Glossary of Terms
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
A/C Represents a first order air-conditioning compressor speed related vibration
ALT Represents a first order alternator speed related vibration
Amplitude The measurement of how hard or harsh a vibration is. Low amplitude vibrations usually can not be felt or heard. High amplitude vibrations can be heard or felt or both depending on the frequency of the vibration. Decreasing the amplitude level of a vibration concern is the primary objective in the repair procedure. On the EVA's live data screen, a the lower the G's number, the milder the vibration. Typically there is not a specification for how low is acceptable; you must take before and after amplitude readings to verify that your repairs were worthwhile.
Angular Velocity The rate of speed at which a component is rotating.
Backlash is the endplay between the gear teeth as the gear sets rotate relative to one another.
Clearance is the distance between the top of one gear tooth and the bottom of the area between two gear teeth it is meshing with.
Coast Side The Coast Side is the concave side of the gear tooth and is used during deceleration.
Component A part of an automobile that can rotate and cause a vibration.
Component Group A group of parts on an automobile that rotate together at the same speed. Vibrate 5.0 helps to identify the component group or groups responsible for the vibration on an automobile. Example: Tires, wheels, hub/axle, drum/rotor.
Cycle One complete disturbance or shake
Crossover SUV - A vehicle which is normally front-wheel drive, but has a 4-wheel drive option, or a all-wheel drive option. The engine is transversely mounted. On a crossover SUV, the engine's power is transferred through the transaxle to the power transfer unit and the front wheels. When engaged, the transfer unit transfers power to the rear axle.
Example Vehicles: Buick Rendezvous and Terraza, Chevrolet Equinox and Venture, Chrysler Pacifica, Town & Country, and Voyager, Dodge Caravan. Ford Escape, Five-Hundred, and Freestyle. Honda CR-V and Element, Hyundai Santa Fe, Izusu Axiom, Kia Sportage and Sorento. Land Rover Freelander, Lexus RX 300, RX 330, Mazda Tribute. Mercury Montego and Mariner, Mitsubishi Endeavor and Outlander, Nissan Murano. Oldsmobile Silhouette. Pontiac Montana, Montana SV6, Aztec, and Vibe, Saab 9-2X, Saturn Relay and Vue, Toyota Highlander, Matrix, RAV4, and Sienna. Volvo XC 70 and XC 90. See the powertrain example shown below.
Damping The ability of a damper to change the frequency of another object either by adding additional mass or weight to the object, or by providing a cancellation of the objects vibrations.
Default vibration worksheet The vibration vibration worksheet that is displayed when the program is started.
Drive Side The Drive Side is the convex side of the gear tooth and is used during acceleration and steady speed driving.
Dynamic Vibrations that cause side to side and up and down shakes.
Dynamic Dampers (Rubber Mounted Big Heavy Weight) act to cancel the vibrations of a certain object. The following photograph is of a dynamic damper in the front bumper of a Honda Accord. Notice that the damper is a thick, heavy piece of metal.
A closer view of this dynamic damper reveals that it is rubber mounted.
E1 Represents a first order engine speed related vibration
E2 Represents a second order engine speed related vibration
E3 Represents a third order engine speed related vibration
E4 Represents a fourth order engine speed related vibration
E5 Represents a fifth order engine speed related vibration
E6 Represents a sixth order engine speed related vibration
Engine Speed Related Vibrations An engine speed related vibration will usually always occur at the same engine RPM regardless of vehicle speed. This type of vibration can usually be detected with the vehicle stopped.
Face The Face of a gear tooth is the upper half of the gear tooth contact area.
Fifth Order Vibration A vibration or motion that is felt or heard five times per revolution of a particular rotating component.
First Order Vibration A vibration or motion that is felt or heard once per revolution of a particular rotating component.
Flank The Flank of a gear tooth is the lower half of the gear tooth contact area.
Fourth Order Vibration A vibration or motion that is felt or heard four times per revolution of a particular rotating component.
Fractional Part The part of a number that can be expressed an a fraction or a decimal. Example: 1/2 or 0.5
Frequency The number of cycles that are heard or felt in a certain amount of time. The unit of measurement for vibration frequency is typically Hertz (Hz); however, RPM, indicating cycles per minute, can be used also. The advantage of using RPM rather than Hz is the ease of matching the RPM of the vibration to the RPM of a rotating component. For example: If the vibration frequency measured is 2000 RPM and the engine RPM is also 2000, there is an easy match to see. However, if Hz is used, a vibration frequency of 33.33 Hz is not an obvious match for the 2000 engine RPM. Pressing the RPM/Hz key will change the frequency units to Hertz (Hz).
Gear Ratio A numeric indication of the difference in number of teeth on two gears. Example: A gear with thirteen teeth drives a gear with forty-two teeth, the ratio would be equal to 42 divided by 13 which is equal to 3.23. The correct method of indicating this gear ratio is 3.23:1. This means that for one rotation of the driven gear, the drive gear had to rotate 3.23 times.
Geromatic is a combination of a disc clutch and a G- rotor pump, reacting to the difference in revolutions by building up pressure and activating the clutch. An internal valve system provides constant torque difference revs in relation to temperature. A high-pressure valve limits the torque and prevents the drivetrain from overloading. In the Twin-Geromatic version there is no bevel wheel differential in the rear axle. The unit functions as a coupling of the rear axle to the drive as well as a differential across the rear axle, including a lock. In special cases it can be turned off externally, e.g. use of small spare wheel. Source: www.magnasteyr.com
Heel The Heel end of a ring gear is on the outside diameter of the gear.
Hz The abbreviation of Hertz, Cycles Per Second. The unit of measurement for frequency.
Intersecting Point A point where two lines cross each other on the vibration vibration worksheet. One line is from a vibration frequency reading, the other point is from an engine RPM reading.
Lateral Runout Side to side runout in a rotating component.
Mass Damper (Big Heavy Weight) add mass or weight to an object to slow down or decrease the vibration frequency. The following photograph is of a mass damper on the exhaust system of a mini-van Notice that the damper is a thick, heavy piece of metal.
Non-fractional Part The part of a number that has no fraction or decimal. Example: 10 or 4
Natural Frequency The frequency that an object vibrates the easiest at. An example is a piano tuning fork or an open ended hand wrench. A microwave oven vibrates water molecules at their natural frequency, 2.4GHz, to get them to vibrate and heat up. The natural frequency of automotive suspension systems has typically been between 10 and 15 Hz; however, later suspension designs have raised the frequency to 20 - 25 Hz.
Nick To make a notch, indentation, or small cut in a surface.
Order The number of disturbances or shakes in one revolution of a rotating component.
P1 Represents a first order propshaft speed related vibration
P2 Represents a second order propshaft speed related vibration
P3 Represents a third order propshaft speed related vibration
Pitch Line The Pitch Line is an imaginary line that divides the upper and lower halves of the gear tooth contact area.
Pitch-Line Runout (PLRO) is a variation in gear tooth depth and width consistency of the ring gear or pinion gear teeth.
Point of Resonance - The vehicle speed or engine RPM where the amplitude levels from two or more different frequencies will add together creating a much harsher vibration at that point than at any other point. If the vehicle speeds up or slows down, the vibration will change or even go away.
Propshaft Speed Related Vibrations A propshaft speed related vibration is a vibration caused by the propshaft or some component spinning the same speed as the propshaft.
PS Represents a first order power steering pump speed related vibration
Radial Runout Up and Down Runout in a rotating component.
Responding Component - The responding component is the part that the driver notices or feels is vibrating. It can be the floor, the seat, the steering wheel, the sun visor, the dash or instrument panel, etc.
Scan Tool A device that interfaces and communicates with the on-board computer on the vehicle. Engine RPM information can be obtained without a tachometer with this tool. Each automobile or truck manufacturer will have their own specialized scan-tool. There are aftermarket scan-tools also available; however, they often lack many of the crucial functions required to diagnose today's complex vehicles. GM's scan tool, shown below, is called the Tech-2.
Second Order Vibration A vibration or motion that is felt or heard twice per revolution of a particular rotating component.
Sixth Order Vibration A vibration or motion that is felt or heard six times per revolution of a particular rotating component.
Spalling The breakup of material into small chips or flakes.
Source - The source of the vibration. Most of the time the source of the vibration is a rotating component that is out-of-round or out-of-balance. In these cases, the source of the vibration can be repaired. Engines however, have vibrations which are a natural part of the engine running. If the engine is the source of the vibration, it cannot be repaired because it is not broken. Instead, the transfer path for the vibration must be repaired.
Static Vibrations that only cause up and down shakes.
T1 Represents a first order tire speed related vibration
T2 Represents a second order tire speed related vibration
T3 Represents a third order tire speed related vibration
Tachometer A device that can measure engine speed in revolutions per minute RPM.
Third Order Vibration A vibration or motion that is felt or heard three times per revolution of a particular rotating component.
Tire Speed Related Vibrations A tire speed related vibration is a vibration caused by the tires or some component spinning the same speed as the tires.
Toe The Toe end of a ring gear is on the inside diameter of the gear.
Transfer Path - The transfer path can be anything that is connected to, or touches both the vibration source and the responding component that the driver notices or feels. It can be the suspension system, a motor mount, transmission mount, body mount, exhaust system, propshaft, running boards, etc. Whenever normal engine vibrations are felt in the passenger compartment, the transfer path should be repaired rather than the source.
Undercut is the bottom of the area between two gear teeth where no gear-to gear contact should be made.
Vehicle Speed Related Vibrations A Vehicle speed related vibration will usually always occur at the same vehicle speed regardless of engine RPM. This type of vibration cannot be detected with the vehicle stopped.
Vibration A repetitive motion back and forth past a central position. This motion can be felt or heard or both.
Working Angle A working angle is the angle between two components. For example:
This page was last modified Monday, June 16, 2008 07:33:02 PM
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