Haryana BSEH Secondary NSQF Automotive cheat sheet

Fire classes: A solid combustibles, B flammable liquids, C electrical, D metals; CO2 and dry powder suit B and C, water is forbidden on B, C and live electrical fires.

Stop, drop and roll applies to burning clothing; a fire blanket or CO2 extinguisher is used to smother a person or a small fuel spill fire, never water on burning petrol.

A carbon monoxide detector is mandatory in any enclosed space where an engine runs; CO is odourless, colourless and binds haemoglobin about 200-250 times more strongly than oxygen.

Battery charging releases hydrogen; keep flames and sparks at least 1 m away, charge in a ventilated area, and add acid to water, never water to acid.

Jack stands replace a jack once the vehicle is raised; a hydraulic jack alone is a lifting device, not a support device, and wheels must be chocked on the opposite axle.

Compressed air for cleaning must stay below about 2 bar (30 psi) at the nozzle and never be aimed at skin; air embolism and hearing damage are the documented risks.

Eye protection is required for grinding, chiselling, compressed-air use and battery work; a face shield is added over goggles for grinding because high-speed wheel fragments travel tangentially.

Before welding or cutting a vehicle, disconnect the battery, remove or shield fuel lines, and check for fuel-vapour accumulation; a fuel tank is purged or removed before any heat is applied near it.

Spanner size refers to the across-flats distance of the fastener; a 13 mm spanner fits a hex head measuring 13 mm across opposite flats, not the thread diameter.

Six-point sockets grip more flats and resist rounding better than 12-point sockets; 12-point sockets are chosen for speed and for square or spline fasteners.

Torque wrench types: click (breaks over at set torque), beam (deflection read on scale), and electronic; a click wrench is calibrated periodically and returned to its lowest setting after use.

A torque wrench measures torque, not force; torque in N·m equals force in newtons multiplied by lever length in metres (T = F × L).

Micrometer least count equals pitch of screw divided by number of divisions on the thimble; a 0.5 mm pitch with a 50-division thimble gives 0.01 mm least count.

Vernier calliper least count equals smallest main-scale division divided by number of vernier divisions; a 1 mm main scale with 50 vernier divisions gives 0.02 mm.

Feeler gauges measure clearance by blade thickness; a set is stacked to match a gap, and the gap is the thickest blade that enters with slight drag.

Dial gauge (DTI) measures small linear displacement and runout; one revolution of the pointer typically equals 1 mm or 0.01 mm per division depending on the model, so read the dial face before use.

A bench vice is used with the workpiece gripped close to the jaws and the handle pulled, not hammered; files are cleaned with a file card and never used without a handle.

Four-stroke cycle order: intake, compression, power (expansion), exhaust; the crankshaft makes two revolutions per complete cycle and the camshaft makes one.

Compression ratio equals (swept volume + clearance volume) divided by clearance volume; petrol engines typically run 8:1 to 12:1, diesel 16:1 to 22:1.

Engine capacity (cc) equals number of cylinders × (π/4) × bore² × stroke, with bore and stroke in cm giving cm³ directly.

Valve clearance is set cold for most engines and measured between rocker and valve stem; too little clearance causes valve leakage and burnt valves, too much causes noise and reduced lift.

Firing order spreads power strokes; common orders are 1-3-4-2 (four-cylinder inline) and 1-5-3-6-2-4 (six-cylinder inline); the distributor or ECU must match it.

Diesel engines ignite by compression heat; a glow plug assists cold starting, while a petrol engine uses a spark plug fired by the ignition coil.

Piston rings: compression rings seal combustion gas, oil control ring scrapes oil from the bore; ring end gap is measured in the bore with the ring squared by a piston.

Turbocharging uses exhaust gas energy to drive a compressor; a wastegate limits boost, and an intercooler cools compressed air to increase density.

Timing belt versus chain: a belt runs quieter and needs scheduled replacement, a chain lasts longer but stretches; on either, alignment marks must match before rotation.

Clutch function: transmit engine torque smoothly, allow disengagement for gear change, and slip to protect the driveline; the pressure plate clamps the friction disc against the flywheel.

Clutch free play is the gap between release bearing and pressure-plate fingers; too little free play causes slip, too much causes incomplete disengagement and gear clash.

Manual gearbox ratios: overall ratio equals gearbox ratio × final drive ratio; a lower numeric ratio gives higher speed for the same engine rpm.

Vehicle speed (km/h) equals (engine rpm × 60 × rolling circumference in km) divided by (overall gear ratio × 1000) when circumference is in metres.

Synchromesh uses a cone clutch to equalise shaft speeds before the dog teeth engage; worn baulk rings cause crunching on downshift.

Automatic transmission uses a torque converter with a fluid coupling and stator; the stall speed is the engine speed reached with the output held stationary at full throttle.

CV joint (constant velocity) is used on independent front suspension driveshafts; a torn boot lets grease out and grit in, causing clicking on turns.

Differential allows inner and outer wheels to turn at different speeds in a corner; the ring gear to pinion teeth count gives the final drive ratio.

Propshaft universal joints transmit torque through changing angles; incorrect phasing causes vibration that repeats twice per shaft revolution.

Hydraulic braking follows Pascal's law: pressure is equal throughout a confined fluid, so a larger wheel-cylinder area gives greater force but less travel.

Brake fade is loss of friction from heat; DOT 3 and DOT 4 glycol brake fluid are hygroscopic and absorb water, lowering boiling point, so fluid is tested and replaced periodically.

DOT 5 silicone fluid is not mixable with DOT 3 or DOT 4; mixing causes seal swelling and poor braking.

Disc brakes self-adjust and cool better; drum brakes use a leading and trailing shoe, and a star-wheel adjuster sets shoe-to-drum clearance.

Steering geometry: camber is wheel tilt from vertical, caster is the steering-axis tilt giving self-centring, toe is the difference in front and rear of tyre centre distances.

Ackermann geometry makes the inner wheel steer a larger angle than the outer wheel in a turn; turning circle radius is measured to the outer front wheel path.

Rack-and-pinion converts rotary steering-wheel motion into linear rack travel; a worn tie-rod end shows as play felt with the wheel rocked while the tyre is loaded.

MacPherson strut combines a damper, coil spring and upper pivot in one unit; a double-wishbone suspension separates spring and damper and controls camber better.

Wheel alignment order: set tyre pressures and ride height, then caster and camber, then toe last, because toe is affected by camber changes.

Ohm's law: V = I × R; power P = V × I = I²R = V²/R, with V in volts, I in amperes, R in ohms, P in watts.

Series circuit: current is common, voltages add, total resistance adds. Parallel circuit: voltage is common, currents add, total resistance is less than the smallest branch.

A 12 V battery with a 55 W lamp draws about 4.6 A (I = P/V = 55/12); the same lamp on 24 V draws about 2.3 A.

Battery capacity in ampere-hours (Ah) is current × time; a 60 Ah battery delivers 3 A for about 20 hours at the rated discharge rate.

Starter motor draws hundreds of amperes; a voltage drop above about 0.5 V on a cable under load indicates high resistance at a terminal or ground.

Alternator output is rectified three-phase AC; the voltage regulator holds about 13.8 to 14.4 V on a 12 V system when charging.

Fuse rating protects the wiring, not the device; a fuse must be replaced with the same rating, and a blown fuse indicates a fault to be found, not a bigger fuse.

LED and ECU circuits are polarity sensitive; the ECU reads sensor voltages, and a shorted sensor signal wire can pull the reference voltage down and disable several sensors.

Multimeter use: volts measured in parallel across a load, amperes in series with the circuit, ohms only with the circuit dead and isolated.

Stoichiometric air-fuel ratio is about 14.7:1 by mass for petrol and about 14.5:1 for diesel; rich mixture means excess fuel, lean means excess air.

Diesel injection timing is set in degrees of crankshaft rotation before top dead centre; late timing raises exhaust temperature and smoke.

Fuel filter replacement direction matters; most filters are marked with flow arrows, and a diesel system needs priming or bleeding after filter change to remove air.

Engine oil viscosity grade SAE 10W-40: the number before W is cold-flow behaviour, the number after W is high-temperature thickness; multi-grade oil covers both.

API and ACEA oil service categories indicate performance level; using a lower category than specified can cause sludge, wear or catalyst damage.

Oil pressure warning at idle with correct oil level points to a worn pump, a stuck relief valve or excessive bearing clearance; oil pressure is not the same as oil level.

Cooling system: thermostat opens near 82-90 °C to route coolant to the radiator; the radiator cap holds pressure, raising the boiling point by roughly 3 °C per 10 kPa.

Coolant is a mix of water and antifreeze (ethylene glycol) with corrosion inhibitors; a 50:50 mix protects to about -37 °C and raises boiling point.

Air lock in a cooling system causes local overheating; bleeding at the highest point or heater hose removes trapped air after a refill.

Pre-delivery or periodic service sequence: check fluid levels and leaks, tyre pressures and tread, brake and steering play, lights and horn, then road test and record findings.

Tyre tread minimum is 1.6 mm in the central three-quarters of the tread for cars; tread wear indicators show the limit, and uneven wear indicates alignment or inflation faults.

Tyre pressure is checked cold; pressure rises about 0.1 bar per 10 °C of running temperature, so a hot reading must not be used to set pressure.

Engine oil change interval is set by the manufacturer; the drain plug washer is replaced, the filter changed, and the level checked after the engine runs briefly.

Brake inspection includes pad or lining thickness, disc runout, fluid level and moisture, hose condition and a road test for pull or pedal feel.

Battery test order: visual check, state of charge by open-circuit voltage (about 12.6 V for a fully charged 12 V battery), then a load or conductance test.

A road test after service confirms steering centring, brake balance, gear selection and absence of warning lights; any warning lamp that stays on is recorded before release.

Service records and torque values are recorded per job; a fastener tightened without a specified torque relies on feel and is not traceable.

Cast iron is strong in compression and wear resistant, used for cylinder blocks and brake drums; aluminium is lighter but needs liners or coated bores for wear resistance.

Steel classification by carbon content: low carbon up to about 0.3 %, medium 0.3-0.6 %, high above 0.6 %; higher carbon raises hardness and lowers ductility.

Alloying elements: chromium improves corrosion resistance and hardness, nickel improves toughness, vanadium and molybdenum improve high-temperature strength.

Heat treatment: annealing softens and relieves stress, normalising refines grain, hardening followed by tempering trades hardness for toughness.

Gasket materials: copper and steel for high-temperature joints, composite fibre for coolant and oil joints, rubber O-rings for low-pressure sealing; a gasket seals by deformation under clamp load.

Plastics and composites are used for intake manifolds, covers and panels; they resist corrosion but have lower heat resistance and need correct fastener torque to avoid cracking.

Friction materials in brake linings must resist fade and not contain banned asbestos; semi-metallic, organic and ceramic linings differ in heat range and dust.

Dissimilar metals in contact with an electrolyte form a galvanic cell; aluminium against steel corrodes the aluminium, so insulating washers and coatings are used.

Unit conversions: 1 inch = 25.4 mm, 1 bar = 100 kPa = 14.5 psi, 1 kgf = 9.81 N, 1 hp = 0.746 kW.

Micrometer reading = main scale + thimble reading; with 0.5 mm pitch and 50 thimble divisions, each division is 0.01 mm, so 5.5 mm plus 23 divisions equals 5.73 mm.

Vernier calliper reading = main scale value + (coinciding vernier division × least count); with 0.02 mm least count, 12 mm plus 7 divisions equals 12.14 mm.

Bore and stroke from swept volume: swept volume per cylinder = (π/4) × bore² × stroke; total capacity = that value × number of cylinders.

Torque calculation: a force of 200 N applied at 0.3 m gives 60 N·m; a longer wrench increases torque for the same force.

Compression ratio = (swept volume + clearance volume) / clearance volume; a 400 cm³ swept volume with 40 cm³ clearance gives 11:1.

Gear ratio and speed: output speed = input speed × (driving teeth / driven teeth); a 20-tooth driver turning a 40-tooth driven gear halves the speed.

Percentage error = (measured value − true value) / true value × 100; a 0.02 mm error on a 20 mm dimension is 0.1 %.

A resume for a technician lists qualifications, tools handled, systems worked on and safety training; it does not list duties without evidence of skill.

Interview STAR method: Situation, Task, Action, Result; each answer gives a concrete example with a measurable result.

Workplace communication: report faults in writing with vehicle identification, symptom, conditions and action taken; verbal-only reporting loses detail.

Team role in a workshop: the technician reports to the supervisor, and any safety hazard is reported immediately and recorded, not deferred.

Time management uses job cards and priority by safety-critical work first, then customer commitments, then routine maintenance.

Digital literacy includes reading service information systems, using diagnostic scan tools and recording data accurately in a job card.

Right to safety and right to be heard are consumer rights; a customer complaint is logged, investigated and answered with the action taken.

Continuous learning: NSQF levels map skills from helper to master technician, and each level requires documented competence, not just years served.

Entrepreneurship terms: turnover is total sales, profit is turnover minus costs, and working capital is current assets minus current liabilities.

Break-even quantity = fixed costs / (selling price per unit − variable cost per unit); below that quantity the business makes a loss.

A workshop business plan covers location, tools and equipment, staffing, service menu, pricing, licences and a cash-flow forecast.

GST registration thresholds and invoicing rules apply to vehicle service businesses; a proper tax invoice shows GSTIN, HSN or SAC code and tax breakup.

Customer communication: explain the fault, the options and the cost before work starts, and obtain approval for additional work found during repair.

Marketing for a small workshop relies on service quality, referrals, a Google business listing and transparent estimates rather than only on discounts.

Record keeping: job cards, parts purchase bills, labour records and warranty claims are retained so that profit and liability can be verified.

A partnership or sole proprietorship differs in liability and capital; a current account in the business name separates personal and business money.