GB339376A - Improvements in or relating to washer boxes for coal and the like - Google Patents

Abstract

339,376. Norton, B. Sept. 16, 1929. Jigs.-In a jig in which the amplitude of the water pulsations at the shale outlet is controlled automatically by variations in the pressure in air chambers according to the amount of shale to be discharged, a lost-motion device is provided so that only those movements of the actuator which exceed a certain value result in any variation of air pressure in the chambers. Air chambers 7, 8, Figs. 1 and 2, connected by a pipe 9 to a valve 10 are mounted immediately in front of the shale outlet 5. A float 13 which rests on the shale on the screen 3 is connected to vertical supports 14 by links 15, one of which is rigidly connected to a sector-shaped member 16 carrying two adjustable stops 17. The stops engage a rocking link 18, pivoted about the same axis as the member 16, which works the valve 10 through the link 19, the valve being opened when the shale bed has increased in thickness to a predetermined amount. The shale is then discharged over an extension shelf 20 into a chamber 6, the coal passing over the shelf 11. The extension shelf 20 is provided to prevent any discharge of shale when the valve 10 is closed. In a modification, Figs. 3 and 4, the float 21 is disposed in a tube 26 entering the washer below the screen and open to the air and is connected to a rocker 22 by a link 23, the end of the rocker lying between two adjustable stops 24 on a sector-shaped member 25 connected to the valve. An oil dash-pot 27 with plunger 28 connected to the rocker 22 is provided so that there is little resistance to the upward movement of the float but considerable resistance to its downward movement. As the depth of the shale bed increases more water will be forced up the tube 26 and when the limit of the lost motion device is exceeded the valve will be opened and shale discharged. One washer may, instead of the two control chambers, be provided with a single chamber open to the atmosphere and fitted with one or more transverse partitions with valves or flaps and control chambers may be provided at both ends of the washer. The float and valve may be connected electrically or by compressed air mechanism. Specifications 206,151, 254,709, and 306,169 are referred to.