Tractors require more pedals than road vehicles; the placement of these pedals presents a complex task for the designer. Since pedal position is an important determinant of the posture of a vehicle driver's pelvis and spine, it is essential that this problem be carefully considered. (The tractor driver's spine is already potentially at risk through high vibration levels and the need to twist in the seat while monitoring tools at the rear of the vehicle.) Anecdotal evidence suggests that an increasing number of women wish to drive tractors. The consequent increase in the variability of the user population will exacerbate existing design problems; pedal resistance must be within the strength capability of the weakest female driver but must not be so low as to make control difficult for a heavy footed male. The ergonomic literature concerning human strength in the operation of pedals, although extensive, is not entirely adequate for the tractor designer. Studies have either been conducted on subjects in specific postures, defined in anatomical terms which are not easy to relate to workspace design problems, or else have been ad hoc investigations of single pedal locations in specific vehicles. The present study is aimed at elucidating the biomechanical factors which influence human strength in the operation of a pedal. A better fundamental understanding of these problems would allow better advice to be given to designers. The following variables were investigated: (a) horizontal distance in front of the seat reference point (SRP), (b) vertical distance above and below SRP, (c) lateral distance from the midline, (d) direction of thrust, (e) use of the steering wheel for ‘bracing’. Equal numbers of male and female subjects were tested.Solid shoes were worn and maximal voluntary isometric thrusts were made with the instep. The pedal was set in positions defined by percentages of the individual subject's stature; hence posture was relatively constant (given that the linkages of the lower limb are in similar proportion for most individuals). Distance ranged from 40 to 55% stature in front of the SRP, from 2.5% stature above the SRP to 12.5% below and from 10 to 20% to the right of the midline. From consideration of published evidence it was anticipated that the greatest forces would be exerted in the upper outer part of this range (55% stature in front of SRP, 2.5% above). This proved to be true. However, a pedal placed in this position would result in a very inappropriate driving posture. For a pedal location of 12.5% stature below SRP and 47.5% in front there was only a 12% reduction in thrust. Since the latter position results in a better driving posture than the former it is to be preferred. The paper concludes with a consideration of appropriate design specifications for tractor pedals and the ways in which they should be developed.