Arm flexion exercise machine

DETAILED DESCRIPTION The disclosed invention consist of a stable frame which includes provision for supporting an operator in a seated position with the positions of his upper arms fixed.
Journaled in this frame, on an axis which is both approximately common with the axes through the operator's elbow joints and approximately parallel with the ground plane, is a rotating effort arm which includes body-machine force-transmitting contact surfaces at its distal end which engage the operator's hands and apply resistive force from the rotating effort arm to the operator's wrist joints through circular paths about the operator's elbow joints throughout the range of the exercise movement.
Also journaled in the machine's frame on an axis which is both parallel with and offset by a specific distance from the axis of rotation of the rotating effort arm, is a rotating weight arm which, as its name indicates, contains provision for loading weights onto at a point offset from its axis of rotation.
The rotating effort arm and the rotating weight arm are mechanically linked to each other at axes which are both parallel with and offset by specific distances from their respective axes of rotation by a rigid connecting link which also has a specific length between its centers of connection.
These two rotating assemblies, the link joining them, and the frame of the machine join together to form a double-rocking-lever 4-bar linkage which acts in conjunction with the rotating weight arm to vary the resistive force applied to the operator's wrist joints through body-machine contact between the operator's hands and the rotating effort arm throughout the arm flexion exercise movement.
Through a simple kinematic analysis, the specific lengths and orientations of the moving parts which constitute the 4-bar linkage/rotating weight arm force-varying mechanism can be specified to apply a load, at the hand-engaging contact surfaces on the rotating effort arm, which varies in accordance with the normal strength-to-position force applying capabilities of the average operator in the arm flexion exercise movement