In a gear synchronizer assembly of the well-known type, a clutch sleeve is formed at its inner periphery with an internal radial projection, and a thrust mechanism comprises a radially contractible annular resilient member supported in place by engagement with the inner circumference of an outer cylindrical hub portion of a hub member fixed to a transmission shaft. The resilient member has an axial leg extending therefrom toward the internal radial projection of the clutch sleeve and having a radial projection which is arranged to be engaged with the internal radial projection in shifting operation of the clutch sleeve toward a spline piece integral with a change-speed gear and arranged to abut against and urge a synchronizer ring toward the spline piece upon engagement with the internal radial projection.

A synchronizing arrangement for a gear transmission includes a synchronizing ring and the surrounding annular spring, the ring having at least three equally spaced support elements at the circumference of the ring at which the spring is snugly supported with a press-fit about the ring. The support elements and the spring define opposing contact surfaces which are relatively adjustable upon assembly of the annular spring about the ring in order to balance manufacturing tolerances.

An inertia lock type synchronous clutch mechanism in which elastic ring members on blocking rings are engaged by a shift sleeve splined to a clutch hub at a plurality of sloped circumferential cam portions protruding from the inner circumference of the sleeve so that the blocking rings are moved axially into frictional engagement with tapered cone portions of synchronized gears by the force applied through the elastic ring members by the axial shifting action of the shift sleeve. Each of the elastic ring members is formed with a plurality of outwardly convex portions corresponding to the respective cam portions and concave portions between the convex portions so that the elastic ring member concave portions engage grooves formed in the outer circumference of the boss portion of each of the blocking rings, whereby excess bulging of the elastic ring member is prevented.

Spline teeth 66 formed in the inner periphery of a sleeve 45 slidably supported on a hub 63 fixed to a rotation shaft each comprise a projecting portion 66a constituted by a first inclined surface .alpha., a flat surface .gamma. and a second inclined surface .beta., and these projecting portions 66a bias a blocking ring via a synchro-spring 71 in an axial direction to thereby generte a synchronizing load between the sleeve 45 and a gear 37. Immediately before the projecting portions 66a of the spline teeth 66 of the sleeve 45 moving rightward mesh with dog teeth 37a of the gear 37, the second inclined surfaces .beta. of the projecting portions 66a move and ride on the synchro-spring 71 so as to gradually reduce a pressing force axially applied to the blocking ring 67, thereby making it possible to provide a smooth mesh engagement between the spline teeth 66 of the sleeve 45 and the dog teeth 37a of the gear 37.

A hydraulically operative clutch type transmission especially for industrial and loading vehicles comprises a casing accommodating shift gear mechanism therein, a housing connected to the casing, an input shaft journalled to the housing, a main shaft connected to the input shaft, a gearing member, a hydraulically operative clutch device which comprises a clutch drum connected to the main shaft and a clutch hub connected to the gearing member, a washer plate interposed between the gearing member and sleeve end of the clutch drum, the main shaft including a large diameter portion having a notch with a plain surface, and a small diameter portion, a gear member of the gearing member being rotatably supported on the large diameter portion, the clutch drum mounted on the small diameter portion, and the washer plate including a fasting portion which is engaged with the notch.