## Spiral and Worm Gearing: A Treatise of the Principles, Dimensions, Calculation and Design of Spiral and Worm Gearing, Together with Chapters on the Methods of Cutting the Teeth in These Types of Gears (Google eBook) |

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### Common terms and phrases

45 degrees approximate arbor axis blank center distance change gears circular pitch cos3 diagram diameter of gear diametral pitch differential mechanism dimensions driven gear driving efficiency equal face feed formula friction give Given or assumed helical gears helix angle herringbone gears Hindley Worm hobbing machine hobbing process horsepower inches involute gear irD cot large gear lead of spiral length linear pitch load Machinery Fig marked on cutter mesh method milling cutter milling machine multiply normal pitch number of cuts number of flutes number of gashes number of teeth number of threads obtained pinion pitch diameter pitch line produced rack radius revolution revolutions per minute revolving right angles rotation Rule self-locking shape shown in Fig small gear speed spindle spiral angle spiral gear spur gears taper hob teeth marked thread angle tion tool tooth angle tooth space velocity wheel width worm and gear worm gearing worm thread

### Popular passages

Page 158 - To find the helix angle of the worm and the gashing angle of the 'worm-wheel tooth, multiply the pitch diameter of the worm by 3.1416, and divide the product by the lead; the quotient is the cotangent of the tooth angle of the worm.

Page 159 - Multiply the radius of curvature of the worm-wheel throat by the cosine of half the face angle, subtract this quantity from the radius of curvature, multiply the remainder by 2, and add the product to the throat diameter of the worm-wheel.

Page 110 - After a cut is completed the cutter should be prevented from dragging over the teeth when being returned for another cut. This can be done by lowering the blank slightly or by stopping the machine and turning the cutter to such a position that the teeth will not touch the work. If the gear has teeth coarser than 10 or 12 diametral pitch, -it is well to...

Page 160 - To find the velocity ratio of a worm and worm-wheel, divide the number of teeth in the wheel by the number of threads in the worm. Be sure that the proper meaning is attached to the phrase "number of threads" as explained before under Rule 1.

Page 166 - Linear pitch Divide the lead by the number of threads. It is understood that by the number of threads is meant, not number of threads per inch, but the number of threads in the whole worm — one, if it is singlethreaded; four, if it is quadruple-threaded, etc. ... P — i...

Page 80 - It has often been argued that the ordinary herringbone tooth is stronger than the Wuest tooth, because the latter lacks the support given by the junction of the teeth at the center. This argument would be sound if gear teeth were ever stressed to anywhere near their breaking point. But it has been found in practice that considerations of wear so far outweigh those of mere breaking strength that a gear which is designed to give reasonable service will carry anywhere from ten to twenty times the working...

Page 158 - Worm-wheel. Multiply the number of teeth in the wheel by the linear pitch of the worm, and divide the product by 3.1416.

Page 74 - The third principle of herringbone gearing is that the bending stress on the teeth does not fluctuate from maximum to minimum as in straight gears, but remains always near the mean value.

Page 4 - To find the pitch diameter of a helical gear, divide the number of teeth by the product of the normal pitch and the cosine of the tooth angle.

Page 28 - ... should equal twice the product of the center distance multiplied by the normal diametral pitch, multiplied by the sine of the tooth angle of the first gear.