SAAB 9000. Manual - part 59

Glossary of Technical Terms

REF•13

Catalytic converter A silencer-like device in
the exhaust system which converts certain
pollutants in the exhaust gases into less
harmful substances.

Catalytic converter

Circlip A ring-shaped clip used to prevent
endwise movement of cylindrical parts and
shafts. An internal circlip is installed in a
groove in a housing; an external circlip fits
into a groove on the outside of a cylindrical
piece such as a shaft.
Clearance The amount of space between two
parts. For example, between a piston and a
cylinder, between a bearing and a journal, etc.
Coil spring A spiral of elastic steel found in
various sizes throughout a vehicle, for
example as a springing medium in the
suspension and in the valve train.
Compression Reduction in volume, and
increase in pressure and temperature, of a
gas, caused by squeezing it into a smaller
space.
Compression ratio The relationship between

cylinder volume when the piston is at top
dead centre and cylinder volume when the
piston is at bottom dead centre.
Constant velocity (CV) joint A type of
universal joint that cancels out vibrations
caused by driving power being transmitted
through an angle.
Core plug A disc or cup-shaped metal
device inserted in a hole in a casting through
which core was removed when the casting
was formed. Also known as a freeze plug or
expansion plug.
Crankcase The lower part of the engine
block in which the crankshaft rotates.
Crankshaft The main rotating member, or
shaft, running the length of the crankcase,
with offset "throws" to which the connecting
rods are attached.

Diagnostic code Code numbers obtained by
accessing the diagnostic mode of an engine
management computer. This code can be
used to determine the area in the system
where a malfunction may be located.
Disc brake A brake design incorporating a
rotating disc onto which brake pads are
squeezed. The resulting friction converts the
energy of a moving vehicle into heat.
Double-overhead cam (DOHC) An engine

that uses two overhead camshafts, usually
one for the intake valves and one for the
exhaust valves.

Drivebelt(s) The belt(s) used to drive
accessories such as the alternator, water
pump, power steering pump, air conditioning
compressor, etc. off the crankshaft pulley.

Crankshaft assembly

Crocodile clip See Alligator clip

Accessory drivebelts

Driveshaft Any shaft used to transmit
motion. Commonly used when referring to the

axleshafts on a front wheel drive vehicle.
Drum brake A type of brake using a drum-
shaped metal cylinder attached to the inner
surface of the wheel. When the brake pedal is
pressed, curved brake shoes with friction
linings press against the inside of the drum to
slow or stop the vehicle.

EGR valve A valve used to introduce exhaust
gases into the intake air stream.
Electronic control unit (ECU) A computer
which controls (for instance) ignition and fuel
injection systems, or an anti-lock braking

system. For more information refer to the
Haynes Automotive Electrical and Electronic
Systems Manual.
Electronic Fuel Injection (EFI) A computer
controlled fuel system that distributes fuel
through an injector located in each intake port
of the engine.
Emergency brake A braking system,
independent of the main hydraulic system,
that can be used to slow or stop the vehicle if
the primary brakes fail, or to hold the vehicle
stationary even though the brake pedal isn't
depressed. It usually consists of a hand lever
that actuates either front or rear brakes
mechanically through a series of cables and
linkages. Also known as a handbrake or
parking brake.

Endfloat The amount of lengthwise
movement between two parts. As applied to a
crankshaft, the distance that the crankshaft
can move forward and back in the cylinder
block.

Engine management system (EMS) A
computer controlled system which manages

the fuel injection and the ignition systems in
an integrated fashion.

Exhaust manifold A part with several
passages through which exhaust gases leave

the engine combustion chambers and enter
the exhaust pipe.

Fan clutch A viscous (fluid) drive coupling
device which permits variable engine fan
speeds in relation to engine speeds.

Feeler blade A thin strip or blade of hardened
steel, ground to an exact thickness, used to
check or measure clearances between parts.

Feeler blade

Firing order The order in which the engine
cylinders fire, or deliver their power strokes,
beginning with the number one cylinder.

Flywheel A heavy spinning wheel in which
energy is absorbed and stored by means of
momentum. On cars, the flywheel is attached

to the crankshaft to smooth out firing

impulses.

Free play The amount of travel before any
action takes place. The "looseness" in a
linkage, or an assembly of parts, between the
initial application of force and actual
movement. For example, the distance the
brake pedal moves before the pistons in the
master cylinder are actuated.

Fuse An electrical device which protects a
circuit against accidental overload. The

typical fuse contains a soft piece of metal
which is calibrated to melt at a predetermined
current flow (expressed as amps) and break
the circuit.

Fusible link A circuit protection device

consisting of a conductor surrounded by
heat-resistant insulation. The conductor is
smaller than the wire it protects, so it acts as
the weakest link in the circuit. Unlike a blown
fuse, a failed fusible link must frequently be
cut from the wire for replacement.

REF•14

Glossary of Technical Terms

Gap The distance the spark must travel in

jumping from the centre electrode to the side

electrode in a spark plug. Also refers to the
spacing between the points in a contact
breaker assembly in a conventional points-

type ignition, or to the distance between the

reluctor or rotor and the pickup coil in an
electronic ignition.

Adjusting spark plug gap

Gasket Any thin, soft material - usually cork,
cardboard, asbestos or soft metal - installed
between two metal surfaces to ensure a good
seal. For instance, the cylinder head gasket
seals the joint between the block and the
cylinder head.

Gasket

Gauge An instrument panel display used to
monitor engine conditions. A gauge with a
movable pointer on a dial or a fixed scale is an
analogue gauge. A gauge with a numerical
readout is called a digital gauge.

Halfshaft A rotating shaft that transmits
power from the final drive unit to a drive

wheel, usually when referring to a live rear
axle.
Harmonic balancer A device designed to
reduce torsion or twisting vibration in the
crankshaft. May be incorporated in the
crankshaft pulley. Also known as a vibration
damper.
Hone An abrasive tool for correcting small
irregularities or differences in diameter in an
engine cylinder, brake cylinder, etc.
Hydraulic tappet A tappet that utilises
hydraulic pressure from the engine's
lubrication system to maintain zero clearance
(constant contact with both camshaft and
valve stem). Automatically adjusts to variation
in valve stem length. Hydraulic tappets also
reduce valve noise.

Ignition timing The moment at which the
spark plug fires, usually expressed in the
number of crankshaft degrees before the
piston reaches the top of its stroke.
Inlet manifold A tube or housing with
passages through which flows the air-fuel
mixture (carburettor vehicles and vehicles

with throttle body injection) or air only (port
fuel-injected vehicles) to the port openings in
the cylinder head.

Jump start Starting the engine of a vehicle
with a discharged or weak battery by
attaching jump leads from the weak battery to
a charged or helper battery.

Load Sensing Proportioning Valve (LSPV)

A brake hydraulic system control valve that
works like a proportioning valve, but also
takes into consideration the amount of weight
carried by the rear axle.
Locknut A nut used to lock an adjustment
nut, or other threaded component, in place.
For example, a locknut is employed to keep
the adjusting nut on the rocker arm in
position.
Lockwasher A form of washer designed to
prevent an attaching nut from working loose.

MacPherson strut A type of front

suspension system devised by Earle
MacPherson at Ford of England. In its original
form, a simple lateral link with the anti-roll bar
creates the lower control arm. A long strut -
an integral coil spring and shock absorber - is
mounted between the body and the steering
knuckle. Many modern so-called MacPherson
strut systems use a conventional lower A-arm
and don't rely on the anti-roll bar for location.
Multimeter An electrical test instrument with
the capability to measure voltage, current and
resistance.

NOx Oxides of Nitrogen. A common toxic
pollutant emitted by petrol and diesel engines
at higher temperatures.

Ohm The unit of electrical resistance. One
volt applied to a resistance of one ohm will
produce a current of one amp.
Ohmmeter An instrument for measuring
electrical resistance.
O-ring A type of sealing ring made of a
special rubber-like material; in use, the O-ring
is compressed into a groove to provide the
sealing action.
Overhead cam (ohc) engine An engine with

the camshaft(s) located on top of the cylinder
head(s).

Overhead valve (ohv) engine An engine with
the valves located in the cylinder head, but
with the camshaft located in the engine block.
Oxygen sensor A device installed in the
engine exhaust manifold, which senses the
oxygen content in the exhaust and converts

this information into an electric current. Also
called a Lambda sensor. .

Phillips screw A type of screw head having a
cross instead of a slot for a corresponding

type of screwdriver.

Plastigage A thin strip of plastic thread,
available in different sizes, used for measuring
clearances. For example, a strip of Plastigage
is laid across a bearing journal. The parts are

assembled and dismantled; the width of the
crushed strip indicates the clearance between

journal and bearing.

Plastigage

Propeller shaft The long hollow tube with
universal joints at both ends that carries
power from the transmission to the differential
on front-engined rear wheel drive vehicles.
Proportioning valve A hydraulic control
valve which limits the amount of pressure to
the rear brakes during panic stops to prevent
wheel lock-up.

Rack-and-pinion steering A steering
system with a pinion gear on the end of the
steering shaft that mates with a rack (think of
a geared wheel opened up and laid flat).
When the steering wheel is turned, the pinion

turns, moving the rack to the left or right. This

movement is transmitted through the track
rods to the steering arms at the wheels.
Radiator A liquid-to-air heat transfer device
designed to reduce the temperature of the
coolant in an internal combustion engine
cooling system.
Refrigerant Any substance used as a heat

transfer agent in an air-conditioning system.
R-12 has been the principle refrigerant for
many years; recently, however, manufacturers
have begun using R-134a, a non-CFC
substance that is considered less harmful to
the ozone in the upper atmosphere.
Rocker arm A lever arm that rocks on a shaft
or pivots on a stud. In an overhead valve
engine, the rocker arm converts the upward
movement of the pushrod into a downward
movement to open a valve.

Glossary of Technical Terms

REF•15

Rotor In a distributor, the rotating device
inside the cap that connects the centre
electrode and the outer terminals as it turns,
distributing the high voltage from the coil
secondary winding to the proper spark plug.

Also, that part of an alternator which rotates

inside the stator. Also, the rotating assembly
of a turbocharger, including the compressor
wheel, shaft and turbine wheel.
Runout The amount of wobble (in-and-out
movement) of a gear or wheel as it's rotated.

The amount a shaft rotates "out-of-true." The
out-of-round condition of a rotating part.

Sealant A liquid or paste used to prevent
leakage at a joint. Sometimes used in
conjunction with a gasket.
Sealed beam lamp An older headlight
design which integrates the reflector, lens and

filaments into a hermetically-sealed one-piece

unit. When a filament burns out or the lens

cracks, the entire unit is simply replaced.
Serpentine drivebelt A single, long, wide
accessory drivebelt that's used on some

newer vehicles to drive all the accessories,
instead of a series of smaller, shorter belts.

Serpentine drivebelts are usually tensioned by
an automatic tensioner.

Serpentine drivebelt

Shim Thin spacer, commonly used to adjust
the clearance or relative positions between
two parts. For example, shims inserted into or
under bucket tappets control valve
clearances. Clearance is adjusted by
changing the thickness of the shim.
Slide hammer A special puller that screws
into or hooks onto a component such as a
shaft or bearing; a heavy sliding handle on the
shaft bottoms against the end of the shaft to
knock the component free.

Sprocket A tooth or projection on the

periphery of a wheel, shaped to engage with a
chain or drivebelt. Commonly used to refer to

the sprocket wheel itself.
Starter inhibitor switch On vehicles with an
automatic transmission, a switch that
prevents starting if the vehicle is not in Neutral
or Park.
Strut See MacPherson strut.

Tappet A cylindrical component which
transmits motion from the cam to the valve
stem, either directly or via a pushrod and
rocker arm. Also called a cam follower.
Thermostat A heat-controlled valve that
regulates the flow of coolant between the
cylinder block and the radiator, so maintaining
optimum engine operating temperature. A
thermostat is also used in some air cleaners in
which the temperature is regulated.
Thrust bearing The bearing in the clutch
assembly that is moved in to the release
levers by clutch pedal action to disengage the
clutch. Also referred to as a release bearing.
Timing belt A toothed belt which drives the
camshaft. Serious engine damage may result
if it breaks in service.

Timing chain A chain which drives the
camshaft.
Toe-in The amount the front wheels are
closer together at the front than at the rear.
On rear wheel drive vehicles, a slight amount
of toe-in is usually specified to keep the front
wheels running parallel on the road by
offsetting other forces that tend to spread the
wheels apart.
Toe-out The amount the front wheels are
closer together at the rear than at the front.
On front wheel drive vehicles, a slight amount
of toe-out is usually specified.
Tools For full information on choosing and
using tools, refer to the Haynes Automotive
Tools Manual.
Tracer A stripe of a second colour applied to
a wire insulator to distinguish that wire from
another one with the same colour insulator.

Tune-up A process of accurate and careful

adjustments and parts replacement to obtain
the best possible engine performance.

Turbocharger A centrifugal device, driven by
exhaust gases, that pressurises the intake air.

Normally used to increase the power output

from a given engine displacement, but can
also be used primarily to reduce exhaust
emissions (as on VW's "Umwelt" Diesel
engine).

Universal joint or U-joint A double-pivoted
connection for transmitting power from a
driving to a driven shaft through an angle. A
U-joint consists of two Y-shaped yokes and a
cross-shaped member called the spider.

Valve A device through which the flow of

liquid, gas, vacuum, or loose material in bulk
may be started, stopped, or regulated by a
movable part that opens, shuts, or partially
obstructs one or more ports or passageways.

A valve is also the movable part of such a
device.
Valve clearance The clearance between the
valve tip (the end of the valve stem) and the
rocker arm or tappet. The valve clearance is
measured when the valve is closed.
Vernier caliper A precision measuring

instrument that measures inside and outside

dimensions. Not quite as accurate as a
micrometer, but more convenient.
Viscosity The thickness of a liquid or its
resistance to flow.
Volt A unit for expressing electrical
"pressure" in a circuit. One volt that will
produce a current of one ampere through a
resistance of one ohm.

Welding Various processes used to join
metal items by heating the areas to be joined
to a molten state and fusing them together.
For more information refer to the Haynes

Automotive Welding Manual.
Wiring diagram A drawing portraying the

components and wires in a vehicle's electrical
system, using standardised symbols. For
more information refer to the Haynes

Automotive Electrical and Electronic Systems

Manual.

REF•16

Conversion Factors

Length (distance)

Inches (in)
Feet (ft)
Miles

Volume (capacity)

Cubic inches (cu in; in

)

Imperial pints (Imp pt)
Imperial quarts (Imp qt)
Imperial quarts (Imp qt)
US quarts (US qt)
Imperial gallons (Imp gal)
Imperial gallons (Imp gal)
US gallons (US gal)

Mass (weight)

Ounces (oz)
Pounds (Ib)

Force

Ounces-force (ozf; oz)
Pounds-force (Ibf; Ib)
Newtons (N)

Pressure

Pounds-force per square inch
(psi; Ibf/in

; Ib/in

)

Pounds-force per square inch
(psi; Ibf/in

; Ib/in

)

Pounds-force per square inch
(psi; Ibf/in

; Ib/in

)

Pounds-force per square inch
(psi; Ibf/in

; Ib/in

)

Kilopascals (kPa)

Millibar (mbar)
Millibar (mbar)

Millimetres of mercury (mmHg)

Inches of water (inH

Torque (moment of force)

Pounds-force inches

(Ibf in;

in)

Pounds-force inches

(Ibf in;

in)

Pounds-force inches

(Ibf in;

in)

Pounds-force feet (Ibf ft; Ib ft)

Pounds-force feet (Ibf ft; Ib ft)
Newton metres (Nm)

Power

Horsepower (hp)

Velocity (speed)

Miles per hour (miles/hr; mph)

Fuel consumption*

Miles per gallon, Imperial (mpg)
Miles per gallon, US (mpg)

Temperature

Degrees Fahrenheit = (°C x 1 .8) +

25.4

0.305 =
1

.609

16.387

0.568
1.137
1.201
0.946
4.546
1.201
3.785

28.35
0.454

0.278
4.448

0.1

0.070

0.068

0.069

6.895

0.01

100

0.0145

0.75

0.401
0.535

0.036

1.152

0.113

0.083

0.138

1.356

0.102

745.7

1.609

0.354
0.425

=
=
=
=
=
=
=
=

=
=

=
=
=

=
=

Millimetres (mm)
Metres (m)
Kilometres (km)

Cubic centimetres (cc; cm

)

Litres (I)
Litres (I)
US quarts (US qt)
Litres (I)
Litres (I)
US gallons (US gal)
Litres (I)

Grams (g)
Kilograms (kg)

Newtons (N)
Newtons (N)
Kilograms-force (kgf; kg)

Kilograms-force per square

centimetre (kgf/cm

; kg/cm

)

Atmospheres (atm)

Bars

Kilopascals (kPa)

Kilograms-force per square
centimetre (kgf/cm

; kg/cm

)

Pascals (Pa)
Pounds-force per square inch
(psi; Ibf/in

; Ib/in

)

Millimetres of mercury (mmHg)
Inches of water (inH

Inches of water (inH

Pounds-force per square inch

(psi; Ibf/in

; Ib/in

)

Kilograms-force centimetre

(kgf cm;

cm)

Newton metres (Nm)

Pounds-force feet (Ibf ft; Ib ft)

Kilograms-force metres

(kgf

m; kg m)

Newton metres (Nm)
Kilograms-force metres

(kgf

m; kg m)

Watts (W)

Kilometres per hour (km/hr; kph)

Kilometres per litre (km/I)
Kilometres per litre (km/I)

0.0394
3.281
0.621

0.061

1.76

0.88

0.833
1.057

0.22

0.833
0.264

0.035
2.205

3.6

0.225

9.81

14.223

14.696

14.5

0.145

98.1

0.01

68.947

1.333

2.491

1.868

27.68

0.868

8.85

7.233

0.738
9.804

0.0013

0.621

2.825
2.352

=
=

=
=
=
=
=
=
=

=
=

=
=
=

=
=

=
=
=

=
=

Degrees Celsius (Degrees Centigrade; °C) =

Inches (in)
Feet (ft)
Miles

Cubic inches (cu in; in

)

Imperial pints (Imp pt)
Imperial quarts (Imp qt)
Imperial quarts (Imp qt)
US quarts (US qt)
Imperial gallons (Imp gal)
Imperial gallons (Imp gal)
US gallons (US gal)

Ounces (oz)
Pounds (Ib)

Ounces-force (ozf; oz)

Pounds-force (Ibf; Ib)
Newtons (N)

Pounds-force per square inch
(psi; Ibf/in

; Ib/in

)

Pounds-force per square inch
(psi; Ibf/in

; Ib/in

)

Pounds-force per square inch
(psi; Ibf/in

; Ib/in

)

Pounds-force per square inch
(psi; Ibf/in

; Ib/in

)

Kilopascals (kPa)

Millibar (mbar)
Millibar (mbar)

Millimetres of mercury (mmHg)

Inches of water (inH

Pounds-force inches

(Ibf in;

in)

Pounds-force inches

(Ibf in;

in)

Pounds-force inches

(Ibf in;

in)

Pounds-force feet (Ibf ft; Ib ft)

Pounds-force feet (Ibf ft; Ib ft)
Newton metres (Nm)

Horsepower (hp)

Miles per hour (miles/hr; mph)

Miles per gallon, Imperial (mpg)
Miles per gallon, US (mpg)

(°F

32)

0.56

* It is common practice to convert from miles per gallon (mpg) to litres/100 kilometres (1/100km),

where mpg (Imperial) x 1/100 km = 282 and mpg (US) x 1/100 km = 235

Content .. 57 58 59 60 ..