1 GUIDE-O-LEARN MOTOR MECHANICS ENGINE FUELS ENGINE OIL TRANSMISSION BRAKES SUSPENSION STEERING WHEELS and TYRES GLOSSARY AUTOMOTIVE TERMS Reproduced by Speciss College with permission from Chris Longhurst www.carbibles.com 2 TABLE OF CONTENTS Page ENGINE SECTION Taking in air, Squeezing the air, Burning the air-fuel mixture, Getting rid of the burnt gases Engine layouts The difference between 4 stroke and 2 stroke engines Spark-ignition engine components How 2 stroke engines work How 4 stroke engines work Compression-ignition engine components 4 stroke diesel engines 2 stroke diesel engines "Clean" diesels? Toyota's D-Cat and DPNR Interference versus non-interference engines Top Dead Centre (TDC) and ignition timing Checking ignition timing Check the timing marks first Timing marks on cam belt pulleys Spark plugs How does the fuel-air mix happen? Carburettors How they work Float and diaphragm chambers Carb icing Complexity for the sake of it Fuel injection Different types of injector systems ECU maps Valves and valve mechanisms Spring-return valves Tappet valves 16v and the other names you'll find on the back of a car Variable valve timing Rotary / Wankel engines Engine cooling systems Air cooling Oil cooling Water cooling The complexities of water cooling FUEL SECTION Petrol E10 Ethanol Fuel: you're using it right now Detonation, pre-ignition, pinking, pinging and knocking Compression ratio Reproduced by Speciss College with permission from Chris Longhurst www.carbibles.com 3 Octane ratings - how to stop detonation Measuring octane - RON, MON What factors affect detonation? Octane and altitude Octane and power Octane and petrol mileage Octane boosters Lead Replacement Petrol (LRP) and valve seats Fuel filters - without them, all this means nothing Why filter the fuel? Won't the debris just burn? Why change the filter? Where is my fuel filter? The 'sock' filter The carburettor internal filter ENGINE OIL SECTION What does my oil actually do? What do the numbers around the 'W' mean? For example 5W40? A quick guide to the different grades of oil Mineral or synthetic? Synthetics Pure synthetics Flushing oils Do I need a flushing oil? Engine oil categories Engine oil grades How often should I change my oil? Maintenance minders - when the car tells you when to change the oil What else happens when I change the oil? Checking the oil in your engine, and topping up What happens when an engine is overfilled with oil? What's the best way to check the oil level? Can I use diesel engine oil in my petrol engine? Oil filters and filtration TRANSMISSION SECTION Manual gearboxes - what, why and how? How gears work Making gears work together to make a gearbox The synchromesh - why you don't need to double-clutch What about reverse? Crash gearboxes or dog boxes Before the gearbox - the clutch Motorcycle 'basket' clutches Automatic gearboxes How planetary gear-sets work Locking planetary gear-set components Reproduced by Speciss College with permission from Chris Longhurst www.carbibles.com 4 The automatic gearbox hydraulic system - how it changes gears Parking Torque converters TipTronic® Gearboxes CVT - continuously variable transmission Toroidal CVT (Nissan Extroid) Differentials Is there a differential on each axle? Open differentials Limited-slip differentials Torsen differentials How does a Torsen 'sense' torque? Locking differentials Viscous couplings Hydraulic clutch couplings 2WD - two-wheel drive 4WD - four-wheel drive AWD - all-wheel drive type 1 AWD - all-wheel drive type 2 FWD, RWD, FE, ME, RE BRAKES SECTION Brakes - what do they do? Thermodynamics, brake fade and drilled rotors The different types of brakes Bicycle wheel brakes Drum brakes - single leading edge Drum brakes - double leading edge Disc brakes Brake pad compounds Brake squeal Brake actuators Single-circuit hydraulic Dual-circuit hydraulic Brake-by-wire Mechanical advantage Mechanical advantage as applied to hydraulics Power brakes and master cylinders The components of a master cylinder Cross-linked brakes - why there are two brake circuits A word about handbrakes When to use handbrakes When not to use handbrakes Anti lock Braking Systems - ABS Newer generation ABS systems ABS and skid control Brake-assist and collision warning systems Other brake technologies Reproduced by Speciss College with permission from Chris Longhurst www.carbibles.com 5 Brake hoses - not just rubber Brake fluids D.O.T. ratings Brake warning lights LED replacement bulbs SUSPENSION SECTION What does it do? Suspension types Front suspension - dependent systems Front suspension - independent systems MacPherson strut or McPherson strut Double wishbone suspension systems Coil spring type 1 Coil spring type 2 Multi-link suspension Trailing-arm suspension Twin I-beam suspension Moulton rubber suspension Transverse leaf-spring Rear suspension - dependent (linked) systems Solid-axle, leaf-spring Solid-axle, coil-spring Beam axle 4-bar Derivatives of the 4-bar system De Dion suspension, or the de Dion tube Rear suspension - independent systems Hydrolastic suspension Hydropneumatic suspension Digital suspension systems Ferrofluid or magneto-rheological fluid dampers - Audi Magnetic Ride Air suspension Why air suspension? Bags and struts Ride height sensors Control panels Anti-roll bars (sway bars/stabilizers) Suspension bushes Sprung vs. unsprung weight Progressively wound springs Torsion bars STEERING SECTION Basic steering components The Ackermann Angle : your wheels don't point the same direction Why 'Ackermann'? Reproduced by Speciss College with permission from Chris Longhurst www.carbibles.com 6 Steering ratios Turning circles Steering system designs: Pitman arm types Worm and sector Worm and roller Worm and nut or recirculating ball Cam and lever Steering system designs: Rack and pinion Variable-ratio rack and pinion steering Vehicle dynamics and steering - how it can all go very wrong Understeer Oversteer Counter-steering TYRES & WHEELS SECTION How to read your tyre markings OE manufacturer letters DOT codes and the 6-year shelf life The E-mark Tyre size notations Tyre size markings Ultra high speed tyre size notations Speed ratings Load indices Car tyre types Tyre constructions Comparison of radial vs cross-ply performance A subset of tyre construction: tyre tread Tread patterns Tread depth and tread wear indicators Aquaplaning / hydroplaning Coloured dots and stripes - what’s that all about? Caster, camber, toe-in toe-out alignment Caster Camber Toe in and out Rotating your tyres Diagnosing problems from tyre wear Trouble Shooting Chart for Tyre Wear GLOSSARY AUTOMOTIVE TERMS Reproduced by Speciss College with permission from Chris Longhurst www.carbibles.com 7 ENGINE SECTION back to ToC Taking in air, Squeezing the air, Burning the air-fuel mixture, Getting rid of the burnt gases… ....is the common description for how an internal combustion engine works. The basic way all internal combustion engines work is to take a mixture of fuel and air, compress it, ignite it either with a spark plug or by self- ignition (in the case of a diesel engine), allow the explosion of combusting gasses to force the piston back down and then expel the exhaust gas. The vertical movement of the piston is converted into rotary motion in the crank via connecting rods. The crank then goes out to the gearbox via a flywheel and clutch, and the gearbox sends the rotary motion to the wheels, driving the vehicle forwards. Reproduced by Speciss College with permission from Chris Longhurst www.carbibles.com 8 The diagram above illustrates these concepts. It shows an inline-4 engine with dual overhead cams. Engine layouts Here are some illustrations of the most common types of cylinder layout you'll find in engines today. Singles are typically used in motorbikes, chainsaws etc. V-twins are also found in motorbikes. Inline-fours are the mainstay of car engines, as well as being found in some motorbikes too such as the BMW K1200S. Inline fives used to be used a lot in Audis but have found a new home in current Volvos. The V5 is something you'll find in some VWs. The V6 has the benefits of being smoother than an inline-four but Reproduced by Speciss College with permission from Chris Longhurst www.carbibles.com 9 without the fuel economy issues of a V8. Boxer engines are found in BMW motorbikes (twins) and Porsches and Subarus (fours and sixes). The difference between 4 stroke and 2 stroke engines Almost every car sold today has a 4 stroke engine. So do a lot of motorbikes, lawnmowers, and other mechanical equipment. But 2 stroke engines are often found in smaller motorbikes, smaller lawnmowers, etc. The difference between the two engine types is the number of times the piston moves up and down in the cylinder for a single combustion cycle. A combustion cycle is the entire process of sucking fuel and air into the piston, igniting it and expelling the exhaust. Spark-ignition engine components Basic engine The cylinder head attaches to the cylinder block. components A gasket makes a seal between them. Some cylinder blocks have passages to carry oil and coolant. 4 & 2-stroke Ports in the cylinder head or walls carry air-fuel engine mixture and exhaust gases. In 4-stroke engines, differences valves open and close the ports. A rocker arm acts on a valve spring to operate the valve. Engine cams & A cam is a lobe on a camshaft, shaped to camshaft control how the valve opens and closes. The camshaft keeps all of the valves working with the correct timing and in the correct sequence. Engine power Power can be transferred from the crankshaft to transfer the camshaft by timing gears, a timing chain running on sprockets, or a timing belt running on toothed pulleys. 2-stroke power The crankcase is the lower part of the cylinder transfer block. In a 2-stroke gasoline engine, air-fuel mixture flows through a transfer port from the crankcase to the combustion chamber.