Mechanical Designs of Elliptical Machines
Elliptical machines are bar-linkage systems. There are two basic designs:
- Four-Bar Linkage
- Glide Linkage
Four-Bar Linkage Design
Rear-drive ellipticals are typically based on a planar four-bar linkage structure. Their mechanics is simple and reliable.
Most commercial elliptical machines are designed with a four-bar linkage structure, characterized as two long coupler bars where the pedals set and a large flywheel at the rear.
Glide Linkage
Glide Linkage designs evolved from the classic four-bar linkage. Intead of having the pedal fixed to the coupler bar, a seperate pedal bar is added and hinge on the coupler bar. The one end of the coupler keep hinged to the crank, but the other end glide through a roller on either a rail fixed on the machine frame or on the rotating crank joint.
Glide on Fixed Rail
Glide on Crank Joint
The glide-roller design adds an additional degree of freedom to the four-bar linkage, allowing the pedal motion to be less restricted by the coupler position.
This design brings a decent stride range and proper tilt to a relatively short-frame elliptical machine.
Most front-drive and center-drive types of elliptical machines adopt one of these two glide-roller designs.