Dictionary of Automotive Terms: J-K-L

- J -

JACKSHAFT: A shaft used between two other shafts.

JET: Small hole or orifice used to control flow of gasoline in various parts of carburetor.

JOULE: Metro-kilogram-second (mks) unit of energy or work equal to a force of 1 newton applied through a distance of 1 meter. Joule is the equivalent of 0.737324 foot-pounds.

JOURNAL: Part of shaft prepared to accept a bearing. (Connecting rod, main bearing.)

- K -

KEY: Parallel-sided piece inserted into groove cut part way into each of two parts, which prevents slippage between two parts.

KEYWAY: Slot cut in shaft, pulley hub, wheel hub, etc. Square key is placed in slot and engages a similar keyway in mating piece. Key prevents slippage between two parts.

KICKDOWN SWITCH: Electrical switch that will cause transmission, or overdrive unit, to shift down to lower gear. Often used to secure fast acceleration.

KILL SWITCH: Special switch designed to shut off ignition in case of emergency.

KILOMETRE: Metric measurement equivalent to 5/8 of mile.

KINGPIN: Hardened steel pin that's passed through the steering knuckle and axle end. The steering knuckle pivots about the kingpin.

KINGPIN or STEERING AXIS INCLINA TION: Tipping the tops of the kingpins .in ward towards each other. This places the centerline of steering axis nearer centerline of tire-road contact area.

KNOCKING (Bearing): Noise created by part movement in a loose or worn bearing.

KNOCKING (Fuel): condition, accompanied by audible noise, that occurs when gasoline in cylinders burns too quickly. Also referred to as detonation.

KNUCKLE: A part utilizing a hinge pin (kingpin, swivel pin) that allows one part to swivel around another part. An example is a steering knuckle.

KNURL: To roughen surface of piece of metal by pressing series of cross-hatched lines into the surface and thereby raising area between these lines.

- L -

LACQUER (Paint): Fast drying automotive body paint.

LAMINATED: Something made up of many layers.

LAND: Metal separating a series of grooves.

LANDS (Ring): Piston metal between ring grooves.

LAP: One complete trip around race track or route laid out for racing.

LAP or LAPPING: To fit two surfaces together by coating them with abrasive and then rubbing them together.

LATENT HEAT: Amount of heat (Btu’s) beyond boiling or melting point, required to change liquid to a gas, or a solid to a liquid.

LATENT HEAT OF EVAPORATION: Amount of heat (Btu’s) required to change a liquid to a vapor state without elevating vapor temperature above that of the liquid. LB: Pound.

LEAD BURNING: Connecting two pieces of lead by melting edges together.

LEADED GASOLINE: Gasoline containing tetraethyl lead, an antiknock additive. It must not be used in vehicles with catalytic converters.

LEAF SPRING: Suspension spring made up of several pieces of flat spring steel. Varying numbers of leaves (individual pieces) are used depending on intended use. One car uses single leaf in each rear spring.

LEAN MIXTURE (Fuel): A fuel mixture with an excessive amount of air in relation to fuel.

LETTER DRILLS: Series of drills in which each drill size is designated by letter of alphabet—A, B, C, etc.

LEVER: A rigid bar or shaft pivoting about a fixed fulcrum (shaft, pin, etc.). It is used to increase force or to transmit or change motion.

LEVERAGE: Increasing force by utilizing one or more levers.

L-HEAD ENGINE: Engine having both valves in block and on same side of cylinder.

LIGHTENED VALVES: Valves in which all possible metal has been ground away to reduce weight. This will allow higher rpm without valve float.

LIMITED-SLIP DIFFERENTIAL: Differential unit designed to provide superior traction by transferring driving torque, when one wheel is spinning, to wheel that's not slipping.

LINKAGE: Movable bars or links connecting one unit to another.

LIQUID LINE (Air Conditioning): High- pressure liquid refrigerant line between receiver-dehydrator and expansion valve.

LIQUID TRACTION: Special liquid applied to tires of drag racers to provide superior traction.

LIQUID-VAPOR SEPARATOR: Tank which prevents liquid fuel from entering vapor line.

LIQUID WITHDRAWAL (LPG): Drawing LPG from bottom of tank to insure delivery of liquid LPG. Withdrawal from top of tank will deliver LPG in the gaseous state.

LITRE: Metric measurement of capacity— equivalent to 2.11 pints. Five liters equals 1.32 gallon.

LIVE AXLE: Axle upon which wheels are firmly affixed. Axle drives the wheels.

LIVE WIRE: See Hot Wire.

LOAD RANGE (Tire): Letter system (A, B, C, etc.) used to indicate specific tire load and inflation limit.

LOG MANIFOLD: Special intake manifold generally designed to accept four or more carburetors. Each side has bases for carburetors set on a pipe-like log area.

LONG and SHORT ARM SUSPENSION: Suspension system utilizing upper and lower control arm. Upper arm is shorter than lower. This is done so as to allow wheel to deflect in a vertical direction with a mini mum change in camber.

LONGITUDINAL LEAF SPRING: Leaf spring mounted so it's parallel to length of car.

LOUVER: Ventilation slots such as sometimes found in hood of automobile.

LOW BRAKE PEDAL: Condition where brake pedal approaches too close to floor board before actuating the brakes.

LOW LEAD FUEL: Gasoline containing not much more than 0.5 grams of tetraethyl lead per gallon.

LOW PIVOT SWING AXLE: Rear axle setup that attaches differential housing to frame via a pivot mount. Conventional type of housing and axle extend from differential to one wheel. The other side of differential is connected to other driving wheel by a housing and axle that's pivoted at a point in line with differential to frame pivot point.

LOW PRESSURE LINE (Air Conditioning): Low pressure refrigerant line between evaporator outlet and compressor.

LPG: Liquefied petroleum gas.

LUBRICANT: Any material, usually of a petroleum nature such as grease, oil, etc., that's placed between two moving parts in an effort to reduce friction.

LUBRICATION: Reducing friction between two parts by coating them with oil, grease, etc.

LUG (Engine): To cause engine to labor by failing to shift to a lower gear when necessary.