Portable screening plant

Claim 1

A portable screening plant comprising: a support frame including an inclined conveyor support disposed in an inclined path; an elongated endless loop conveyor belt disposed along said inclined path and extending between a lower supply end and an upper discharge end; means mounted on said support frame and coupled to said conveyor belt for causing movement of the belt along said path; a hopper attached to said support frame and disposed in a generally vertical disposition with its discharge end in association with the lower end of the conveyor belt and including a grizzly disposed over the upper supply end; a plurality of wiper blades disposed within the hopper and each rotatably mounted for wiping contact with a respective hopper side wall; hydraulic means coupled to the wiper blades and operative to cause rotatable reciprocating movement of the blades; a wheel assembly attached to and supporting said support frame and operative to permit trailing of the plant; said wheel assembly being attached to the support frame by telescoping members by which the support frame and conveyor belt can be raised to intended operating heights; a shaker adjustably attached to the upper end of the support frame and capable of being disposed in a raised position to receive material discharged from the conveyor belt, and in a lowered position for stowage below the conveyor belt; said shaker including: a shaker screen; a rigid frame pivotally connected at one end to said support frame near the upper end of said inclined conveyor support; a linkage mechanism securing the shaker to the support frame and including a pair of articulated two section links each pivotally connected at one end to said support frame at a position below the pivotal connection of the shaker frame, and at the other end to the shaker frame at a position outward of the pivotal connection thereof to the support frame, each of said links being centrally hinged; a pair of hydraulic actuators each interconnecting a respective one of said links and said support frame each pivotally connected at one end to said support frame and at the other end to an associated link; said hydraulic actuators being operative in a retracted position to retain said links in an open linear disposition to maintain the shaker in its raised operating position, and being operative in an extended position to cause folding of said links and downward pivoting of the shaker into its lowered position.