THROW OF THE ECCENTRICITY – Twice the eccentricity or the amount of reciprocating motion produced.
TWO STAGE COMPRESSOR – A compressor in which compression begins in one cylinder and is completed in the second cylinder. It divides the compression range between the two cylinders and permits cooling between the cylinders.
TWO STAGE CYLINDER – A cylinder of special construction with a step piston, the low pressure being at the top while the high pressure is formed around the trunk.
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.
TIMING MARK (injection) – The mark made on the vibration damper or flywheel, used to check injection timing.
TURBULENCE – Violent swirling motion. Fuel injection produces some turbulence. Additional turbulence is provided by the design features of the combustion chamber.
TURBULENCE CHAMBER – A combustion chamber connected to the cylinder through a throat. Fuel is injected across the chamber and turbulence is produced in the chamber by the air entering during compression.
TWO STAGE COMBUSTION – Combustion occurring in two distinct steps such as in a pre-combustion chamber.
TRUE CENTRIFUGAL CASTING – is used for producing thin or thick walled hollow cylinders with a bore concentric with the outside.
TERNARY ALLOY – An alloy that contains three principal elements.
THERMIT – Powdered form of finely divided iron oxide and aluminium which burns intensely to produce superheated liquid steel at a temperature of about 30.35°C, used for welding wrought iron and steel forgings and castings.
THERMOPLASTICS – Materials which when heated begin to soften at temperatures as low as 56.5°C, and then can be moulded without any change in chemical structure.
THERMOSETTING MATERIALS – Materials that undergo a chemical change when moulded and cannot be resoftend by heating to reshape them.
TIN – A silvery white, soft metal used in solders and as a plating material.
TITANIUM – A strong, greyish metal that weighs less than steel.
TOOL STEEL – A special group of steels that is designed to specific uses, such as heat resistant steels that can be heat treated to produce certain properties mainly hardness and wear resistance.
TROOSTITE – Structure in steel (consisting of very finely divided iron carbide in what is known as “alpha iron”) produced either by tempering a martenistic steel at between 250°C and 450°C or by quenching steel at a speed sufficient to suppress the thermal change point fully.
TUNGSTEN – Hard, greyish, semiprecious metal with very high melting point of 3300°C, used for electrical contacts, filaments in electric lamps etc. Used as an alloying element in high speed steel.
TUNGSTEN CARBIDE – An iron gray powder composed of carbon and tungsten and used in sintered form as a cutting tool material.
TUNGUM BRONZE – Trade name for high strength bronze.
TWIN CRYSTAL – A crystal grain in which the crystal lattices of two parts are related to each other in orientation as mirror images across the interface known as the twinning plane.
TAPERED ROLLER BEARING – An antifriction bearing where the rolling element is similar to a roller bearing, however it has a taper along its axis, allowing it to accept axial loads in one direction.
THICK FILM LUBRICATION – Lubrication arrangement wherein there is no metal to metal contact. Also called PERFECT LUBRICATION.
THIN FILM LUBRICATION – Type of lubrication that occurs when the condition of bearing operation reduce the thickness of the oil film sufficiently to make the rubbing of the bearing surfaces a near possibility. Oiliness of the lubricant is important in this type of lubrication.
THRUST BEARING – In the engine, the main bearing has thrust faces
which prevent excessive endwise movement of the crankshaft.
TETRA ETHYL LEAD – A chemical put into engine fuel which increases octane rating, or reduces knock tendency. Also called ethyl and tel.
TORCH – Combustible material on a metal rod, such as oil soaked rags, used to light up oil and gas burners. The torch is extinguished by being plunged into a prepared receptacle.
TUYERES – Castings appearing as components of underfeed stokers and designed to admit air to the green coal moving through the retorts.
TAPERED BLADES – The turbine blades taper (decrease in depth) from base to tip, so as to diminish the centrifugal stress at the various sections, at the base or hub sections of the blade.
TERTIARY ZONE – Portion of the combustion chamber wherein the left out 50% of air is mixed with the burnt gases so as to cool them down to the temperature suitable to turbine materials.
THRUST OF A JET – Sum total of the pressure thrust and that due to change of momentum.
TOTAL HEAD EFFICIENCY – Ratio of the actual work output to the maximum possible work output that could be obtained with the existing leaving energy.
TOTAL HEAD PRESSURE – Pressure of the moving fluid corresponding to the stagnation or total head temperature.
TURBINE MECHANICAL EFFICIENCY – Ratio of shaft horse power to rotor (internal) horse power.
TURBINE STAGE EFFICIENCY – Ratio of the work delivered to the rotor per unit of gas flowing divided by the isentropic drop available in each unit of gas flowing.
TURBO PROP UNIT – The unit in which the gas turbine drives a propeller and the gases after leaving the turbine are exhausted as a jet to augment the thrust of the propeller.
TWISTED BLADES – Long turbine blades are usually twisted from hub to tip so as to compensate for blade velocity variations and in some cases as well as to satisfy radial pressure equilibrium conditions.
TEMPERING STEEL – Heat treatment designed to relieve the stresses and brittleness set up in carbon or alloy steel tools and other parts after hardening and to restore the required degree of toughness and ductility to hardened steel.
TINNING – Application of a layer of tin to the surface of another metal, either as a protection against corrosion or as a preliminary to soldering.
TANK UNIT – The unit of the fuel indicating system that is mounted in the fuel tank.
TAIL PIPE – carries the exhaust gases from the muffler and exhausts the same into the atmosphere. The tail pipe end is sometime cut on a bias (at an angle) to reduce exhaust noise.
THERMAL EFFICIENCY – Relationship between the power output and the energy in the fuel burned to produce the output.
THERMOSTAT – A temperature sensitive device used in a cooling system to adjust flow of coolant as coolant temperature changes.
THERMOSTATICALLY CONTROLLED AIR CLEANER – An air cleaner which uses a thermostat to control the preheating of intake air.
THROW A ROD – Expression used to designate an engine with a loose, knocking connecting rod bearing, or an engine that has broken a connecting rod and showed it through the cylinder block or oil pan.
TIMING – In the engine, refers to timing of valves, and timing of ignition, and their relation to piston position in the cylinder.
TIMING CHAIN – A chain driven by a sprocket on the crankshaft, that drives the sprocket on the camshaft.
TIMING GEARS – are a pair of meshing gears (one bigger gear mounted on the camshaft and another smaller gear mounted on the crankshaft) meant for driving the camshaft at the required speed ratio by the crankshaft.
TOP DEAD CENTRE (TDC) – The piston position at which the piston has moved to the top of the cylinder and the centre line of the connecting rod is parallel to the cylinder wall.
TORQUE – The twisting force at the end of the crank shaft multiplied by the distance of this force application from the shaft centre, measured in kilogram meters or Newton meters.
TORSIONAL VIBRATION – Back and forth motion around a turning centre. Vibration in a rotary direction that causes a twist-untwist action on a rotating shaft, a rotating shaft that repeatedly moves ahead or lags behind the remainder of the shaft; for example, the actions of a crankshaft responds to the cylinder firing impulses.
TUNED INTAKE SYSTEM – An intake system in which the manifold has the proper length and volume to introduce a ramjet or supercharging effect.
TUNE UP – The procedure of inspection, testing and adjusting an engine and replacing any worn parts to restore the engine to its best performance.
TURBOCHARGER – A supercharger driven by the gas turbine which is operated by the engine exhaust gases.
TWO STROKE CYCLE – The series of events namely intake, compression, power and exhaust all of which take place in two piston strokes. Also called TWO CYCLE in a short form.
TAPER PLUG GAUGE – A solid internal gauge in the form of a frustum of a cone having diameter, taper and length suitable for measuring the dimensions of an internal taper of specified size.
TAPER RING GAUGE – An external gauge, the internal diameter of which confirms to the frustum of a cone having diameter, taper and length suitable for measuring the dimensions of an external taper of specified size.
TEMPLATE – A flat pattern or guide plate usually made from sheet metal and used as a gauge or guide when laying out, drilling, forming in a machine or filing irregular shapes on metal work-pieces.
TELESCOPING GAUGES – Adjustable gauges which consists of a handle attached to a fixed contact within which a plunger contact expands or telescopes under spring tension when the gauge is inserted into the hole that is to be measured.
THREAD GAUGE – Tool for checking the form and pitch of screw threads.
TOOL MAKERS MICROSCOPE – Instrument used in accurate inspection of thread forms, form tools and complex contours.
TORQUE METER – Torsion measuring device fitted to a rotating shaft or component to measure the torque developed at any given moment under actual running conditions.
TORSIOGRAPH – Instrument used to measure and record the amplitude and frequency of torsional vibrations in a rotating shaft or other part.
TRAMMELS – are generally used for laying off and checking dimensions of several feet, they are generally used in conjunction with a large steel rule, which may be from 3 to 10 ft long.
TRANSFER CALIPER – A caliper designed to take measurement in recesses or over a projection. One leg can be separated or opened to remove the caliper and then returned to the measured size.
TRY SQUARE – Instrument used for setting and checking a line, an edge or a face which is required to be at right angles to some other plane which should be regarded as a datum or reference plane.
TABLE (marking off) – Table used for marking off, or setting out a job to be machined.
TAILSTOCK – The principal part of the engine lathe, used for supporting one end of a workpiece by means of a center point held in the spindle. May be moved along the ways and clamped in different positions and offset from the true axis of the lathe for turning tapers.
TAPER PINS – Steel pins used for locating and holding machine parts in position on a shaft.
TAPER TURNING ATTACHMENT – Device fitted to a lathe, to cause movement of cutting tool at an angle to the axis of the lathe so as to produce the required taper on the workpiece.
TAYLOR CHUCK – Special chuck designed so that the jaws are supported at right angles to the direction of the pressure.
T-BOLT – A threaded bolt having a square or rectangular end which fits into the T slot of a machine table for clamping work-pieces.
THREAD CHASING DIAL – A device consisting of a short shaft with a dial at the top and a worm gear at the bottom to mesh with the lead screw on an engine lathe which is attached to the lathe carriage, so that the operator can engage the split nut lever at the correct position when cutting screw threads.
THREE JAW CHUCK – Chuck for gripping general work using three jaws, usually concentrically, simultaneously, a feature which makes the chuck particularly suitable for holding either round or hexagon stock.
THUMB SCREW – A type of screw having a winged or knurled head for turning by hand when a quick and light clamping effect is desired.
TOOL HEAD – The part of machine tool that carries the cutting tool and is adjustable for moving and setting the cutting tool into the workpiece being machined.
TOOL HOLDER – Slotted shank in which the tool bit can be held.
TOOL POST – A clamping device for holding tool holder in position on a machine tool.
TOP SLIDE – Means of traversing the tool on the tool post of a lathe.
T–SLOT – A recessed or undercut slot made with a special T shaped cutter in the tables of machine tools to receive the square head of a T bolt for clamping work-pieces.
TUMBLER GEARS – Two gears acting as idler gears between the spindle gear and the fixed stud gear on a lathe gear train. Used to reverse the direction of rotation of the lead screw for thread cutting or the feed rod for turning.
TURRET – Rotatable device for holding several cutting tools set in position to operate in turn.
TWO JAW CHUCK – Chuck furnished with two jaws, diametrically opposite.
TAPER – A shaft or hole that gets gradually smaller toward one end.
TAPER PINS – Steel pins used for locating and holding the machine parts in position on a shaft.
T-BOLT – A threaded bolt having a square or rectangular end which fits into the T slot of a machine table for clamping workpieces.
TEMPLATE – A flat pattern or guide plate usually made from sheet metal and used as a gauge or guide when laying out, drilling, forming in a machine or filing irregular shapes on metal pieces.
THUMB SCREW – A type of screw having a winged or knurled head for turning by hand when a quick and light clamping effect is desired.
TOLERANCE – A fractional allowance for variation from the specifications.
T-SLOT – A recessed or undercut slot made with a special T shaped cutter in the tables of machine tools to receive the square head of a T bolt for clamping workpiece.
TAPE CONTROLLED MACHINES – Machines which have partial automation in which the movements of a machine tool and cutters are automatically controlled by a magnetic tape or cards which have been punched to indicate data previously planned for the sequence of each operation to be performed.
TAPPING MACHINE – Machine designed to cut threads in holes in nuts and other parts.
TESTING MACHINE – Machine designed to apply accurately measured loads to a test piece and, in many cases, to measure the resulting extension, compression or deflection, in order to ascertain the physical properties of materials.
THYRISTOR – A type of semiconductor device that acts as a switch. It turns on when a certain voltage is applied to the gate, and it turns off when the current flowing between the other two terminals stops or reverses.
TOOL GRINDER – Special machine for the grinding of turning, planing and other tools.
THREAD MILLER – A machine that cuts threads by using a rotating milling cutter.
TROCHOID PUMP – An oil pump consisting primarily of a pair of rotors of special shape.
TURBO CHARGER – An exhaust gas driven turbine directly coupled to a compressor wheel.
TURRET LATHE – Machine generally larger than a capstan lathe, but using similar tools. The main difference between them is that the turret saddle has longitudinal movement on the guides of the bed.
TAPER – A shaft or hole that gets gradually smaller toward one end.
TAPER PINS – Steel pins used for locating and holding the machine parts in position on a shaft.
T-BOLT – A threaded bolt having a square or rectangular end which fits into the T slot of a machine table for clamping workpieces.
TEMPLATE – A flat pattern or guide plate usually made from sheet metal and used as a gauge or guide when laying out, drilling, forming in a machine or filing irregular shapes on metal pieces.
THUMB SCREW – A type of screw having a winged or knurled head for turning by hand when a quick and light clamping effect is desired.
TOLERANCE – A fractional allowance for variation from the specifications.
T-SLOT – A recessed or undercut slot made with a special T shaped cutter in the tables of machine tools to receive the square head of a T bolt for clamping workpiece.
TAPE CONTROLLED MACHINES – Machines which have partial automation in which the movements of a machine tool and cutters are automatically controlled by a magnetic tape or cards which have been punched to indicate data previously planned for the sequence of each operation to be performed.
TAPPING MACHINE – Machine designed to cut threads in holes in nuts and other parts.
TESTING MACHINE – Machine designed to apply accurately measured loads to a test piece and, in many cases, to measure the resulting extension, compression or deflection, in order to ascertain the physical properties of materials.
THYRISTOR – A type of semiconductor device that acts as a switch. It turns on when a certain voltage is applied to the gate, and it turns off when the current flowing between the other two terminals stops or reverses.
TOOL GRINDER – Special machine for the grinding of turning, planing and other tools.
THREAD MILLER – A machine that cuts threads by using a rotating milling cutter.
TROCHOID PUMP – An oil pump consisting primarily of a pair of rotors of special shape.
TURBO CHARGER – An exhaust gas driven turbine directly coupled to a compressor wheel.
TURRET LATHE – Machine generally larger than a capstan lathe, but using similar tools. The main difference between them is that the turret saddle has longitudinal movement on the guides of the bed.
TAPER – A shaft or hole that gets gradually smaller toward one end.
TAPER PINS – Steel pins used for locating and holding the machine parts in position on a shaft.
T-BOLT – A threaded bolt having a square or rectangular end which fits into the T slot of a machine table for clamping workpieces.
TEMPLATE – A flat pattern or guide plate usually made from sheet metal and used as a gauge or guide when laying out, drilling, forming in a machine or filing irregular shapes on metal pieces.
THUMB SCREW – A type of screw having a winged or knurled head for turning by hand when a quick and light clamping effect is desired.
TOLERANCE – A fractional allowance for variation from the specifications.
T-SLOT – A recessed or undercut slot made with a special T shaped cutter in the tables of machine tools to receive the square head of a T bolt for clamping workpiece.
TAPE CONTROLLED MACHINES – Machines which have partial automation in which the movements of a machine tool and cutters are automatically controlled by a magnetic tape or cards which have been punched to indicate data previously planned for the sequence of each operation to be performed.
TAPPING MACHINE – Machine designed to cut threads in holes in nuts and other parts.
TESTING MACHINE – Machine designed to apply accurately measured loads to a test piece and, in many cases, to measure the resulting extension, compression or deflection, in order to ascertain the physical properties of materials.
THYRISTOR – A type of semiconductor device that acts as a switch. It turns on when a certain voltage is applied to the gate, and it turns off when the current flowing between the other two terminals stops or reverses.
TOOL GRINDER – Special machine for the grinding of turning, planing and other tools.
THREAD MILLER – A machine that cuts threads by using a rotating milling cutter.
TROCHOID PUMP – An oil pump consisting primarily of a pair of rotors of special shape.
TURBO CHARGER – An exhaust gas driven turbine directly coupled to a compressor wheel.
TURRET LATHE – Machine generally larger than a capstan lathe, but using similar tools. The main difference between them is that the turret saddle has longitudinal movement on the guides of the bed.
TANK TRUCK – A truck in which liquids are transported.
TRACTOR – A crawler or wheel mounted, self propelled vehicle designed to perform agricultural, earthmoving, road making, load carrying and other work.
TRACTOR TRAILER TRAIN – The combination of a puller unit with a train of wheeled dollies.
TRAVELLING CANTILEVER WALL CRANE – Crane arranged to travel over tracks secured to a side wall of the building.
TRAVELLING GANTRY CRANE – A crane which has a rigid four legged gantry travelling over a track laid along the work area, topping the gantry is a rotary part with a jib, a movable counter weight, hoisting and luffing units.
TRUCK – A self powered wheel vehicle used for carrying loads and people.
TRUCK CRANES – Cranes mounted on chassis of standard design or on special purpose chassis with tyred wheels.
TYPE I HAND CRANK – Unit directly linked to the load brake and requiring a constant effort in order to lower the load which descends at a rate corresponding to the rate of crank rotation.
TYPE II HAND CRANK – An arrangement to effect lowering of load at a speed exceeding that of hoisting and finds application where this mode of operation is called for by process requirements.
TWO WAY PALLET – A pallet design that permits forks or hand pallet trucks to enter from two sides only and in opposite directions.
TARNISHING – A chemical reaction of a metal with its environment which results in formation of films which coat the metal.
TEMPER – (1) In ferrous metals, the stress relief of steels that are hardened by quenching for the purpose of toughening them and reducing their BRITTLENESS. (2) In non-ferrous metals, temper is a condition produced by mechanical treatment such as cold working. An alloy may be cold worked to the hard temper, fully softened to the annealed temper, or two intermediate tempers.
TENSION LOAD – A load applied to joined parts that attempt to separate them by a pulling or stretching action.
TENSILE STRESS – Tensile stress is the tension load per unit area perpendicular to the load.
THERMAL CONDUCTIVITY – The quantity of heat that is transmitted per unit time, per unit cross-section, per unit temperature gradient through a given substance. All materials are in some measure conductors of heat.
THERMAL EXPANSION – The increase of the dimension of a material that results from the increased movement of atoms caused by increased temperature.
THERMAL SHOCK – A stress induced on the surface of a material such as carbide tools or fire brick caused by a rapid rate of heating and surface expansion.
THERMAL STRESS – Shear stress that is induced in a material due to unequal heating or cooling rates. The difference of expansion and contraction between the interior and exterior surfaces of a metal that is being heated or cooled is an example.
THERMOPLASTIC – Material capable of softening or fusing when heated and of hardening again when cooled.
THERMOSETTING – Material capable of becoming permanently rigid when cured by heating will not soften by reheating.
TOUGHNESS – Ability of a metal to absorb energy and deform plastically before fracturing. Work per unit volume required to fracture a metal and is equal to the area under the stress strain curve.
TOXICITY – The degree of danger posed by a substance to animal or plant life.
TRANSFORMATION TEMPERATURE – The temperature at which one phase transforms into another phase, for example, where ferrite or alpha iron transforms into austenite or gamma iron.
TRANSITION TEMPERATURE – The temperature at which normally ductile metals become brittle.
TAPER FIT – Type of fit in which a taper on the mating surfaces is combined with an interference fit between the parts when assembled.
TAPER TURNING – Method of turning a taper on a work in the lathe.
TAP GRINDING – Sharpening of a tapping tool by grinding a taper on the end and a clearance behind the cutting edge along this taper.
TAPPING – Operation of producing an internal thread by means of a tap.
TEMPER ROLLING – Process used in the production of tin -plate, in which the annealed coils or strips are subjected to a small amount of cold reduction in a four high mill in order to increase the stiffness of the dead soft material without unduly reducing its ductility.
THERMIT WELDING – Method of uniting iron or steel parts by surrounding the joint with thermit mixture at a sufficiently high temperature to fuse the adjacent surfaces of the parts together.
THREAD GRINDING – Grinding of screw threads so as to remedy such main variations in form or size as may have occurred as a result of the hardening treatment of a part or tool.
THREAD MILLING – Operation of producing threads, both external and internal, by means of thread milling cutters, either single or multi-ribbed, according to the type of thread required and the design of the thread milling machine employed.
THREAD ROLLING – Method of producing threads on screws, bolts, screw caps etc. by rolling under pressure so as to make contact with the rollers, to which the required pitch and form of screw threads have previously been given.
TONGUE SHAPING – Forming a narrow projection (called a tongue) from solid metal on a shaping machine.
TREPANNING – Removal of a circular piece of material from inside a steel bar, plate or billet.
TRIMMING – Cutting away excess material left from previous operations.
TUMBLING – Process of cleaning, polishing, or crushing in which the articles to be treated are mixed with balls, pieces of hard material or abrasive and rotated in a more or less horizontal container.
TURNING – Process of reducing the diameter of materials held in a lathe and the general name given to the process whereby material which is turned by means of a driven spindle to which it is attached, is brought into contact with a stationary tool having cutting edges.
TANGENTIAL ACCELLERATION – The time rate of change of velocity of a point in a direction tangent to its path. This results from a change in its linear velocity.
TRANSLATION – A body has translation if it moves so that all straight lines in the body move in parallel positions.
TEMPERATURE CONTROL – An electric switch responsive to temperature of thermostatic bulb or element.
TERMINAL DEWARS – Insulated containers used to prevent heat transfer and permit the individual conductor phases to be connected into thermally and electrically graded pot head assemblies.
THERMAL LIMITER FUSES – Designed to protect the A/C system compressor against damage when the refrigerant charge is partially or totally lost.
THERMOELECTRIC REFRIGERATION – Depends upon passing electrical energy to a couple through two dissimilar semiconductors.
THERMOPNEUMATIC AIR CONDITIONING SYSTEM – System which uses the mechanical principles of the thermostat to monitor vacuum motors which adjust the air valves and switches.
THERMOSTAT – An automatic switch, the opening and closing of which is actuated by change of temperature.
THERMOSTATIC EXPANSION VALVE – Control valve which maintains constant superheat in the evaporator, also used for the temperature control, operates on increased pressure resulting from a rise in temperature. Also called THERMOSTATIC VALVE.
THROTTLING VALVE – Dampens fluctuations of pressure gauge and provides a way to close off the port entirely.
TON REFRIGERATION – Ton refrigeration (TR) is that rate of removal of heat which would transform water at 0°C into ice at the same temperature at the rate of one ton in every 24 hours.
THROTTLE (valve) – A round disc valve in the throttle body of the carburettor that can be turned by the driver to admit more or less air fuel mixture, thereby control the engine speed.
THROTTLE CRACKER – Linkage from the starting motor switch to the throttle, which opens the throttle slightly when the engine is being cranked.
THROTTLE RETURN CHECK – A device in the carburettor which prevents excessively sudden closing of the throttle, also called dashpot.
TIMING LIGHT – A light that is connected to the ignition system to flash each time the number one spark plug fires, used for adjusting the timing of the ignition spark.
TIMING UNIT – A device that determines, when the ignition system fires the spark plugs.
TRANSISTOR ASSISTED CONTACT IGNITION (TAC) – An ignition system similar to battery point ignition but which uses a transistor to eliminate heavy current flow at the contact points.
TRANSISTOR POINTLESS IGNITION – A battery assisted ignition system using a pulse generator to trigger a transistor to fire the spark plug.
TURBULENCE – The state of being violently disturbed. In the engine, the rapid swirling motion imparted to the air fuel mixture entering the cylinder.
TURNS RATIO – The ratio of the number of coils in the primary and secondary windings of an ignition coil.
TWO BARREL CARBURETTOR – A dual carburettor in which there are two throttle valves.
THERMAL LIQUID HEATER – A closed vessel in which a heat transfer medium other than water is heated without vaporization and the heated fluid gives up its heat and does useful work outside the closed vessel.
THROUGH TUBE BOILER – A vertical shell boiler having tubes extending from the lower tube sheet to the full length of the shell.
TRAVELLING GRATE or CHAIN GRATE – A type of overfeed stoker consisting of an endless grate composed of short sections of bars passing over sprockets at the front and rear of the furnace.
TUBE SHEET – A sheet of a water tube boiler where tubes are inserted, either in a flat sheet or a drum.
TAPERED BLADES – Blades tapered in width along the length of the blade so as to obtain an even more uniform centrifugal stress.
THERMAL EFFICIENCY OF RANKINE CYCLE – Ratio of the thermal equivalent of output to thermal equivalent of input of a unit working on Rankine cycle.
THERMOCOMPRESSOR or BOOSTER EJECTOR – Compression device designed to handle steam instead of other gases.
THROTTLE GOVERNING – Governing affected in a steam engine by varying the initial steam pressure within the engine cylinder. The governor is called THROTTLE GOVERNOR. Power output is varied by varying initial steam pressure.
TRANSONIC NOZZLE – A nozzle usually of the reamed type and this is used in small impulse steam turbines, or velocity compounded stages where large enthalpy drops are required.
TEMPERATURE – A measure of the intensity of heat in a substance with reference to a fixed reference point and of its ability to pass its heat into anything at a lower temperature than itself.
THERMAL CONDUCTIVITY – Ability to a material to allow the passage of heat. Stated as the number of kilocalories that can flow in one hour through a block of material, one square meter in area and one meter thick with one degree centigrade difference in temperature between the opposite surfaces.
THERMAL GRADIENT – The slope of the temperature curve produced by measuring the temperature at various points across a body or heated section.
THERMODYNAMICS – Study of energy, heat and work, properties of media employed and the processes involved.
THERMODYNAMIC SYSTEM – is any space or any matter or group of matter within a prescribed boundary, to which attention is directed for the purpose of analysis.
THERMODYNAMIC CYCLE – is said to occur when a working fluid of a system undergoes a number of operations and processes which take place in a certain order and finally return the fluid to the initial state itself.
THERMODYNAMICS – ZEROTH LAW – That two systems having equal temperatures with a third system also have equal temperatures with each other.
THERMODYNAMICS – FIRST LAW – In ordinary processes, matter can neither be created nor destroyed. Energy can take different forms but cannot be created or destroyed.
THERMODYNAMICS – SECOND LAW – There is a definite limit to the amount of mechanical energy that can be obtained from heat energy.
THERMOELECTRIC INDICATORS – Temperature measuring instruments which operate on the principle that minute quantities of electric current may be produced by heating two dissimilar metals which are joined at one end.
THERMOSTAT – Operating control which reacts to temperature.
THROTTLING PROCESS – is one that occurs when a gas or vapour is expanded through an aperture of minute dimensions, such as a slightly opened valve or a narrow throat. In this process, no heat transfer takes place, no work is done.
TOTAL HEAT – Sum of the sensible heat and latent heat. Also called enthalpy of steam or vapour.
TRANSIT ENERGY – is that energy which crosses the system boundaries. Examples are heat, work, velocity energy and electrical energy.
TRIPPLE POINT – The temperature and pressure at which a substance can exist simultaneously in solid, liquid and vapour forms.
TUBE AND FIN RADIATOR CORE – One type of radiator core, consisting of tubes to which cooling fins are attached, water flows through the tubes.
TELESCOPIC FORK – Front suspension unit made up of two fork tubes and two sliders that telescope up and down the tubes against spring pressure.
THROTTLE CABLE – A cable consisting of an outer housing and an inner cable which connects carburettor to throttle twist grip.
THROTTLE STOP SCREW – An idle speed adjustment screw used in slide type carburettor. This screw contacts base of throttle slide. As the screw is turned in, throttle slide is raised, increasing idle speed.
THROTTLE TWIST GRIP – A device mounted on the end of handle bar which locates one end of outer throttle cable and pulls inner cable as the twist grip is rotated.
TRAIL – The distance between the center of the tyre contact patch and the imaginary point where the steering head axis strikes the ground.
TRANSFER PORT – Opening in the cylinder wall of a two stroke engine which connects cylinder to crankcase.
TRANSFER PORT TIMING – Amount of time transfer port is open, expressed in crankshaft degrees or piston position.
TRANSMISSION – The part of the drive train that uses a series of gears and shafts to increase the torque and provides gear shifting to allow increases in speed without overworking the engine.
TREAD WEAR PATTERN – The pattern of wear on the tyre which can be read to diagnose problems in the front suspension.
TRIPPLE CLAMPS – An assembly that consists of the steering stem and two brackets that position the fork tubes.
TRIPPLE ROW CHAIN – A chain having three rows of rollers. Triple row chains are used for primary drives.
TWO STROKE CYCLE – A cycle of overlapping events (intake, transfer, compression, power and, exhaust) which all occur during one revolution of crankshaft.
TYRE PRESSURE GAUGE – A pressure gauge used to check tyre air pressure.
TACK WELD – A weld made to hold parts of a weldment in proper alignment until final welds are made.
THERMIT MIXTURE – A mixture of metal oxide and finely divided aluminium with the addition of alloying metals as required.
THERMIT WELDING – Welding process that produces coalescence of metals by heating them with superheated liquid metal from a chemical reaction between a metal oxide and aluminium, with or without the application of pressure.
T-JOINT – A joint between two members located approximately at right angles to each other in the form of a T.
TORCH BRAZING – A brazing process in which the heat required is furnished by a fuel gas flame.
TWIN CARBON ARC WELDING – Process that produces coalescence of metals by heating them with an electric arc between two carbon electrodes. No shielding is used.
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