Rajasthan PSC — Assistant Agriculture Engineer (Agriculture Engineering syllabus) · India · Rajasthan Public Service Commission
Original practice questions written to the published syllabus · not past papersSprayers, weeders, mowers, reapers, combines and threshers: how they work, how to calibrate them and where losses come from.
In the exams: GATE AG Section 2 (sprayer problems in 6 of 8 papers 2019–26); ICAR AIEEA-PG Unit V; ICAR AICE subject 39 Unit 2; PRC ABE
How our questions for Rajasthan PSC spread across the units of Farm Machinery & Equipment II — Plant Protection, Harvesting, Threshing. Difficulty: 32 easy, 8 medium, 2 hard.
| Sprayer calibration and application rate | 5 | |
| Weeders and inter-cultivation equipment | 4 | |
| Threshers | 4 | |
| Sprayers: hydraulic, air-assisted and electrostatic | 3 | |
| Dusters | 3 | |
| Combine harvester: header, threshing cylinder and concave | 3 | |
| Harvesting and threshing losses | 3 | |
| Straw and residue management machines | 3 | |
| Nozzles and droplet spectra | 2 | |
| Mowers: reciprocating and rotary; mechanics of cutting | 2 | |
| Reapers | 2 | |
| Combine separation and cleaning: straw walker and cleaning shoe | 2 | |
| Chaff cutters | 2 | |
| Root-crop diggers | 2 | |
| Cotton and sugarcane harvesting | 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 hydraulic sprayer, strainers are made progressively finer from the tank filling opening towards the nozzle so that
D. the smallest opening in the system, the nozzle orifice, does not block
Coarse strainers stop large debris early; the finest strainer is just before the nozzle, which has the smallest orifice. Strainers do not raise pressure; they cause a small pressure drop.
In the field, the sprayer's forward speed for calibration should be found by
B. timing the sprayer over a measured distance in the field to be sprayed
Wheel slip and soft or uneven ground change actual speed, so the reliable value comes from timing a measured run in the field. For example, 100 m in 60 s is 100/60 × 3.6 = 6 km/h.
In a hand-operated rotary duster, the air stream is produced by
A. a fan driven at high speed by a crank through a gear train
The rotary duster uses a crank and step-up gears to spin a fan; the same drive usually turns the hopper agitator. Bellows and plunger dusters are separate types.
On a standard reciprocating cutter bar, the knife stroke, section spacing and guard spacing are each
A. 76.2 mm
The standard cutter bar uses a 3 in (76.2 mm) stroke with sections and guards at 76.2 mm spacing, so each section moves from one guard centre to the next. 50.8 mm (2 in) and 101.6 mm (4 in) are not the standard; 38.1 mm is the crank radius, half the stroke.
A vertical conveyor reaper (VCR)
B. cuts the crop and conveys it upright to one side, laying it in a windrow
The VCR's lugged belts carry the cut stems across and drop them in a windrow at right angles to travel. Binding is done by a reaper-binder; threshing by a combine; stripping by a stripper header.
The straw walkers of a conventional combine
A. lift and toss the straw rearward so free grain falls through
Crank-driven walker sections loosen the straw mat repeatedly; free grain falls through the decks to the grain pan. Threshing happens at the cylinder and air cleaning at the shoe.
Loss counts behind a wheat combine average 50 grains per m², and the thousand-grain weight is 40 g. The loss is
B. 20 kg/ha
Loss = 50 × 40/1000 = 2 g/m² = 2 × 10 = 20 kg/ha (kg/ha = grains/m² × TGW/100). The factor of ten slip gives 2 or 200. 0.2 kg/ha is a factor-of-100 slip.
To obtain a shorter length of cut on a chaff cutter at the same flywheel speed, the operator should
D. reduce the feed roll speed through the gearbox
Length of cut = feed speed / cuts per second; slower feed rolls give shorter pieces. Removing a knife would double the length. Wider clearance gives ragged cuts.
In an elevator-type potato digger, soil is separated from tubers mainly by
D. passing the lifted mass over a rod-link elevator that is agitated so loose soil falls through
The share lifts soil and tubers onto the rod-chain elevator; agitators shake soil through the gaps and tubers are dropped on the surface.
The primary extractor fan on a sugarcane harvester
D. removes trash
It removes extraneous matter after chopping; setting its speed trades trash removal against cane loss. The fan blows leaves and trash out of the cane stream.
Ten here, 42 in the app. The Laisha app has every practice question we have written to Rajasthan PSC in this subject, marked as you go, with timed papers, a jump-to-unanswered list and a certificate when you pass at 70 per cent.
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