Helical gears can drive either nonparallel or parallel shafts. When these gears are used with nonparallel shafts, the contact is a point, and the design and manufacturing requirements are less critical than for gears driving parallel
shafts.
Spiral-bevel gears, found in many machine tools, automobile rear-axle drives, and helicopter transmissions, are important elements for transmitting power.
Gear surface fatigue endurance tests
were conducted on two groups of 10
gears each of carburized and hardened
AlSI 9310 spur gears manufactured from
the same heat of material
Gear shaving is a free-cutting gear finishing operation which removes small amounts of metal from the working surfaces of the gear teeth. Its purpose is to correct errors in index,
helical angle, tooth profile and eccentricity. The process can also improve tooth surface finish and eliminate, by crowned tooth forms, the danger of tooth end load concentrations
in service. Shaving provides for form modifications that reduce gear noise. These modifications can also increase
the gear's load carrying capacity, its factor of safety and its service life.
The proper design or selection of gear cutting tools requires thorough and detailed attention from the tool designer. In addition to experience, intuition and practical knowledge, a
good understanding of profile calculations is very important.
One of the current research
activities here at California State University at Fullerton is systematization of existing knowledge of design of planetary gear trains.
When designing gears, the engineer is often faced with the problem of selecting the number of teeth in each gear, so that
the gear train will provide a given speed ratio
Your May/June issue contains a
letter from Edward Ubert of Rockwell
International with some serious questions
about specifying and measuring tooth thickness.
Much of the information in this article
has been extracted from an AGMA
Technical Paper, "What Single Flank
Testing Can Do For You", presented in
1984 by the author