Glossary “four wheel steering (4WS)” Definition:
System whereby all four wheels are used to steer a vehicle.

Glossary “four wheeling” Definition:
Off-road travel in a four-wheel vehicle.

Glossary “four wheel drive” Definition:
A vehicle having a driving axle in front and rear, so all four wheels are driven. Also referred to as 4WD.

Glossary “four speed transmission” Definition:
Transmission providing four forward-gear ratios, one reverse ratio, and neutral, permitting closer matching of engine speed to load requirements than a three-speed transmission.

Glossary “four stroke cycle” Definition:
1). A cycle of engine operation whereby the combustion occurs in every cylinder on every second revolution of the crankshaft. 2). A complete cycle includes intake or induction, compression, combustion or expansion, and exhaust. 3). Also known as four cycle.

Glossary “four stroke engine” Definition:
An engine in which a piston must complete four stroke to complete one cycle. The four strokes are; intake, compression, power, and exhaust. Also known as Otto-cycle engine.

Glossary “four valve” Definition:
Four valves, two intake and two exhaust, per cylinder.

Glossary “four valve head” Definition:
Head design having four valves per cylinder.

Glossary “four wheel alignment” Definition:
Method of wheel alignment done on many newer cars that are equipped with rear wheel alignment capability.

Glossary “four wheel drift” Definition:
Controlled four-wheel slide on a paved surface.

Glossary “four on the floor” Definition:
Four-speed manual transmission with a floor-mounted shift lever.

Glossary “four point seat belt” Definition:
A safety-belt system with two shoulder straps, two lap straps, and a single buckle.

Glossary “four speed” Definition:
Manual transmission with four forward gears.

Glossary “four cammer” Definition:
V-type engine with dual overhead camshafts on each cylinder bank.

Glossary “four corners scuffing” Definition:
Damage to the piston that usually occurs as a result of an external cause, such as too lean an A/F mixture, which causes the top of the piston to run too hot.

Glossary “four cycle” Definition:
Term used for four-stroke cycle.

Glossary “four cycle engine” Definition:
Combustion ocurrs every other revolution of the crankshaft; a cycle being considered as 1/2 revolution of the crankshaft. These cycles or strokes are: (1) intake stroke, (2) compression stroke, (3) power stroke, (4) exhaust stroke. Also known as Otto cycle engine.

Glossary “four gas analyzer” Definition:
Exhaust gas analyzer able to detect and measure exact amounts of HC, CO, CO2, and O2.

Glossary “four by” Definition:
Term used for 4×4.

Glossary “four banger” Definition:
1). A four-cylinder engine. 2). Vehicle equipped with a four-cylinder engine.