A weight stack for an exercise machine may include one or more primary and secondary load elements that are selectively joined to a weight carriage. The load elements may be supported from below by one or more support beams and positioned at spaced apart locations on the support beam when the weight carriage is located at its rest position or when the load elements are not joined to the weight carriage during an exercise. The load elements may include engagement surfaces that engage the beam either directly by contacting the beam or indirectly via a divider structure positioned between the load elements and the beam. For some load elements, the engagement surfaces define a portion of a slot in the load element. The exercise machine may further include a single guide pole that constrains the weight carriage to move substantially linearly and vertically relative to the exercise machine's support frame.