MITO Heavy Auto L4 cheat sheet

Diesel compression-ignition cycle: intake air is compressed roughly 14:1 to 23:1, reaching 700-900 °C at the top of the stroke; fuel is injected near TDC and ignites without a spark.

Common-rail fuel systems separate pressure generation (high-pressure pump) from injection timing (ECU-controlled injectors); rail pressure typically spans about 200 bar at idle to over 2,000 bar under load on modern heavy engines.

Air-to-fuel ratio for complete diesel combustion is about 14.5:1 by mass; visible black smoke indicates insufficient air or over-fuelling, white smoke indicates unburnt fuel or low combustion temperature, blue smoke indicates lube oil entering the combustion chamber.

OBD-II diagnostic trouble codes: P = powertrain, B = body, C = chassis, U = network. A code identifies a circuit or system, not automatically the failed component; verify with live data and a physical test before parts replacement.

Brake system rule: DOT 4 glycol brake fluid is hygroscopic; boiling point drops as water content rises, so fluid is typically replaced on a time interval regardless of mileage. Air in the circuit causes a spongy pedal and must be bled.

Electrical basics: Ohm's law V = I × R; power P = V × I. A voltage drop test under load across a cable or ground should read near zero volts; measurable drop indicates excess resistance.

Torque-to-yield head bolts are tightened to a torque figure plus a specified angle; they stretch into the plastic range and must be replaced, not reused, at every teardown.

Cooling system: a pressurised cap raises the coolant boiling point roughly 3 °C per 10 kPa of cap rating; a failed cap causes overheating only under load and is often missed during diagnosis.

Stopping distance = perception/reaction distance + braking distance. Reaction distance grows linearly with speed; braking distance grows with the square of speed, so doubling speed roughly quadruples braking distance.

Axle and gross weight limits are set per jurisdiction; payload = permissible gross vehicle mass minus kerb (tare) mass minus driver, fuel, and accessories. Overloading an axle is a violation even when gross mass is legal.

Load securing: the required lashing force is calculated from the cargo mass times a coefficient (commonly 0.5 forward, 0.5 rearward, 0.5 sideways in European practice) minus friction; friction coefficient for wood on steel is roughly 0.2, for rubber on dry asphalt roughly 0.6-0.8.

Driver hours rules typically require a break after a continuous driving block (for example 45 minutes after 4.5 hours in EU rules) and set daily and weekly driving maxima; exceeding them shifts liability to the operator as well as the driver.

Tachograph and telematics records are legal evidence; manual entries must be made for any period the card was not inserted, and record tampering is a serious offence.

Pre-trip inspection covers tyres (tread depth and pressure), brakes (air pressure build-up and leak-down), lights, coupling security, load restraints, and fluid levels; defects are graded and a dangerous defect prohibits dispatch.

Air brake system: pressure should build from zero to operating range within a specified time, and leak-down must stay within limits with the engine off and service brakes applied. Low-pressure warning must activate before reserve pressure is exhausted.

Centre of gravity rule: raising the load raises the rollover threshold risk; a high centre of gravity reduces the lateral acceleration the vehicle can sustain before tipping, so cornering speed must fall as load height rises.

Hazardous goods transport requires placarding, a transport document, and driver training; segregation rules prevent incompatible classes from sharing a load space.