PROBLEM TO BE SOLVED: To facilitate the maintenance of an operating oil filter and an operating oil cooler by reducing the number of pipes of an operating oil supplying system of an HST type transmission provided with an HST-type continuously variable transmission for traveling and an HST-type continuously variable transmission for turning and in which two hydraulic pumps and two hydraulic motors are arranged. ;SOLUTION: In a structure in which two hydraulic pumps and two hydraulic motors are integrally arranged, two hydraulic pumps are arranged in series, pump shafts of respective hydraulic pumps are connected to each other by a coupling and driven, a center section in which an oil passage is formed is arranged on a part on which the coupling is arranged, two hydraulic pumps are provided on the center section, and a system of operating oil from an operating oil tank T to an HST type transmission is formed into a single system in which discharged oil from a charge pump is supplied from a charge pipe A2 and returned through a drain pipe D to the operating oil tank.;COPYRIGHT: (C)1998,JPO
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