11,869. Foster, W. H. May 17. Actuating; plug lift valves; sliding valves; leakage, preventing. - Comprises a construction of valve of the type described in Specification 897/74. The valve 2 is operated by a screwed spindle 3 working within a tapped plug 6 passing through a stuffing-box 5' in the bonnet 5. Screwed to the plug 6 is a cap 7, which is secured to the plug by a screwed pin 9 and bears on a ring 8 in the stuffing-box. A handle 10 is fastened to the cap 7 by a screw 11 which passes through an aperture in a disk 12 resting in a recess in the handle. The lower end 6<2> of the plug 6 is of conical shape and engages with a corresponding shoulder on the casing to form a fluid-tight joint. The valve shown is of the sliding type, but any form of non-rotating lift valve may be employed. Wear of the plug 6 can be taken up by unscrewing the pin 9 and screwing the cap 7 further on to the plug.