Resources

Torque Table & Equations

Download a PDF version of the chart here.

The above torque table was developed and simplified for marine applications, and is based on material strength.

Torque Table Equations

First, the units:

𝑇 𝑃 𝐼

Threads Per Inch

𝑑 𝑛 𝑜 𝑚

Nominal diameter

𝐴 𝑡

Tensile Stress Area

𝐹 𝑦

Yield Strength

𝐹 𝑖

Preload

𝑆 𝑝

Proof Strength

𝐾

Coefficient of friction (=0.15 for lubricated screws)

To determine Preload:

𝐹 𝑖 = 0.75 𝐹 𝑝

for non permanent connections¹.

𝐹 𝑝 = 𝐴 𝑡 𝑆 𝑝

𝑆 𝑝 = 0.85 𝐹 𝑦

for proof strength

To calculate bolt torque:

𝑇 = 𝐾 𝐹 𝑖 𝑑

Which can also be written as:

𝑇 = (0.15) (0.75) 𝐴 𝑡 (0.85) 𝐹 𝑦 𝑑 𝑛 𝑜 𝑚

References

Shigley’s Machine Design, 1998. p. 427 (Eq. 8-30)
Shigley’s Machine Design, 1998. p. 423 (Eq. 8-27)

Engineering Aids

Below are a links to websites and calculators that our engineers have found useful.

Machine Design

Fits and Limits

Calculation of shaft and hub fits according to ISO 286 (2010)

Winch Drum Capacity Estimator

Ingersoll Rand calculator to estimate the amount of wire that can be stored on a drum. Accounts for drum surface condition (grooved or smooth)

Through our proven partners in manufacturing and assembly Einhorn Engineering supplies equipment ready to go to sea. Featured here are a number of talented manufacturers with whom we team to build our designs.

Machining & Welding

Harbor Island Machine Works, Inc.