A conveyor system for transporting sand including a transportation element for moving the sand, and a drive subassembly for moving the transportation element on a predetermined path. The drive subassembly includes a sprocket driven by a motor for moving the transportation element along the predetermined path, and a floating idler wheel supportable by the transportation element and positioned on the predetermined path downstream from the sprocket. The floating idler wheel is movable between an upper location and a lower location, depending on the tension to which the transportation element is subjected. The drive subassembly also includes a limit switch activatable upon the floating idler wheel moving to the lower location. Upon activation, the limit switch transmits a signal to a motor switch to de-energize the motor.