TOROIDAL TYPE CONTINUOUSLY VARIABLE TRANSMISSION

PROBLEM TO BE SOLVED: To prevent generation of negative pressure by hydraulic servo by a structure capable of being compacted at low cost. SOLUTION: In a hydraulic control device A, an oil channel e is kept at lubrication pressure Plube, a first bypass check valve 136 or a second bypass check valve 135 keeps cut off between the oil channel e and, oil channels b1, b2, b3, b4 or oil channels c1, c, c3, c4 when first servo pressure PS1 or second servo pressure PS2 is higher than normal lubrication pressure Plube and, the same establishes communication between the oil channel e and, the oil channels b1, b2, b3, b4 or the oil channels c1, c, c3, c4 when the first servo pressure PS1 or the second servo pressure PS2 gets lower than the lubrication pressure Plube. Consequently, an oil chamber expanded by movement of a power roller is prevented from getting to negative pressure without providing, in an embodiment, an accumulator, a bypass valve or the like. COPYRIGHT: (C)2008,JPO&INPIT