Question

The handle height of a push-pull type manual weeder for workers with average acromial height of 135 cm need to be

• A. 75 cm
• B. 95 cm
• C. 115 cm
• D. 135 cm

Hint:

For manual push-pull farm tools, the handle height is designed to be around the waist-to-chest height of the operator, which is roughly 70% of their shoulder (acromial) height.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Ergonomics in agricultural tool design focuses on matching the physical dimensions of tools with the anthropometric data of the operators.
This minimizes physical fatigue, reduces musculoskeletal disorders, and improves working efficiency.
The acromial height refers to the vertical distance from the standing surface to the acromion (shoulder joint).

Step 2: Detailed Explanation:
For manually operated, push-pull type weeding implements, the handle height must be designed to allow the worker to apply thrust and pulling forces efficiently without bending their spine excessively.
- Ergonomic studies indicate that for push-pull activities, the optimal handle height is approximately \( 70% \) to \( 80% \) of the worker's acromial (shoulder) height.
This range allows the worker to maintain an upright or slightly inclined posture, which optimizes muscle activation in the arms and torso.
- Let us calculate the recommended height range using the given acromial height of \( 135 \text{ cm} \):
\[ \text{Minimum handle height} = 135 \times 0.70 = 94.5 \text{ cm} \]
\[ \text{Maximum handle height} = 135 \times 0.80 = 108.0 \text{ cm} \]
Evaluating the given options:
- (A) \( 75 \text{ cm} \): This is too low and would force the worker to bend forward, causing lower back strain.
- (B) \( 95 \text{ cm} \): This falls directly at the lower end of the ergonomically optimal range (\( 94.5 \text{ cm} \)), making it the most appropriate choice.
- (C) \( 115 \text{ cm} \): This is too high, requiring the worker to raise their shoulders, leading to neck and shoulder fatigue.
- (D) \( 135 \text{ cm} \): This is equal to the shoulder height, making it impossible to apply downward force on the weeder.
Therefore, a handle height of \( 95 \text{ cm} \) is the optimal choice.

Step 3: Final Answer:
The recommended handle height for the given acromial height is 95 cm.