Motor Trade Theory Grade 6 Term 4 Revision Booklet PDF

Grade 6 Term 4 Revision Booklet  Module 1: Safety and health in the workshop =========================================== TEACHING SAFETY MEASURES ------------------------ GOOD HOUSEKEEPING -----------------  ACCIDENTS --------- HYGIENE AND SAFETY IN...

Grade 6 Term 4 Revision Booklet  Module 1: Safety and health in the workshop =========================================== TEACHING SAFETY MEASURES ------------------------ GOOD HOUSEKEEPING -----------------  ACCIDENTS --------- HYGIENE AND SAFETY IN THE WORKSHOP ----------------------------------  SAFE HANDLING OF COMPRESSORS ---------------------------- SAFE HANDLING OF HYDRAULIC PRESSES AND APPARATUS ------------------------------------------------  HOISTS, JACKS AND TRESTLES -------------------------- CARE, STORAGE AND SAFE HANDLING OF CUSTOMERS' VEHICLES ------------------------------------------------------  TOWING A VEHICLE ---------------- Module 2: Workshop measuring tools ================================== TOOLS IN THE MODERN WORKSHOP ---------------------------- BASIC HAND TOOLS ---------------- - Spanners; - Pliers; - Screwdrivers; - Hammers; - Hacksaws; - Files; - Chisels; and - Centre and prick punches.  SPECIAL WORKSHOP TOOLS AND EQUIPMENT ------------------------------------  GENERAL TOOLS USED IN A WORKSHOP -------------------------------- - Trestles; - Hydraulic jack; - Battery charger; - Manual and electrical hydraulic presses; - Motor car creeper and tool stand; and - Ball joint puller. MEASURING AND MARKING INSTRUMENTS ---------------------------------  Module 3: Engine components =========================== THE CYLINDER BLOCK ------------------  WATER JACKET ------------  THE CYCLINDER HEAD ------------------ THE CRANKSHAFT --------------  THE PISTON ---------- PISTON RINGS ------------  THE CAMSHAFT ------------ TIMING (CAMSHAFT) GEARS, CHAINS AND BELTS -----------------------------------------  VALVE LIFTERS ------------- PUSHRODS --------  ROCKERS ------- VALVES AND SPRINGS ------------------  EXHAUST AND INLET MANIFOLDS --------------------------- GASKETS AND SEALS -----------------  CYLINDER HEAD ------------- CARBURETTOR -----------  IGNITION COIL ------------- SPARK PLUGS -----------  DISTRIBUTOR ----------- STARTER MOTOR -------------  ALTERNATOR ---------- BEARINGS AND BUSHES -------------------  PISTON RINGS ------------ FLYWHEEL --------  FUEL PUMPS ---------- WATER PUMP ----------  MATERIALS USED IN MOTOR VEHICLES -------------------------------- PROPERTIES OF MATERIALS ----------------------- - Tenacity; - Elasticity; - Malleability; - Ductility; - Plasticity; - Toughness; and - Hardness.  Module 4: Drive trains ====================== THE SINGLE PLATE CLUTCH ----------------------- THE CLUTCH ASSEMBLY -------------------  PRESSURE PLATES --------------- THE CLUTCH PLATE ---------------- - It must create a firm link between the engine and the gearbox without slipping; - Be able to be completely released quickly and easily take up the drive smoothly without sticking or jerking; and - Be able to dissipate all the heat created by friction without damage, even under heavy loads. CLUTCH RELEASE MECHANISMS -------------------------  THE CLUTCH RELEASE BEARING -------------------------- CLUTCH PEDAL FREE PLAY ----------------------  CLUTCH PROBLEMS --------------- - Slipping clutch; - Dragging clutch; - Grabbing clutch; and - Shuddering clutch. Module 5: Heat engines ====================== TYPES OF ENGINES ---------------- - Motorcars and motorbikes; - Boats; - Trucks; - Lifting equipment; - Water pumps; and - Generators.  THE FOUR-STROKE PETROL ENGINE -----------------------------  THE THREE-PORT TWO-STROKE PETROL ENGINE --------------------------------------- ADVANTAGES OF PETROL INJECTION IN COMPARISON TO CARBURETTORS ------------------------------------------------------------ - The air fuel mixture may be measured exactly at all engine speeds. - Ignition knock is improbable. - Air pollution is reduced. - More than 100% volumetric efficiency is possible. - Higher CR's may be used because of better mixture control. - Icing of inlet manifold cannot occur as only air passes through.  COMPRESSION IGNITION ENGINES (DIESEL ENGINES) --------------------------------------------- THE FOUR-STROKE C.I. ENGINE --------------------------- - Cylinder; - Piston; - Connecting rod; - A hinge action; - Crankshaft; - Main bearings; - Crankshaft timing gear; - Camshaft; and - Valve mechanism.  THE TWO-STROKE C.I. ENGINE -------------------------- 1. Engines with ports in the bottom end of the cylinder which are used to scavenge exhaust gases and admit the fresh air charge. (Port-type) 2. Engines where the intake port is in the bottom end of the cylinder and the exhaust port is in the cylinder head. The closing and opening of the exhaust port in this case is controlled by poppet valves. (Uniflow-type) THE PORT-TYPE TWO-STROKE ENGINE -------------------------------  THE 'UNIFLOW'-TYPE TWO-STROKE ENGINE ------------------------------------ THE OPPOSED-PISTON TWO-STROKE DIESEL ENGINE -------------------------------------------  THE ROTARY ENGINE ----------------- - An oval rotor casing with ports, a water jacket and flat end casings; - A triangular rotor with curved sides and flat ends; - An eccentric crankshaft; - An annular gear inside the rotor that engages with fixed gear on one end casing; and - Inlet and exhaust ports and spark plugs in the casing. Module 6: Mounting an engine ============================ POSITIONING AND MOUNTING AND ENGINE -----------------------------------  MOUNTING AN ENGINE ------------------ - Four-point system: The engine is attached to the frame at four different - Three-point system: The engine is attached to the frame at three different points. This system is used in passenger cars and light motor vehicles. FRAMES ------  BEAMS ----- Module 7: Lubrication systems ============================= LUBRICATION -----------  LUBRICANTS ---------- ENGINE LUBRICATING SYSTEMS --------------------------  OIL CONTROL METHODS ------------------- - Oil seals and retainers; - Oil restrictors; - Gaskets or packing; - Oil throwers; and - Oil turbines. OIL PRESSURE IN AN ENGINE -------------------------  ABNORMAL OIL CONSUMPTION ------------------------ - Burning in the combustion chamber; - Leaking out pst gaskets and seals in liquid form; and - Leaking through the breather pipe as a vapour. CRANKCASE VENTILATION ---------------------  OIL COOLERS ----------- OIL FILTERS -----------  OIL PUMPS --------- Module 8: Cooling systems ========================= TEMPERATURE CONTROL -------------------  DIRECT WATER COOLING -------------------- DIRECT AIR COOLING (AIR-COOLED) -------------------------------  INDIRECT AIR COOLING (WATER COOLED) ----------------------------------- RADIATORS ---------  WATER PUMPS ----------- - The positive pump consists of a housing of aluminium alloy or cast iron - The impeller pump acts on the same principle as the positive pump except that the impeller is inserted directly in the water jacket, while the housing carrying the shaft bearings with their water seal and the by-pass and inlet ports is bolted to the engine block. THERMOSTAT ----------  THE BYPASS ---------- WATER DISTRIBUTING TUBES ------------------------  RADIATOR SHUTTERS ----------------- OVERHEATING -----------  Module 9: Batteries =================== BATTERIES --------- BATTERY CHECKING AND CHARGING ----------------------------- - Electrolyte levels must be checked occasionally and the battery topped up - To check the battery charge, the specific gravity of the electrolyte must be measured and a load test performed. The battery condition can be determined from the results of both. - Batteries may need to be charged before putting into a vehicle. There are two methods, a quick charge or a slow charge. SULPHATION ----------  TESTING A BATTERY WITH A V METER -------------------------------- - Connect the meter across the battery terminals and turn on the car's headlights or heater fan to provide a light load. - Take a reading with the meter. - A well-charged battery should register over 12 V, but if the meter reads about 11,5 V, the battery is not necessarily defective.  CARE AND MAINTENANCE OF THE BATTERY ----------------------------------- REMOVING A BATTERY ------------------ - Remove the cable carefully so that you do not damage the terminals. - Loosen the battery nut, open up the connector's open end sufficiently and pull the cable straight up. - Loosen the battery clamp nut, remove the bolt, remove the clamp, and lift the battery case. - Lift the battery case straight up - tilting it to one side may allow the electrolyte to spill out. CONNECTING BATTERIES IN SERIES OR PARALLEL ------------------------------------------ - Series circuit: When two 12V batteries are connected in series, they form a 24V battery that has the capacity for starting heavy-duty vehicles equipped with a 24V system. - Parallel circuit: When two 12V batteries are connected in parallel, they form a 12V battery with more power, greater cranking ability and a longer useful life than a single 12V battery.  Module 10: Wheels and tyres =========================== TYPES OF WHEELS AND RIMS ------------------------ - Disc wheels; - Pressed-steel disc wheels; - Cast light-alloy disc wheels; and - Single-piece rim wheels. TYRES AND TUBES ---------------  TUBES TYRES AND TUBELESS TYRES ------------------------------ TYRE PRESSURES AND LOADS ------------------------  INFLATION AND TYRE WEAR -----------------------  MATCHING TYRES --------------