Tailstock powering device

A tailstock power device for a tailstock having a housing selectively positionable on a bed, a carrier mounted in said housing for longitudinal shifting extensile and retractile movement with respect to said housing, and an actuating shaft threadedly engaged with said carrier in said housing and extending exteriorly therefrom for threaded rotation relative to said carrier and shifting movement therewith, said device comprising:

• a first cylinder for mounting on said housing and surrounding said shaft with the latter extending in slidable and rotatable sealed relation through said cylinder, a first piston shiftable in said first cylinder and connected to said shaft for shifting movement with said shaft and carrier, fluid operating means selectively communicable with said cylinder to drive said piston in a desired direction for selective movement and positioning of said shaft and carrier, said shaft being rotatable upon fixed positioning of said piston in threaded engagement with said carrier to shift the latter, a second cylinder, a second piston shiftable in said second cylinder, and fluid operating means comprising a source of pressure fluid selectively communicable with said first mentioned cylinder on one side of sad first mentioned piston to feed said carrier and selectively communicable with said second cylinder on one side of said second piston to feed the latter, metering means communicable between said first mentioned cylinder on the other side of said first mentioned piston and said second cylinder on the other side of said second piston to meter fluid passing therebetween upon feeding of said carrier, and one-way valve means communicable in the direction between said second cylinder on said other side of said second piston and said first cylinder on said other side of said first piston, for rapidly returning metered fluid and consequently rapidly returning of said carrier.