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.
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.
This paper presents two new techniques for
aligning and maintaining large ring gears. One technique uses lubricant temperature analysis, and the other uses stop action photography.
Hobbing is probably the most popular gear manufacturing process. Its inherent accuracy and productivity makes it
a logical choice for a wide range of sizes.