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Mark II Chair Lift
Mark II Chair Lift
An adult male is in the process of transferring from the tractor’s seat to the lift chair for descent to the ground.

The Mark II Chair Lift, which utilizes an electric linear actuator-powered parallelogram linkage, has wide application on tractors that have low operator station height. This type of devise is probably not feasible for tractors or combines that require greater vertical lift, because a much larger parallelogram linkage and longer linear actuator would have to be used. The lift's mounting bracket consists of horizontal tubing bolted to the tractor frame (near the front wheel) with a vertical post rising up from the bracket. The parallel linkage is a pinned, 30-inch by 18-inch rectangular frame that pivots at each joint. One of the 18-inch sides is pinned on the vertical post so it can swing side-to-side; the other 18inch side holds the lift seat. An electric linear actuator is positioned diagonally in the parallelogram and operates directly off the tractor's battery. A 12-volt DC motor, drawing up to 18 amps, drives a screw in a sealed, permanently lubricated gear train to extend and retract the actuator, which changes the shape of the parallelogram linkage to raise/lower the seat while keeping it horizontal. The operator must grab hold of the tractor fender to swing the lift seat around to transfer to the tractor seat. On some versions of the lift, an automatic swivel linkage has been installed to push the lift seat toward the tractor operator's station as the lift rises. A self-centering, reversible toggle switch, located underneath the seat, is used to raise/lower the lift. The Mark II Chair Lift is easy to service because there are few moving parts. Very accessible grease fittings have been installed at key points to reduce wear and load on the actuator. Also installed has been an electrical harness to keep the wires secure and protected from damage.

Estimated Cost Cost range: See below

Limitations Limitations Addressed by Product: Lower extremity

SourceBreaking New Ground Resource Center
ABE Building
225 S University Street
West Lafayette, IN, 47907
Last updated: Mar 01, 2019

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