334,503. Salerni, P. M., May 1, 1929. Clutches, claw ; facilitating changing speed.- Relates to power-transmission mechanism for mechanically-propelled vehicles, wherein in addition to the main engine clutch a coupling is employed, for example between the gear-box and the road wheels, as described for instance in Specifications 306,636, and 333,222, so as to permit coasting and facilitate speed-changing. Movement of the main clutch pedal unclutches the main clutch and the coupling against the resistance only of the main clutch spring, which latter in returning the main clutch, sets the operating spring of the coupling in readiness to reclutch the coupling when required, for example when its parts are running in synchronism. The coupling is preferably of the type described in Specifications 333,222 and 333,234, in which a baulking-ring with inclined teeth engaging similar teeth on the driven part of the coupling prevents re-engagement of the coupling except upon synchronism. The driving-shaft A carries a sliding clutch member A<1> engageable with the driven member B<1>, as described in Specification 333,234, but the baulking-ring is, as described in Specification 333,222, formed in three parts C, C<1>, C<2> interconnected for common rotation by pins C<5> secured in the part C<2>, and the projections B<5> on the member B' have additional inclined faces B<5>x for engagement by the pins C<5> when effecting clutch re-engagement before the shafts synchronize naturally. The part C<2> engages an antifrictional washer D on a sleeve A<3> splined to the member A<1> and is spaced by springs C<6> from the ring part C', additional springs (not shown) spacing the part C<2> from the presser-plate E<1> of a multiplate clutch E interconnecting the pins C<5>, and thus the whole baulking-ring, with a sleeve A<4> splined to the member A<1>. A loose ring F is arranged between the washer D and a series of brake, plates G splined on the member A<1>, and the ring F is trunnioned to a bell-crankoperating-lever H, H<1> on a rock shaft I, a cross pin J<3> in which pivotally supports a cam J with projections J', J<2> adapted for engagement respectively with lugs K<1>, K<2> on a lever K which carries a toothed segment L' engaged by a similar segment on a shaft M which is linked to move with the main engine clutch pedal. A lever N moving with some lost motion relatively to the lever K is secured to one end of a torsion spring (not shown) of which the other end is secured to the shaft L to which the lever K is keyed. A spring plunger J<4> parallel with the shaft I slides in the casing and, as the shaft rotates, swings the cam J about its pivot pin J<3> to move the projections J<1>, J<2> alternatively into the paths of the lugs K<1>, H<2>. When the clutch A<2>, B<2> is engaged, full depression of the main clutch pedal turns the shafts M, L so that the lug K<1> engages the projection J<1> and turns the arm H farther to the right than the position shown so as to press the brake plates G against a stationary member G', so disengaging the clutch and slowing the shaft A<1> to facilitate speed changing. Release of the main clutch lever then allows return of the parts to the position shown, further movement of the part A<1> being prevented, while the shaft B is overrunning, by the baulking-ring. During the return of the lever K, the arm N moves freely therewith until it strikes the temporarily stationary lever H' on the shaft I. when its lost-motion connection with the lever K permits it to stop, so that the torsion spring exerts a force opposing that of the main engine clutch spring, partial engagement only of the main clutch to speed up the shaft A thus being possible. Meanwhile the pressure of the torsion spring, but not of the main clutch spring, owing to the main ' clutch parts being in engagement, is exerted upon the arm H<1> so as to cause engagement of the clutch A<2>, B<2> when the shaft speeds synchronize. This action takes place without compression of the springs C<6> ; further. it removes the opposing effect of the torsion spring, so allowing the main clutch to engage fully, and it allows the arm N to move downwards to a position in which it prevents return movement of the lever H<1> to disengage the clutch A<2>, B<2>. If it is desired to engage the clutch A<2>, B<2> before the shaft A synchronizes with the shaft B. as when the engine is stalled upon a down slope, the engine clutch pedal is again depressed and as the projection J<2> is, due to the plunger J<4>, in the path of the lug K<2> the shaft I is turned in the opposite direction, so that the baulking-ring part C<2> is moved against the springs C<6> to cause the heads of the pins C<5> to engage the faces B<5x> of the projections B<5> and turn the baulking-ring to permit engagement of the clutch A2, B<2> under pressure of the foot. At the same time. the pressure plate E<1> is moved by pressure of the part C<2> against the additional springs referred to, to engage the clutch E to connect the member A<1> to the baulking-ring, and thus frictionally to the rapidly moving driven member B, so that the member A<1> is brought to approximate synchronism with the member B'. When the abutment of the part C upon the member B is thus released, the part C advances upon the pins C<5> to release the clutch E and free the ring from, the member A<1>.