Agricultural harvesting machines with crop pick-up mechanisms

Abstract

An agricultural harvesting machine comprises a frame, a crop pick-up mechanism mounted on the frame for flotational movement with respect thereto, and counterbalancing means operable to counterbalance at least a portion of the weight of the pick-up mechanism. The counterbalancing means comprise a combined sheave structure rotatably mounted on the frame and having a first sheave coaxial with the axis of rotation, and a second sheave connected for rotational movement with the first sheave and having a nonuniform radius relative to the axis of rotation, resilient means coupled between the frame and the sheave structure and first and second interconnecting means interconnecting the combined sheave structure with the pick-up means and the resilient means respectively. The first and second interconnecting means extend around the first and second sheave respectively of the combined sheave structure and the arrangement is such that as the sheave structure rotates, the moment about the axis of rotation of the sheave structure produced by the resilient means is always substantially equal to the moment about the same axis produced by the weight of the pick-up means irrespective of the position of the latter relative to the frame.