1.1 Basic rack
This standard defines a basic rack for spur and helical plastic gears. However, the specific basic rack can be applied to any type of gear which
employs the basic rack concept to help define its geometry.
NOTE: This basic rack is an optional alternative to other
AGMA basic racks. It will often be preferred for those
applications in which tooth bending strength is a major
factor in the design of plastic gears.
A detailed description of the basic rack concept,
including its features and its application to various
types of gears, is given in annex A.
The data for three other basic racks, differing primarily
in depth of engagement, are given in annex B.
1.2 Gear tooth proportions
This standard shows how basic rack dimensions determine the tooth proportions of the gear once the tooth thickness has been established. Specific
values of the gear tooth thickness and the resulting
gear tooth proportions are not covered by this standard. However, many of the considerations that go into such a selection are discussed in annex C.
The tip relief from a modified basic rack is discussed in annex D.
1.3 Non-traditional practices for defining tooth
proportions
1.1 Basic rack
This standard defines a basic rack for spur and helical plastic gears. However, the specific basic rack can be applied to any type of gear which
employs the basic rack concept to help define its geometry.
NOTE: This basic rack is an optional alternative to other
AGMA basic racks. It will often be preferred for those
applications in which tooth bending strength is a major
factor in the design of plastic gears.
A detailed description of the basic rack concept,
including its features and its application to various
types of gears, is given in annex A.
The data for three other basic racks, differing primarily
in depth of engagement, are given in annex B.
1.2 Gear tooth proportions
This standard shows how basic rack dimensions determine the tooth proportions of the gear once the tooth thickness has been established. Specific
values of the gear tooth thickness and the resulting
gear tooth proportions are not covered by this standard. However, many of the considerations that go into such a selection are discussed in annex C.
The tip relief from a modified basic rack is discussed in annex D.
1.3 Non-traditional practices for defining tooth
proportions
manufacture. These practices include modifying
standard basic racks, creating custom designed
basic racks, and designing tooth proportions without
reference to basic racks. In the annexes, the description of each method is accompanied by
potential advantages and design cautions. An example of one procedure for the last method,designing without reference to basic racks, is presented in annex F.