Progressive weight resistance weightlifting mechanism

A progressive weight resistance mechanism for a weightlifting machine comprising:

• (a) a base;
• (b) at least three spaced vertical guide members upstanding from the base;
• (c) a carriage cooperating with said vertical guide members, said carriage adapted for vertical reciprocative motion along said vertical guide members;
• (d) a stack of a plurality of weights between pairs of vertical guide members with each weight having a pin slot;
• (e) an apertured selector post associated with each weight stack, each selector post being slidable through an aperture in the carriage and extending downward into the weight stack, a first pin insertable into a slot in the lowermost weight of a selected subset of weights of the stack and through an aperture in said selector post to add the selected subset of weights to the post;
• (f) a stop on the upper end each of selector post;
• (g) a slidable collar on at least one selector post above the carriage, said collar having an aperture and a second pin insertable through said collar aperture and a selected mating aperture in the selector post to lock the collar into a selected position above the carriage whereby the carriage engages the collar and so moves the selector posts in the mechanism to lift the selected subsets of selected weights in a progressive sequence determined by the carriage sequentially engaging said collars or stops during a single user repetition.