Important Terms and their Meaning of Mechanical Engineering-Automotive Vehicles:
ACCELERATOR
– A pedal connected to the carburettor throttle valve of a motor vehicle or
to the fuel injection control where oil engines are used.
ACKERMAN
PRINCIPLE – Steering geometry in which the outer ends of the steering arms
are bend slightly inward so that when the vehicle is making a turn, inside
wheel will turn more sharply than the outer wheel. This principle produces toe
out on turns.
ACKERMAN
STEERING – Arrangement whereby a line extended from the track arms, when
the wheels are set straight ahead, should meet on the chassis centre line at
2/3 of the wheel base from the front, allowing inner stub axle to move through
a greater angle than the outer.
AERODYNAMIC
DRAG – Is the air resistance to the motion of the vehicle. This consists of
profile drag, induced drag, skin friction drag, interference drag, and cooling
and ventilation drag.
AERODYNAMIC
LIFT – Is the vertical component of the resultant force caused by the
pressure distribution on the vehicle body.
AIR
BLEEDER – A device used to remove air from a hydraulic system. Types
include a needle valve, capillary tubing to the reservoir, and a bleed plug.
AIR BRAKE
– A braking system which uses compressed air to supply the effort required
to apply brakes.
AIRFOIL –
Device, similar to a stubby wing.
AIR
RESISTANCE – The motion of an automobile is associated with the displacement
of air particles, which requires some power of the engine. Air resistance
depends on the size and shape of the vehicle body, speed of the vehicle and
wind velocity.
AIR
SPRING – Container and plunger are separated by air under pressure. When
container and plunger attempt to squeeze together, air compresses and produces
a spring effect. Air spring has been used in some suspension systems.
ALL
WEATHER TYRE – A tyre designed to provide good traction on dry, wet and
dirt and snow covered roadways.
ANTI
DAZZLE MIRROR – One having a photoelectric control circuit which changes it
from a fully reflecting condition to partial reflection from a glass air
interface when actuated by the head lamp beam of a following vehicle.
ANTILOCK
BRAKE SYSTEM (ABS) – If the brakes are applied so hard that the wheels tend
to stop turning and thus a skid starts to develop, the antilock brake system
comes into operation and partly releases the brakes. This makes the wheels
continue to rotate. However, intermittent braking continues. But it is held
below the point where the skid would start.
ANTIMIST
PANEL – A panel fitted to the rear window enclosing a volume of still air
between itself and the outer glass.
ANTIROLL
BAR – Torsion bar mounted transversely in the chassis in such a way so as
to counteract the effect of opposite spring deflections.
ARCH –
The curve of a leaf spring. If the centre is lower than the ends, it is called
positive arch, if the centre is higher than the ends, it is called negative
arch.
ARCING
(brakes) – Grinding new brake linings to the same diameter (arc) as that of
the brake drum surface.
ASPECT
RATIO – The ratio of the width to the length. On tyres, it is the fully inflated
height divided by the cross section.
AUTOMOBILE
– is a self propelled vehicle. The power required to propel the vehicle is
supplied by the engine (also called prime mover). Scooters, motor cycles, cars,
buses, trucks etc., are different types of automotive vehicles.
AUTOMATIC
LEVEL CONTROL – A suspension system which compensates for variations in
load in the rear of the car, positioning the rear at a pre-designed level
regardless of load.
AUTOMATIC
TRANSMISSION – A power transmission system for road vehicles, in which the
approximately optimum engine speed is maintained through mechanical or
hydraulic speed changing devices which are automatically selected and operated
by reference to the road speed of the vehicle.
AXLE –
A cross bar supporting a vehicle on which one or more wheels turn.
AXLE
(full floating) – Axle used to drive rear wheels. It does not hold the wheels
on nor support them.
AXLE (semi
quarter or one quarter floating) – Axle used to drive wheels, hold them on
and support them.
AXLE
THREE QUARTER FLOATING – Axle used to drive rear wheels as well as hold
them on and support them.
AXLE
FLANGE – A flat surface on the outboard end of the axle shaft to allow
wheel attachment.
AXLE GEAR
– A gear in the differential carrier that drives the driving wheels.
AXLE
RATIO – Relationship or ratio between the numbers of times the propeller shaft
or drive shaft must revolve to turn the axle shafts one turn.
AXLE
SHAFT – The shaft used to transmit power from the differential to the
wheels.
BACK
LOCKING – The steering gear is so constructed that it is easy to turn the
vehicle by steering wheel, but it is difficult to turn the steering wheel by
turning the front wheels. This back locking prevents the bumps and shocks
experienced by the wheel on the road surface from being transmitted to the
steering wheel.
BACKING
PLATE – A mounting plate that holds the brake shoes, cam lever, pivot pins
and springs inside the brake drum.
BALL
JOINT – Flexible joint utilizing ball and socket type of construction, used
in steering linkage set ups, steering knuckle pivot supports etc.
BALL
JOINT ROCKER ARMS – Rocker arms that instead of being mounted on shaft, are
mounted upon ball shaped devices on end of stud.
BALL
JOINT STEERING KNUCKLE – Steering knuckle that pivots on ball joints
instead on king pin.
BALL
JOINT SUSPENSION – A type of front suspension, which does not use a
steering knuckle. Instead, the wheel spindle is attached directly to the upper
and lower suspension arms through ball joints. Allows movement up and down as
well as rotation.
BALL STUD
– Stud with a ball on end, commonly used in steering linkage to connect
pitman arm to linkage, or to connect tie rods.
BALL AND
TRUNNION JOINT – A type of universal joint which combines the universal joint
and slip joint in one assembly.
BEAD
(tyre) – Steel wire reinforced portion around a tyre opening that engages
the wheel rim.
BELL
HOUSING (clutch housing) – Metal (cast iron or aluminium) cover that
surrounds flywheel and clutch, or torque converter assembly.
BELL
MOUTH – The taper of a brake drum.
BELTED
TYRE – A tyre that is reinforced with a build up of cord under the tread
area.
BENCH
BLEEDING – Process of removing air from the master cylinder pressure area
before installing it in the vehicle.
BENDIX
TYPE STARTER – A self engaging starter drive gear. Gear moves into
engagement when starter armature shaft starts spinning and automatically
disengages when starter stops and engine speed increases.
BIAS
BELTED TYRE – A tyre in which plies are laid on the bias, criss crossing
each other, with a circumferential belt on top of them. The rubber tread is
vulcanized on top of the belt and plies.
BINDERS –
Compounds that hold the friction materials together in brake linings.
BLEEDING –
Removing air, pressure, fluid etc. from a closed system as in the brake system
or air conditioning system.
BLEEDING
(brakes) – Removal of air from hydraulic system. Bleeder screws are
loosened at each wheel cylinder (one at a time) and brake fluid is forced from
master cylinder through lines until all air is expelled.
BLEEDING
(steering) – A process by which air is removed from a hydraulic system
(power steering) by bleeding off part of the fluid or operating the system to
work without the air.
BODY –
The assembly of sheet metal sections together with windows, doors, seats and
other parts, that provide an enclosure for the passengers, engine and so on.
BODY
PANELS – Sheets or panels of steel which are fastened together by welding
to form the vehicle body.
BODY ROLL
– The vehicle body leaning sideways as the vehicle turns.
BOGIE –
A small truck, of short wheel base running on rails, commonly used for the
conveyance of coal, gold or other ores, concrete etc.
BONDED
BRAKE LINING – Brake lining that is attached to the brake shoe by adhesive.
BONNET –
British term for car hood.
BOOSTER –
Device incorporated in a car system (such as brake and steering), to increase
pressure output or decrease amount of effort required to operate or both.
BORG
WARNER OVER DRIVE – A method of reducing engine rpm in relation to road
speed. The unit is attached at the rear of the gear box and operates through
epicyclic gears.
BRAKE –
An energy conversion device that converts the energy of motion into heat energy
and thereby slows down or stops a moving vehicle.
BRAKE
(disc type) – Braking system which uses steel disc with calliper type lining
application. When brakes are applied, section of lining on the calliper piston
on each side of the spinning disc is forced against the disc thus imparting
braking force. This type of brake is very resistance to brake fade. Also called
disc brake system.
BRAKE
ANCHOR – Steel stud upon which one end of brake shoes is either attached to
or rests against. Anchor is firmly affixed to backing plate.
BRAKE
ANTIROLL DEVICE – Unit installed in brake system to hold brake line
pressure when car is stopped on upgrade, and brake pedal is released. Antiroll
device will keep brakes applied until either clutch is released or, as in some
models, accelerator is depressed.
BRAKE
BACKING PLATE – Rigid steel plate upon which brake shoes are attached.
Braking force applied to shoes is absorbed by backing plate.
BRAKE
BAND – Band faced with brake lining, that encircles a brake drum. Used on
several parking brake installations.
BRAKE
BIAS – The stopping effort of the front wheels compared to that of the rear
wheels.
BRAKE
CALIPER – The hydraulic cylinder at the wheel used to apply the disc brake
linings against the rotor.
BRAKE
CLEARANCE – is the clearance provided between the lining and the drum or
disc. Wear and tear of the lining increases this clearance and hence to be
adjusted periodically.
BRAKE
DRUM – Metal drum mounted to the vehicle wheel which forms the outer shell of the brake. Brake shoes
when moved out or moved apart press against the rotating drum to slow or stop
drum and wheel rotation.
BRAKE
EFFECTIVENESS – is how effectively the brakes perform their function. This
depends on the area of the brake lining, amount of pressure applied to the
brake shoes, radius of the brake drum, vehicle wheel radius, coefficient of
friction of braking surfaces and coefficient of friction between the tyre and
the road surface.
BRAKE
FADE – A reduction or fading out of braking effectiveness due to loss of
friction between brake shoes and drum. This is caused by overheating (heat
build up) from excessively long and hard brake application for instance, when
coming down a long hill or mountain.
BRAKE
FEEL – The reaction of the brake pedal against the drivers foot, that tells
him how heavily he is applying the brakes.
BRAKE
FLUID – A special non -mineral oil fluid used in hydraulic braking system.
Never use anything else in place of regular fluid.
BRAKE
FLUSHING – Cleaning brake system by flushing with alcohol or brake fluid.
Done to remove water, dirt or any other contaminant. Flushing fluid is placed
in master cylinder and forced through lines and wheel cylinders where it exits
at cylinder bleed screws.
BRAKE
LINE – Special hydraulic tube made of steel, plastic or reinforced rubber
suitably designed to withstand extreme pressure without deforming.
BRAKE
LINING – A special high friction material made of asbestos and other
materials bonded to brake shoes and brake pad plates. Brake lining produces
friction and heat when it is forced against the brake drum or disc.
BRAKE
PULL – A condition in which the vehicle turns each time the brakes are
applied.
BRAKE
ROTOR – The brake friction surface that rotates at wheel speed designed for
contact with the brake pads on disc brake assemblies.
BRAKE
SELF ADJUSTERS – A cable operated device used to adjust brake shoes
automatically.
BRAKE
SHOES (disc brakes) – Flat metal pieces lined with brake lining which are
forced against the rotor face. Also called brake pads.
BRAKE SHOES
(drum brakes) – Arc shaped metal pieces lined with heat resistant fibre.
When forced against the brake drum, stops wheel rotation.
BRAKE
SHOE HEEL – End of brake shoe adjacent to anchor bolt or pin.
BRAKE
SHOE TOE – Free end of brake shoe, not attached to or resting against an
anchor pin.
BRAKING
SYSTEM EFFICIENCY – is measured in terms of the rate at which brake will
bring the vehicle to a stationary position from a given speed. It is expressed
as the ratio of the vehicle deceleration rate to the acceleration due to
gravity.
BREAKE
(tyre) – Rubber or fabric (or both) strip placed under the tread to provide
additional protection for main tyre carcass.
BULK HEAD
– The structural part of the vehicle connecting the front of the floor
assembly to the roof structure.
BUMPER –
which is attached to the vehicle frame takes the shock of impact or collision
and transfer the same to the frame. By this means, damage to engine parts,
radiator, lamps etc. is avoided.
BUMP
STEER – The steering effect caused by the suspension moving through its
travel.
CALIPER –
A housing for the hydraulic components of a disc brake system.
CAMBER –
Tilting of the top of wheels from the vertical, when the tilt is outward,
camber is positive.
CAMBER
ANGLE – The outward (positive) or inward (negative) angle of the wheel
centre line to absolute vertical.
CARDAN
UNIVERSAL JOINT – A universal joint of the ball and socket type.
CARLIFT –
An air, electrical or hydraulically operated piece of shop equipment which can
lift the entire vehicle, or in some cases, one end of the vehicle.
CARRIER
BEARINGS – Bearings upon which differential case is mounted.
CASING OF
TYRE – The tyre casing, made of fabric or cord to which rubber is
vulcanized. It is the outer part of the tyre assembly.
CASTER –
The tendency of a wheel to follow the direction of the pivot movement. Tilt of
the top of the king pin forward or backward from the vertical. When tipped
forward it is called negative caster. Backward tilt from the vertical is called
positive caster.
CASTER
ANGLE – The rearward (positive) or forward (negative) angle of the steering
axis to absolute vertical.
CENTRE
STEERING LINKAGE – Steering system utilizing two tie rods connected to
steering arms and to central idler arm. Idler arm is operated by drag link that
connects idler arm to pitman arm.
CENTRIFUGAL
CLUTCH – Clutch that utilizes centrifugal force to expand a friction device
on driving shaft until it is locked to a drum on driven shaft. The clutch comes
into action as it spins faster.
CHANNELED
– Car body lowered down around frame.
CHASSIS –
Generally chassis refers to the unit that consists of frame, engine, front and
rear axles, springs, steering and brake systems, controls, drive train and fuel
tank. It is an assembly of mechanisms that make up the major operating part of
the vehicle. In short, it is assumed to include everything except the vehicle
body and fenders.
CLASSIC
or NORMAL CONTROL TRUCK – has the engine located in front of the driver’s
cabin.
CLUTCH –
Device used to connect or disconnect flow of power from one unit to another. In
a vehicle, the mechanism in the power train that connects the engine crankshaft
to or disconnects it from the transmission and thus with the remainder of the
power train.
CLUTCH
CHATTER – A shaking or shuddering of the vehicle as the clutch is operated.
CLUTCH
DIAPHRAGM SPRING – Round dish shaped piece of flat spring steel, used to
force pressure plate against clutch disc in some clutches.
CLUTCH
DISC – Part of the clutch assembly splined to transmission clutch or input
shaft, faced with friction material. When clutch is engaged, disc is squeezed
between flywheel and clutch pressure plate.
CLUTCH
DRAG – A problem in which the clutch disc does not come to a complete stop
after the clutch pedal is depressed.
CLUTCH
EXPLOSION – Clutches have literally flown apart (exploded) when subjected
to high rotational speed. Scatter shield is used on competition cars to protect
driver and spectators from flying parts in event clutch explodes.
CLUTCH
HOUSING – A metal housing that surrounds the flywheel and clutch assembly.
CLUTCH
LINKAGE – The rods and levers that allow the driver to operate the clutch.
CLUTCH
PEDAL – A pedal in the driver’s compartment that operates the clutch.
CLUTCH
PEDAL FREE TRAVEL – Specified distance clutch pedal may be depressed before
throw out bearing actually contacts clutch release fingers.
CLUTCH
PILOT BEARING – A small bronze bushing or ball bearing positioned in the
crankshaft end or centre of flywheel, used to support outboard end of
transmission input shaft.
CLUTCH
PRESSURE PLATE – Part of a clutch assembly, that through spring pressure,
squeezes clutch disc against flywheel thereby transmitting driving force
through the assembly. To disengage clutch, pressure plate is drawn away from
the flywheel via linkages.
CLUTCH
SEMI CENTRIFUGAL RELEASE FINGERS – Clutch release fingers that have a
weight attached to them, so that at high rpm release fingers place additional
pressure on clutch pressure plate.
CLUTCH
SHAFT – The shaft on which the clutch is assembled, with the gear that
drives the countershaft in the transmission on one end. It has external splines
that can be used by a synchronizer drum to lock the clutch shaft to the main
shaft for direct drive.
CLUTCH
SLIPPAGE – A condition in which the engine over revs during shifting or
acceleration.
CLUTCH
THROWOUT FORK – In the clutch, a Y shaped member into which is assembled
the throw out bearing.
CLUSTER
or COUNTER GEAR – Cluster of gears that are all cut on one long gear blank.
Cluster gears ride in the bottom of transmission. Cluster provides a connection
between transmission input shaft and output shaft.
COEFFICIENT
OF FRICTION – An index of the frictional characteristics of a material.
COEFFICIENT
OF ROLLING RESISTANCE – is numerically equal to the ratio of the force
causing uniform rolling of the wheel to the normal reaction of the road.
COIL
SPRING CLUTCH – A clutch using coil springs to hold the pressure plate
against the friction disc.
COLLAPSIBLE
STEERING COLUMN – is the steering column which will collapse in its length
due to the impact of the driver on to the steering wheel, on a front end crash.
This safety device prevents the possibility of the driver getting injured.
CONE CLUTCH
– Clutch utilizing cone shaped member that is forced into a cone shaped
depression in the flywheel, or the other driving unit. Although no longer used
in cars, cone clutch finds some applications in small riding tractors, heavy
power movers etc.
CONSTANT
VELOCITY JOINT – Two closely coupled universal joints arranged so that
their acceleration and deceleration effects cancel out each other, resulting in
an output driven shaft speed to be always identical with drive shaft speed.
CONTACT
PATCH – The part of a tyre that is in contact with the road surface.
CONTROL
ARM – A suspension member mounted horizontally with one end attached to the
frame and the other end the knuckle or axle housing.
CORD –
A string or thread that makes up the fabric used in tyre plays.
CORNERING
WEAR – A type of tyre tread wear caused by taking turns at excessive
speeds.
COUNTERSHAFT
– Intermediate shaft that receives motion from one shaft and transmits it
to another. It may be fixed (gears turn on it) or it may be free to rotate. In
the transmission countershaft is driven by the clutch gear, gears on the
countershaft drive gears on the main shaft when the latter are shifted into
gear.
COWL –
Part of car body between engine firewall and front of dashboard.
CROSS
SHAFT (steering) – Shaft in steering box that engages steering shaft worm.
Cross shaft is splined to pitman arm.
CURB
WEIGHT – The weight of the complete vehicle with its normal load, less
driver and passengers but with a full tank of fuel, engine and vehicle oil and
coolant.
CUT OUT –
operates as an automatic switch which connects and disconnects the battery with
the generator, according to the speed of the latter.
DAMPERS –
are nothing but a piston in a cylinder filled with oil or gas. The damper
restrains undesirable bounce of the sprung vehicle mass and restrains the wheel
assembly from loosing ground contact by being excited at its natural frequency.
DASH
BOARD – Part of body containing driving and control instruments, switches
etc.
DEAD AXLE
– Axle that does not rotate or deliver power but merely forms a base upon
which wheels may be mounted.
DEDION –
Rear axle set up in which driving wheels are attached to the frame by a central
pivot. Differential unit is bolted to frame and is connected to the driving wheels
by drive axles.
DEPENDENT
SUSPENSION – Wheel connected through an axle member so that movement of one
wheel moves the other wheel.
DIAGONAL
SPLIT BRAKE SYSTEM – A brake system design that will allow application of
brakes on one front wheel and a diagonally opposite rear wheel, when part of
brake system fails.
DIAPHRAGM
CLUTCH – Uses a diaphragm or conical spring instead of coil springs to
produce adequate pressure required for keeping the clutch in the engaged
position.
DIFFERENTIAL
– A mechanism between axles that permit one wheel to turn at a different
speed than the other while transmitting power from the drive shaft to the wheel
axles, when the vehicle is negotiating a turn.
DIFFERENTIAL
CASE – A steel unit to which the ring gear is attached. Differential case
drives spider gears and forms an inner boring surface for axle and gears.
DIFFERENTIAL
LOCK – The differential lock grips one or both of the side gears to the
differential case. This prevents their rotation on the pins. This enables a larger
torque to be transmitted to the gripping wheel than that to the slipping wheel.
DIRECT
ACTING SHOCK ABSORBER – Type of shock absorber which shortens or lengthens
in action. Also called telescopic shock absorber.
DIRECT
DRIVE – Such as high gear when crankshaft and drive shaft revolve at same
speed.
DIRECTIONAL
STABILITY (steering) – Ability of vehicle to move forward in straight line
with minimum of driver control. Vehicle with good directional stability will
not be unduly affected by side wind, road irregularities etc.
DISC
BRAKE – When the brake pedal is depressed, pads lined with friction material
are forced towards one another. In doing so, they come in contact with the disc
(attached to the wheel) which normally rotates between them. This provides
braking effort.
DISC
WHEEL – Wheel constructed of stamped sheet.
DIVE –
The front wheel of the vehicle lowering during braking.
DOLLY
BLOCKS – Blocks of metal, variously shaped and contoured, used to
straighten body panels and fenders. The dolly block is held on one side of the
panel while the other side is struck with a special hammer.
DOUBLE
LEADING SHOE – A drum brake having two leading shoes and no trailing shoes.
Each shoe has its own actuating mechanism and pivot.
DOUBLE
PISTON CALIPER – A hydraulic brake calliper with two pistons and provision
for applying hydraulic pressure equally to both pistons. The calliper body is
fixed solidly.
DOWN
SHIFT – Shifting to lower gear.
DOUBLE
LEADING BRAKE – A drum brake assembly with both front shoes self energized
during forward wheel rotation.
DOUBLE
REDUCTION AXLE – In the double reduction or triple reduction type final
drive, the required speed reduction is obtained in two or more steps. This
enables higher torque to be available at the road wheels. In heavy duty and off
highway vehicles, multiple reduction is used.
DOUBLE
TRAILING BRAKE – A drum brake assembly with both shoes self energized
during rearward wheel rotation only.
DRAG –
To accelerate a vehicle from standing start, over course one fourth mile in
length. Also used by some drivers when referring to challenging another driver
to an acceleration race.
DRAG LINK
– A steel rod connecting pitman arm to one of steering knuckles. On some
installations, drag link connects pitman arm to a centre idler arm.
DRAGSTER –
Car especially built for drag racing.
DRAG
WHEEL – Special steering wheel used on some dragsters. Often consists of
cross bar spoke and portion of rim on each end.
DRIP
MOULDING – is a U shaped channel, added to the side rails of the roof
panel. It catches water on the roof and direct it to the back of the car during
raining.
DRIVE
LINE or DRIVE TRAIN – Propeller shaft, universal joints etc. connecting
transmission output shaft to axle pinion gear shaft.
DRIVE
PINION – A gear in the differential connected to the drive shaft.
DRIVE or
PROPELLER SHAFT SAFETY STRAP – A metal strap or straps, surrounding drive
shaft to prevent shaft from falling to ground in the event of a universal joint
or shaft failure.
DRIVE
SHAFT – An assembly of one or two universal joints connected to a hollow
tube and used to transmit torque and motion. A shaft in the power train that
extends from the transmission to the differential and transmits power from one
to the other. Also called PROPELLER SHAFT.
DROP
CENTRE RIM – Centre section of rim being lower than two outer edges. This
allows bead of tyre to be pushed into lower area on one side while the other
side is pulled over and off the flange.
DROPPED
AXLE – Front axle altered so as to lower the frame of the vehicle. Consists
of bending axle downward at outer ends (solid front axle).
DRUM
BRAKE – A brake unit using curved brake shoes which press against the inner
circumference of a metal drum to produce braking action.
DUALS –
Two sets of exhaust pipes and mufflers one for each bank of cylinders.
DUAL
BRAKE SYSTEM – Tandem or dual master cylinder to provide a brake system
that has two separate hydraulic systems, one operating the front brakes, the
other operating the rear brakes.
DUAL
SERVO BRAKES – A drum brake assembly with both front and rear shoes, self
energized during forward and rearward wheel rotations.
DUMMY
AXLE – provided in some vehicles increases the load carrying capacity of
the vehicle. Wheels on the dummy axle can rotate freely.
DUNY
BUGGY – Off road vehicle set up to run on sand.
ELLIOT
TYPE AXLE – Solid bar front axle on which ends span or straddle steering
knuckle.
EMERGENCY
BRAKE – is the hand brake, operated by a lever, is used when the vehicle is
left parked and prevents the vehicle from moving. The hand brake can be applied
to stop the vehicle when the service brake fails.
EPICYCLIC
GEAR – In the epicyclic gearing, at least one gear not only rotates about
its own axis, but also rotates about some other axis.
EQUALIZER
LINK – A common connector in the parking brake system that causes both rear
brakes to be applied with the same cable tension.
EVASIVE
MANEUVER – Rapid steering changes to avoid obstacles in the path of the
vehicle.
EXPANSION
TANK – A tank at the top of an automobile radiator which provides room for
heated coolant to expand and give off any air that may be trapped in the
coolant. Also used in some fuel tanks to prevent fuel from spilling from the
tank because of expansion.
FADE
(brake) – A condition that occurs when there is little braking effect with
full brake pedal force.
FIFTH
WHEEL – is the swivelling type arrangement at the rear of a tractor unit.
The fifth wheel carries the front part of the semitrailer.
FINAL
DRIVE – The final gear reduction between the engine and the drive wheels.
FIXED
CALIPER DISC BRAKES – Disc brakes using a calliper which is
fixed in
position and cannot move.
FLOATING
CALIPER DISC BRAKES – Disc brakes using a calliper mounted through rubber
bushings which permit the calliper to float, or move, when the brakes are
applied.
FLUID FLY
WHEEL – A liquid coupling used to transmit the engine effort (torque) to a
clutch and transmission. This coupling is always a major part of the engine
flywheel.
FOOT
PRINT – Area of road that is in contact with the tyre.
FORWARD
CONTROL TRUCK – has the engine either in or below the driver’s cabin.
FORWARD
EFFICIENCY – is the ratio of the amount of driver input torque which is
available at the wheels to turn the same to the total amount of input torque
from the driver at the steering wheel.
FOUR
WHEEL DRIVE – Some cross country vehicles (Jeeps) have this arrangement. In
this case, the engine power is transmitted to all the four wheels of the
vehicle. The main advantage of this arrangement is the entire vehicle weight is
available for traction.
FOUR
WHEEL STEERING – Type of steering system in which all the four wheels of a
vehicle are turned for steering.
FOUR
SPEED TRANSMISSION – A transmission with four forward speeds or gear
ratios.
FRAME –
The assembly of metal structural parts and channel sections that forms the base
and supports the engine and body and is supported by the vehicle wheels.
FRONT
AXLE – In a vehicle, the front axle transmits the weight of the front part
of the vehicle to the road surface through the front wheels. It also carries
the mechanism for steering the vehicle. In the case of front wheel drive, it
incorporates both steering and driving mechanisms.
FRONT END
GEOMETRY – The angular relationship between the front wheels, wheel
attaching parts, and vehicle frame. Includes camber, caster, king pin
inclination, toe in and toe out on turns.
FULL
FLOATING AXLE – An axle design usually used on heavy trucks where the vehicle
weight is carried by bearings in the wheel hubs, or the drive wheels and the
axles are used only to transfer driving torque.
GEAR –
A wheel with teeth that engage or mesh with teeth of another wheel.
GEAR BOX –
A unit which has a series of gears and shafts to vary the speed of the gearbox
output shaft compared to the engine speed. This in turn increases the torque
and thereby improves acceleration of the vehicle.
GEAR
CLASH – A condition in which the gears grind during shifting.
GEAR
RATIO – The ratio of the number of teeth on two gears to mesh with each
other.
GENERATOR
– is the device which converts mechanical energy from the automobile engine
into electrical energy. When the generator is sufficiently turned by the
engine, it furnishes electrical energy for all the vehicles circuits and
replenishes the battery to keep it fully charged.
GRAVITY
BLEEDING – A process used to remove air from the brake system using the
natural height of the fluid in the master cylinder above the wheel cylinder.
GRIP
COEFFICIENT – is numerically equal to the ratio of the force causing uniform
wheel slip to the normal road resistance.
HALF AXLE
DRIVE SHAFTS – Two in number, transmit the driving torque from the final
drive and differential unit to the driving road wheels.
HANDLING –
The ease of manoeuvring a vehicle without slipping or skidding.
HARSHNESS
– Bumpy ride produced by a stiff suspension.
HEEL –
Anchor end of a brake shoe.
HOTCHKISS
DRIVE – A rear suspension with open propeller shafts with two or three
universal joints. Braking torques are transferred to the frame through links,
control arms or leaf springs.
HORN
RELAY – A relay connected between the battery and horns, when energized by
closing of the horn button, it connects the horn to the battery.
HYDRAULIC
BRAKE – A brake system using hydraulic fluid, piston and cylinders to
provide extremely high pressure for break application.
HYDRAULIC
CLUTCH – A clutch that uses hydraulic pressure to actuate the clutch. Used
in heavy duty equipment and where the engine is away from the driver’s
compartment so that it would be difficult to use mechanical linkages.
HYDRAULIC
CONTROL VALVES – A system of valves that senses driving conditions and
automatically shifts the transmission.
HYPOID
GEARS – Drive pinion and ring gears whose shape allows them to mesh off
centre.
IMPENDING
SKID – The tyre traction point at which any increase in side or tractive
load will produce tyre skid.
INDEPENDENT
SUSPENSION – A type of suspension system in which each wheel is independently
supported by a spring. A suspension that allows up and down movement of one
wheel without affecting the opposite wheel.
INNER
TUBE (tyre) – The inside rubber tube assembled in the tyre casing, it
maintains the air at sufficient pressure to inflate the casing and adequately
support the vehicle weight.
INTEGRAL
BODY – has the longitudinal and cross members of the chassis incorporated
in the frame work of the load carrying body. With this arrangement, part of the
load previously carried by the chassis, is diffused through the body structure.
ISOFLARE –
A brake tube flaring method that upsets the tube and allows a strong, secure
attachment when used with the proper tube nut and seal.
JOUNCE –
A compression load on the springs as the space between the frame and the axle
is reduced.
JOUNCE
BUMPER – A rubber bumper used to absorb shock during full suspension system
movement.
KING PIN –
The steel pin on which the steering knuckle pivots, it attaches the steering
knuckle to the knuckle support or axle.
KING PIN
INCLINATION – Inward tilt of the king pin from the vertical.
KINGPIN
OFFSET – is the distance between the centre of the tyre contact patch and
intersection of the kingpin or steering axis with the ground. Kingpin offset is
also called scrub radius.
KNOCK
BACK – Slight axial movement that pushes the calliper pistons into their
bore. This causes clearance between the brake lining and the rotor.
KNUCKLE –
The part of the suspension that connects the control arms and supports the
wheel spindle.
LATERAL
LOAD (tyre) – The force on the side of the tyre treads.
LEADING
SHOE – A brake shoe that has the drum rotating from the toe toward heel.
LEADING
TRAILING BRAKE – A drum brake assembly having one shoe energized in either
forward or rearward wheel rotation.
LEAF
SPRING – A spring made up of a series of flat steel plates of graduated length,
assembled one on top of another.
LEVEL
CONTROL (automatic) – A suspension system which compensates for variations
in load in the rear of the car, positioning the rear at a predesigned level
regardless of load.
LIMITED
SLIP DIFFERENTIAL – A differential allowing unequal torques to be delivered
to the axle shafts.
LINKAGE
POWER STEERING – A type of power steering in which the power steering units
(power cylinder and valve) are an integral part of the steering linkage.
LORD
LEVELING SYSTEM – A system used to level a vehicle that is heavily loaded.
LORD
RANGE (tyre) – The amount of weight that can be safely carried by a tyre.
It indicates the number of plies at which a tyre is rated. Load range B equals
4 ply rating, C equals 6 ply rating, and D equals 8 ply rating.
LUG –
The flange stud on an axle or hub on which the drum and wheel are fastened.
MCPHERSON
STRUT SUSPENSION – A suspension system in which both wheels are attached to
a rigid rear axle housing.
MANUALLY
OPERATED TRANSMISSION – A transmission that is shifted from one speed to
another by the operator (driver).
MASTER
CYLINDER – The liquid filled cylinder in the hydraulic braking system where
hydraulic pressure is developed by depression of the brake pedal or movement of
the brake lever.
MECHANICAL
BRAKES – Brakes operated by mechanical linkage (cables and levers) between
the brake pedal and the brakes at the car wheels.
METALLIC
BRAKE LINING – A lining having metallic properties used to provide high
temperature braking efficiency.
METERING
VALVE – A valve that delays pressure build up to the front brakes of a four
wheeled vehicle.
MINOR
BRAKE ADJUSTMENT – Adjustment of brakes to compensate for brake lining
wear.
MODULATOR
– A vacuum canister mounted to the outside of the automatic transmission
that senses engine load.
MULTIPLE
DISC CLUTCH – A clutch that has more than one friction disc, usually there
are several driving discs and several driven discs, alternately placed.
NEUTRAL
STEER – A vehicle that will maintain the selected turn with no driver
input.
NON
DIRECTIONAL SENSE – Steering does not lead in any direction.
NON LOAD
CARRYING BODY – In this, the loads on the vehicle are transferred to the
suspension system entirely by a separate chassis. The body is isolated from the
chassis deflection by rubber mountings.
ONE WAY
CLUTCH – A clutch that holds in one direction but allows movement in
another direction.
OVER
DRIVE – A device in the power train of some vehicles that introduces an
extra set of gears into the power train. This causes the propeller shaft to
overdrive or drive faster than the engine crankshaft. Engine speed is thus
reduced without reduction of vehicle speed.
OVER
RUNNING CLUTCH – A type of clutch that will transmit rotary motion in one
direction only, when rotary motion attempts to pass through in other direction,
then the driving member over runs and does not pass motion to the other member.
OVER
STEER – The tendency of a vehicle to turn sharper than the turn selected by
the driver.
PANHARD
ROD – A control rod that connects the frame on one side of the vehicle to
the axle housing on the other side to keep the axle housing centred under the
vehicle.
PARKING
BRAKES – Mechanically operated brakes that operate independently of the
(hydraulic) service brakes on the vehicle. They may be set for parking the
vehicle or holding the vehicle against rolling. Also called an emergency brake.
PASCAL’S
LAW – A principle of hydraulics which states that pressure at any point in
a confined liquid is same in every direction and applies equal force on equal
areas.
PEDAL
BLEEDING – A method of removing air from the hydraulic system parts by
applying the brake to raise the pressure in the system to help move the air
through the system when the bleeder valves are opened.
PEDAL
PULSATION – A rapid up and down movement of the clutch pedal during
operation.
PITMAN
ARM – That part of the steering gear which is linked to the steering knuckle
arms of the wheels; it swings back and forth for steering.
PITMAN
ARM STOPS – On some cars (particularly those using linkage power steering),
stops are used to prevent excessive pitman arm movement and thus steering
linkage movement.
PITMAN
SHAFT – The shaft to which the pitman arm is attached in a steering gear.
PLANETARY
GEARBOX – A system of gears used in an automatic transmission, a sun gear,
planet gears, a carrier and a ring gear.
PLIES –
The layers of cord fabric in a tyre carcass, each layer is a ply.
PLYSTEER –
The tendency of a tyre to always turn in one direction as it rolls. This is the
result of the way the tyre was constructed.
PNEUMATIC
TYRES – Tyres that are filled with air to the required pressure.
POWER
BOOSTER – A device used to increase the drivers brake pedal force going to
the master cylinder, without an accompanying increase in pedal travel.
POWER
BRAKE – Conventional brake system that utilizes engine vacuum to operate
vacuum power piston. Power piston applies pressure to brake pedal, or in some
cases, directly to master cylinder piston. This reduces the amount of pedal
pressure that the driver must exert to stop the vehicle. Also called POWER
ASSISTED BRAKE.
POWER
RACK – In the saginan power steering unit, a rack that meshes with a sector
on the pitman shaft and transmits to the shaft, power from the power cylinder.
POWER
STEERING – A device that uses hydraulic pressure to multiply the drivers
effort as he turns the steering wheel so that less steering effort is required.
POWER
TRAIN or DRIVE TRAIN – The group of mechanisms that carry the rotary motion
developed in the engine to the vehicle wheels, it includes the clutch,
transmission, drive shaft differential and axles.
PRESSURE
CAP (radiator) – A radiator cap with valves that causes the cooling system
to operate under pressure and thus at a somewhat higher and more efficient
temperature.
PRESSURE
PLATE – That part of the clutch which exerts pressure against the friction
disc, it is mounted on and rotates with the flywheel.
PREVENTIVE
MAINTENANCE – The systematic inspection, detection and correction of
failures in a engine, or in a vehicle, either before they occur, or before they
develop into major defects.
PRIMARY
SHOE – A brake shoe moved by a wheel cylinder to apply the brake.
PROPELLER
SHAFT – A shaft in the power train that extends from the transmission to
the differential and transmits power from one to the other.
PROPORTIONING
VALVE – A valve used to maintain the correct proportion of fluid pressure
between the front disc or drum brakes and rear drum brakes. Usually the rear
brake pressure is a fraction of front brake pressure.
PUNCTURE
SEALING TYRES AND TUBES – Tyres and tubes coated on the inside with a
plastic material. Air pressure in the tyre or tube forces that material through
holes made by punctures. It hardens on contact with the air to seal the
puncture.
RACK AND
PINION STEERING GEAR – A steering gear that uses a pinion on the end of the
steering shaft which is meshed with a rack on the major cross member of the
steering linkage.
RADIAL
BIAS TYRE – A tyre in which the plies are laid on radially, or perpendicular
to the rim, with a circumferential belt on top of them. The rubber tread is
vulcanized on top of the belt and plies.
RADIAL
PLY TYRE – Cords running directly across the tyre carcass from bead to
bead.
RADIAL
SPRING RATE – The amount of radial load required to deflect a tyre (one cm)
unit distance.
RADIATOR –
In the cooling system, the device that removes heat from the coolant passing
through it, it takes hot coolant from the engine and returns the coolant to the
engine at a lower temperature. The hot coolant is cooled in the radiator for
recirculation.
RADIATOR
PRESSURE CAP – The cap placed on the radiator filler tube which pressurizes
the cooling system for more efficient operation.
RADIATOR
SHUTTER SYSTEM – A system of engine temperature control used mostly on
trucks, that controls the amount of air flowing through the radiator by use of
a shutter system.
REACTION
CONTROL – A feedback mechanism that gives the driver a feel of the amount
of input effort being applied.
REAR AXLE
ASSEMBLY – A system of gears and axles that transfers power from the drive
line assembly to the driving wheels of the automobile.
REAR AXLE
RATIO – The ratio between the drive pinion and the ring gear in the
differential assembly.
REAR END
TORQUE – Reactionary torque applied to the rear axle housing as torque is
applied to the wheels; rear end torque attempts to turn the axle housing in a
direction opposite to wheel rotation.
REBOUND –
An expansion of a suspension spring after it has been compressed as the result
of jounce.
RECAPPING
– A form of tyre repair in which a cap of new materials is placed on the
old tread and vulcanized into place.
RECIRCULATING
BALL AND NUT STEERING GEAR – A type of steering gear in which there is a
nut (meshing with a gear sector) assembled on a worm, balls circulate between
the nut and worm threads.
RELEASE
LEVER – In the clutch, a lever that is moved by throw out bearing movement;
the movement causes clutch spring pressure to be relieved so that the clutch is
released or uncoupled.
RETREAD –
A used tyre on which a new tread section is molded.
REVERSE
FLUSHING – A method of cleaning a radiator or engine cooling system by
flushing in the direction opposite to the normal coolant flow.
RIDE –
The characteristic feel as one rides in a vehicle.
RIGID
REAR SUSPENSION – A rear suspension system in which both wheels are
attached to rigid rear axle housing.
RIM –
The metal wheel on which the tyre is mounted.
RING GEAR
– A large gear carried by the differential case, meshed with and driven by
the drive pinion.
ROAD
RESISTANCE – is the resistance of the road surface, which must be overcome
when a vehicle travels along the road. This consists of friction between the
tyre and road.
ROLLING
RESISTANCE – is the resistance caused due to the deformation of the tyres
and road, the friction of the tyres on the road surface and friction in the
wheel bearings.
ROLL
STEER – The steering effect as a result of body lean during a turn.
RUNOUT OF
WHEEL – Lack of alignment of wheel or gear to the axle so that the wheel or
gear runout or move out of alignment, as wheel or gear rotates.
SAFETY
RIM – A type of wheel rim having a hump on the inner edge of the ledge on
which the tyre bead rides. The hump helps hold the tyre on the rim in case of
blow out.
SCRUB
RADIALS – The distance on the road surface under the front tyre between an
extension of the pivot axis and the centre of weight.
SCUFF –
The tyre slide on the road surface during operation.
SCUFF
TRAVEL – The amount of side travel of the tyre as the wheel moves from
maximum jounce to maximum rebound.
SEAT
ADJUSTER – A device to permit forward and backward (and sometimes upward
and downward) movement of the front seat.
SECONDARY
SHOE – A brake shoe that is operated by a primary shoe to apply brake.
SELF
ADJUSTING BRAKE DESIGNS – Brakes that automatically compensate for wear of
the brake linings.
SELF ALIGNING
TORQUE – The natural tendency of the tyre to return to the neutral position
after being turned.
SEMIMETALLIC
BRAKE LINING – A brake lining combining both metallic and organic materials
for improved braking performance.
SENSTRONIC
BRAKE – CONTROL (SBC) – is basically a brake by wire system which
eliminates the need for mechanical linkage between the brake pedal and brake
master cylinder.
SEQUENTIAL
GEAR BOX – is an electromechanical device that replaces the conventional
gear shift mechanism and is bolted to the tunnel section or the floor of the
car. It converts the conventional floor shifter to an electronically activated
sequential shift system that is electronically controlled by microprocessors.
SERIES –
The designation of a tyre aspect ratio.
SERVICE
BRAKE SYSTEM– The main braking system of the vehicle which controls braking
effect proportional to the drivers demand.
SHACKLE –
Swinging support by which one end of a leaf spring is attached to the vehicle
frame.
SHIM –
A slotted strip of metal used as a spacer to adjust front end alignment on many
cars and to make small correction in the position of the body sheet metal and
other parts.
SHIMMY –
Rapid oscillations, in wheel shimmy, for example, the front wheel tries to turn
in and out alternately and rapidly (a violent front wheel shake). This causes
the front end of the car to oscillate or shimmy.
SHOCK
ABSORBER – The assembly on the vehicle that checks excessively rapid spring
movement and oscillations. A device placed at each vehicle wheel to regulate
spring rebound and compression.
SHOE –
The part of a brake that supports the lining.
SHORT
LONG ARM SUSPENSION – A suspension system in which a long and a short
control arms are used to support the wheel.
SINGLE
LEADING SHOE – A drum brake having two shoes; one is leading another is
trailing. Leading shoe tends to wedge itself into the brake drum and provides
more braking action than the trailing shoe.
SINGLE
REDUCTION AXLE – In the single reduction type final drive, the required
speed reduction (say up to 7 to 1) is obtained in one step.
SIPES –
Slits in the tyre tread to produce more blade surface for traction.
SKID –
A tyre sliding on the road surface.
SKID
CONTROL – A device that operates to prevent wheel lock up during braking
and thus skidding.
SLIDING
MESH GEAR BOX – The gear box consists of three shafts and a set of gears,
gear selector mechanism and gear shift lever. Different gears are engaged by
sliding the appropriate gears.
SLIP
ANGLE – The angle between the tyre and the actual directional movement.
SLIP
JOINT – In the power train, a variable length connection that permits the
drive shaft (propeller shaft) to change its effective length.
SOCIETY
OF AUTOMOTIVE ENGINEERS (SAE) – A professional engineering society responsible
for setting many vehicle standards used in the world today.
SPIN
BALANCER – A car tyre balancer which turns the raised tyre at a road speed
where imbalance can be detected by wheel shake.
SPINDLE
(steering system) – A part of the steering knuckle assembly on which the
front wheels are mounted.
SPONGY
PEDAL – A brake pedal that feels soft or spongy.
SPRING
FREQUENCY – Springs are also compared in frequency. Springs which return
quickly to their original shape or oscillate rapidly after being deflected are
said to have higher frequency than those that return or oscillate slowly.
SPRING
RATE – The flexibility of a spring depends on the property called spring
rate. It is defined as the weight in kg required to deflect it one cm. A soft
spring has a lower rate than a stiff or inflexible spring.
SPRING
SHACKLE – Provides a means for the leaf spring assembly to compensate for
changes in its length.
SPRING
SUSPENSION – The operating components of a spring suspension system, which
absorbs the force of road shocks by flexing and twisting.
SPRUNG
WEIGHT – That part of the vehicle which is supported on springs (the frame
and body for example).
SQUIRM –
The twist of the tyre tread in the foot print.
STABILIZER
SHAFT – An interconnecting torsion bar between left and right lower
suspension arms on a vehicle which reduces body roll on turns and adds
stability.
STAR
WHEEL – An adjustable link between the primary and secondary brake shoes.
STEER
ANGLE – The angle the wheels are turned to from straight ahead.
STEERING
AND IGNITION LOCK – A locking device that locks the ignition switch in the
off position, and also locks the steering wheel so that it cannot be turned.
STEERING
ARM – The arm attached to the steering knuckle to turn the knuckle, and
wheel, for steering.
STEERING
AXIS – The centre line of the ball joints in a front suspension system
extended to the road surface.
STEERING
AXIS INCLINATION – The inward tilt of the steering axis or front wheel
pivot from the vertical.
STEERING
COLUMN – The housing that supports the steering shaft.
STEERING
GEAR – That part of the steering system, located at the lower end of the
steering shaft that carries the rotary motion of the steering wheel to the
vehicle wheels for steering.
STEERING
KICKBACK – Sharp rapid movements of steering wheel as the front wheels
encounter obstructions in road, the shocks of these encounters kickback to the
steering wheel.
STEERING
KNUCKLE – The front wheel spindle or stub axle which is supported by the
king pin, so that it and the wheel can be turned for steering. Part of the
front suspension system.
STEERING
LINKAGE – Linkage that connects the steering gears to the front wheels.
STEERING
RATIO – The number of degrees the steering wheel is turned divided by the
number of degrees the vehicle wheels are turned.
STEERING
SHAFT – Shaft extending from steering gear to the steering wheel.
STEERING
STOPS – limit the angular deflections of the front wheels. They avoid
rubbing of tyres against the frame or against the fenders which would cause
undue wear and tear of the tyres.
STEERING
SYSTEM – The mechanism that enables the driver to turn the wheel axles
(usually the front) and thus turn the wheels away from the straight ahead
position so that the vehicle can be guided.
STEERING
WHEEL – The wheel at the top of the steering shaft in the drivers
compartment which is used to guide or steer, the vehicle.
STONE
SHIELD – is bolted to the radiator support and the fenders. It fits beneath
the bumper of the car. It prevents striking of small flying stones on to the
radiator grille and radiator and thus avoids their damage.
STOP
LIGHT SWITCH – A switch applied by the master cylinder pressure that turns
on brake lights.
STOPPING
DISTANCE – is the distance in which a vehicle will be brought to rest from
steady speed, when the brake is applied.
STREAMLINING
– The shaping of an object that moves through a medium (such as air or
water) or past which the medium moves, so that less energy is lost by parting
and reuniting of the medium as the object moves through it.
STUMBLE –
The term related to vehicle driveability, the tendency of an engine to falter
and then catch, resulting in a noticeable stumble effect felt by the driver.
SUSPENSION
– The suspension system supports the vehicle body and at the same time
isolates the vehicle and its occupants from shocks and vibrations generated by
the road surface. It also maintains steering control and stability at all
times.
SUSPENSION
ARM – In the front suspension, one of the arms is pivoted at one end to the
frame and at the other to the wheel (steering knuckle) support.
SUSPENSION
COMPLIANCE – Rearward and upward movement of the suspension when the tyre
meets an obstacle on the road surface.
SUSPENSION
GEOMETRY – The angular action of the suspension as it goes from its static
position to the extremes of travel (compared to vertical lines).
SYNCHROMESH
– A device in the transmission that synchronizes gears about to be meshed
so that there will not be any gear clash. Also called SYCHRONIZER.
TACTILE
SENSOR – A sensor that allows the vehicle operator to feel when a certain
condition is reached. Disc brake pads are made to vibrate when worn to the
point where replacement is necessary and this vibration is felt in the brake
pedal.
TANDEM
MASTER CYLINDER – is the unit installed in some large cars and commercial
vehicles have a split hydraulic system with two separate cylinders and
reservoirs in the master cylinder. This avoids the possibility of complete
brake failure due to a fracture in the pipe line leading to one brake cylinder.
THROWOUT
BEARING – Bearing operated by the clutch linkage used to disengage the
clutch.
TIE RODS –
In the steering system, the rods that link the pitman arm to the steering
knuckle arms.
TILT
STEERING WHEEL – A type of steering wheel which can be tilted at various
angles, due to a flex joint in the steering shaft.
TOE –
The leading edge of the brake shoe. The angle between the centre lines of the
front wheels.
TOE IN –
The turning in of the front wheels, wheels are closer together at the front
than at the back of the wheels.
TOE OUT –
The turning out of the front wheels, where wheels are farther apart at the
front than at the back of the wheels.
TOE OUT
DURING TURNS – Difference in angles between the two front wheels and the
car during turns. Inner wheel, in a turn, turns out or toes out more. Also
called steering geometry and cornering wheel relationship.
TORQUE
CONVERTOR – A device in the power train consisting of three or more
rotating members. It transmits power from the engine through a fluid to the
reminder of the power train and provides varying drive ratios with speed
reduction and increase in torque.
TORQUE
DRIVE TRANSMISSION – A transmission similar to the power glide but lacking
the self shifting ability.
TORQUE
TUBE DRIVE – The type of rear suspension in which the torque tube
surrounding the propeller shaft absorbs the rear end torque.
TORSIONAL
LOAD – Loads on the brakes and suspension caused by torque.
TORSION
BAR SPRING – A long, straight bar, fastened to the frame at one end and to
a suspension part at the other.
TRACKING –
The following of the rear wheels, directly behind, or in the tracks of, the
front wheels.
TRACTIVE
FORCE – The friction force in the contact patch that causes torque on the
wheel.
TRAILING
SHOE – A brake shoe with its anchor at the toe end.
TRAMP –
Up and down motion or hopping of the front wheels experienced at higher speeds
due to unbalanced wheels or to excessive wheel run out. Also called high speed
shimmy.
TRANSAXLE
– A drive assembly combining the transmission and final drive assemblies in
one casing.
TRANSFER
CASE – A unit located at the back of the regular gear box, in the four
wheel drive arrangement. A pinion fixed to the gear box shaft, drives a wheel
in the transfer case. The driven wheel in the transfer case has a differential
which distributes the drive equally between the front and rear axles.
TRANSMISSION
– The device in the power train that provides different gear ratios between
the engine and rear wheels, as well as reverse.
TRANSMISSION
DRAIN PLUG – A plug at the bottom of the transmission to drain the
lubricant.
TRANSMISSION
FILLER PLUG – A plug on the side of the transmission used to add
transmission lubricant.
TRIM
HEIGHT – Specified level, vehicle height above the road surface.
TRIPLE
POINT JOINT – A universal joint using bearings on three axes to maintain a
constant plane of drive, making it a constant velocity joint.
TUBED
TYRE – Inside the tyre, there is an endless tube fitted with a valve. Air
is forced through the valve and is retained inside the tube under pressure. The
air acts as the cushioning medium.
TUBELESS
TYRE – A tyre that has the air sealed between the rim and tyre and does not
use an inner tube.
TURNING
RADIUS – The relative angles of the two front wheels during a turn.
TWO DISC
CLUTCH – A clutch having two friction discs for additional holding power
used in heavy duty equipment.
TYRE –
The casing and tube assembled on a vehicle wheel to provide pneumatically
cushioned contact and traction with the road.
TYRE BEAD
– The inner reinforced edge of a tyre that holds it to the wheel rim.
TYRE
CARCASS – The main structural part of the tyre to which tread rubber is
attached.
TYRE
CONTACT PATCH – The part of a tyre that contacts the road surface making a
footprint.
TYRE FOOT
PRINT – The area on the road in contact with the tyre.
TYRE
FORCE VARIATION – Changes in the tyres radial spring rate as it rolls under
radial loads.
TYRE SLIP
– A slight tyre slide while making a turn.
TYRE
ROTATION – Changing the position of tyres on the automobile to even out the
amount of wear.
TYRE
RUNOUT – The amount the tyre wobbles as it rotates.
TYRE
SERIES – The groupings of tyre sizes having the same aspect ratio.
TYRE
TREAD – is that part of the tyre that is designed to run on the road surface.
The tread rubber is grooved with a pattern that will provide maximum friction
force, (which provides good traction and reduces the possibility of skidding)
and minimum noise.
UNDER
STEER – The tendency of the vehicle not to turn as much as the wheels are
turned.
UNITIZED
CONSTRUCTION – A type of automobile body and frame construction in which
the frame and body parts are welded together to form a single unit.
UNSPRUNG
WEIGHT – That part of the vehicle which is not supported on springs (the
wheels and tyres for example). The vehicle weight moved by variations in the
road surface.
UNIVERSAL
JOINT – The part of the drive line assembly that allows for a change in
angle of the drive line as the vehicle goes over bumps.
VACUUM
BRAKE – is the device in which the braking effect is due to the difference
of pressures that acts on the opposite sides of a diaphragm. In this unit, one
side of the piston or diaphragm is exposed to atmospheric pressure while the
other side to a pressure which is below the atmospheric pressure.
VARIABLE
RATE SPRINGS – provide a low rate for ordinary service and higher rate for
heavy obstruction or loads. These consist of a conventional spring and below
which is placed a small auxiliary spring with several leaves. Under heavy
loads, the auxiliary or helper spring strengthens the main spring more and more
as the main spring is compressed.
VARIABLE
RATIO STEERING – A steering gear that provides a different ratio during
parts of a turn.
WADDLE –
A sideways vehicle shake due to a faulty radial tyre. Most noticeable when a
vehicle moves slowly.
WANDER –
A condition in which the vehicle does not follow a straight path and randomly
drifts in one direction or the other.
WEIGHT TRANSFER
– The changes in radial loads on the front and rear wheel tyres due to the
centre of gravity location ring braking.
WHEELS –
The wheels (wheel and tyre assembly) support the weight of the vehicle. The
assembly provides ride quality, load carrying capacity, and vehicle handling
characteristics.
WHEEL
ALIGNMENT – The position of the front wheels in relation to the suspension
and steering geometry.
WHEEL
BALANCER – A device that checks a wheel, either statically or dynamically,
for balance.
WHEEL BASE
– Distance between center of the front wheel and center of rear wheels.
WHEEL
CYLINDER – In the hydraulic braking system, hydraulic cylinders placed in
the brake mechanisms at the wheels; hydraulic pressure from the master cylinder
causes the wheel cylinders pistons to move the brake shoes.
WHEEL
FIGHT – The tendency of a steering system to be easily deflected by uneven
road surfaces. Causes changes in toe that result in tyre wear.
WHEEL
OFFSET – The distance between wheel attachment flange and the wheel rim
centre plane.
WHEEL
PACK BEARING – A pre-assembled self-lubricated bearing assembly used on the
drive wheels with independent suspension.
WHEEL
SIDEWAYS DISPLACEMENT – Sideways movement of the wheel as the suspension
goes from jounce to rebound.
WHEEL
SIZES – are indicated by three measurements, namely rim diameter, rim width
and flange height.
WHEELSLlP
– Sideways movement of the tyre tread across the foot print.
WHEEL
RUNOUT – The amount the wheel wobbles as it rotates.
WHEEL
TRAMP – Tendency of the wheel to move up and down so it repeatedly bears
hard or tramps, on the pavement. Sometimes called high speed shimmy.
WIND
SHIELD WIPER – A mechanism which utilizes a rubber blade to wipe the wind
shield, it is either vacuum or electrically operated.
Blogger Comment
Facebook Comment