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Chassis Drives

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Definitions of Terms - Chassis Drives



ABRASION - Wearing or rubbing away of a part.

ALIGNMENT - An adjustment to a line or to bring into a line.

ANTI-CLOCKWISE ROTATION - Rotating the opposite direction of the hands on a clock. The same as counter - clockwise rotation.

ANT -FRICTION BEARING - A bearing constructed with balls, rollers or the like between the journal and the bearing surface to provide rolling instead of sliding friction.

AXIAL - Parallel to the shaft or bearing bore.

AXLE - The shaft or shafts of a machine upon which the wheels are mounted.

AUTOMATIC TRANSMISSION - A transmission in which gear or ratio changes are self - activated.

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BACKLASH - The clearance or "play" between two parts, such as meshed gears.

BALL BEARING - An anti-friction bearing consisting of a hardened inner and outer race with hardened steel balls which roll between the two races.

BOG - Bottom dead center.

BEARING - The supporting part which reduces friction between a stationary and rotating part.

BEVEL SPUR GEAR - Gear that has teeth with a straight center - line cut on a cone.

BONDED LINING - A method of cementing brake linings to shoes or bands which eliminates the necessity of rivets.

BRAZE - To join two pieces of metal with the use of a comparatively high melting point material. An example is to join two pieces of steel by using brass or bronze as a solder.

BREAK-IN - The process of wearing - in to a desirable fit between the surfaces of two new or reconditioned parts.

BROACH - To finish the surface of metal by pushing or pulling a multiple - edge cutting tool over or through it.

BURNISH - To smooth or polish by the use of a siliding tool under pressure.

BUSHING - A removable liner for a bearing.

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CARRIER - An object that bears, cradles, moves, or transports some other object or objects.

CASE-HARDEN - To harden the surface of steel.

CASTELLATE - Formed to resemble a castle battlement, as in a castellated nut.

CENTER OF GRAVITY - The point at which a mass of matter balances. For example, the center of gravity of a wheel is the center of the wheel hub.

CENTRIFUGAL FORCE - A force which tends to move a body away from its center of rotation. Example: whirling a weight attached to a string.

CHAMFER - A bevel or taper at the edge of a hole or a gear tooth.

CHASE - To straighten up or repair damaged threads.

CHILLED IRON - Cast iron on which the surface has been hardened.

CLEARANCE - The space allowed between two parts, such as between a journal and a bearing.

CLUTCH - A device for connecting and disconnecting the engine from the transmission or for a similar purpose in other units.

COEFFICIENT OF FRICTION - The ratio of the force resisting motion between two surfaces in contact to the force holding the two surfaces in contact.

COMPOUND - A mixture of two or more ingredients.

CONCENTRIC - Two or more circles, having a common center.

CONSTANT MESH TRANSMISSION - A transmission in which the gears are engaged at all times, and shifts are made by sliding collars, clutches or other means to connect the gears to the output shaft.

CONTRACTION - A reduction in mass or dimension; the opposite of expansion.

CORRODE - To eat away gradually as if by gnawing, especially by chemical action.

COUNTERBORE - To enlarge a hole to a given depth.

COUNTER-CLOCKWISE ROTATION - Rotating the opposite direction of the hands on a clock.

COUNTERSHAFT - An intermediate shaft which receives motion from a main shaft and transmits it to a working part. Sometimes called a lay shaft.

COUNTERSINK - To cut or form a depression to allow the head of a screw to go below the surface.

COUPLING - A connecting means for transferring movement from one part to another; may be me - chanical, hydraulic, or electrical.

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DEAD AXLE - An axle that only supports the machine and does not transmit power.

DEFLECTION - Bending or movement away from normal due to loading.

DENSITY - Compactness; relative mass of matter in a given volume.

DIAGNOSIS - A systematic study of a machine or machine parts to determine the cause of improper performance or failure.

DIAL INDICATOR - A measuring instrument with the readings indicated on a dial rather than on a thimble as on a micrometer.

DIFFERENTIAL GEAR - The gear system which permits one drive wheel to turn faster than the other.

DIRECT DRIVE - Direct engagement between the engine and driveshaft where the engine crankshaft and the driveshaft turn at the same rpm.

DISTORTION - A warpage or change in form from the original shape.

DOUBLE REDUCTION AXLE - A drive axle construction in which two sets of reduction gears are used for extreme reduction of the gear ratio.

DOWEL PIN - A pin inserted in matching holes in two parts to maintain those parts in fixed relation one to another.

DRIVE LINE - The universal joints, drive shaft and other parts connecting the transmission with the driving axles.

DROP FORGING - A piece of steel shaped between dies while hot.

DUAL REDUCTION AXLE - A drive axle construction with two sets of pinions and gears, either of which can be used.

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ECCENTRIC - One circle within another circle wherein both circles do not have the same center. An example of this is a cam on a camshaft.

ENDPLAY - The amount of axial or end-to-end movement in a shaft due to clearance in the bearings.

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FEELER GAUGE - A metal strip or blade finished accurately with regard to thickness used for measuring the clearance between two parts; such gauges ordinarily come in a set of different blades graduated in thickness by increments of 0.001 inch.

FILLET - A rounded filling between two parts joined at an angle.

FIT - The contact between two machined surfaces.

FLANGE - A projecting rim or collar on an object for keeping it in place.

FLUID DRIVE - A drive in which there is no mechanical connection between the input and output shafts. and power is transmitted by moving oil.

FOOT POUND (or Ibs. ft.) - This is a measure of the amount of energy or work required to lift 1 pound a distance of 1 foot.

FREE-WHEELING CLUTCH - A mechanical device which will engage the driving member to impart motion to a driven member in one direction but not the other. Also known as an "overrunning clutch."

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GEAR - A cylinder - or cone - shaped part having teeth on one surface which mate with and engage the teeth of another part which is not concentric with it.

GEAR RATIO - The ratio of the number of teeth on the larger gear to the number of teeth on the smaller gear.

GRIND - To finish or polish a surface by means of an abrasive wheel.

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HAZARD - Dangerous object or situation that has the potential to cause injury.

HEAT TREATMENT - Heating, followed by fast cooling, to harden metal.

HEEL - The outside, larger half of the gear tooth.

HELICAL - Shapes like a coil spring or a screw thread.

HELICAL GEAR - Gears with the teeth cut at an angle to the axis of the gear.

HERRINGBONE GEAR - A pair of helical gears de - signed to operate together. The angle of the pair of gears forms a V.

HUB - The central part of a wheel or gear.

HYDRAULIC PRESSURE - Pressure exerted through the medium of a liquid.

HYPOID GEAR - A gear that is similar in appearance to spiral bevel gear, but the teeth are cut so that the gears match in a position where the shaft centerlines do not meet.

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ID - lnside Diameter.

IMPELLER - The pump or driving member in a torque converter.

INPUT SHAFT - The shaft carrying the driving gear by which the power is applied, as to the transmission.

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JOURNAL - A bearing with a hole in it for a shaft.

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KEY - A small block inserted between the shaft and hub to prevent circumferential movement.

KEYWAY - A groove or slot cut to permit the insertion of a key.

KNURL - To indent or roughen a finished surface.

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LAPPING - The process of fitting one surface to another by rubbing them together with an abrasive material between the two surfaces.

LIMITED SLIP DIFFERENTIAL - Differential assembly designed to automatically balance driving power to the available traction at each wheel.

LINKAGE - Any series of rods, yokes, and levers, etc., used to transmit motion from one unit to another.

LIVE AXLE - A shaft that transmits power from the differential to the wheels.

LOST MOTION - Motion between a driving part and a driven part which does not move the driven part. Also see Backlash.

LOW SPEED - The gearing which produces the highest torque and lowest speed of the wheels.

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MISALIGNMENT - When bearings are not on the same centerline.

MULTIPLE DISK - A clutch with a number of driving and driven disks as compared to a single plate clutch.

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NEEDLE BEARING - An anti - friction bearing using a great number of long, small - diameter rollers. Also known as a quill bearing.

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OD - Outside diameter.

OSCILLATE - To swing back and forth like a pendulum.

OUTPUT SHAFT - The shaft or gear which delivers the power from a device, such as a transmission.

OVERDRIVE - Any arrangement of gearing which produces more revolutions of the driven shaft than of the driving shaft.

OVERRUN COUPLING - A free - wheeling device to permit rotation in one direction but not in the other.

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PEEN - To stretch or clinch over by pounding with the rounded end of a hammer.

PINION - The smaller of two meshing gears.

PINION CARRIER - The mounting or bracket which retains the bearings supporting a pinion shaft.

PLANETARY GEAR SET - A system of gearing which is modeled after the solar system. A pinion is surrounded by an internal ring gear and planet gears are in mesh between the ring gear and pinion around which all revolves.

PLANET CARRIER - In a planetary gear system, the carrier or bracket in a planetary system which contains the shafts upon which the pinions or planet gears turn.

PLANET GEARS - The gears in a planetary gear set which connect the sun gear to the ring gear.

POWER SHIFT TRANSMISSION - A transmission in which gear changes are selected manually but are power actuated; no master clutch is involved.

PRELOAD - A load within the bearing, either purposely built in, or resulting from adjustment.

PRESS FIT - Mounting with interference, i.e., bore of bearing is smaller than OD of shaft, or OD of bearing is larger than bore of housing, or both.

PUMP - A device which produces motion in a liquid. In a torque converter, the driving member. (Also see "Impeller")

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RACE - A channel in the inner or outer ring of an anti-friction bearing in which the balls or rollers roll.

RADIAL - Perpendicular to the shaft or bearing bore.

RADIAL CLEARANCE (Radial displacement) - Clearance within the bearing and between balls and races perpendicular to the shaft.

RADIAL LOAD - A force perpendicular to the axis of rotation.

RATIO - The relation or proportion that one number bears to another.

REACTOR - See "Stator"

REAM - To finish a hole accurately with a rotating fluted tool.

RECIPROCATING - A back - and - forth movement, such as the action of a piston in a cylinder.

RING GEAR - A gear which surrounds or rings the sun and planet gears in a planetary system. I Also the name given to the spiral bevel gear in a differential.

RIVET - A headed pin used for uniting two or more pieces by passing the shank through a hole in each piece, and securing it by forming a head on the opposite end.

ROLLER BEARING - An inner and outer race upon which hardened steel rollers operate.

RPM - Revolutions per minute.

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SCORE - A scratch, ridge or groove marring a finished surface.

SEAT - A surface, usually machined, upon which another part rests or seats; for example, the surface upon which a valve face rests.

SEPARATORS - A component in an anti-friction bearing which keeps the rolling components apart.

SHIM - Thin sheets used as spacers between two parts, such as the two halves of a journal bearing.

SHRINK-FIT - Where the shaft or part is slightly larger than the hole in which it is to be inserted. The outer part is heated above its normal operating temperature or the inner part chilled below its normal operating temperature or both and assembled in this condition; upon cooling an exceptionally tight fit is obtained.

SLIDING-FIT - Where sufficient clearance has been allowed between the shaft and journal to allow free - running without overheating.

SLIDING GEAR TRANSMISSION - A transmission in which gears are moved on their shafts to change gear ratios.

SLIP-IN BEARING - A liner made to extremely accurate measurements which can be used for replacement purposes without additional fitting.

SPIRAL BEVEL GEAR - A ring gear and pinion wherein the mating teeth are curved and placed at an angle with the pinion shaft.

SPIRAL GEAR - A gear with teeth cut according to a mathematical curve on a cone. Spiral bevel gears that are not parallel have center lines that intersect.

SPLINE - Splines are multiple keys in the general form of internal and external gear teeth, used to prevent relative rotation of cylindrically - fitted parts.

SPUR GEAR - Gears cut on a cylinder and the teeth are straight and parallel to the axis.

STALL CONDITION - A condition in a torque converter when the driving element (pump) is turning and the driven element (turbine) is stopped. Stall produces maximum vortex flow.

STATOR - In a torque converter, the third member [in addition to turbine and pump) which changes direction fluid under certain operating conditions.

STRESS - The force to which a material, mechanism, or component is subjected.

SUN GEAR - The central gear in a planetary gear system around which the rest of the gears rotate.

SYNCHROMESH TRANSMISSION - Transmission gearing which aids the meshing of two gears or shift collars by matching their speed before engaging them.

SYNCHRONIZE - To cause two events to occur at the same time. For example. to bring two gears to the same speed before they are meshed.

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TAP - To cut threads in a hole with a tapered, fluted, threaded tool.

TEMPER - To change the physical characteristics of a metal by applying heat.

TENSION - Effort which elongates or "stretches:" a material.

THRUST LOAD - A load which pushes or reacts through the bearing in a directon parallel to the shaft.

TOLERANCE - A permissible variation between the two extremes of a specification or dimension.

TORQUE - A twisting motion, usually measured in Ibs (N - M).

TORQUE CONVERTER - A turbine device utilizing rotary pump, one or more reactors (stators) and driven circular turbine or vane whereby power transmitted from a driving to a driven member, hydraulic action. It provides varying drive ratios; with a speed reduction, it increases torque.

TORQUE WRENCH - A special wrench with a built-in indicator to measure the applied force.

TORUS SECTION - The confines of a flow circuit in a radial plane in a torque converter or fluid )upler.

TRANSAXLE - Type of construction in which the tansmission and differential are combined in one unit.

TRANSMISSION - An assembly of gears, or other eIements which gives variations in speed or direction between the input and output shafts.

TROUBLES HOOTING - A process of diagnosing the source of the trouble or troubles through observation and testing.

TUNE-UP - A process of accurate and careful adjustments to obtain the best performance.

TURBINE - A rotary device for obtaining mechanical power from a pressurized flow of gases or liquids.

TURBULENCE - A disturbed or irregular motion of fluids or gases.

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VANES - Any plate, blade or the like attached to an axis and moved by air or a liquid.

VORTEX - A whirling movement or mass of liquid or air.

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WORM GEAR - A gear with teeth that resemble a thread on a bolt. It is meshed with a gear that has teeth similar to a helical tooth except that it is dished to allow more contact.

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