What is the 'centre of power' in an agricultural machine?
A
The position where soil is cut
B
The point where power is transmitted to the implement
C
The center of implement's weight
D
The balance point of tractor
Analysis & Theory
Centre of power is the point on a tractor or machine where power is delivered to pull or drive implements.
Where is the centre of power typically located in a tractor?
Analysis & Theory
Centre of power is at the drawbar or power take-off (PTO) point.
What is the 'centre of resistance'?
A
Point where soil resists the implement
C
Mid-point of tractor length
Analysis & Theory
Centre of resistance is the point on the implement where total soil resistance acts.
Line of pull connects which two points?
A
Tractor axle and soil surface
B
Operator and steering wheel
C
Centre of power and centre of resistance
Analysis & Theory
Line of pull is the straight line between the centre of power and the centre of resistance.
What is 'pull' in tillage operation?
B
Distance moved by implement
C
Force required to move implement through soil
D
Vertical lifting of plough
Analysis & Theory
Pull is the force exerted to drag or move an implement through soil.
When the line of pull is not straight, it causes:
Analysis & Theory
An improper line of pull creates side draft, pulling the implement sideways.
Which factor affects the amount of pull required?
C
Soil resistance and implement depth
Analysis & Theory
Greater resistance and depth increase the force required to pull.
Which of the following reduces effective field capacity?
C
More overlap and idle time
Analysis & Theory
Overlap and idle time reduce effective field use.
Theoretical field capacity (TFC) is calculated as:
C
Implement width × Speed × Efficiency
D
Implement weight × Speed
Analysis & Theory
TFC (ha/hr) = (Width in m × Speed in km/h) / 10
Which of the following defines effective field capacity (EFC)?
Analysis & Theory
EFC is actual working capacity considering efficiency losses.
Field efficiency is expressed as:
Analysis & Theory
Field efficiency is the ratio of effective to theoretical capacity, expressed in percentage.
Which practice helps improve field efficiency?
Analysis & Theory
Wider headlands reduce time lost during turns.
What causes a decrease in field efficiency?
A
Efficient path planning
C
Frequent turns and overlaps
Analysis & Theory
Overlaps and turns waste time and reduce efficiency.
If theoretical capacity is 1.5 ha/hr and field efficiency is 75%, EFC is:
Analysis & Theory
EFC = TFC × Efficiency = 1.5 × 0.75 = 1.125 ha/hr (rounded to 1.0).
What is a typical field efficiency for ploughing?
Analysis & Theory
Ploughing typically has 60–80% field efficiency due to turns and overlaps.
What happens when line of pull is above center of resistance?
D
Lifting of front wheels
Analysis & Theory
A high line of pull may cause instability in the tractor.
Centre of resistance depends on:
C
Implement design and soil reaction
Analysis & Theory
It is influenced by implement structure and resistance from soil.
Which of the following affects field capacity?
Analysis & Theory
All these factors affect how much area is covered per hour.
Which tool is used to measure pull force in field?
Analysis & Theory
Dynamometer measures the pulling force applied during field operation.
If field efficiency is 80%, what percentage of time is lost?
Analysis & Theory
20% is the time lost due to turning, adjustment, etc.
What is 'drawbar pull'?
C
Force available at tractor drawbar to pull implement
Analysis & Theory
Drawbar pull is the horizontal force available at the drawbar for pulling implements.
Implement width and speed being constant, increase in overlap leads to:
B
Less effective coverage
Analysis & Theory
Overlap reduces actual area covered per pass, lowering field efficiency.
A properly aligned line of pull ensures:
C
Smooth implement operation
Analysis & Theory
A straight line of pull ensures balanced, efficient implement movement.
Field efficiency is always:
Analysis & Theory
Field efficiency accounts for real-world losses and is always < 100%.
Line of pull must pass through:
A
Only centre of resistance
C
Both centre of power and resistance
Analysis & Theory
The line of pull connects centre of power and resistance for smooth operation.
Field capacity increases with:
Analysis & Theory
Wider implements cover more ground, increasing capacity.
Time losses in field work include:
Analysis & Theory
All these contribute to time not spent on actual field coverage.
Which field operation has the highest field efficiency?
Analysis & Theory
Spraying has high coverage and minimal overlap or turning, giving high field efficiency.
If implement width = 2m, speed = 5 km/h, TFC = ?
Analysis & Theory
TFC = (2 × 5) / 10 = 1 ha/hr.