Dictionary of Automotive Terms Abbreviations

DICTIONARY OF AUTOMOTIVE TERMS - "Sl"

SL

Acronym for Special ledge
API SL Category

An API designation of gasoline engine oil for 2001-04 passenger cars, sports utility vehicles, vans and light trucks Oils meeting API SL requirements have been tested according to the American Chemistry Council (ACC) Product Approval Code of Practice and may utilize the API Base Oil Interchange and Viscosity Grade Engine Testing Guidelines. It replaces API Service Category SJ and was replaced, in turn, by the latest SM oils.

Slack

The amount of free play in a chain or belt too much slack could cause the chain/belt to slip and jump the sprockets; too little slack (the chain seems tight) causes excessive wear on the final drive system.
Brake actuator stroke prior to effective application of force.

Also see Belt slack

Slack adjuster: An adjustable member that transmits brake appliction force and permits compensation for lining wear.

Slagging: Formation of hard deposits on boiler tubes and/or piston crowns, usually due to the presence of sodium, vanadium, and sulfur.

Slag inclusions: Non-fused, non-metallic substances in the weld metal.

Slant engine: This is an in-line engine in which the Cylinder block has been tilted from a vertical plane. Also called Inclined engine

Slap: See
Piston slap.

Slapper: A colloquial term for a Bumping blade

SLA suspension: Acronym for Short arm/long arm suspension

Slatted grille: An aerodynamic radiator grille developed by Ford in 1976. The horizontal aerofoil grille elements are shaped like aircraft wings to allow the cooling air to flow towards the radiator at low speeds, whereas excess airflow is directed upwards across the front of the car at higher speeds to produce an effect similar to that of a spoiler

Slave con rod: A connecting rod of two-stroke dual piston engines which is articulated on the master con rod, not directly on the crankpin. Also see Master con rod

Slave cylinder: A small cylinder containing a piston which, under hydraulic pressure from a master cylinder, operates the brake shoes or pads in hydraulic brakes or the working part in any other hydraulically operated system (such as a clutch slave cylinder). Also see Master cylinder

Sled

A snowmobile.
A vehicle which is in poor shape and worth little or nothing.

Also See
Lead sled

Sledge hammer: A large, heavy hammer usually with a long handle. The head is double sided so that either end can be used to strike an object

Sleeper: A sleeping compartment mounted behind a truck cab, sometimes attached to the cab or even designed to be an integral part of it.

Sleeper Team: A pair of truck drivers who take turns driving and resting.

Sleeve

A tube fitted externally over two cylindrical parts in order to join them.
A cylindrical insert.

Also See
Adjusting sleeve
Coupling sleeve
Cylinder sleeve
Dry sleeve
Liner
Re-sleeve
Shaft sleeve
Wet sleeve

Sleeve bearing (SLV)

Any bearing of tubular or sleeve-like construction
A bearing that resembles a short length of bronze tubing with grooves to direct oil flow. Good for low noise level.

Sleeve nut: See
Inner cap nut.

Sleeve valve: Consists of metal sleeves located between the Piston and cylinder wall. When moved up and down, holes in the sleeves coincide with inlet and exhaust parts to provide passage for the gases at the right time.

Slewed axles: Axles that are not parallel.

Slick: A very wide tire, without a Tread pattern, designed to provide a maximum amount of Traction. It is used for racing on dry surfaces.

Slide: See
Pocket slide caliper

Slide caliper: See
Pocket slide caliper

Slide carburetor: A type of carburetor often used in motorcycle engines, in which a slide valve modifies the venturi of the carburetor

Slide hammer: Slide Hammer Dent Puller

A tool with a long round shaft on which a hammer weight slides; the force produced by quickly moving the weight towards the end of the shaft is used for loosening or pulling off tight parts; often used in combination with pullers. Also see Panel puller

Slide-in camper: Slide-in camper

A structure which fits into a truck bed for camping purposes. It usually has beds and possibly cooking and washing facilities. Also called a Truck camper" or just camper.

Slide-on camper: See
Truck camper

Slider

(CVT) A device which senses the position of the half of a primary pulley that slides.
The lower (moving) tube on a bicycle suspension fork which is attached to the front hub.
A mechanism that allows a tandem axle suspension to be moved back and forth at the rear of a semitrailer, for the purpose of adjusting the distribution of weight between the axles and fifth wheel.

Also See
Pin slider caliper disc brake

Slider caliper: See
Pin slider caliper disc brake

Slider caliper disc: See
Pin slider caliper disc brake

Slider caliper disc brake: See
Pin slider caliper disc brake

Slide valve: A valve that slides across an aperture to expose the port or opening

Sliding caliper

Similar to a floating caliper, but instead of riding on guide pins and bushings, the caliper slides on machined ways and is retained by keys or spring plates.
Single piston calipers which use pins or rails to obtain a self-centering action. The caliper slides on these pins or rails to center over the disc when the brakes are applied.

Sliding-caliper disc brake: A disc brake design with a sliding caliper. In one type, the caliper floats on the caliper frame grooves. The major components are caliper (a casting with one cylinder and piston), caliper frame (casting) which is bolted to the suspension. In another type, the caliper floats on caliper locating pins. See Pin slider caliper disc brake. A third type, is the Floating-frame disc brake. Sometimes subtle design differences are used to differentiate between sliding caliper disc brakes and floating caliper disc brakes, but usually these terms are treated synonymously.

Sliding contacts: An ignition assembly developed by Lucas, that causes the moving contact to slide vertically across the face of the fixed contact when the spark is advanced

Sliding Fifth Wheel: A Fifth wheel mounted to a mechanism that allows it to be moved back and forth for the purpose of adjusting the distribution of weight on the tractor's axles. Also provides the capability to vary vehicle combination lengths.

Sliding fit: Parts that are assembled so that there is clearance between them so that one part can slide in or on the other. Also called clearance fit

Sliding-fit: See
Running-fit.

Sliding friction: A frictional resistance to relative movement of surfaces on loaded contact. Also see Rolling friction

Sliding gear: A Transmission gear that is Splined to the shaft. It may be moved back and forth for shifting purposes.

Sliding joint: See
Slip joint

Sliding-mesh gearbox: An obsolete type of transmission or gearbox in which the gears on the layshaft are fixed to the shaft rigidly, whereas the gears on the main shaft can slide on it by means of splines but are otherwise in permanent rotational mesh with the shaft. Also see Constant-mesh gearbox

Sliding-pillar suspension: A once popular front suspension layout (e.g., in Lancia and Morgan cars), in which a carrier-mounted stub axle slides up and down a vertical pillar with enclosed coil springs providing the suspension; less sophisticated versions were used in several pre-war cycle cars

Sliding side window: A window style of classic roadsters, consisting of aluminum frames with tracks for two sliding window panels made of clear Plexiglas, and with draught seals; on some cars, also furnished with flaps. Also see Side curtain

Sliding Tandem: A mechanism that allows a tandem axle suspension to be moved back and forth at the rear of a semitrailer, for the purpose of adjusting the distribution of weight between the axles and fifth wheel. Also called a slider.

Sliding T-bar: A drive handle with square drive sliding on round bar for T-handle turning operation

Sliding-vane pump: A positive displacement pump in which an eccentric rotor revolves in an eccentric or circular case. Also see External-vane pump. The pumping element consists of multiple blades which slide in slots in the rotor and divide the crescent-shaped fluid space into variable volumes. Some sources state that in the sliding-vane type, vanes do come into contact with the casing, whereas in vane-type pumps a clearance of about 0.004 inches is maintained between vanes and casing.

Sliding weight: A functional part of a Sliding hammer that provides the inertia required for the pulling force

Slinger: A ring on a shaft that throws oil from the shaft before it gets to the oil seal. See Oil slinger.

Sling psychrometer: Measuring device with wet and dry bulb thermometers. Moved rapidly in air, it measures relative humidity.

Slingshot

A form of Dragster using a rather long thin Frame with a very light front axle and wheel assembly.
A maneuver in which the driver of the trailing vehicle in a draft line breaks the draft by turning (usually to the left if on an oval track), propelling the car around the leader.

Slip

The relative motion between driving and driven parts.
The difference between the speed of the rotating magnetic field (which is always synchronous) and the rotor in a non-synchronous induction electric motor. Slip is expressed as a percentage of synchronous speed and generally increases with an increase in load

Also See
Belt slip
Clutch slip
Half-moon slip joint pliers
Limited slip differential
Wheelslip

Slip angle: The difference in the actual path taken by a vehicle making a turn and the path it would have taken if it had followed exactly as the wheels were pointed. The slip angle is the result of the tire carcass's flexibility and is the angular difference between the direction the wheel is travelling and the direction of the Tread. If the slip angles of the rear tires are greater than the slip angles of the front tires, the vehicle is said to be Oversteering.
Also See
Oversteer
Tire deviation angle

Slip-control differential: See
Automatic slip-control differential

Slip differential: See
Limited slip differential
Torque sensitive limited slip differential

Slip friction: See
Sliding friction

Slip-in bearing: A liner, made to extremely accurate measurements which can be used for replacement purposes without additional fitting

Slip joint

A Joint that will transfer driving Torque from one shaft to another while allowing longitudinal movement between the two shafts. A variable length connection that permits the Driveshaft or axle shaft to change its length as the shaft moves up and down. The British term is sliding joint.
A connection in an exhaust pipe where one pipe slips into another.

Also See
Half-moon slip joint pliers

Slip joint pliers: See
Half-moon slip joint pliers

Slip-on: Any device which slides on to the main component, e.g., a slip on muffler slides onto the existing exhaust pipe

Slipper piston: A Piston with the lower edge cut away so that the Piston skirt is short on the two sides not used as thrust surfaces. Such a design lightens the piston making it easier to accelerate and decelerate, wastes less power, and is easier on the bearings. Cutting away the skirt also allows the Connecting rod to be made shorter but leaves enough room between the Counterweights and the pistons so the overall height of the engine can be reduced.

Slip ring

One of several conductive metal rings attached to the Rotor shaft in an alternator that periodically changes the direction of current flow.
A conductor band, mounted on an armature and insulated from it. A conductor strip slides on the band as the armature rotates. The function of the slip ring system is essentially the same as a commutator and brushes. Slip rings are also used to transmit current from the armature in a generator application

Slip-ring end bracket: A cover housing the bearing at the slip-ring end of an alternator. At the other end is the Drive end bracket

Slip roll: See
Sheet metal roller

Slip stream

A stream of air behind a moving vehicle.
A racing technique in which one vehicle tucks in closely behind another (catches a tow). The total Aerodynamic drag acting on the two vehicles is actually less than the drag that acts on each vehicle when they are separated by greater lengths; this allows both vehicles to gain straightaway Speed. The lead vehicle cuts into the air acting as a wind break for the following vehicle, and the closeness of the second vehicle reduces the turbulence normally generated at the rear of the first vehicle. Also called Drafting.

Slip tank: A large auxiliary fuel tank mounted in the back of a pickup truck

Slip the clutch: To operate the clutch so that it partially disengages, as when keeping up the revs when driving off; causes wear on the clutch. Also see Clutch slip

Slip yoke: Slip yoke

A component at the front of the first U-joint which accommodates changes in drive shaft length as the rear axle assembly moves up and down with the rear suspension. Internal splines on the U-joint yoke slide in and out on the external splines of the transmission output shaft. This splined coupling also allows the drive shaft to be removed from the vehicle when the rear U-joint is disconnected. The drive shaft may fall to the ground and be ruined if either U-joint breaks while the vehicle is in motion.

Slit: See Metering slits.

Slog: To procede up a hill at a slow arduous pace.

Slope: The percentage of full hydrauklic system pressure sukpplied to the rear brakes by the proportioning valve. Expressed as the ratio of rear pressure to front pressure.

Sloper: A colloquial term for an Inclined engine

Sloping headlight: An old headlight type used on the VW Beetle prior to 1967

Slop tank: A container in a tanker into which the residue of tank washing are pumped.

Slot: A narrow channel or aperture, especially the groove in the head of a screw which receives the tip of the blade of a screwdriver.

Also See
T-slot
Valve slot
Ventilation slot
Vent slot

Slotted piston: See
Split skirt piston

Slow charging: The charging of a battery by using a charging current which corresponds to 10% of the battery capacity. Also see Fast charger

Slow down indicator: An indicator light on the instrument panel that warns the driver to slow down in the event of excessive catalytic converter temperature. A protective warning circuit causes the indicator to flash if the catalytic converter becomes overheated. If the temperature increases beyond a certain second level, the lamp will glow continuously

Slow leak: A tire which loses its air pressure over a period of time. It is usually caused by a small puncture, a leaking tire valve, or a tire that is not properly seated on the rim.

Slow passer: A vehicle off in the distance behind you in your lane that is driving faster than you. When he pulls out to overtake you, he drives at your speed for several minutes before picking up speed again to finish the passing action.

Slow-running: See
Idling

Sludge

A thick, black, mushy, greasy deposit found throughout the interior of the engine. Caused from a mixture of dust, oil, Gasoline, water, and Blowby being whipped together by the moving parts. Some engines oils have Detergent to break down sludge. A composition of Oxidized Petroleum products along with an emulsion of oil and water, forming a pasty substance that clogs oil lines and passages and interferes with engine lubrication. Sludge is formed in engines with neglected oil changes.
Deposits in fuel tanks and caused by the presence of wax, sand, scale, asphaltenes, tars, water, etc. The sludge formed in a #6 fuel oil storage tank is mostly composed of heavy hydrocarbons. Alken Even-Flo® 905 eliminates this type of sludge by breaking the sludge into small particles and re-suspending them in the fuel for more efficient combustion. The sludge formed in diesel storage tanks is a combination of water with fungus and bacteria, which grow on the unevenly mixed water/fuel interface. Adding Alken Even-Flo® 910 and 910S to stored fuel promotes a clean separation of water and fuel, reducing the substrate upon which bacteria and fungus can grow. Since the bacteria and fungus bind to the separated water, they can be removed by draining the water from the storage tank. If draining the storage tank is impossible, EF 905 and 910E will emulsify the water into tiny droplets and break the sludge into such small particles that they will no longer clog filters and will efficiently burn.
A dense, slushy, liquid-to-semifluid product that accumulates as an end result of an industrial or technological process designed to purify a substance. Industrial sludges are produced from the processing of energy-related raw materials, chemical products, water, mined ores, sewerage, and other natural and man-made products. Sludges can also form from natural processes, such as the run off produced by rainfall, and accumulate on the bottom of bogs, streams, lakes, and tidelands.

Also See
Oil sludge

Slug: 1-unit of mass equal to the weight (in US units) of object divided by 32.2 (acceleration due to the force of gravity). 2-Detached mass of liquid or oil which causes an impact or hammer in a circulating system.

Slugging: Condition in which mass of liquid enters compressor causing hammering.

Sluggish: Unresponsive; functioning at below normal rate or level

Sluggish acceleration: To increase speed slowly. See Acceleration.

Slush: Soft melting snow. Also see Powder slush molding

Slush box: A derogatory colloquial term for an Automatic transmission used by those who prefer a Manual transmission.

Slushbox: A derogatory colloquial term for an Automatic transmission used by those who prefer a Manual transmission.

Slush molding: A thermoplastic casting in which a liquid resin is poured into a hot, hollow mold where a viscous skin forms; excess slush is drained off, the mold is cooled, and the molded product is stripped out. Also see Powder slush molding

SLV: Acronym for Sleeve bearing