A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
F
F.W.D.: Front wheel drive.
Fail Safe: A device or feature that prevents total failure in the event of a fault occurring.
Fan Cowl: A protective shield around a fan.
Farad: The unit of capacitance.
Fascia Panel: The panel inside the vehicle below the front windscreen. It carries the instruments, heater ducts and accessories.
Fast Charge: Rapid charge for a battery. 5 times the Ah capacity for about an hour is the recommended maximum.
Fast Idle: The cold engine running speed achieved by a stepped cam on the throttle linkage or by an air bleed valve.
Fatigue: Failure in a material due to excessive and repeated loading usually of an intermittent nature.
Fault Code: A code generated in and output from an ECU. Used for diagnostics.
Feathering: Term used to describe the way a tyre wears when the tracking is set incorrectly. The tread scuffs up like feathers.
Feed Cable: The main supply wire to a component.
Feedback: A feature used in electronic control systems to monitor performance by the use of a sensor downstream of an actuator. An example is an exhaust oxygen sensor monitoring the fuel injection quantities.
Feedback Resistor: A variable resistor used to indicate position of a moving component.
Feeler Gauge: Set of accurate blades used to set or measure small gaps (valve clearances for example).
Ferrous: Iron or a metal alloy containing mainly iron.
Field (Magnetic): A magnetic flux about a permanent magnet or live electrical conductor.
Field Circuit: An electrical control circuit for the field coils used to regulate the output from a generator.
Field Coil: An electrical winding round a magnet pole shoe that is used to create a magnetic field when an electrical current flows through the windings. The direction of current flow determines the polarity of the magnetic pole. Used in generators and electrical motors.
Field Coil (Winding): An electrical winding round a magnet pole shoe that is used to create a magnetic field when an electrical current flows through the windings. The direction of current flow determines the polarity of the magnetic pole. Used in generators and electrical motors.
Filament (Bulb): The tungsten element in a bulb that glows to produce light.
Filaments: The tungsten elements in a bulb that glow to produce light.
Filler Neck: The connection into the fuel tank for refuelling.
Fillet Radius: A machined curve between two faces of a component. An example is the curve between a crankshaft web and journal.
Filter: A fine mesh or paper screen used to remove dirt and other contaminants from a liquid or gas (air).
Final Drive: The gearing immediately before the driven wheels. It provides a split to each driven wheel with a final gear reduction for the transmission. Can also be used to turn the drive through 90 degrees with the use of bevel gears.
Firewall: Substantial structural panel of vehicle body in front of passenger compartment. Also known as a bulkhead.
Firing Order: The sequence for ignition of individual cylinders in an engine.
Fixed Caliper: A disc brake caliper in which the two halves and pistons are made as a single unit attached to the axle assembly.
Fixed Choke Carburettor: A carburettor with a fixed diameter venturi (choke tube).
Fixed Venturi: A narrowed section in a carburettor - the size of which remains fixed.
Flame Plug: Cold start device fitted in the inlet manifold on some direct injection diesel engines.
Flame Trap: Incorporated into the air cleaner unit to prevent the spread of fire caused by fuel igniting in the carburettor if blow back occurs.
Flange: Flat face to flat face butted fitting. Method used to secure exhaust system.
Flange Bolts: Bolts that secure a flat face to flat face butted fitting.
Flange Fitting: Flat face to flat face butted fitting. Method used to secure exhaust system.
Flare
Flat Seat Valve: A valve that operates by one part operating against a flat component to control flow.
Flat Spot: A temporary drop in power that occurs at the point of initial acceleration when the throttle plate is opened. Occurs as a result of a rise in venturi pressure (drop in vacuum) and a resultant loss of fuel supply into the venturi. Remedied by the addition of an accelerator pump.
Flat-seat Valve: A valve that operates by one part operating against a flat component to control flow.
Flex Plate: The mounting plate for a torque converter where it is attached to the crankshaft. Fits in place of the flywheel.
Flexible Coupling: A rubber or fabric reinforced rubber coupling that is used to join two shafts. Usually incorporates two forks that act as a safety device in the event of failure of the rubber component.
Flexing: Another word for bending.
Flitch Panel: Structural panel of vehicle body on sides of engine.
Float: A buoyant component used to indicate or control fluid levels. In a carburettor used with a needle valve to control the petrol level in the float chamber.
Float Chamber: Part of carburettor holding petrol at a controlled level.
Floating Caliper: A disc brake caliper that has a fixed component attached to the axle assembly and a single piston and caliper that is 'floating' by sliding or pivoting on the fixed component.
Flow Meter: A sensor that determines flow of a fluid or gas.
Fluid Coupling: A drive coupling that uses a fluid to transmit drive. Also sometimes a viscous coupling.
Fluid Flywheel: A drive coupling that uses a fluid to transmit drive.
Fluid Pump: A pump for moving or pressurising a fluid.
Flyweights: Weights that act on pivots and move outwards due to centrifugal force.
Flywheel: (1) Component of the clutch. (2) Massive wheel or disc attached, for example, to the crankshaft of an engine, to store energy of rotation and smooth the output from the irregular firing of the cylinders. In many automotive engines, the flywheel incorporates the ring-gear and acts as one friction face of the clutch. (3) Maintains the momentum of the engine.
FO: Fuel Octane Adjustment.
Foaming: A term used to describe the aeration of an oil.
Focal Length: The distance between the focal point and the reflector.
Focal Point: The point within a reflector from where a light source produces parallel beams.
Follower (Cam): The component in contact with the cam on a camshaft.
Foot Pound: Old unit of torque. Also pounds/feet. Torque is now given in the SI units of Newton metres (Nm).
Footprint: When applied to tyres describes the area and shape of the part of the tyre in contact with the road.
Force: Exerted to overcome a load.
Force Ratio: The comparison of the force applied to the force produced via some kind of machine or system.
Forging: A component forming process applied to hot metal with a hammer or die either by hand or machine. Also hot stamping.
Fork: Part of the door latch mechanism, clutch or gearbox. Fits around another component to hold or move that component.
Four Stroke Cycle: The conventional operating principle for the modern internal combustion engine consisting of the induction, compression, combustion/power and exhaust strokes.
Four Wheel Drive (4WD) (4x4): Transmission system that uses all four wheels of a vehicle to provide a drive. This term is usually used on vehicles with selectable four wheel drive. The term AWD for all wheel drive is used for vehicles with permanent four wheel drive.
Four Wheel Steering (4WS): A steering system that applies turning movement to front and rear wheels. The rear wheel steer is initially opposite to the front wheels, neutral and then with the front wheels. This provides steering characteristics that aid manoeuvrability.
Four Wheel Steering 4WS
: A steering system that applies turning movement to front and rear wheels. The rear wheel steer is initially opposite to the front wheels, neutral and then with the front wheels. This provides steering characteristics that aid manoeuvrability.
FP: Fuel Pump.
FPR: Fuel Pump Relay.
Free Electrons: The electrons in the valency shell of an atom that can link with and move on from other atoms. A material with free electron flow makes a good electrical or heat conductor.
Free Play: The amount of free movement in or between components that is not transmitted to the next component in the sequence. May also be referred to as 'backlash' in some applications such as when applied to gears.
Free Travel: The free play in a clutch linkage before it operates the clutch mechanism.
Freeplay: The amount of free movement in or between components that is not transmitted to the next component in the sequence. May also be referred to as 'backlash' in some applications such as when applied to gears.
Freewheeling: Overrun of a one way clutch. Vehicle movement when the transmission is not engaged to the engine.
Frequency: The number of oscillations per unit of time. Examples are a sound wave or alternating electrical current. The unit for frequency is the Hertz, which equals one oscillation per second.
Friction: Resistance a body encounters in moving over another.
Friction Disc: Term used to refer to a clutch drive plate.
Friction Discs: Component of the clutch. The centre plate that is gripped between the flywheel and pressure plate to transmit a drive to the gearbox input shaft.
Friction Material: A material with consistent performance characteristics used to provide a rubbing surface for brake and clutch components.
Friction Plate: Component of the clutch. The centre plate that is gripped between the flywheel and pressure plate to transmit a drive to the gearbox input shaft.
FT: Fuel Temperature Sensor.
Fuel Distributor: The component in a mechanical injection system that controls and distributes the fuel.
Fuel Efficiency: Performance of engine/vehicle. Rate of fuel usage.
Fuel Filter: A filter to remove contamination from fuel.
Fuel Gauge Sender: Sensor, usually a variable resistor, which supplies information on fuel quantity in the tank.
Fuel Injection: The injection of fuel under pressure into the intake air stream of petrol engines by the use of electrical solenoid valves in place of a carburettor.
Fuel Line: The pipes and hoses that connect the fuel system components.
Fuel Pressure Regulator: In a fuel system the component that keeps the pressure across injectors constant. It consists of a valve, diaphragm and spring.
Fuel Rail: A tube or pipe used to supply fuel to electrical injectors. The quantity of fuel in the rail is relatively large so that the pressure remains constant when the injectors operate.
Fulcrum: A pivot for a lever. Usually a supporting point or shaft.
Fulcrum Ring: A ring on which clutch release fingers pivot.
Full Flow Lubrication: An engine lubrication system where all of the oil flows through the oil filter before entering the engine oil galleries.
Full Load: Describes the engine condition when it is working as hard as it is able - for acceleration for example.
Full Load Enrichment: A device in a carburettor that provides additional fuel during full throttle and heavy load conditions.
Full Wave Rectification: Alternating current converted to direct current by reverse flow of the negative bias so that it is added to the forward bias electrical flow. Modern rectifiers using a diode bridge achieve full wave rectification.
Fully Floating Axle: An axle hub arrangement that carries the load on two bearings and therefore does not apply a shear or bending force on the axle shaft.
Fuse: A safety device in an electrical circuit that will burn and melt to break the circuit when an excess current is applied.
Fuse Box: A central termination block in a vehicle electrical system that carries the fuses.
Fuse Rating: The rated value of a fuse before failure due to an excess current load. The rating can be either a constant or a surge value and is given in amps. Fuses are usually colour coded and marked for the fuse rating.
Fuzzy Logic: A digital control system that makes 'educated' guesses.