Refeed and discharge systems of hydraulic circuits of hydrostatic transmissions

Claim 1

Device for refeeding and discharging the hydraulic circuits of a hydrostatic transmission, which comprises a pair of discharge valves, a pair of refeed valves and a pair of ports connected to the main pipe lines of the transmission, respectively, and opening into fluid chambers communicating with said valves, characterized in that said chambers disposed at the opposite ends of a main bore connected to a compensating pump constitute with said bore a pair of shoulders engageable by said refeeding valves, each refeed valve comprising a seat-forming flange engaging one of said shoulders, said refeed valves further comprising axially aligned first and second bores interconnecting the ends of said valves, the first bore of greater diameter than the second bore having its opening directed towards said main bore, at least one radial passage being further provided for connecting said first bore to the outer surface of a sliding member guiding said refeed valve in said main bore; each one of said discharge valves, disposed coaxialy within said refeed valves, engaging a seat consisting of the intersection edge formed between said first and second bores, and being urged against said seat by a common spring disposed between said discharge valves, stop means limiting the axial movements of said discharge valves in the closing direction thereof whereby when one of said discharge valves is seated under the force of said common spring the refeed valve is moved away from the corresponding shoulder and the radial passage is closed by said main bore.