Saturday, 27 April 2024, 12:39 AM
Site: IMI eLearning
Course: IMI eLearning (IMI eLearning)
Glossary: Automotive Glossary
U
U BoltsU shaped bolts used to fix leaf springs to the axle or other similar tasks such as fixing a steering rack to the body. |
U/JUniversal Joint. |
Ultra VioletA frequency of light that is above the visible spectrum. |
UltravioletLight/Radiation lying in the ultraviolet range; wave lengths shorter than light but longer than X rays i.e. beyond the violet end of the spectrum/rainbow. |
Ultraviolet (UV) LightThat portion of the spectrum which is largely responsible for the degradation of paints. It is invisible to the eye and may also be referred to as "black light." Special UV lamps can be used to cure some paints and adhesives. |
ULWUnladen Weight – The weight of a vehicle inclusive of the body and all parts which are ordinarily used with the vehicle when working on a road. Unladen weight does not include the weight of water or fuel used for the propulsion of the vehicle, |
Unburned HydrocarbonsEngine or fuel tank emissions in the exhaust gas, fuel line vents or lubricating oil vapours. Harmful to health. Also HC or THC (total hydrocarbon content of exhaust gas). |
Under-bakeThe result of curing a paint film at too low a combination of time and temperature. The film may be too soft for good durability. |
UndercoatA first coat; primer, sealer, or surfacer applied to the substrate. Frequently used to provide corrosion protection and adhesion. |
UndersteerSteering condition of a turning vehicle when the vehicle attempts to turn by a lesser degree than the steered position taken by the driver. This condition is usually provided by vehicle design in order to improve the driveability of the vehicle. |
UnderwrittenSign and accept liability (legal). |
Unequal WishbonesSuspension type with an upper wishbone shorter than the lower wishbone. The geometry of this layout keeps the wheel camber reasonably constant during suspension movements. Also SLA suspension. |
UnidirectionalMove in one direction only. |
Unidirectional ClutchA clutch, used in starter motors for example, to only allow drive to pass in one direction. |
Union NutA hollow nut used to secure hydraulic pipes. |
Unit-body ConstructionVehicle body and chassis constructed as a single unit. As distinct from a separate chassis and body construction. Also unitary body construction. |
Unitary Body ConstructionVehicle body and chassis constructed as a single unit. As distinct from a separate chassis and body construction. Also unit-body construction. |
Universal JointsRotating shaft coupling that permits angular axial displacement. Some types will also operate with linear misalignment of axes. |
UnladenNot carrying a load. |
Unleaded PetrolPetrol without any added lead to improve the octane rating. |
Unsprung MassThe part of the vehicle not supported by the suspension springs. The road wheels, hubs, brakes and part of the suspension system. |
Unsprung Mass (Weight)The part of the vehicle not supported by the suspension springs. The road wheels, hubs, brakes and part of the suspension system. |
Up DraftA carburettor where the choke tube (venturi) is fitted vertically and the air enters from the bottom. Upwards movement of air. |
Upper BeamThe upper of the two headlamp beams. Also driving beam and main beam. |
Upper Control ArmThe upper and shorter wishbone in an independent suspension system. |
Upper QuartileData is split into 4 equal quarters. The highest quarter is referred to as the Upper Quartile. For example the Upper Quartile of 100 is the highest 25 of the numbers. |
UrethaneA type of paint or polymer which results from the reaction of an isocyanate with a hydroxyl containing component. Urethanes are noted for their toughness and abrasion resistance. |
USA United States of America: North American republic containing 50 states - 48 states in North America plus Alaska in northwest North America and the Hawaiian Islands in the Pacific Ocean; achieved independence in 1776. |
UVUltra violet. |
UV StabilizersChemicals added to paint to absorb the ultraviolet radiation present in sunlight. Ultraviolet radiation decomposes the polymer molecules in a paint film and thus UV stabilizers are used to prolong paint life. |