Your Answer : (Not Answered)

Correct Answer : B

The ground wheel turns at about 24.6 rpm.

The forward speed is 2.5 km/h = 41.67 m/min. With 10% skid the wheel slides, so each revolution covers 10% more ground than its circumference:

\[ \begin{aligned} \text{travel/rev} &= \pi(0.49)(1.1) = 1.693\ \text{m} \\ N &= \frac{41.67}{1.693} = 24.6\ \text{rpm} \end{aligned} \]

Without skid the wheel would turn at 27.1 rpm, which is not offered. 28.3 and 32.6 rpm would need a smaller wheel or a higher speed, and 20.3 rpm overstates the effect of skid.

Your Answer : (Not Answered)

Correct Answer : C

The facility is the Swinging handle.

The women-friendly drum seeder for direct sowing of sprouted paddy in puddled fields is pulled by the operator walking backwards. It is fitted with a swinging-type pulling handle, which keeps the pull steady and lets the operator walk comfortably while the drums drop seed in lines.

A seed hopper only holds seed, a rotor plate meters it, and a strap is not the feature provided for pulling.

Your Answer : (Not Answered)

Correct Answer : B

The device is the Aspirator blower.

In a pneumatic (vacuum) seeder, a blower working as an aspirator draws air out of the inlet chamber behind the metering plate, creating suction that holds single seeds against the holes of the plate until they are released over the furrow. The blower's speed sets the level of suction.

The hopper only holds seed, the ejector knocks seed off the plate at the release point, and the rotor or plate carries seeds; none of them creates the suction.

Your Answer : (Not Answered)

Correct Answer : A

The mechanism is Fluted rollers.

A fluted roller (fluted feed) is a grooved cylinder that turns at the bottom of the seed box. The flutes carry seed out at a rate set by the length of roller exposed, so the same drill can be adjusted to sow seeds of different sizes, from small cereals to pulses. That versatility is why it is the most widely used metering mechanism in seed drills.

A stationary orifice suits only free-flowing seeds, and helical rollers and vertical rotors are used in particular drills and planters rather than as the general mechanism.

Your Answer : (Not Answered)

Correct Answer : C

The keyed reach height is 4 m.

A tractor drawn hydraulically operated platform is an orchard aid that carries workers on a platform lifted by the tractor's hydraulic system so that they can prune, thin, spray or harvest tree crops without ladders. To serve ordinary fruit trees it has to lift the worker several metres: the tractor-drawn orchard platforms reported in the literature work at about 3 to 4.5 m, and one designed for litchi and longan orchards has a working height of 4.0 m.

The other options, 1 m, 1.5 m and 2.5 m, are heights a person can reach by standing on the ground or on a low stool, so they would not justify a hydraulic platform at all. The question gives only the printed value and no source, so the answer rests on the key and on the typical working height of these machines, not on a derivation.

Your Answer : (Not Answered)

Correct Answer : B

The approximate weeding efficiency is 80-85%.

The gender friendly (women friendly) rice weeder is a light, hand-pushed rotary weeder designed for wetland rice sown or transplanted in rows. Its rotor cuts and uproots the weeds between the rows and presses them into the puddled soil, so the three actions in the stem (cutting, uprooting and incorporation) happen in one pass. Field trials on a weeder of this type, for example one reported from IGKVV Raipur, gave plot readings of 78 to 86 percent with a mean near 82 percent, which sits inside the keyed range.

The other ranges are lower (50-55%, 60-65%, 70-75%). Mechanical weeders in rows leave the weeds that grow within the hill uncut, so efficiency never reaches 100 percent, but a well-set rotary weeder removes the large majority of inter-row weeds, which is why the upper-middle range fits better than the lower ones.

Your Answer : (Not Answered)

Correct Answer : A

The draft control system was invented by Harry Ferguson.

The Irish engineer Harry Ferguson developed the three-point linkage with automatic draft control in the 1920s. The draft of the implement is sensed through the top link, and the hydraulic system raises or lowers the implement to keep the load steady, transferring weight to the tractor's rear wheels for better traction. It became the basis of the Ferguson System used on almost all modern tractors.

Brixius is known for equations predicting tyre traction, not for draft control, and the other names are not linked with this invention.

Your Answer : (Not Answered)

Correct Answer : B

The pulling power is Zero.

In traction mechanics, a wheel is called self-propelled when the torque applied to it is just enough to overcome its own motion (rolling) resistance and keep it moving. All the torque is used up in moving the wheel itself, so nothing is left to pull a load and the net pull (drawbar pull) is zero.

Only when more torque is applied than the motion resistance requires does the wheel develop a positive pull. Five, two and three are numbers with no meaning in this definition.

Your Answer : (Not Answered)

Correct Answer : C

The flow rate is \(1.563 \times 10^{-3}\) m³.h^-1.

Four rows at 25 cm spacing give a working width of 1 m. At 2.5 km/h the drill covers

\[ \begin{aligned} 1\ \text{m} \times 2500\ \text{m/h} &= 2500\ \text{m}^{2}/\text{h} = 0.25\ \text{ha/h} \\ \dot{m} &= 5.0 \times 0.25 = 1.25\ \text{kg/h} \\ Q &= \frac{1.25}{800} = 1.563 \times 10^{-3}\ \text{m}^{3}/\text{h} \end{aligned} \]

\(1.172 \times 10^{-3}\) is what three rows (0.75 m width) would give, \(0.391 \times 10^{-3}\) is the flow from a single row, and \(1.953 \times 10^{-3}\) would need a width of 1.25 m, that is five rows.

Your Answer : (Not Answered)

Correct Answer : B

The most harmful vibration range for a human being is 1 to 20 Hz.

The human body is most sensitive to whole-body vibration at low frequencies, because the body and its organs have natural (resonant) frequencies there: about 4 to 8 Hz for the trunk and abdominal organs in vertical vibration, and lower for horizontal vibration. Tractor operators are exposed to exactly this band from rough fields, which is why seat suspension is designed to isolate it.

Below 1 Hz the main effect is motion sickness rather than injury. 50 to 2000 Hz is felt mainly through the hands (hand-arm vibration from tools), and 75,0000 Hz is far above anything relevant to whole-body vibration.

Your Answer : (Not Answered)

Correct Answer : A

The term \(R\theta\) is the vertical motion due to the tractor's pitch motion.

R is a longitudinal distance, measured fore and aft from the centre of gravity to the seat. A rotation \(\theta\) that moves a point at a longitudinal distance R up or down by \(R\theta\) (for small angles) is a rotation about the lateral (transverse) axis through the CG, which is pitch.

Roll is rotation about the longitudinal axis; it would produce vertical motion in proportion to a lateral distance, not a longitudinal one. Yaw is rotation about the vertical axis and moves points sideways, not up and down, and lateral motion is a sideways translation.

Your Answer : (Not Answered)

Correct Answer : B

The theoretical capacity is 5.25 t/h.

Each knife cut removes a slab of straw whose cross-section is the throat (width × clearance) and whose thickness is the length of cut. The number of cuts per minute is knives × speed:

\[ \begin{aligned} V &= 0.45 \times 0.15 \times 0.010 \times 4 \times 540 \\ &= 1.458\ \text{m}^{3}/\text{min} \\ m &= 1.458 \times 60 \times 60\ \text{kg/h} \\ &= 5248.8\ \text{kg/h} \approx 5.25\ \text{t/h} \end{aligned} \]

(the first 60 is the bulk density in kg/m³, the second converts minutes to hours). The moisture content is not needed because the bulk density is given for the straw as fed. 1.31 t/h is what you get with one knife instead of four, and the larger values do not follow from these dimensions.

Your Answer : (Not Answered)

Correct Answer : A

The attachment is the jointer.

A jointer is a small plough bottom, a miniature mouldboard, fixed to the beam ahead of the main bottom. It skims a narrow, shallow strip off the top of the furrow slice and turns surface trash, weeds and roots towards the main furrow, so that the mouldboard then buries them completely. That is exactly the description in the question.

A coulter is a disc or knife that cuts vertically through the soil and trash ahead of the share, but it does not turn a furrow. A subsoiler is a heavy tine that breaks hardpan well below normal ploughing depth. A weed hook is a curved rod or chain that drags tall weeds into the furrow; it is not a plough bottom.

Your Answer : (Not Answered)

Correct Answer : A

The shank is mainly subjected to bending.

A rigid tyne is a cantilever clamped to the tool frame. The soil resistance acts on the sweep at its lower end, well below the clamp, so the horizontal draft force produces a large bending moment that grows towards the clamp. This is why tyne shanks are designed on bending stress and are deep in the direction of travel.

Direct shear from the same force is small beside that moment. Torsion arises only if the soil force is off the shank's centre line, which a symmetrical sweep largely avoids, so neither torsion alone nor bending and torsion together is the main loading.

Your Answer : (Not Answered)

Correct Answer : A

Lateral stability on a turn is increased by increasing the radius of the turn.

On a turn, centrifugal force \(mv^{2}/r\) acts outwards at the centre of gravity and tends to overturn the tractor sideways. A larger turning radius r reduces this force at a given speed, so the tractor is less likely to tip.

Raising the centre of gravity increases the overturning moment, so it reduces stability. A front end loader, especially with its bucket raised, raises the centre of gravity too. Adding weight increases both the overturning force and the restoring moment in proportion, so it does not by itself improve lateral stability unless it lowers the centre of gravity.

Your Answer : (Not Answered)

Correct Answer : B

The pin diameter is about 10.6 mm.

Rated torque at the PTO, then the 150% torque at which the pin must shear:

\[ \begin{aligned} \omega &= \frac{2(3.14)(540)}{60} = 56.52\ \text{rad/s} \\ T &= \frac{40\,000}{56.52} = 707.7\ \text{N.m} \\ T_{f} &= 1.5 \times 707.7 = 1061.6\ \text{N.m} \end{aligned} \]

The pin sits 60 mm from the shaft axis and is loaded in single shear by the force \(F = T_{f}/r\):

\[ \begin{aligned} F &= \frac{1061.6}{0.060} = 17\,693\ \text{N} \\ A &= \frac{F}{\tau} = \frac{17\,693}{200} = 88.5\ \text{mm}^{2} \\ d &= \sqrt{\frac{4A}{\pi}} = \sqrt{112.7} \approx 10.6\ \text{mm} \end{aligned} \]

Forgetting the 150% overload factor and sizing for the rated torque gives about 8.7 mm, close to the 8.6 option. 7.5 and 6.1 mm would shear well below even the rated torque.

Your Answer : (Not Answered)

Correct Answer : B

The instability is avoided by adding weight on the front axle.

When a tractor pulls a heavy drawbar load, weight transfers from the front axle to the rear. If the dynamic load on the front axle falls below about 20% of the tractor's weight, the front end becomes light: steering control is lost, and in the extreme the tractor rears up and overturns backwards. Ballast (front weights) added to the front axle restores enough load there to keep the tractor stable and steerable.

Adding weight on the rear axle, or removing it from the front, moves more load to the rear and makes the instability worse. Reducing rear weight would lose traction without directly restoring the front-axle load.

Your Answer : (Not Answered)

Correct Answer : D

The differential lock ensures distribution of higher amount of torque to the wheel under better traction.

An open differential always sends equal torque to both wheels, and that torque is limited by the wheel with the poorer grip: when one wheel slips, it spins and the other gets little. Locking the differential makes both wheels turn together, so the wheel on firm ground can now take as much torque as its traction allows, far more than the slipping wheel.

Equal torque is what the open differential gives, the condition the lock is meant to escape. Equal power is not a design feature of either. Sending more torque to the wheel with poor traction would only make it spin faster.

Your Answer : (Not Answered)

Correct Answer : D

The diameter is 45 mm.

The ASAE standard for rear power take-off shafts specifies three types. Type 1 runs at 540 rpm and has a 35 mm (1 3/8 in) shaft with 6 splines. Type 2 runs at 1000 rpm on a 35 mm shaft with 21 splines. Type 3 runs at 1000 rpm on a 45 mm (1 3/4 in) shaft with 20 splines.

So a 1000 rpm shaft with 20 splines is the 45 mm Type 3. 35 mm is the shaft of Types 1 and 2, which have 6 and 21 splines, and 30 mm and 40 mm are not standard PTO shaft sizes.

Your Answer : (Not Answered)

Correct Answer : C

The statement that is not appropriate is It is dimensionless.

Cone index is the force needed to push a standard cone penetrometer into the soil divided by the area of the cone's base. It is therefore a pressure, reported in kPa or MPa, and has dimensions of force per unit area.

The other statements are accepted. Cone index is used as an index of soil strength for trafficability and tillage work. It is a composite parameter, because the penetration resistance mixes shear, compression and soil-metal friction rather than measuring one soil property. The ASAE standard penetrometer is pushed at a constant rate of about 30 mm/s (1829 mm/min).