Ratio control spool valve for a toroidal type infinitely variable traction roller transmission

Claim 1

In a transmission control spool valve for a toroidal type infinitely variable traction roller transmission comprising: a pair of power rollers disposed between and in rotating engagement with a pair of coaxial input and output discs for varying the transmission ratio by changing their tilting angle, a pair of roller support structures for supporting said power rollers and being slidable in an axial direction, a rotatable, circular cam disc connected to at least one of said roller support structures, a fluid operated actuating means for slidably urging said roller support structure and cam disc in an axial direction; the improvement wherein said control spool valve comprises: a valve housing fixedly attached to a fixed member and incorporating therein fluid passages, a spool slidably disposed in said valve housing so as to control supply of pressurized fluid to said fluid operated actuating means, a rotatable cam follower disposed between said spool and said circular cam disc, a resilient member allowing said cam follower to travel in an axial direction with respect to said spool, and a transmission ratio setting means for relatively moving said cam follower along an inclined cam face of said cam disc in the rotational direction of said cam disc to achieve a desired relative location between said spool and said fluid passages.