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Operational forces on the pin were found for a lower bound on the pin diameters. The operational force was found by using 600N transferred to the pinion from the steering system (see FEA of rack extension), the torque transferred to the steering column would be 7500 N*mm with a pinion radius of 12.5mm. The inner diameter of the steering column is 19.05mm, therefore the operational force on the pin would be 393 787 N.
The minimum diameter for the pin to operate in each material using a safety factor of 2, and F=393N787N:
Material | τallow (MPa) | Diameter (mm) |
|---|---|---|
Nylon | 70 | 23.6878 |
Aluminum (6061-T6) | 207 | 12.5620 |
Steel (ASTM - A36) | 400 | 1.1258 |
Previous on MSXII, the shear pin used was (believed) to be 4-5mm nylon pin, therefore, it would be suitable for MSXIV to also use a nylon pin, from calculations above, the nylon pin should be between 2.68 to 6.33mm in diameter.