extending sleeve A<3> which, in normal drive, closes the end of the duct N as shown in Fig. 2, so that the liquid pressure is maintained on the clutch &c. The yielding produces a turning of the sleeve A<3> relatively to the other coupling member C<2> in the direction of the arrow, so that ultimately a port N<2> opens the duct N to exhaust, releases the clutch, and disconnects the drive. A second relief port N<3> is provided to prevent the member B from driving the shaft A<1>. In a modification shown in Fig. 3, additional narrow and progressively narrowing ports N<4>, N<5>, N<6> are provided which have the effect of engaging the clutch &c. driving-mechanism gradually in starting. In the arrangements particularly described, the driving-mechanism is variable-speed epicyclic gearing actuated by friction clutches and brakes of the plate type as described in Specification 236,545, the whole being applicable for locomotives driven by internalcombustion engines. In Fig. 1 is shown an epicyclic gear yielding three definite speeds with intermediate ratios produced by slipping of the plate devices. Planet elements. B<3> are carried by the shaft B. An intermediate shaft E carries a sung gear E<1>. There is a brake 1 for arresting the internal ring F<1>, a clutch 2 for connecting the shaft A to the ring F<1>, a clutch 3 for connecting the shafts A, E. and a brake 4 for connecting the shaft E to a fixed frame G. The definite ratios are effected by actuating in combination the devices 1, 3, the devices 2, 4, and the devices 2, 3 respectively. The plate devices 1, 2, 3, 4 are actuated by plungers H actuated by pressure liquid distributed by the sliding central valve K. The three speeds correspond to positions K<1>, K<2>, K<3> of the valve K. In the position shown, the bore of the valve is connected to relief passages L<5>, L<6> and the drive is disconnected. The spring control coupling C acts in the manner described to release clutches and brakes on any speed. The pressure liquid is drawn by a pump M from a chamber M<1>, there being a safety device M<5>. In a modification shown in Figs. 4 and 5, the pressure-easing control valve 0 is arranged externally of the gear structure. Each of the coupling members C<1>, C<2> carries its own set of planet gears Q<1> and R<1>. The effect of yielding in the coupling is to set up differential action displacing a lever V and with it the valve 0.