CONTINUOUSLY VARIABLE TRANSMISSION

PROBLEM TO BE SOLVED: To suppress a decline of transmission efficiency of the whole HMT by suppressing an efficiency decline of HTS especially in the region of a high change gear ratio in a continuously variable transmission which operates a change gear in multiple-divided modes. SOLUTION: A mechanical transmission is interposed between an input shaft 1 and an output shaft 2, and a hydrostatic transmission 4 is disposed in parallel. A third planetary gear mechanism P3 , which decelerates the number of revolution of the input shaft to 1/2.5 time in the region of low to medium change gear ratio, and the fourth clutch mechanism CL4, which transmits the number of revolution of the input shaft as it is in the region of a high change gear ratio bypassing the third planetary gear mechanism P3 , are interposed between the input shaft and the input side of MT. Intermittent switching control of clutch mechanisms CL1-CL6 is operated by a clutch control part 17, and swash-plate angle control of a variable swash plate and a swash plate is operated by a swash-plate control part 18, in the regions of all change gear ratios divided into five modes. The switching from a third mode to a fourth mode is performed at the time of a small swash-plate angle of the variable swash plate 51 before reaching the maximum swash-plate angle, and the swash plate 61 is changed to 7 degrees on the side of a medium change gear ratio to the high change gear ratio side of the fourth mode and in the fifth mode.