Subtopic: Type, selection, maintenance and repair of tractors and power tillers
Question Statement:
In agricultural tractor design guidelines (ASABE Standards / Liljedahl), the typical recommended ballasted operational weight-to-power ratio for a standard 2WD farm tractor engaged in heavy primary tillage (ploughing) is approximately:
Options:
(A) $20\text{--}25\text{ kg/kW}$
(B) $55\text{--}65\text{ kg/kW}$
(C) $120\text{--}140\text{ kg/kW}$
(D) $200\text{--}250\text{ kg/kW}$
Answer Key:
B
Step-by-Step Solution & Explanation
- **Tractor Weight-to-Power Ratio:**
- For standard 2WD farm tractors engaged in heavy draft operations at typical field speeds of $6\text{--}8\text{ km/h}$, optimum ballast weight is approximately $55\text{--}65\text{ kg/kW}$ ($90\text{--}110\text{ lb/hp}$).
- This provides sufficient tractive adhesion to prevent excessive wheel slip (gt; 15\%$) while avoiding excessive soil compaction and rolling resistance.