GATE — Agricultural Engineering (AG) · India · IITs and IISc on rotation (2026: IIT Guwahati)
Original practice questions written to the published syllabus · not past papersEverything between the engine and the implement: clutch, gearbox, differential, PTO, brakes, steering, hydraulics, hitch and tyres.
In the exams: GATE AG Section 3 Tractors and Power Tillers; ICAR AIEEA-PG Unit V; ICAR AICE subject 39 Unit 4; ASRB NET FMP; PRC ABE
GATE — Agricultural Engineering (AG)
Section 3 'Tractors and Power Tillers': numerical questions on overall gear ratio and travel speed, differential speeds, clutch torque capacity (uniform wear vs uniform pressure), PTO speed and power, Ackermann steering angles, and hydraulic force and power; conceptual MCQ/MSQ on gearbox types, draft vs position control, open vs closed centre hydraulics. NAT answers are sensitive to radius vs diameter and rev/min vs rev/s.
How our questions for GATE spread across the units of Tractor Systems & Controls. Difficulty: 22 easy, 29 medium, 14 hard.
| Power take-off: standards and speeds | 8 | |
| Hydraulic system: open and closed centre | 8 | |
| Steering geometry (Ackermann) and power steering | 6 | |
| Gearbox and transmission: sliding, constant and synchromesh | 5 | |
| Clutch: single and dual plate | 5 | |
| CVT and power-shift transmissions | 5 | |
| Differential and differential lock | 4 | |
| Final drive | 4 | |
| Brakes | 4 | |
| Tyres and ballasting | 4 | |
| Three-point hitch: categories, free and restrained links | 3 | |
| Tractor types and selection | 3 | |
| Power tillers | 2 | |
| Draft and position control | 2 | |
| Operator controls and ROPS | 2 |
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
In a two-stage reduction, a 15-tooth pinion on the input shaft drives a 45-tooth gear on the countershaft, and a 12-tooth pinion on the countershaft drives a 48-tooth gear on the output shaft. If the input turns at 1,800 rev/min, the output speed is
D. 150 rev/min
Ratio = (45/15) × (48/12) = 3 × 4 = 12. Output = 1,800/12 = 150 rev/min. Adding the ratios (3 + 4 = 7) gives 257; using only the first stage gives 600; multiplying instead of dividing gives 21,600.
A single-plate clutch has linings of outer radius 150 mm and inner radius 100 mm, μ = 0.3, and spring force 4000 N. Assuming uniform wear, the torque capacity is
C. 300 N·m
Uniform wear: R_m = (R_o + R_i)/2 = 0.125 m. T = μ W n R_m = 0.3 × 4000 × 2 × 0.125 = 300 N·m (n = 2 because the single driven plate has two friction faces). Uniform pressure gives R_m = 0.1267 m and 304 N·m; n = 1 gives 150 N·m; using the outer radius gives 360 N·m.
A tractor engine develops a maximum torque of 250 N·m. The single-plate dry clutch must carry 1.4 times this torque. Linings: outer radius 140 mm, inner radius 90 mm, μ = 0.35. Using the uniform-wear assumption, the total spring force needed is closest to
A. 4,348 N
Design torque = 250 × 1.4 = 350 N·m. R_m = (0.14 + 0.09)/2 = 0.115 m. W = T/(μ n R_m) = 350/(0.35 × 2 × 0.115) = 4,348 N. Using one friction face doubles it to 8,696 N; ignoring the service factor gives 3,106 N, a clutch that slips at peak load; using the outer radius gives 3,571 N.
An operator holds a tractor's open-centre hydraulic lever against the stop after the cylinder has reached the end of its stroke. The gear pump delivers 30 L/min and the relief valve is set at 17.5 MPa. The rate of heat generation in the oil is
D. 8.75 kW
All the flow passes over the relief valve and does no work, so heat = Δp × Q = 17.5 MPa × 30 L/min/60 = 8.75 kW. /600 applies to bar, not MPa. This is why levers must not be held against the relief valve and why open-centre systems overheat when misused.
A 2WD tractor must develop a net pull of 18 kN on a soil where the usable net traction ratio at acceptable slip is 0.45. The dynamic load on the rear wheels is at present 32 kN. The ballast to add over the rear wheels is about
D. 815 kg
Required rear load = pull/ratio = 18.0/0.45 = 40 kN. Extra load = 40 − 32 = 8 kN = 8,000 N ÷ 9.81 = 815 kg. 4,077 kg is the whole rear load, not the addition; 8,000 forgets to convert newtons to kilograms. Check slip in the field afterwards, because the traction ratio varies with soil. 1,835 kg converts the whole 18 kN pull to mass (18,000/9.81).
The synchroniser in a synchromesh gearbox
B. uses a cone clutch to match speeds before the dogs engage
The synchro ring rubs on the gear cone to bring both to the same speed, then the collar's dogs engage without clash, allowing shifts on the move.
A 35 mm PTO shaft with 21 splines is designed to run at
A. 1,000 rev/min
Type 1 is 35 mm with 6 splines at 540 rev/min; type 2 is 35 mm with 21 splines at 1,000 rev/min; type 3 is 45 mm with 20 splines at 1,000 rev/min. Different splines prevent mismatching.
The recirculating-ball steering gear uses balls
C. running between a worm and a nut to reduce friction
Steel balls roll in the grooves between the worm and nut and recirculate through a return tube, giving low friction and wear.
Rear drive tyres with chevron lugs should be mounted so that
B. the point of the chevron contacts the ground first as the wheel rolls forward
Mounted correctly the lugs dig in and self-clean; mounted backwards they pack with soil and lose traction.
If an MFWD tractor is fitted with front tyres of a smaller rolling circumference than specified, the likely result is
C. the front wheels lag the rear, causing tyre scrub, power circulation and drive-train wear
The front axle ratio is set for a small lead with the specified tyres. Smaller front tyres reduce or reverse the lead, so the axles fight each other.
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