The jig consists of the main body, hydraulic system and electrical system. The main body is composed mainly of the following: tank, bed-moving mechanism, lifting wheel, product chute and discharge mechanism.

The hydraulic system functions to bring the screenplate into motion and operate the reject discharge mechanism.

The electrical system is mainly used for master control of jig operation (heavy-current control) and checking and control of the automatic reject discharge operation.

The screenplate of the jig is directly brought into upward and downward motion in the water medium by means of external driving force. As the materials on the screenplate are caused to go into cyclic loosening, a coal separation according to the density is effected.

The jig differs with an air pulsating jig in that: 1) There is no need to use flush and under-screen water; 2) The jig bed mobility is determined by the bed motion characteristic rather than the air and water systems.

The water in the jig is not in pulsating motion. When the jig bed goes upward, the bed particles are not seen as a whole to move relatively to the screenplate. However, the water medium is seen to undergo a downward motion relative to the particles. At the same time, when the jig bed moves downward, the water medium forms an upward current relative to the jig bed under the effect of the resistance of the medium. As the particles undergo a hindered settling in the water medium, the separation of the articles according to density is made possible.

For details, refer to the attached schematic diagram of the movable-bed jig.

The screenplate moving mechanism 5 is brought into upward and downward reciprocating motion around the pin hinge 13 by means of the hydraulic cylinder 6. The raw coal fed into the jig will form a bed on the screenplate and is loosened under the effect of the upward and downward motion of the screenplate. Through repeated jigging operations, the bed particles go into stratification according to density. After stratification, the lighter materials pass over the overflow weir 8 and fall into the rear section 10 of the lifting wheel and are finally brought up by the lifting wheel for discharge out of the jig as clean coal through the chute 11. The heavier product passes through the reject rotor 1 and falls into the fore section 9 of the lifting wheel for discharge out of the jig via the reject chute 12. The finer materials which pass through the screenplate and drop down to the bottom of the conical part of the jig are finally discharged via a sluice gate or a bucket elevator.