Mould for precast plaster slabs - uses motor driven screw jack to extract parallel rod internal passage formers

摘要

The moulds for precast plaster slabs with internally formed passages uses a screw jack mechanism to extract the passage formers (94). The mould comprises two major face panel forms of which one swings away for striking, a soffit form, and two lateral forms. The forming rods extend for the length of the slab, and align horizontally at regular vertical intervals. Moulds may be used in parallel pairs with vertical strong backs acting as anchorages for the projecting ends of the rod formers. The screw-jack comprises a threaded shaft and a square nut.