Shear Pin Calculator
Size a shear pin for single or double shear, compare pin materials, apply shock factors, and check lug bearing pressure with imperial or metric inputs.
⚙Workshop presets
📐Pin and load inputs
Full calculation breakdown
🧪Selected material/spec comparison
📊Reference tables
| Pin material | Approx shear strength | Typical use | Design note |
|---|---|---|---|
| Low carbon steel | 36 ksi / 248 MPa | Intentional weak links | Predictable and easy to replace |
| SAE Grade 5 bolt steel | 74 ksi / 510 MPa | General machinery joints | Good strength without Grade 8 brittleness concerns |
| SAE Grade 8 bolt steel | 92 ksi / 634 MPa | High strength clevis pins | May protect the pin but overload connected parts |
| 304 or 316 stainless | 30 to 32 ksi / 207 to 221 MPa | Wet and outdoor hardware | Corrosion resistance can matter more than strength |
| 6061-T6 aluminum | 30 ksi / 207 MPa | Light duty sacrificial pins | Low weight, lower bearing durability |
| C360 brass | 26 ksi / 179 MPa | Non-sparking or soft shear pins | Useful when mating parts must be protected |
| Diameter | Area per plane | Grade 5 single shear | Grade 5 double shear |
|---|---|---|---|
| 1/4 in / 6.35 mm | 0.049 sq in | 3.63 kip ultimate | 7.27 kip ultimate |
| 5/16 in / 7.94 mm | 0.077 sq in | 5.67 kip ultimate | 11.35 kip ultimate |
| 3/8 in / 9.53 mm | 0.110 sq in | 8.17 kip ultimate | 16.35 kip ultimate |
| 1/2 in / 12.70 mm | 0.196 sq in | 14.53 kip ultimate | 29.06 kip ultimate |
| 5/8 in / 15.88 mm | 0.307 sq in | 22.70 kip ultimate | 45.41 kip ultimate |
| Service condition | Shock factor | Common examples | Practical note |
|---|---|---|---|
| Steady pull | 1.00 | Static linkage, slow clamp | Use only when loading is smooth and known |
| Light shock | 1.25 | Gate pivot, light winch latch | Good default for many shop mechanisms |
| Moderate shock | 1.50 | Mower, auger, compact machinery | Better for start-stop or reversing loads |
| Heavy shock | 2.00 | PTO driveline, impact stop | Check connected shafts and lugs carefully |
| Severe impact | 2.50 | Jam-prone drives, crash stops | Use with conservative material assumptions |
| Joint type | Typical shear mode | Useful safety factor | Extra check |
|---|---|---|---|
| Single strap link | Single shear | 2.5 to 4.0 | Plate tear-out and edge distance |
| Clevis and tongue | Double shear | 2.0 to 3.5 | Tongue bearing and fork alignment |
| Sacrificial drive pin | Single or double | 1.3 to 2.0 | Desired breakaway torque or load |
| Multi-pin bracket | Shared shear planes | 3.0 to 5.0 | Unequal load share and hole tolerance |
💡Calculation tips
A shear pin is component that is spesifically design to break when a specific amount of force is place onto the machine that contains the shear pin. Functionally, the shear pin act as a fuse for the machine; if the machine encounter an obstacle that creates a strong force against the machine, the shear pin will break to prevent the remaining expensive component of the machine from breaking. Thus, the failure of a shear pin is a beneficial failure that ensures the machine components will not be damage.
The strength of the shear pin that a person use within a machine must be carefully select. If a person select a shear pin that is too weak, the shear pin will break and have to be replace very frequent during normal operation of the machine. However, if a person select a shear pin that is too strong, the shear pin will not break when the machine encounter an obstacle, and the remaining components of the machine will be at risk of breaking.
Shear Pins: What They Do and How to Choose Them
Thus, care must be taken in selecting the correct shear pin strength to ensure the shear pin perform its beneficial function of protecting the machine from costly component failure. Another factor to consider is whether the shear pin will be in a single shear or double shear configuration. With single shear configuration, the shear pin is placed in a component such that it is only in contact with a single flat surface; in this case, the shear pin will break along a single plane of the pin.
For double shear configuration, the shear pin is placed within a fork or clevis that allow the pin to break along two different planes. Because a double shear configuration split the shear pin into two different area along which it can break, the double shear configuration effectively double the strength of the shear pin. Thus, double shear configuration are typically a better choice than single shear configuration.
In addition to the configuration of the shear pin, the material of the shear pin must also be chosen careful. Many people make the mistake of choosing a strong bolt, such as a Grade 8 bolt, for use as a shear pin. However, because Grade 8 bolts are so strong, they may not break when the machine encounter an obstacle; instead, the machines other component may break.
Thus, shear pins should be made of an inexpensive material that is easily and cheaply replace. Another factor to consider is whether the shear pin will be expose to shock loads. Shock loads are load that are applied to a component suddenly and in short burst.
For example, shear pins for components that employ a PTO shaft may be expose to shock loads caused by the PTO shaft becoming jammed. Thus, shear pins in these application may require a higher safety factor to counteract the effects of these shock loads. Bearing pressure is another factor to consider when using shear pins.
The bearing pressure of a shear pin is the force that it place against the walls of the hole in which it sit. If the shear pin is too strong for the component in which it is place, such as a soft aluminum component, the shear pin will not break but will create an oval shaped hole in that component. Such a break is known as a bearing failure, and it may destroy the component’s expensive mounting bracket.
The fit of the shear pin within the component also impact the life of the shear pin. If the shear pin is allowed to move within the components hole, it will “hammer” against the side of the hole as the component perform its task. This hammering will wear the shear pin over time.
Thus, a shear pin with a tight fit within the component is generally better than a shear pin with a loose fit. However, the shear pin should still be able to be remove from the component after it break. Finally, the goal in creating a shear pin system is to create a system that is as predictable as possible.
Shear pins should use a safety factor (ratio of shear pin strength to component strength) that ensure that the shear pin will not break due to vibration or other minor force, but that will break if a significant obstacle is encounter by the component. Thus, a safety factor of 1.0 indicate that the shear pin is at the limit of it’s strength and, therefore, is not safe; safety factor of 2.5 or 3.0 are typically used. Overall, by treating the shear pin as a fuse for the component, the designer of that component has ensure that the failure of that component will occur in the most affordable manner possible.
