# How can I calculate the bending moment of a pin in double shear?

• itsBart
In summary, the designer is looking for a custom-engineered system for a particular application that uses hydraulic cylinders.
itsBart
TL;DR Summary
I'm trying to calculate the diameter required for a pin in double shear, but I'm having a brain fart for the calculation of the bending moment.
I have attached an Excel-worksheet in which the problem should be clearified. The problem concerns the calculation of the bending moment acting in a pin in double shear, experiencing a certain load from a hydraulic cylinder. The plate thicknesses should be taken into account. Specifications and material properties are visible inside the Excel file.
Thanks in advance for any assistance.

#### Attachments

• TEMP Pin Calculation.xlsx
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There is an easier way. Hydraulic cylinder end fittings and pins are designed by the cylinder manufacturer for the loads from the cylinder. Buy a cylinder with a clevis end and the matching clevis fitting and pin, then you will have an engineered system designed for any load that the cylinder can apply.

jrmichler said:
There is an easier way. Hydraulic cylinder end fittings and pins are designed by the cylinder manufacturer for the loads from the cylinder. Buy a cylinder with a clevis end and the matching clevis fitting and pin, then you will have an engineered system designed for any load that the cylinder can apply.

I think you have a viable solution for simple designs indeed. In my case though, I'm looking at multiple cylinders with a bore of 200 mm applying almost 500 kN of force used for the rotation of a big platform. This requires bearings and possibly less customary pin material such as duplex (1.4462) or such, which arenot included in the cylinder options. At least our customary supplier does not offer them (or any clevis design for that matter). I don't think clevis systems come with the bearings required for the product, which in turn will differ in size and properties depending on the environment (off-shore, in my case).
In short: I'm pretty sure I need a custom engineered system contrary to a pre-engineered clevis system (my apologies if you disagree).

I took a quick look at the Parker hydraulic cylinder catalog. They have catalog options for underwater use to 5000 feet depth. That's salt water, so their anticorrosion options should be good for offshore above water use.

Your force and cylinder bore require a pressure of "only" 2300 PSI, which is well below the 3000 PSI rating of Parker cylinders. Parker is not the only manufacturer of top quality hydraulic cylinders, just the one that I have had experience with.

You may need to look at other hydraulic cylinder manufacturers. I suggest contacting the hydraulic manufacturer directly before designing your own cylinder mountings. Designing your own mountings should be an absolute last resort.

itsBart
jrmichler said:
I took a quick look at the Parker hydraulic cylinder catalog. They have catalog options for underwater use to 5000 feet depth. That's salt water, so their anticorrosion options should be good for offshore above water use.

Your force and cylinder bore require a pressure of "only" 2300 PSI, which is well below the 3000 PSI rating of Parker cylinders. Parker is not the only manufacturer of top quality hydraulic cylinders, just the one that I have had experience with.

You may need to look at other hydraulic cylinder manufacturers. I suggest contacting the hydraulic manufacturer directly before designing your own cylinder mountings. Designing your own mountings should be an absolute last resort.

Alright, I think you're right. I started off with my project without much in-depth knowledge about cylinders, so my apologies for not looking into it sufficiently. I will contact the hydraulic manfucturer(s). Thank you for your help.

jrmichler and Tom.G

## 1. How do I determine the load on the pin in double shear?

The load on the pin in double shear can be determined by calculating the total force acting on the pin. This can be done by summing up all the external forces acting on the system, such as weight, tension, or pressure.

## 2. What is the formula for calculating the bending moment of a pin in double shear?

The formula for calculating the bending moment of a pin in double shear is M = F * d, where M is the bending moment, F is the load on the pin, and d is the distance from the load to the point where the bending moment is being calculated.

## 3. How do I determine the distance from the load to the point where the bending moment is being calculated?

The distance from the load to the point where the bending moment is being calculated can be determined by measuring the distance between these two points on the pin. Alternatively, if the geometry of the system is known, the distance can be calculated using trigonometry.

## 4. What factors can affect the bending moment of a pin in double shear?

The bending moment of a pin in double shear can be affected by factors such as the magnitude and direction of the load, the material properties of the pin, and the geometry of the system. Other factors such as temperature, corrosion, and wear can also affect the bending moment.

## 5. How can I ensure the pin is strong enough to withstand the calculated bending moment?

To ensure the pin is strong enough to withstand the calculated bending moment, it is important to choose a material with appropriate strength and stiffness properties. The pin should also be designed with a sufficient cross-sectional area and proper support to distribute the load and minimize stress concentrations.

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