Single belt, multiple conveyor system

In a variable length conveyor apparatus for conveying concrete including at least a first and second conveyor frame, said first conveyor frame having a first forward portion and a first rear portion, said second conveyor frame having a second forward portion, a second rear portion and a longitudinal axis, said second conveyor frame being adapted to move relative to said first conveyor frame between a collapsed, retracted state and at least one extended state, the improvement comprising in combination:

• a single, continuous, and substantially slack-free conveyor belt positioned on said first and second conveyor frames;
• means for guiding said conveyor belt about said first and second conveyor frames, said guiding means defining a closed path wherein said conveyor belt passes forward from the first rear portion to the first forward portion, forward from said first forward portion to said second forward portion, back from said second forward portion to said second rear portion, forward from said second rear portion to said first forward portion, and back from said first forward portion to said first rear portion, said closed path having a substantially constant length in said collapsed and extended states, said conveyor belt defining a concrete-bearing portion along said second forward portion of said second conveyor frame in said extended state;
• and
• at lease one non-binding, self-training idler assembly positioned on said second forward section, said idler assembly including a base member, means for rigidly securing said base member to said second conveyor frame substantially along said longitudinal axis, a roller assembly rotatably secured to said base member to support said concrete-bearing portion of said conveyor belt said rotatable roller assembly having a pair of rollers defining a substantially V-shaped trough and a pair of rods secured to said rotatable roller assembly substantially parallel to said pair of rollers, respectively, said rod including an upwardly turned end portion, said rods cooperatively defining means for rotating said roller assembly in response to lateral movement of said conveyor belt to align said conveyor belt with said idler assembly and second conveyor frame, said rollers and said rotating means cooperatively defining means for freely engaging and disengaging said conveyor belt and idler assembly during movement of said second conveyor frame relative to said first conveyor frame between said collapsed and extended states.