Abstract: In a fixed ratio planetary-type traction roller transmission wherein planetary traction rollers are disposed in the annular space between, and in engagement with, a traction ring and a central sun roller for the transmission of motion therebetween, the planetary traction rollers have smooth side faces and are supported between, and guided by, a mounting plate structure at one side and a guide plate at the opposite side both having planar areas adjacent the traction roller side faces and being urged toward one another for retaining the traction rollers therebetween in parallel alignment.