Terms Starting with S
Scrub Line-An imaginary line drawn from the bottom of the wheel rim on one side of the vehicle to the bottom of the tire on the other side of the vehicle. Also, an imaginary line drawn from the bottom of the rim on the front wheels to the bottom of the tires on the back wheels and vise versa. No component on the bottom of the vehicle can be below this line or it may hit the ground on rough roads.
Slave cylinder-A type of hydraulic cylinder used as a means to move the clutch mechanism. As the clutch pedal is pushed down, the hydraulic pressure produced in the slave cylinder is used to move the clutch mechanism.
Slip joint-A splined shaft that can slide in a mating shaft to allow changes in drive shaft length.
Slipper skirt-A piston that has a cutaway skirt so that the piston can come closer to the counterweights on the crankshaft. This makes the overall size of the engine smaller.
Sludge-Material formed as a result of oil in the presence of various acids.
Snap rings-Small rings on the external or internal surface of a shaft to prevent gears and pulleys from sliding off.
Solenoid-A device that converts electrical energy in a coil of wire to mechanical energy that moves back and forth and operates similar to a relay.
Specific gravity-The weight of a solution as it relates to water. Water has a specific gravity of 1.000. Sulfuric acid, being heavier than water, has a specific gravity of 1.835.
Splines-External or internal teeth cut into a shaft, used to keep a pulley or hub secured on a rotating shaft.
Spool valve-A cylindrical rod with different sized diameters. Usually the cylindrical body is placed inside a bore inside the transmission valve body. As the valve is moved in and out, different hydraulic circuits are operated.
Sprag-A pointed steel piece inside an overrunning clutch mechanism that allows rotation in one direction but locks up rotation in the opposite direction.
Squirrel cage blower-A type of air pressure fan shaped like a squirrel cage, used to move air throughout a ventilation system, run by a motor, and placed inside a housing to improve its efficiency of operation.
Stabilizer bar-A reinforcement component on a suspension system that prevents the vehicle body from diving or leaning on turns.
Stance-The manner of standing or being placed. A vehicle’s stance refers to the level or evenness of its position in reference to the road.
Static balance-Equal distribution of weight around a center point. Static means stationary, and static balance is done with the wheels stationary.
Stator-The stationary part in an alternator that cuts the magnetic lines of force. The part of a torque converter that is stationary and used to direct the flow of fluid back to the rotary pump at the correct angle.
Steering axis inclination-The inward tilt of the spindle support arm ball joints in the steering system.
Stellite-A very hard metal made from cobalt, chromium, and tungsten used for insert-type valve seats.
Stoichiometric ratio-A 14.7 to 1 air fuel ratio. This is the best ratio to operate an internal combustion engine.
Stroke-The distance from TDC to BDC of piston travel.
Strut rod-A rod on the suspension system located ahead of or behind a lower control arm to retain the arm in its intended position.
Sump-A pit or well where a fluid is collected. Engine oil is collected in the oil sump.
Supercharger-A device placed on a vehicle to increase the amount of air and fuel that is sent into the engine.
Suspendability-The ability of a fluid to suspend heavier dirt particles within the oil, rather than letting them fall to the bottom in the sump.
Suspension system-Components that support the total vehicle, including springs, shock absorbers, torsion bars, axles, and connecting linkages.
Swash Plate-An angled plate attached to a rotating shaft with small pistons attached to the plate. As the swash plate is rotated, the pistons move in and out of their individual cylinder, causes a pressure to be created. Air compressors for air conditioning use a swash plate pump
Sway bar-A bar on the suspension system that connects the two sides together. It is designed so that during cornering, forces on one wheel are shared by the other.
Synchronizer-An assembly in a manual transmission used to make both gears rotate at the same speed before meshing.
Synthetic-A manmade product made by combining various chemical elements.