Gear Terminology

The following terminology of gears are used in our product catalog. Our catalog includes not only product information, but also has gear technical references. It would be our pleasure if you make use of our catalog as a reference and guide book on gears.

	Gear Terminology	Gear Technical Reference (PDF)	Gear World Tools
A	Accumulative pitch error Addendum Allowable bending stress at root Allowable hertz stress Allowable stress factor Allowable tangential force Allowable worm wheel torque Amount of shift Angular backlash Anti corrosion property Axial force Axial module Axial pitch		Gear Trains (Flash Player) Cars are essential for everyone today. They work with some sophisticated mechanism, such as a transmission, a differential gear, a rack and pinion, a planetary gear train, etc., etc. Here you can see the video images of such mechanisms. The photographic images how KHK stock gears are used. KHK stock gears are used in every kind of machines in manufacturing industry - machine tools, construction machinery, transport equipment, hydraulic machinery, food processing machinery, medical appliances, etc. The images cover only part of them. The examples of the use of gears (PDF file format) The toys you once used to play with contain a lot of gears, though they are seldom visible outwardly. It is possible that the goods around you contain some gears. Look around you and you will find that gears are used in your household articles, your office supplies, in the machines and equipment in your workplace. Gears for Small Robots Applications of KHK gears in small robots, showing how compact and lightweight gears can actually be! Virtual factory tour The manufacturing processes of KHK stock gears Playback time 9' 29" File size 20.2 MB The gear cutting of a spur gear Playback time 32" File size 2.75 MB Gear Technology References The ABCs of Gears Introduction to Gears This "Introduction to Gears", written simply in an informal style,is for beginners. It begins with "Types of gears" followed by "Characteristics of each type of gear" and so on. Tools to assist gear designers Downloading of CAD data on KHK Stock Gears 2D CAD data in DXF file format, and 3D CAD data are available. To use these data for your design needs Drawing System for Custom Gears This system automatically produces the drawing of custom gears based on the data provided by you.To get the drawing you need, input the numerical code for the required items of specifications (or gear dimensions) of the gear you want to draw. The drawings available for spur gears, helical gears, internal gears, racks, bevel gears, screw gears or worm gear pair. Please try. Q & A concerning Gears Please utilize the following KHK computer-based system as design aid to save your time and expense: Selection Help - enables you to select gears by using 4 search functions Downloads - Downloading of 2D or 3D CAD data on KHK Stock Gears Drawings - Display of Drawings Creating Drawings for KHK-Stock Gear-Modification use Creating Drawings for Custom Gears
B	Backlash Base circle Base cylinder Base diameter Base pith Basic load Basic rack Bending Strength Formulas Between pin (ball) measurement Bevel gear Bevel gear in nonright angle drive
C	Carburizing Carrier of planetary gear Center distance Center distance error Center distance modification coefficient Central toe contact Chamfering Chordal height Chordal tooth thickness Circumferential backlash Coefficient of friction Common tangent Coniflex gear Constrained gear system Contact ratio factor Concave surface Convex surface Crest width Crossed contact Crowning Cutting diameter effect factor Cylindrical gear Cylindrical worm gear
D	Datum Dedendum Dedendum (height) Dedendum modification Deep tooth Desired life Determining Diameter factor Diametral pitch Dimension factor Double helical gear Drive gear Driven gear Drop method Duplex lead worm gear pair Dynamic load factor
E	Effective face width Efficiency End relief Entry gap Enveloping worm gear pair Equivalent load Equivalent number of teeth Equivalent tangential force Even placement External gear
F	Face cone Face gear Face width Forced oil circulation lubrication Full depth tooth
G	Gear Gear mesh Gear ratio Gear shaper Gear tooth modification Gear train Gear types Generating Gleason spiral bevel gear Gleason straight bevel gear Grease lubrication
H	Hardness ratio factor Height of pitch line Helical gear Helical rack Helicoid line Helix angle factor Helix hand Hertz stress Hob (tool) Hobbing machine Horizontal profile shift Hypocycloid mechanism Hypoid gear
I	Idler gear Idle gear (Idler) Idler gear Induction hardening Inherent lubricity Inner end Inner tip diameter Interfering point Internal gear Involute Involute function Involute function Table Involute gear Involute interference Involute tooth profile
J	Japan gear manufacturers association (JGMA)
L	Lead Lead angle Left tooth flank Left-hand helix Length of path of contact / Active length Life factor Limit of sliding speed Line of contact Linear speed Load distribution factor Locating distance error Longitudinal load distribution factor Lubricant Lubricant factor Lubrication factor
M	Material factor Mating gear Maximum allowable surface stress Mean cone distance Minimum number of teeth free of undercutting Miter gear Module Modulus of elasticity Mounting distance Mounting distance error
N	Negative correction Nitriding No lubrication Noise Nonparallel and nonintersecting axes gear Normal backlash Normal module Normal pitch Normal pressure angle Normal profile shift coefficient Normal tooth thickness Normalizing Number of teeth
O	Offset Offset error Oil mist method Orthogonal axes (90°shaft angle) Outer cone distance Outer end Over pin or ball measurement Over pins measurement Overlap ratio Overload factor
P	Parallel axes gear Pinion Pinion cutter Pitch Pitch cone surface Pitch cylinder Pitch diameter Pitch plane Pitch point Pitting Planetary gear Poisson's ratio Positive correction Pressure angle Profile shift coefficient Profile shifted spur gear
R	Rack Rack form tool Radial force Radial backlash Reduction ratio Reference circle Reference cone angle Reference cylinder Reference cylinder helix angle Reference diameter Reference　pitch diameter Reliability factor Right tooth flank Right-hand helix Root angle Rotational direction Rotational speed Rotational speed coefficient Runout
S	Safety factor Screw gear Self locking Semitopping Shaft angle Shaft angle error Shallow tooth Shim adjustment Single pitch error Single side method Single-stage gear train Sliding speed Sliding speed factor Sliding speed limit before scoring Soft nitriding Solar type Span measurement over k teeth Span number of teeth Speed factor Speed-increasing gear Speed-reducing gear Spiral angle Spiral bevel gear Splash lubrication Spray method Spread blade method Spur gear Standard spur gear Standard straight bevel gear Star type Starting factor Straight bevel gear Sun gear Surface durability equations Surface fatigue Surface roughness factor
T	Tangential force Temperature coefficient Test for tooth-contact analysis Three wire method Throat surface radius Thrust Time factor Tip and root clearance Tip and root clearance designed to be parallel Tip angle Tip circle Tip diameter Tooth angle Tooth contact Tooth contact factor Tooth profile Tooth profile factor Tooth space half angle Tooth thickness Tooth thickness half angle Tooth trace / Thread helix Tooth trace modification Tooth width Topping Torque Total helix deviation Total profile deviation Total radial composite deviation Transmission efficiency Transmission ratio Transmitted tangential force Transverse contact ratio Transverse module Transverse pitch Transverse pressure angle Transverse profile shift coefficient Transverse tooth thickness Transverse working pressure angle Trimming Trimming interference Trochoid interference Two-stage gear train 2K-H type Type III worm
U	Under cut Undercutting
V	Viscosity
W	Water absorption property Working factor Working pitch radius Working pressure angle Worm Worm gear Worm wheel
Y	Young’s modulus
Z	Zerol bevel gear Zone factor