What is ISO 4156-3 about?
ISO 4156-3 is the third part in the multi-series that is applicable to the straight cylindrical involute splines.
ISO 4156‑3 provides data, guidance and requirements for the inspection of straight (non-helical) side fitting cylindrical involute splines.
ISO 4156-3 introduces you to product parameters such as limiting dimensions, tolerances, manufacturing deviations and their effects on the fit between connecting coaxial spline elements by providing various formulas. 
Note: Limiting dimensions, tolerances, manufacturing deviations and their effects on the fit between connecting coaxial spline elements are defined and tabulated. Linear dimensions are expressed in millimeters and angular dimensions in degrees.
Who is ISO 4156-3 for?
ISO 4156-3 on straight cylindrical involute splines is useful for engineering professionals involved with the design, manufacture and inspection of involute spline components. ISO 4156-3 largely caters to the following industries:
- Aerospace
- Automotive
- Defense
- Mining
- Marine application
- Power generation
- Manufacture of machine tools
- Food handling and processing
Why should you use ISO 4156-3?
Straight cylindrical involute splines manufactured in obedience to ISO 4156-3 are used for sliding, clearance and interference connections of shafts and hubs, and contain all the necessary characteristics for the assembly, economic production and transmission of torque.
ISO 4156-3 also provides size inspection measuring instruments, methods and priorities. As an engineering professional dealing with involute spline, ISO 4156-3 can help in minimizing tooling costs. Adopting a standardized framework on inspection of straight cylindrical involute splines can help achieve uniformity and consistency in the manufacturing process, that caters to your specific engineering needs.
Moreover, ISO 4156-3 can help you develop the expertise of product end-users, expand reach to wider markets and build global credibility.
What’s changed since the last update?
ISO 4156‑3:2021 supersedes ISO 41563:2005, which is withdrawn. ISO 4156‑3:2021 includes some technical changes with respect to ISO 41563:2005. These include:
- Symbols of length and arc length between two points, according to ISO 800003, have been adopted and used in the formulae
- Ball or pin contact diameter, internal spline has been added
- Measurement W, an indication of base pitch, circular base thickness, and base diameter have been corrected
