Abstract: A cam is disclosed. The cam may include a body having an outer surface at a substantially constant diameter extending between a first end and a second end, a first path helically disposed inward from the outer surface, around the body in a first direction, wherein a first end of the first path is proximate the first end of the body, and a second path helically disposed inward from the outer surface, around the body in a second direction, wherein a first end of the second path is proximate the second end of the body.

Abstract: A yieldable gripper unit for a conveyor of the type in which the gripper units form two endless tracks which converge to engage and support a sheet of material clamped between them. The gripper units of the endless tracks move on rails mounted on tubular supports. One of the endless conveyor tracks is equipped with non-yielding gripper units and the other is equipped with yieldable gripper units. Each yieldable gripper unit includes a generally rectangular base plate having one side facing the sheet of material which is to be clamped and the other side facing its tubular supports. A yieldable arm is cantileverly attached to the base plate and is inclined at an acute angle relative to its base plate on the sheet material side thereof to permit the arm to yield towards the base plate when the sheet of material is clamped. A plurality of rubber buttons are mounted on the yieldable arm and are positioned to engage the sheet of material which is to be clamped by the gripper unit.