Patent GB-346548-A (GB)
Title: Improvements in power transmission mechanism
Filed: 1930-03-19
Abstract: 346,548. Claw and free-wheel clutches ; facilitating changing speed. KNIGHT, J. A., 13, Dickson Chambers, Blackpool. March 19, 1930, No. 8746. [Class 80 (ii).] In a free-wheel isolating clutch of the pivoted pawl type for use in motor vehicles, to be placed either in the gearbox on each speed of the speedchange mechanism, between the gearbox and propeller shaft, or in duplicate in the rear axle to form a free-wheel differential, driving pawls fare held in engagement with a driven ratchet wheel a by centrifugal force and gravity acting on slightly heavier counterweights s, and are held out of engagement during overrunning by the oil carried round by the ratchet wheel. The driving member c whereon the pawls are pivoted is freely mounted on the driven shaft b and is driven by dogs c3, g2 on itself and on the driving shaft g. Dog clutch looking means h, d are provided, the sliding dog h being operated against a spring r by a rod l connected with the reverse gear or by a rod # connected to a hand control, pins and slots m, n, p, q permitting independent operation. In place of the casing shown in Fig. 1 (Comp.), a casing may be formed by the cast driving member c which then has an outer flange to which member c<1> is bolted. In this form there is a clutch-stop-like brake shoe connected with the main clutch and pressing on the casing to retard it and the change speed pinions whilst the main clutch is disengaged, to facilitate changing speed. Holes are provided in the casing to permit free entry and egress of oil in which the casing may be immersed. There is an odd number of ratchet teeth to an even number (four) of pawls as shown in Fig. 4 (Comp.) to reduce slip on engagement. In the form shown in Fig. 6 (Comp.), the counterweights are outside the casing on short arms on the pivots e of the flat pawls f which fit closely in the casing. The pawls are engaged by flat ratchet teeth a<1> and shock of engagement is cushioned by oil trapped between the flat surfaces. During overrunning the pawls lie back in recesses in the casing under the influence of the oil flow. With reference to Fig. 1 (Prov.), there is described a modified locking device in conjunction with a free-wheel clutch of the form described with reference to Fig. 6 (Comp.) above, this comprising ratchet-faced looking members b, h, the driving member h being directly connected by arms j to a slidable operating collar i connected by tension springs k to a disc e fixed to the driving shaft #. The collar i is operated by the main clutch pedal through a rod #, and carries hinged rods passing through holes in a controlling disc m the position of which determines the radial position of the free ends of the rods and whether they, by passing through slots t in the disc d, shall permit engage. ment of the members b, h upon release of the pressure on collar i. The slots t at one end are inwardly enlarged and slight relative rotation is permitted between member d and the driving shaft. With disc m close to collar i, Fig. 1 (Prov.), positive engagement is prevented and the device functions as a simple free-wheel. In the intermediate position of disc m positive engagement is prevented until the engine commences to overrun. In the final position with disc m against disc e the rods can pass through the slots regardless of the relative shaft positions. The Provisional Specification states also that the mechanism is applicable generally.