Development of Engineering Controls to Reduce Foldable ROPS Overturn Fatalities

Foldable rollover protective structures (ROPS) are a popular addition to mowers and tractors used on orchards that have been shown to lower rollover fatalities. The foldable ROPS for tractors allows the ROPS structure to be lowered for ease of maneuvering under trees and other low clearance structures. However, these devices usually require many steps to raise and lower, and thus they often remained lowered. Once lowered, the ROPS cannot protect the operator in the event of a tractor rollover.

For this project, Paul Ayers developed a universal lift assist lever that allows the operator to raise and lower a foldable ROPS from the operator seat. Using this device reduces the effort required by the operator to raise/lower the ROPS, and thus aims to decrease the amount of time the operator leaves the device in the lowered (unprotected) position.

Once developed, the design was tested to determine if the universal lift assist lever met appropriate ergonomic standards for operator required force and comfort. This was achieved by measuring the required force to lift the ROPS in to place while using the lift assist lever and establishing the zone of comfort and the zone of reach for its use on three different ROPS devices. With the addition of a torsion spring for heavy foldable ROPS models, the lever met all the ergonomic standards.

Funded By: National Institute for Occupational Safety and Health (NIOSH)
Funding Period: 2016-2019



Foldable rollover protective structures: Universal lift-assist design
PD Ayers, FK Khorsandi, MJ Poland, CT Hilliard. Biosystems Engineering 2019, 185: 116-125.

ROPS Designs to protect operators during agricultural tractor rollovers
P Ayers, F Khorsandi, X Wang, G Araujo. Journal of Terramechanics 2018. 75: 49-55.

Universal Lift-Assist Lever Design Drawings

Schematic drawing of the complete universal lift assist lever

Computer-aidied design (CAD) drawings are precise, technical drawings that provide the instructions needed to manufacture the universal lift-assist lever. Individuals and ROPS installers can download the designs for and build the universal lift-assist lever in their own machine shops.

The universal lift-assist lever was designed using public funds from the National Institute for Occupational Safety and Health/Centers for Disease Control and Prevention. As such, these designs are available to use and distribute free of charge. No other entities may make ​claims of ownership on the design.

Principal Investigator

Paul Ayers
Paul Ayers, PhD

Principal Investigator

Biosystems Engineering and Soil Science
University of Tennessee