Some Human Engineering Investigations on the Seat and Controls of Tractors. (I)

On the Convenience of Mounting and Dismounting, Front-visibility and Comfortability of Seat

Abstract

Statical measurements of tractors (18 domestic and 16 imported) suggested several problems to be improved or corrected as follows.
(1) Convenience of mounting and dismounting: The steps of imported tractors are about 24% higher than domestic ones, and are not adequate for Japanese phisique. Access for mounting and dismounting are too narrow in both domestic and imported tractors. The worst case is found in the longitudinal dimension of a access of a certain domestic tractor, which is negative.
(2) Front-visibility: The average invisible area of domestic and imported tractors is 1.56m² and 2.53m², respectively.
(3) Suspension of seat: Most domestic tractors use gum-torsion suspensions which are simple to manufacture, bnt require larger energy consumption for operators.
(4) Shape of seat: Most domestic tractors are equipped with bucket-type seats, which have many physiological faults. Regardless of makes or countries, the shape and structure of tractor seats seem to need improvements to be not resonant with operators' bodies.
(5) Dimensions of seat: Both height and width are too large for Japanese operators in case of imported tractors. On the contrary, those of domestic tractors are generally too small. The depth of seat is nearly the most appropriate in imported tractors, but too small in a half of domestic.
(6) Inclination of seat surface: The greater part of investigated tractors has no inclination, those of the remainder are stronger than the optimum (4 to 6 degrees to horizontal line).
(7) Adjustability of seat position: A majority of tractors has no adjustment devices. Even in the remainder equipped with such devices, the adjustable range is not sufficient for the optimum (1/8 to 1/9 of stature).
(8) Accessories of seat: The heights of backrests have appropriate dimensions (about 220mm over the seat surface) except four tractors, in which the height is either short or exceeding. Except five domestic tractors, footrests have no inclination, the most suitable angles of which are 28 to 30 degrees to horizontal line.