Assam ASSEB HSLC NSQF Automotive cheat sheet

Fire classes: A solid combustibles, B flammable liquids, C electrical, D metals; CO2 and dry powder are used for B and C, water never on B, C or live electrical fires.

Eye protection (goggles or face shield) is mandatory during grinding, cutting, chiselling and battery work; a face shield alone does not replace goggles for dust.

Before any welding, drain, purge and disconnect fuel lines; keep a fire watch and extinguisher within 10 m of the work area.

Jack stands must be rated above the vehicle's supported corner load and placed on level, solid ground; a hydraulic jack alone is never a support device.

Exhaust gas carbon monoxide is odourless; never run an engine in a closed bay without extraction to outside air.

Battery charging releases hydrogen: no sparks or open flames, keep vent caps on, and charge in a ventilated area.

Compressed air must not exceed about 2 bar (30 psi) for cleaning; never point an air gun at skin or use it to clean clothing.

Lockout/tagout: isolate and tag energy sources before servicing lifts, compressors or hybrid high-voltage systems.

Torque = force x perpendicular distance (T = F x d); a 1 m bar with 50 N at right angles gives 50 N·m.

Torque wrench types: click (preset, audible), beam/deflecting (direct read), electronic (peak/hold); recalibrate at least annually or after a drop.

Socket sizes: metric 8, 10, 12, 13, 14, 17, 19, 21, 22 mm cover most automotive fasteners; 6-point sockets resist rounding better than 12-point.

Spanners: open-end for flats in tight space, ring for full hex contact and higher torque, combination for both; flare-nut spanner for hydraulic pipe unions.

Micrometer reading = main barrel scale + thimble scale x least count (typically 0.01 mm); read to 0.001 mm with a vernier micrometer.

Vernier caliper least count is usually 0.02 mm (metric) or 0.001 in (imperial); check zero before every measurement.

Feeler gauge measures valve clearance, plug gaps and bearing end float by stacking blades; clean blades and never force them.

Special tools: cylinder bore gauge for taper/ovality, dial indicator with magnetic base for runout, compression tester for cylinder sealing.

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

Compression ratio = (swept volume + clearance volume) / clearance volume; petrol engines typically 8:1 to 12:1, diesel 16:1 to 23:1.

Engine displacement = cylinder area x stroke x number of cylinders; bore and stroke in cm gives cc directly.

Valve clearance is set cold on most engines with a feeler gauge between rocker and valve stem; too tight causes burning, too loose causes noise and lost lift.

Timing belt/chain alignment marks must match crank and cam; incorrect timing causes valve-to-piston contact on interference engines.

Firing order (e.g. 1-3-4-2 for many four-cylinders) determines ignition and injection sequencing; identify cylinder 1 before any timing work.

Turbocharger needs clean oil supply and a cool-down idle period; oil coking in the bearing housing is a common failure cause.

Diagnosis signals: blue smoke = oil burning, white smoke = coolant or unburnt fuel, black smoke = rich mixture or restricted air.

Manual clutch parts: flywheel, friction disc, pressure plate, release bearing, fork; the release bearing moves toward the pressure plate diaphragm to disengage.

Clutch free play is typically 10-25 mm at the pedal; no free play causes slip, excessive free play causes incomplete disengagement and gear crunch.

Gear ratio = driven gear teeth / driving gear teeth; overall ratio = gearbox ratio x final drive ratio.

Constant-mesh gearbox uses helical gears always in mesh with synchro hubs; synchromesh cones equalise shaft speed before dog engagement.

Automatic transmission uses a torque converter (fluid coupling with stator) and planetary gearsets; clutch packs and bands select ratios.

CV joints: inner (tripod or double-offset) allows plunge, outer (Rzeppa) allows steering articulation; a split boot leads to grease loss and joint failure.

Differential allows wheels to turn at different speeds in a corner; final drive ratio affects acceleration versus top speed and speedometer accuracy.

Driveline layout: front-engine rear-wheel drive uses propeller shaft with universal joints; front-wheel drive uses half shafts with CV joints.

Hydraulic brake force: pressure = force / area (P = F/A); a larger master cylinder piston reduces line pressure for the same pedal force.

DOT 3 and DOT 4 brake fluids are glycol-based and hygroscopic; DOT 5 is silicone and must not be mixed with glycol fluid.

Brake fade from heat reduces friction; bleeding removes air because air compresses while fluid does not.

Disc runout is checked with a dial indicator; typical limit about 0.05-0.10 mm depending on specification.

Steering: rack-and-pinion converts rotation to linear motion; toe-in or toe-out is set with the wheels straight ahead and is measured in mm or degrees.

Caster affects straight-line stability and self-centring; camber affects tyre wear and cornering grip; toe affects tyre scrub.

Suspension types: MacPherson strut (integrated spring and damper), double wishbone, trailing arm; worn dampers cause bounce and uneven tyre wear.

Wheel alignment angles must be set with correct tyre pressure and load; incorrect toe is the most common cause of rapid tyre shoulder wear.

Ohm's law: V = I x R; power P = V x I = I²R. A 12 V circuit drawing 5 A has 2.4 ohm resistance and consumes 60 W.

Series circuit: current is the same, voltages add. Parallel circuit: voltage is the same, currents add.

Battery: 12 V nominal, six cells of about 2.1 V each; specific gravity of a fully charged lead-acid cell is about 1.265.

Alternator output is regulated to about 13.8-14.5 V; a reading below 13 V with the engine running suggests a charging fault.

Starter circuit draws hundreds of amps; voltage drop above 0.5 V on a cable indicates high resistance.

Multimeter use: volts in parallel with the load, amps in series (never across a supply), ohms with the circuit unpowered.

Fuses protect circuits by current rating; replace with the same rating, never higher. Relays use a small coil current to switch a large load current.

CAN bus is a twisted-pair differential network; measure about 60 ohm between CAN-H and CAN-L with the bus powered down and modules asleep.

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

Fuel injection: port injection delivers fuel at the intake port; direct injection delivers into the cylinder at high pressure (common-rail diesel up to 2000 bar).

Diesel injection timing and quantity are controlled electronically; air in the fuel line causes hard starting and requires bleeding.

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

API and ACEA oil categories define performance level, not viscosity; use the grade and category specified for the engine.

Oil pressure warning at idle with correct level often indicates worn bearings or a faulty pressure relief valve; check with a mechanical gauge.

Cooling system: thermostat regulates flow, radiator dissipates heat, pressure cap raises boiling point (about 1.2 bar raises it roughly 25 °C).

Coolant is typically 50:50 glycol and water; never open a hot pressurised cap, and bleed air from the highest point after refilling.

Chassis types: ladder frame (separate body, high strength for load), monocoque/unibody (body and frame combined, lighter and stiffer), space frame.

Crumple zones absorb energy in a collision; the passenger safety cell is designed to stay rigid.

Body panel materials: mild steel, high-strength steel, aluminium, and composites; each needs different repair methods and isolation to prevent galvanic corrosion.

Panel gap and flushness measurements detect misalignment; check door, bonnet and boot gaps against specification after structural repair.

Underbody sealant and cavity wax protect against corrosion; stone chips and blocked drain holes are common corrosion starting points.

Wheelbase, track width, ride height and kerb weight are key chassis dimensions; changing ride height alters suspension geometry.

Body repair sequence: assess damage, straighten or replace structure, restore corrosion protection, then refinish and check alignment.

Horns, lights, wipers and mirrors are legal safety items; aim headlamps and check operation after any front-end body work.

Steel classification by carbon content: low carbon up to about 0.3 %, medium 0.3-0.6 %, high above 0.6 %; higher carbon gives harder, less ductile parts.

Cast iron is brittle in tension but excellent in compression and damping; used for cylinder blocks and brake discs.

Aluminium alloys are about one-third the density of steel; use thread inserts or torque limits carefully because threads strip more easily.

Fastener grade markings: metric property class 8.8 or 10.9 on the bolt head; imperial grade 5 has three radial lines, grade 8 has six.

Thread pitch is the distance between adjacent threads; metric coarse M10 is 1.5 mm pitch, M8 is 1.25 mm pitch.

Torque-to-yield bolts stretch permanently and must be replaced after use; angle-tightening is used for cylinder head and suspension bolts.

Measurement tools: steel rule (0.5 mm), vernier caliper (0.02 mm), micrometer (0.01 mm), dial gauge (0.01 mm), bore gauge for internal diameters.

Tolerance is the permitted variation; clearance is the gap between mating parts, interference means the shaft is larger than the hole.

Service intervals follow the manufacturer's schedule by distance or time, whichever comes first; severe-duty use shortens intervals.

Daily checks: engine oil level, coolant level, brake fluid level, tyre pressure and tread depth (legal minimum 1.6 mm in many jurisdictions).

Troubleshooting logic: verify the complaint, gather symptoms, form a hypothesis, test, then repair and confirm; never replace parts without a test.

Compression test: crank with the throttle open and ignition disabled; a low dry reading that rises with oil indicates worn rings, no rise suggests valves.

Cylinder leakage test uses regulated air and measures percentage loss; listen at intake, exhaust and oil filler to locate the leak.

Scan tool reads diagnostic trouble codes (DTCs); a code identifies a circuit or system, not automatically the failed component.

Brake inspection: pad thickness, disc condition, fluid level and pedal feel; a spongy pedal indicates air in the hydraulic system.

Road test after repair confirms the fix; record the complaint, cause, correction and parts used on the job card.

Job card content: customer details, vehicle identification number, odometer, complaint, work performed, parts used and technician signature.

Active listening technique: repeat the customer's complaint back and confirm the symptom, conditions and time of occurrence before starting work.

Estimate versus invoice: an estimate is a quotation before work, an invoice is the final bill; get customer approval before extra work.

Technical terms must be explained in plain language for the customer; avoid jargon such as 'DTC' or 'runout' without explanation.

Entrepreneurship basics: fixed costs (rent, salaries) do not vary with volume, variable costs (parts, consumables) do; break-even = fixed costs / (price - variable cost per unit).

GST and invoicing, labour rate, parts margin and warranty policy are standard items in a workshop business plan.

Workplace records: maintain a parts inventory, service history and warranty register; accurate records support repeat business.

Team communication: report hazards and unfinished work at shift handover; use a written handover note for safety-critical items.

Waste segregation: used oil, coolant, batteries, tyres, metal scrap and general waste must be kept in separate labelled containers.

Used engine oil is hazardous; never pour it into drains or soil, and recycle through an authorised collector.

Lead-acid batteries contain lead and sulphuric acid; store upright on an acid-resistant tray and send to a licensed recycler.

Refrigerant recovery is mandatory before opening an air-conditioning circuit; venting refrigerant to atmosphere is prohibited under most regulations.

Spill response: contain with absorbent, protect drains, collect contaminated absorbent as hazardous waste, and report the spill.

Personal protective equipment for waste handling includes nitrile gloves, goggles and apron; wash hands before eating.

Air quality: spray painting and welding require local exhaust ventilation; solvent vapours are both a health and fire hazard.

Environmental management systems such as ISO 14001 require documented procedures for waste, emissions and legal compliance.