Agricultural Mechanics and Technology
Domain 4: Agricultural Mechanics and Technology
This domain tests safe shop and laboratory practice, welding and metalwork, small-engine operation, electrical circuits, structures, plumbing, hydraulics, and precision agriculture technology. Questions emphasize safety, correct tool use, and applied calculations.
Core rules and concepts
- Personal protective equipment, ventilation, fire prevention, and machine guarding are nonnegotiable in agricultural mechanics.
- A four-stroke engine completes intake, compression, power, and exhaust strokes in two crankshaft revolutions.
- In electrical circuits, Ohm's law states V = I × R; power is P = V × I. AC and DC systems require different test procedures and safety precautions.
- Gear ratios compare driver and driven sizes. A larger driven gear reduces speed and increases torque.
- Hydraulic systems transmit force through incompressible fluid; pressure equals force divided by area.
Worked example
A 12-volt battery is connected to a 4-ohm resistor. Using Ohm's law, I = V ÷ R = 12 ÷ 4 = 3 amperes. Power is P = V × I = 12 × 3 = 36 watts. The reasoning matters: identify the known values, choose the correct formula, and keep units consistent. Do not add resistance and voltage or confuse current with power.
Traps that cost marks
- Mixing AC and DC procedures or ignoring lockout/tagout.
- Reversing the gear-ratio direction: a larger driven gear slows output speed.
- Using the wrong formula for current versus power.
- Treating hydraulic pressure as the same quantity as flow.