From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Diagrams and tables detailing involute gear design, hobbing, and manufacturing limits.
Identifier | ExFiles\Box 136\5\ scan0344 | |
Date | 15th January 1940 guessed | |
COMMON TERMS IN INVOLUTE GEAR DESIGN Fig. #1 Diagram labels: Pitch Point, Base Circle, Pitch Line, PA{Mr Paterson}, Common Tangent, Driver, Angle Of Recess, Arc Of Action With Approach, Full Arc Of Action Without Approach, Minimum Arc Of Action, Angle Of Approach, Desired Approach, Minimum Addendum For Continuous Action. Limits for Single and Multiple Thread Ground Finishing (Spur and Spiral) Gear Hobs Fig. #2 DIAMETRAL PITCH | 1 to 1 3/4 | 2 to 2 3/4 | 3 | 4 | 5 | 6 to 12 | 13 to 50 --- | --- | --- | --- | --- | --- | --- | --- HOLE DIAMETER | Must be lapped straight, parallel, not less than 75% bearing length. Hole within (plus only) | A .0008 B .001 | A .0005 B .0007 | A .0003 B .0005 | A .0002 B .0003 | A .0002 B .0003 | A .0002 | A .0002 | | | | | | B .00025 | B .00025 HUB RUN-OUT Face within | A .0008 B .001 | A .0005 B .0007 | A .0003 B .0005 | A .0002 B .0003 | A .0002 B .0003 | A .0002 | A .0002 | | | | | | B .00025 | B .00025 Diameter within | A .001 B .0012 | A .0007 B .0008 | A .0005 B .0006 | A .0003 B .0005 | A .0003 B .0005 | A .00025 | A .00025 O.D. Run-Out Up to 3" Diameter | A .001 B .001 3 to 4" Inclusive | A .0015 B .0015 | A .001 B .001 Over 4" Diameter | A .003 B .004 | A .002 B .003 | A .0015 B .0015 | A .001 B .001 Spacing from Flute to Flute within | A .002 B .005 | A .002 B .005 | A .0015 B .003 | A .001 B .003 | A .001 B .001 | A .001 B .001 Accumulated error in one revolution must not exceed | A .010 B .012 | A .009 B .010 | A .007 B .009 | A .005 B .008 | A .003 B .005 | A .003 B .004 CUTTING FACES Must be radial within (Cutting Depth) | A .003 B .005 | A .0015 B .0025 | A .001 B .0015 | A .001 B .0008 | A .0007 THREAD Lead variation in any one complete turn must not exceed | A .0025 B .0035 | A .001 B .0025 | A .0006 B .0015 | A .0005 B .0013 | A .0005 B .0010 | A .0004 B .0006 Lead variation from tooth to tooth must not exceed | A .0007 B .001 | A .0005 B .0008 | A .0004 B .0007 | A .0003 B .0005 | A .0002 B .0004 | A .0002 B .0003 TOOTH PROFILE OR PRESSURE ANGLE Must be symmetrical within | A .001 B .0015 | A .0007 B .001 | A .0005 B .0006 | A .0004 B .0005 | A .0003 B .0004 | A .0002 B .0003 | A .0002 B .0002 Straight portion within | A .001 B .0016 | A .0005 B .0008 | A .0004 B .0005 | A .0003 B .0004 | A .0002 B .0003 | A .0002 B .0002 Start of approach within plus or minus | A .020 B .022 | A .018 B .020 | A .015 B .015 | A .010 B .010 | A .008 B .006 | A .005 B .005 Approach on each side of tooth symmetrical within | A .015 B .018 | A .012 B .015 | A .010 B .010 | A .008 B .006 | A .006 B .005 | A .005 B .005 Tooth thickness within minus only | A .003 B .003 | A .002 B .002 | A .002 B .002 | A .002 B .002 | A .001 B .001 | A .001 B .001 MULTIPLE THREADS Circular Pitch Within | A .005 B .005 | A .003 B .003 | A .0020 B .0020 | A .0015 B .0015 | A .0010 B .0010 | A .0007 B .0007 | A .0005 B .0005 The classification of a hob is determined by the finest limit of any one feature. Chart No. 3 Fig. #3 Hob with relief-ground teeth Labels: Machine-relieved portion, Relief-ground portion. Fig. #4 Labels: HOB, GEAR BLANK. Caption: THE INVOLUTE IS GENERATED BY SUCCESSIVE CONTACT OF A NUMBER OF HOB TEETH IN THE GENERATING PLANE. Side label: GEAR TOOTH AS GENERATED BY HOB. | ||