Importance

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Abstract

An arrangement for operating a CVT transmission of a motor vehicle is proposed which comprises a hydraulic circuit supplied from a hydraulic pressure source (8) having two parallel second branches (16, 17) attached to the first branch (9) of the hydraulic circuit each for supplying pressure to a hydraulic actuator (4, 5) for respectively a cone pulley pair (2, 3) of the transmission wherein with the first branch (9) and each second branch (16, 18) an independently controllable pressure valve system (12, 13, 18, 19, 20, 21) is associated for adjusting the hydraulic pressure in the respective branch (9, 16, 17). According to the invention at least one of the pressure valve systems (18, 19, 20, 21) associated with the second branches (16, 17) has a controllable pressure-differential valve (18, 19) connected between the first branch (9) and the second branch (16, 17) concerned. At the same time the control unit (15) is designed for the purpose of optionally working in a first pressure control mode in which it adjusts the pressure in the second branch (16, 17) attached to the pressure-differential valve (18, 19) by control of the pressure valve system (12, 13) associated with the second branch (9) without control of the pressure-differential valve (18, 19), or in a second pressure control mode in which it adjusts this pressure by control of the pressure-differential valve (18, 19) at will under simultaneously control of the pressure valve system (12, 13) associated with the first branch (9).

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First Claim