Dual weight stack exercising machine with coupling arrangement

In a weight stack adjusting system for an exercise machine having a frame, an operating mechanism movably connected to the frame, resisting structure on the frame and connecting means entrained about a first pulley and a second pulley, both being mounted on the frame and joining the operating mechanism with the resisting structure so as to selectively allow moving the resisting structure between a raised position and a lowered position, the system including a first guide rod, a second guide rod, a third guide rod, and a fourth guide rod, each being supported by the frame, and the resisting structure being formed by a primary weight stack having a plurality of plates including a top plate movably mounted on the first and second guide rods and a supplementary weight stack having a plurality of weight plates including a top plate movably mounted on the third and fourth guide rods, the improvement comprising:

• a coupling arrangement disposed upon the primary weight stack top plate and the supplementary weight stack top plate and interconnecting the primary weight stack and the supplementary weight stack together such that a lifting force applied through the connecting means will simultaneously lift the primary weight stack and the supplementary weight stack in a balanced manner, wherein the coupling arrangement includes a force distribution assembly attached to the primary weight stack top plate, and a carriage structure movably mounted on the second guide rod and the supplementary weight stack top plate,
• a drive belt having a first end connected to the operating mechanism, an intermediate portion entrained about the second pulley so as to define a first vertical path tangent to the second pulley, and a second end joined to a center of the top plate of the primary weight stack wherein the second end of the drive belt is joined to the center of the top plate of the primary weight stack by a cable clamp,
• wherein the carriage structure includes a pair of spaced apart, carriage plates, each of the carriage plates having a distal end supported on the cable clamp and a proximal end pivotally connected to the top plate of the supplementary weight stack, and
• wherein the proximal ends of the carriage plates are interconnected by a horizontal member having a downwardly depending tab overlying an upwardly extending tab projecting from a collar located in the center of the top plate of the supplementary weight stack.