Subtopic: Human engineering and safety considerations in design of tractor and agricultural implements
Question Statement:
The height of adult males at 5ᵗʰ, 50ᵗʰ and 95ᵗʰ percentiles are 162 cm, 173 cm and 185 cm, respectively. The minimum inside height of the tractor cab required to ensure the satisfactory design based on the given data, in cm, is __________. (Answer in integer)
Official Answer Key:
185 to 185
Step-by-Step Solution & Explanation
This applies the fundamental ergonomic rule for clearance dimensions.
Clearance dimensions (headroom, doorway height, legroom, escape openings) must accommodate the largest user. They are designed to the 95ᵗʰ percentile, so that at least 95 % of the population fits.
Reach dimensions (control levers, pedals, switches) follow the opposite rule — they are designed to the 5ᵗʰ percentile, so that even the smallest operator can reach them.
Cab inside height is a clearance dimension. Therefore:
Minimum inside cab height = 95ᵗʰ percentile stature = 185 cm
(Designing to the 50ᵗʰ percentile — 173 cm — the classic “design for the average” error, would leave half the operators unable to sit upright.)
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