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ICAR AICE-JRF/SRF Tractor & Automotive Engines (IC Engines): practice questions

ICAR AICE-JRF/SRF (PhD) — Agricultural Engineering subjects 38–43 · India · National Testing Agency for ICAR

Original practice questions written to the published syllabus · not past papers
10worked here, free
25written to this exam in this subject
13syllabus units

About ICAR AICE-JRF/SRF

ICAR AICE-JRF/SRF (PhD) — Agricultural Engineering subjects 38–43 is a PhD, fellowship and lectureship exam run by National Testing Agency for ICAR, for candidates in India. LAN-based computer test, 2 hours, 120 MCQs: 20 Part A (general knowledge and reasoning), 50 Part B (core group), 50 Part C (specialisation); four options.

Source: icar.org.in.

Checked against the exam body's published information. Formats and fees change; confirm the current edition there before you book.

Tractor & Automotive Engines (IC Engines) in ICAR AICE-JRF/SRF

Deeper understanding: combustion stages and knock, common-rail and emission-control technology, fuel maps and engine–implement matching, test codes and the interpretation of test data.

How tractor engines work and how their performance is measured — the single most reliably examined farm-power topic.

Our 25 ICAR AICE-JRF/SRF questions in this subject: 0 easy, 14 medium, 11 hard, across 13 units.

10 practice questions, worked

Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.

These 10 were written to ICAR AICE-JRF/SRF and are not shown on any other exam's page.

Question 1 · hard

An air-standard dual cycle has r = 15, pressure ratio α = 1.4 during constant-volume heat addition and cut-off ratio ρ = 1.5 (γ = 1.4). Its efficiency is closest to

  1. 66.1%
  2. 63.9%
  3. 63.0%
  4. 54.8%
Answer and working

B. 63.9%

η = 1 − (1/r^0.4)(αρ^γ − 1)/[(α − 1) + γα(ρ − 1)] = 1 − (1/2.9542)(2.4698 − 1)/(0.4 + 0.98) = 63.9%. 66.1% is the Otto value; 63.0% is the pure Diesel value; 54.8% omits γ from the second term of the denominator.

Question 2 · medium

A key advantage of a common-rail injection system over a mechanical in-line pump is that

  1. it needs no high-pressure pump
  2. it usually works without any electronic control unit, so it is simpler to service in the field
  3. pressure is held high regardless of engine speed and injection can be split into pilot, main and post events
  4. it injects at a much lower pressure than an in-line pump, which reduces wear on the nozzles, plungers and delivery valves
Answer and working

C. pressure is held high regardless of engine speed and injection can be split into pilot, main and post events

The rail is pressurised by a pump but controlled by the ECU, so pressure does not fall with speed as in a jerk pump, and electronically actuated injectors allow multiple injections per cycle for noise and emission control.

Question 3 · medium

The ignition delay in a diesel engine running at 2,000 rev/min is 1.2 ms. The delay in degrees of crank rotation is

  1. 2.4°
  2. 7.2°
  3. 864°
  4. 14.4°
Answer and working

D. 14.4°

θ = 6Nt = 6 × 2000 × 0.0012 = 14.4°. (N rev/min = 6N degrees per second.) 2.4° forgets the factor 6; 7.2° is the camshaft angle, not the crank angle; 864° uses rev/s × 360 without converting minutes to seconds.

Question 4 · hard

Removing the thermostat from a tractor engine to 'cure' overheating is poor practice mainly because

  1. the pressure cap will stop working
  2. coolant can no longer reach the radiator, because the thermostat housing forms part of the flow path
  3. the engine then runs too cold at light load, causing condensation, sludge, wear and higher fuel use
  4. the water pump will run backwards
Answer and working

C. the engine then runs too cold at light load, causing condensation, sludge, wear and higher fuel use

Without a thermostat coolant goes to the radiator all the time, so the engine may never reach working temperature. Overheating has another cause that must be found.

Question 5 · medium

Diesel engine oils are formulated with a relatively high total base number (TBN) mainly to

  1. raise the oil's viscosity at low temperature
  2. reduce foaming in the sump
  3. increase the oil's flash point
  4. neutralise acids formed from sulphur in the fuel
Answer and working

D. neutralise acids formed from sulphur in the fuel

Combustion of fuel sulphur produces acids that corrode bearings and liners; the alkaline reserve (TBN) neutralises them.

Question 6 · hard

Why is a governor essential on a diesel engine even though it has no throttle?

  1. Without it the injection timing would stay fixed and could not be advanced as engine speed rises under load
  2. With unthrottled air, a fixed rack setting would let the engine overspeed as load drops and idle unsteadily
  3. The governor supplies the high injection pressure
  4. It prevents knock by limiting the effective compression ratio as the engine speed and load change
Answer and working

B. With unthrottled air, a fixed rack setting would let the engine overspeed as load drops and idle unsteadily

Air is always available, so fuel alone sets power. At a given rack setting, removing load lets speed rise until friction balances, which can be destructive; the governor cuts fuel to hold the set speed.

Question 7 · hard

A diesel has an indicated thermal efficiency of 38% and a mechanical efficiency of 82%; its air-standard efficiency at the same compression ratio is 60%. Its relative efficiency and brake thermal efficiency are, respectively,

  1. 51.9% and 38.0%
  2. 63.3% and 31.2%
  3. 157.9% and 46.3%
  4. 82.0% and 49.2%
Answer and working

B. 63.3% and 31.2%

Relative efficiency = ηit/ηair-std = 0.38/0.60 = 63.3%. Brake thermal = ηit × ηm = 0.38 × 0.82 = 31.2%. Dividing by ηm instead of multiplying gives an impossible rise. 51.9% and 38.0% put brake over air-standard as the relative efficiency and quote the indicated efficiency as brake; 157.9% and 46.3% invert both ratios; 82.0% and 49.2% take ηm as relative and multiply ηm by the air-standard value.

Question 8 · medium

On the fuel map (iso-BSFC contours) of a tractor diesel, the lowest BSFC is usually found at

  1. idle speed and no load
  2. maximum speed (high idle) and light load
  3. high load (near full torque) and moderate speed
  4. any point, because BSFC is independent of load
Answer and working

C. high load (near full torque) and moderate speed

At light load friction dominates and BSFC rises steeply; at very high speed friction and pumping losses grow. The best island is at high load, moderate speed, which is why 'gear up, throttle back' saves fuel at light drawbar work.

Question 9 · hard

At constant speed a diesel uses 4 kg/h of fuel at BP = 10 kW and 8 kg/h at BP = 30 kW, and the fuel line is straight. By Willan's line the friction power is

  1. 20 kW
  2. 0.2 kW
  3. 10 kW
  4. 4 kW
Answer and working

C. 10 kW

Slope = (8 − 4)/(30 − 10) = 0.2 kg/h per kW. Fuel = 0 when BP = 10 − 4/0.2 = −10 kW, so FP = 10 kW. 20 kW would be read as the zero-fuel distance from the 10 kW point. 0.2 kW is the slope, and 4 kW reads the 4 kg/h fuel rate as a power.

Question 10 · hard

Retarding the injection timing of a diesel engine generally

  1. lowers both NOx and particulate emissions, because combustion ends closer to TDC
  2. lowers NOx but raises particulate emissions and fuel consumption
  3. raises NOx and lowers particulate emissions
  4. has no effect on emissions
Answer and working

B. lowers NOx but raises particulate emissions and fuel consumption

Later injection lowers peak temperature (less NOx) but leaves less time for soot oxidation and wastes expansion work: the classic NOx–PM trade-off.

A study plan for Tractor & Automotive Engines (IC Engines) in ICAR AICE-JRF/SRF

This plan follows where our questions actually fall, so the time goes where the marks are likely to be. It is our reading of the syllabus, not the exam body's weighting.

  1. First, the heavy units (60% of the 25 questions): Emission norms (5, 20%); BSFC and heat balance (3, 12%); Combustion and knock (3, 12%); Engine performance: IP, BP, FP and efficiencies (2, 8%); Fuel properties (2, 8%).

    Read the manual chapters for these first and do every worked question you can find on them.

  2. Then the middle band: Governing (2, 8%); Otto, Diesel and dual cycles (2, 8%); Air intake and turbocharging (1, 4%); Cooling system (1, 4%); Diesel fuel system: injection pump and injector (1, 4%).

    Aim for one sitting per unit, then mixed questions across them.

  3. Then the lighter units: Engine testing (1, 4%); Lubrication system and lubricants (1, 4%); Two-stroke and four-stroke engines (1, 4%).

    Learn the definitions, classifications and standard numbers; these units are more often recalled than worked.

  4. Leave time for the hard ones: Cooling system (1 hard of 1), Engine testing (1 hard of 1), BSFC and heat balance (2 hard of 3).

    Come back to these after a first pass, untimed, and read every explanation, including for the options you rejected.

  5. Finish timed. Sit the subject as a timed set without notes, mark it, and send each wrong answer back to its unit above.

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