Self-centering matrices for retreading molds

Claim 1

A retreading mold comprising a pair of relatively movable platens, means for supporting said platens during relative movement therebetween, means for imparting relative motion to said platens between spaced open and closed positions thereof, an annular matrix carried by each platen and thereby similarly being moved between said open and closed positions, said motion imparting means including a reciprocal member, said reciprocal member being disposed generally axially of said matrices, means between said reciprocal member and one of said platens for effecting self-centering between said platens in the closed position thereof, and self-centering means being curved surface contact means between said one platen and said reciprocal member, said reciprocal member being a screw having a free terminal end defining said curved surface contact means, said screw having an end portion remote from said free terminal end, said screw having a vertical axis, said motion imparting means including in addition to said screw a nut in exterior threaded relationship to said screw, means for generally precluding vertical movement of said nut, means for selectively oppositely rotating said nut to impart reciprocal movement to said screw whereby said platens are moved between said open and closed positions, a reservoir adapted to house a lubricant, and said reservoir being disposed to receive said screw remote end portion for lubricating the latter.