Patent ID: 8308606

Claim:
A hydraulic supply system for a hydraulically-operated, belt-driven conical pulley transmission having two conical disc pairs connected with each other by an endless torque transmitting means, said hydraulic system comprising: a primary pump that is driven by a primary pump drive for providing hydraulic pressure in a supply line that is connected via a transmission ratio adjusting valve to at least one adjusting chamber associated with at least one conical disk pair; at least one connecting line connected to at least one torque sensing chamber associated with the at least one conical disk pair and through which pressurized hydraulic fluid flows, wherein an outlet flow cross-sectional area available to the pressurized hydraulic fluid that flows through the torque sensing chamber is a function of a torque transmitted to the transmission; a pilot valve connected between the supply line and a control line in which a control valve is located and by which control valve a pressure in the control line that determines a position of the transmission ratio adjusting valve is adjusted; an auxiliary pump driven by an auxiliary pump drive that is separate from the primary pump drive, wherein the auxiliary pump has a unitary discharge line connected with the control line and wherein the unitary discharge line is connected with the supply line by a branch line branching from the auxiliary pump unitary discharge line, wherein, in the auxiliary pump unitary discharge line upstream from the connection of the unitary discharge line with the branch line a first check valve is provided that opens toward the control line; a second check valve is provided in the branch line and opens toward the supply line; wherein a line leading from the at least one connecting line to the control line includes a third check valve that opens toward the at least one connecting line; and wherein the auxiliary pump is operative when the hydraulic pressure provided by the primary pump is inadequate to maintain hydraulic pressure in the supply line.