Dictionary of Automotive Terms: Q-R

- Q -

QUADRANT (Gearshift): A gear position indicator often using a shift lever actuated pointer. Can be marked PRND21 (3-speed), PRN321 (4-speed), etc.

QUADRA-TRAC: See Full Time Four-Wheel Drive.

QUENCHED (Flame): Flame front in combustion chamber being extinguished as it contacts colder cylinder walls. This sharply elevates hydrocarbon emissions.

QUENCHING: Dipping heated object into water, oil, or other substance, to quickly reduce temperature.

QUICKSILVER: Metal mercury. Often used in thermometers.

- R -

RACE (Bearing): Inner or outer ring that provides a contact surface for balls or rollers in bearing.

RACE CAMSHAFT: Camshaft, other than stock, designed to improve performance by altering cam profile. Provides increased lift, faster opening and closing, earlier opening and later closing, etc. Race camshafts are available as semi-race or street grind, three-fourths race or full race. Grinds in between these general categories are also available.

RACING SLICK: Type of tire used in “drag racing” as well as some “stock car” applications. Tread surface of tire is completely smooth, for maximum rubber contact with track surface.

RACK AND PINION GEARBOX (Steering): Steering gear utilizing pinion gear on end of steering shaft. Pinion engages long rack (bar with teeth along one edge). Rack is connected to steering arms via rods.

RADIAL (Direction): Line at right angles (perpendicular) to shaft, cylinder, bearing, etc., center line.

RADIAL COMPRESSOR: A small air conditioning compressor using reciprocating pistons working at right angles to shaft and spaced around shaft in radial fashion.

RADIAL ENGINE: Engine possessing various numbers of cylinders so arranged that they form circle around crankshaft centerline.

RADIAL TIRE: Plies parallel and at right angle to tread, belts under tread area.

RADIATION: Transfer of heat from one object to another when hotter object sends out invisible rays or waves that upon striking colder object, cause it to vibrate and thus heat.

RADIATOR (Engine Cooling): A device used to remove heat from engine coolant. It consists of a series of finned passageways. As coolant moves through passages, heat is con ducted to fins where it transfers to a stream of air forced through fins.

RADIATOR CAP: Pressure cap that fits on radiator neck. It keeps coolant from boiling.

RADIUS: Distance (in a straight line) from center of a circle or circular motion, to a point on edge (circumference).

RADIUS RODS: Rods attached to axle and pivoted on frame. Used to keep axle at right angles to frame and yet permit an up and down motion.

RAIL: Dragster built around a relatively long pipe frame. Often the only body panels used are around the driver’s cockpit area.

RAM AIR: Air “scooped” up by an opening due to vehicle forward motion.

RAM INDUCTION: Using forward momentum of car to scoop air and force it into carburetor via a suitable passageway.

RAM INTAKE MANIFOLD: Intake manifold that has very long passageways that at certain speeds aid entrance of fuel mixture into cylinders.

RATED HORSEPOWER (Engine): Indication of horsepower load that may safely be placed upon engine for prolonged periods of time. This would be somewhat less than the engine maximum horsepower.

RATIO: Fixed relationship between things in number, quantity, or degree. For example, if fuel mixture contains one part of gas for fifteen parts of air, ratio would be 15 to 1.

REACTOR: See Stator.

REAM: To enlarge or smooth hole by using round cutting tool with fluted edges.

REAR AXLE (Banjo Type): Rear axle housing from which differential unit may be removed while housing remains in place on car. Housing is solid from side to side.

REAR AXLE HOUSING (Split Type): Rear axle housing made up of several pieces and bolted together. Housing must be split apart to remove differential.

RECEIVER-DRIER: See Drier.

RECIPROCATING ACTION: Back-and- forth movement such as action of pistons.

RECIRCULATING BALL WORM AND NUT: Very popular type of steering gear. It utilizes series of ball bearings that feed through and around and back through grooves in worm and nut.

RECTIFIER: Device used to change AC (alternating current) into DC (direct current).

RED LINE: Top recommended engine rpm. If a tachometer is used, it will have a mark (Red line) indicating maximum rpm.

REDUCING FLAME: Welding flame in which there is an excess of acetylene.

REDUCTION (Gear): A gear that increases torque by reducing rpm of a driven shaft in relation to that of driving shaft.

REFRIGERANT: Liquid used in refrigeration systems to remove heat from evaporator coils and carry it to condenser.

REFRIGERANT-12: Name applied to refrigerant generally used in automotive air conditioning systems.

REFRIGERANT OIL: Special oil which lubricates air conditioning compressor.

REGULATOR (Electrical): Device used to control generator voltage and current output.

REGULATOR (Gas or Liquid): Device to reduce and control pressure.

RELATIVE HUMIDITY: Actual amount of moisture in a given sample of air compared to total amount that sample could hold (at same temperature).

RELAY: Magnetically operated switch used to make and break flow of current in circuit. Also called “cutout, and circuit breaker.”

RELIEVE: Removing, by grinding, small lip of metal between valve seat area and cylinder — and removing any other metal deemed necessary to improve flow of fuel mixture into cylinder. Porting is generally done at same time.

RELUCTOR: A component in electronic ignition system distributor. It is affixed to the distributor shaft and triggers magnetic pickup. This, in turn, triggers control unit which breaks coil primary circuit causing coil to “fire.”

RESIDUAL MAGNETISM: Magnetism remaining in an object after removal of any magnetic field influence.

RESISTANCE (Electrical): Measure of conductor’s ability to retard flow of electricity. RESISTOR: Device placed in circuit to lower voltage. It will also decrease flow of current.

RESISTOR SPARK PLUG: Spark plug containing resistor designed to shorten both capacitive and inductive phases of spark. This will suppress radio interference and lengthen electrode life.

RESONATOR: Small muffler-like device that's placed into exhaust system near end of tall pipe. Used to provide additional silencing of exhaust.

RETARD (Ignition Timing): To set the ignition timing so that spark occurs later or less degrees before TDC.

REVERSE-ELLIOT TYPE AXLE: Solid bar front axle on which steering knuckles span or straddle axle ends.

REVERSE FLUSH: Cleaning cooling system be pumping a powerful cleaning agent through system in a direction opposite to that of normal flow.

REVERSE IDLER GEAR: Gear used in transmission to produce a reverse rotation of transmission output shaft.

RHEOSTAT: A variable type resistor used to control current flow.

RICARDO PRINCIPLE: Arrangement in which portion of combustion chamber came in very close contact with piston head. Other portion, off to one side, contained more space. As the piston neared TDC on compression stroke, fuel mixture was squeezed tightly between piston and head thus causing mixture to squirt outward into larger area in very turbulent manner. This produced a superior mixture and allowed compression ratios to be raised without detonation.

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

RIDING THE CLUTCH: Riding the clutch refers to driver resting a foot on clutch pedal while car is being driven.

RIM (Tire): The outer portion of a wheel upon which tire is mounted.

RING (Chrome): Ring on which the outer edge has a thin layer of chrome plate.

RING (Pinned): Steel pin, set into piston, is placed in space between ends of ring. Ring is thus kept from moving around in groove.

RING GAP: Distance between ends of piston ring when installed in cylinder.

RING EXPANDER: Spring device placed under rings to hold them snugly against cylinder wall.

RING GEAR: Large gear attached to differential carrier or to outer gear in planetary gear setup.

RING GROOVES: Grooves cut into piston to accept rings.

RING JOB: Reconditioning cylinders and in stalling new rings.

RING RIDGE: Portion of cylinder above top limit of ring travel. In a worn cylinder, this area is of smaller diameter than remainder of cylinder and will leave ledge or ridge that must be removed.

RIVET: Metal pin used to hold two objects together. One end of the pin has head and other end must be set or peened over.

RMA: Rubber Manufacturer’s Association.

ROAD FEEL: Feeling imparted to steering wheel by wheels of car in motion. This feeling can be very important in sensing and predetermining vehicle steering response.

ROCKER ARM: Arm used to direct upward motion of push rod into a downward or opening motion of valve stem. Used in overhead valve installations.

ROCKER ARM SHAFT: Shaft upon which rocker arms are mounted.

ROCKER PANEL: Section of car body between front and rear fenders and beneath doors.

ROCKWELL HARDNESS: Measurement of the degree of hardness of given substance.

ROD: Refers to a car, driving a car hard, or to a connecting rod.

ROD CAP: Lower removable half of connecting rod big end.

RODDING THE RADIATOR: Top and sometimes the bottom tank of the radiator is removed. The core is then cleaned by passing a cleaning rod down through tubes. This is done when radiators are quite clogged with rust, scale, and various mineral deposits.

ROLL BAR: Heavy steel bar that goes from one side of frame, up and around in back of the driver, and back down to the other side of frame. It is used to protect driver in the event that the car rolls over.

ROLLER BEARING: Bearing utilizing a series of straight, cupped, or tapered rollers engaging an inner and outer ring or race.

ROLLER CLUTCH: Clutch, utilizing series of rollers placed in ramps, that will provide drive power in one direction but will slip or freewheel in the other direction.

ROLLER TAPPETS or LIFTERS: Valve lifters that have roller placed on end contacting camshaft. This is done to reduce friction between lobe and lifter. They are generally used when special camshafts and high tension valve springs have been installed.

ROLLING RADIUS: Distance from road surface to center of wheel with vehicle moving under normal load. Rolling radius is dependent on tire size.

ROLLOVER VALVE: Valve in fuel delivery line to prevent escape of raw fuel during an accident in which car is upside down.

ROOM TEMPERATURE: An enclosed space air temperature of around 68-72°F (20.1-22.2°C).

ROTARY ENGINE: Piston engine in which the crankshaft is fixed (stationary) and in which cylinders rotate around crankshaft.

ROTARY ENGINE (Wankel): Internal combustion engine which is not of a reciprocating (piston) engine design. Central rotor turns in one direction only and yet effectively produces required intake, compression, firing, and exhaust strokes.

ROTARY FLOW (Torque Converter): Movement of oil as it's carried around by pump and turbine. Rotary motion is not caused by oil passing through pump, to turbine, to stator, etc., as is case with vortex flow. Rotary flow is at right angles to center line of converter whereas vortex flow is parallel (more or less depending on ratio between speeds of pump and turbine).

ROTARY MOTION: Continual motion in circular direction such as performed by crankshaft.

ROTOR (Distributor): Cap-like unit placed on end of distributor shaft. It is in constant contact with distributor cap central terminal and as it turns, it will conduct secondary voltage to one of the outer terminals.

ROUGHING STONE (Hone): Coarse stone used for quick removal of material during honing.

RPM: Revolutions per minute.

RUNNING-FIT: Fit in which sufficient clearance has been provided to enable parts to turn freely and to receive lubrication.

RUNNING ON: See Dieseling.

RUNOUT: Refers to a rotating object, surface of which is not revolving in a true circle or plane. Runout can be measured in a radial (at right angles to centerline of object) direction or in a lateral (lengthwise to centerline) direction.