Citation

Garg A, Funke S, Janisch D. Int. J. Ind. Ergonomics 1989; 3(3): 207-220.

Copyright

(Copyright © 1989, Elsevier Publishing)

DOI

unavailable

PMID

unavailable

Abstract

A laboratory study was conducted to evaluate ten different lawn mowers for ease of starting, operating controls and handling. Ninety-nine paid subjects (50 males and 49 females) from 14 to 71 years of age with prior experience on lawn mowers were selected randomly. Subjects were asked to identify the various controls, start a lawn mower four times, operate it for approximately 50 m and fill out lawn mower questionnaires on startability and controls. Subjective evaluations were supplemented with objective data.All lawn mowers tested, except one equipped with a primer in place of a throttle, had high startability rates (90-97%). The handle suddenly pulled back in 0-5% cases. However, 70% of the lawn mowers were perceived as less than easy to start and controls were less than easy to operate on 90% of the lawn mowers. Subjects were less than comfortable in the starting position in 9 out of 10 lawn mowers with the rating of perceived exertion ranging from 10 to 12 on the Borg scale. Instructions on 7 out of 10 lawn mowers were rated as less than easy to follow. Ergonomic evaluation found major problems with the location, design, direction of movement and safety in operating various controls. About 95% of the subjects could not identify the safety control lever and the self-propel control on one lawn mower.

Based on ergonomic evaluation and subjective feedback, it is recommended that the starter rope handle should be placed in the middle at the back of the lawn mower at a height of about 70 cm from the floor. The distance of the starter rope handle from the handlebar should be 36 cm and it should be larger in size (about 11.8 cm) to accommodate all four fingers. Both the handlebar and the safety control lever should be semicircular in shape with a diameter ranging from 1.9 to 2.5 cm. The force required to hold the safety control lever should be less than 7 N. Knob-type sliding levers with clear labeling should be used for throttle, self-propel and ground speed controls. These controls should be located near the handlebar for clear visibility, access, reach and ease of operation.

Lastly, detailed studies are needed to determine optimum location of the starter rope handle, direction of pull, length of pull and speed of pulling. Ergonomic principles should not be ignored in the design and placement of controls on lawn mowers.