Hydraulic oscillator

A hydraulic oscillator, said oscillator being self-excited, comprising a main body, said main body being equipped with an oil inflow port having inwardly divergent walls, a first pair of flow ports for alternately receiving and transmitting pressurized oil therethrough, an oil pressure chamber having a wall in said main body, a vibratory member in said oil pressure chamber, said vibratory member being positioned for bringing them into self-excited oscillation by flow of pressurized oil through said oil inflow port and said flow ports, and a pair of resiliently disposed stopper means positioned for regulating the excursion of said vibrating member in each of opposed directions by impact of said vibrating member against said stopper means, both of said stopper means including first and second stoppers adapted to be positionally displaced with respect to each other, and first and second resilient biasing means for respectively resiliently positioning said first and second stopper with respect to said oil pressure chamber, said oil pressure chamber having two opposed ends and having axially aligned bearings proximate both of said ends, said vibratory member being a spool supported slidably inside said oil pressure chamber by said bearings, and being maintained at a predetermined spacing from said wall of said oil pressure chamber, said spool having a first land at a position opposed to said inflow port and being in minus-lap relationship thereto, said first land dividing said chamber into two pockets, said main body having a pair of second ports positioned for connection with each of said pockets, said spool having a pair of second lands for closing and opening each of said pair of second ports alternately during oscillation of said spool, the relation of said first land to said inflow port being such that pressurized oil flows alternately into each of said pockets during oscillation of said vibratory member and out through the corresponding port of said first pair of ports, while oil in the pocket other than that containing pressurized oil can flow out of same through the other corresponding port of said pair of second ports said first land and said pair of second lands being of the same diameter.