The Basic Bulb Bulb uses electrical current to produce light. Filament Support 1 Support 2 Glass Bulb uses electrical current to produce light. Filament held in position by supports. One support connects to centre contact. One support connects to cap. Cap Air removed to reduce heat loss, oxidation and vaporization. Centre contact Next >

The Basic Bulb Filament is heated by current flow and produces light. Centre contact Support 1 Support 2 Cap Glass Filament is heated by current flow and produces light. Emits white light when heated to 2300°C. Bulb produces less light when supply voltage is below bulb rating. Bulb produces more light when supply voltage is above bulb rating, until filament burns away. Next >

Bulb Types Quartz halogen type. Halogen bulb Quartz halogen type. Voltage terminals Metal flange with lugs Used in headlights, spot, driving and fog lights. Quartz Quartz used instead of glass, due to strength and high temperature properties. End shield Shield Interior is pressurized to reduce burning away of filaments. Main filament Dip filament Shields allow bulb to produce required beam patterns. Lugs on metal flange ensure bulb is fitted correctly. Next >

Bulb Types Small bayonet cap, single contact type. Used in side, rear, license plate, fog and indicator lights. Small bayonet cap, twin contact type. Used in combined brake and rear lamps. Xenon HID bulbs, used in headlights. Produce more light than halogen bulbs and use less power. Next >

A Basic Headlight Contains a bulb, a parabolic reflector and a lens. May be fitted with a shield to cut-off light. Voltage terminals Voltage terminals at rear. Shield Headlight is weatherproof. Next >

Basic Headlight Beam Patterns Parabolic reflector Shape of reflector determines beam pattern. Filament at focal point Parallel beam Bulb Parallel beam produced by positioning filament at focal point. Ideal design for spot lights. Next >

Basic Headlight Beam Patterns Filament above focal point Dip beam Parabolic reflector Bulb Dip beam produced by positioning filament above focal point. Side beam produced by positioning filament to one side of reflector. Next >

Basic Headlight Beam Patterns Some bulbs are fitted with shields. Concentrated dip beam A shield under a filament concentrates the beam pattern upward. Shield Next >

Free Form Headlights Reflectors are designed to tight tolerances. Reflector segments Reflector Shield Filament Front view Side Surface focuses and scatters light beams. Dip beam pattern Divided into segments to illuminate segments of road. All of the surface area is used to provide a beam pattern. Lens is a clear cover, with no optical pattern. Next >

Projection Headlights Small in diameter, but produce high output. An ellipsoidal reflector reflects light onto a lens. Lens Ellipsoidal reflector Filament Beam pattern The lens projects light in the required pattern. Shield cuts-off unwanted light. Shield Next >

Flasher Unit Indicator flash rate must be constant. Produced by a device known as a flasher unit. Usually contained in relay / fuse box, under the dashboard. Next >

Flasher Unit - Bimetal Type Bimetal strip and heating element. 12V in, from indicator switch To indicator lights Bimetal strip Contacts Heating element Turn signal switch set to on, current flows through heating element, warming bimetal strip. Bimetal strip bends, contacts open, lights off. While contacts are open, heating element and bimetal strip cool down. Bimetal strip returns to original position, contacts close, lights on. Process repeats until turn signal switch is set to off. Next >

Flasher Unit - Electronic Type Main components: Integrated circuit Relay Capacitor Resistor Next >

Hazard Warning Lights Warn of a possible emergency or hazard. International warning triangle Red hazard warning button Activated by red push button. Usually mounted on steering column. When pushed down, all indicator (hazard) lights flash. Button marked with international warning triangle. Next >

Indicator/Hazard Warning Schematic Ignition switch Hazard switch Indicator flasher unit Indicator switch Indicator lights Battery Indicator operation: flasher unit receives power via fuse, ignition switch and normally closed hazard switch contact. Hazard operation: flasher unit receives power direct from battery, via fuse and hazard switch contacts. Next >