8/12/2019 Symbols for Rules - Gears and Stuff

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Symbols For Rules & Formulas

a Addedendum

ac Chordal Addendum

anc Normal ChordalAddendum

B Backlash

b Dedendum

C Center Distancec Clearance

D Reference Standard

Pitch DiameterDb Base Diameter

DC Datum Circle

DI Internal Diameter

DR Root Diameter

Dt Throat Diameter

DO Outside Diameterdp Operating PitchDiameter

F Face Width

Fe Active Face WidthFt Total Face Width

hk Working Depth

ht Whole Depth

L Lead

m Module

mc Contact Ratio

mF Face Contact RatiomG Gear Ratio

mn Normal Module

mo Modified ContactRatio

mp Transverse Contact

Ratiomt Total Contact Ratio

N Number Of TeethOr Threads

Ne Equivalent Number

Of TeethPd Diametral Pitch

Pnd Normal Diametral

Pitch

P Circular Pitch

Pb Base PitchPm True Position Pitch

Pn Normal CircularPitch

PN Normal Base Pitch

Pt Transverse CircularPitch

Px Axial Pitch

PX Axial Base Pitch

Q Quality NumberQa Arc Of ApproachQr Arc Of RecessQt Arc of Action

Rr Test Radiusrf Fillet Radius (when

constant)

rt Throat Form Radiusrr Tip Or Edge Radius

Of Tool

t Circular Tooth

Thickness

tb Base Circular

Thickness tc Chordal Thicknesstn Normal Circular

Thickness

tnc Normal ChordalThickness

tr Tooth Thickness

Tolerancett Transverse Circular

Thickness

tx Axial Thickness

Vap Total AccumulatedPitch Variation

Vapk Total Accumulated

Pitch Variationwithin a sector of K

Pitches

Vcq Total CompositeVariation (double

flank)

Vcqt Total Composite

Tolerances (double

flank)

Vp Pitch Variation

VpA Allowable Pitch

VariationVpn Normal Pitch

Variation

Vq Tooth-to-Tooth

Composite Variation(double flank)

VqT Tooth-to-Tooth

Composite

Tolerance (double

flank)

Vr Radial Runout

VrT Radial RunoutTolerance

Vs Spacing Variation

Vx Index Variation

VF Profile Variation

V F T Profile Tolerance

V? Tooth AlignmentVariation

V ? T Tooth Alignment

Tolerance

Z Length Of Action

a addendum angle

r Pitch Angle rR Root Angle S Shaft Angle

e Involute Roll Angle

? Involute Polar Angle ? N Angular Pitch

? Lead Angle

?b Base Lead Angle ?o Outside Lead Angle

?p Pitch Lead Angle

p Profile Radius Of

Curvature

F Pressure Angle

F n Normal Pressure

Angle F t Transverse Pressure

Angle

F x Axial PressureAngle

? Helix / Spiral Angle

? b Base Helix Angle

A Allowable VariationG Features Of A Gear

k A Variable

n Normal PlaneP Features On A

Pinion

T Tolerances

t Transverse Pitch

W Features On A

Worm