Ball Detent FAQ's
Ball detent pins are often referred to as quick-release pins, detent pins, cotterless clevis pins, and cotterless hitch pins.
Detent pins with cold formed heads are typically called detent clevis pins:
Detent ring pins feature a key ring on the backside of the pin. A key ring can act as a handle to help remove the pin, as well as an attachment point for a wire rope tether. The tether keeps the pin secured to the application after removal, and can be “yanked” to remove the pin.
Detent clevis pins feature a cold formed head – the same type of head that would be found on a clevis pin with hole or clevis pin with groove. The head acts as a more robust “stop” for the pin as compared to a key ring. A cold formed head offers a more low-profile design compared to the ring style. While the head is less convenient to grab during removal, it is considerably more cost-effective than the ring style.
The removal frequency, need for a tether, and cost sensitivity for your specific application will help you to decide between a detent ring pin and a detent clevis pin.
We can increase the pull-out force to a limited extent. Using a standard ball size, we have the ability to design the pin with a stronger spring. The force that can be generated, however, is limited by the amount of space under the ball into which the spring must fit. Keep in mind, Pivot Point’s standard spring forces are a product of a spring design that is optimized to fit within the pin and perform consistently over the life of the part. Our springs are 300 series stainless in order to resist corrosion. A material change to carbon steel spring wire can offer higher spring force at the cost of lower corrosion resistance. A stronger spring will result in an “overstressed” design, which means the spring can take a “set” as it’s cycled throughout the life of the pin, eventually settling in at a lower force than initially tested.
Prior to exploring an increase in ball force, it’s important to optimize mating hole size and conditions to take full advantage of the standard ball force. Small changes to mating hole sizing can result in significant changes in pull out force. See the "What size should my hole be?" section for more details.
For applications requiring less force to remove the pin, ball size and/or spring force can be reduced relatively easily.
At roughly 30% exposure, the ball in our detent pins is already at maximum height. Allowing more of the ball above the shank of the pin would risk the ball falling out.
Somewhat. The challenge is that the larger the ball becomes, the less space there is below the ball to house a spring. With less space, the spring cannot be designed to apply as much force. While we have already optimized the combination of ball/spring that will fit within the pin’s cross-section, we do typically have the option to use a slightly larger ball or slightly stronger spring.
Proper mating hole size and conditions are critical to the function of a ball detent pin.
Hole Size: With only about 30% of the ball exposed above the pin, the capture height from a ball detent pin is relatively limited. As such, the mating hole should be sized as closely to the shank diameter of the pin as possible. A best practice is to design the mating hole to be .005” larger than the upper limit of the pin diameter. From there, add the manufacturing tolerance needed for the mating hole on top of that value. For example, a detent pin with diameter range of .248/.250” would function well in a mating hole sized .255” minimum (.250” + .005”). If the mating hole is being machined, and requires a .005” total tolerance, then the final mating hole diameter range would be .255/.260”.
Hole Conditions: Mating holes with a square (non-chamfered) edge will retain a ball detent pin most effectively. Chamfering the mating hole will significantly reduce the pull-out force for a ball detent pin. If using a detent pin in an application made from softer material (low-durometer plastics or wood), then the edge of the hole can become rounded/worn with use – leading to weakening pull-out force over time.
In order to replace a single ball with two opposing balls, the ball size must be reduced. Otherwise, there would be no room for a spring in between them. Once this reduction occurs, a double-ball pin does not offer a significant increase in capture height over the single-ball counterpart. Additionally, with the two-ball design having less room for a spring, it’s more difficult to achieve the same ball force as a single ball pin. Double ball detent pins are much more expensive to manufacture than single-ball pins, which can be automated. With no clear functional advantage and a higher cost, it’s difficult to justify the use of a double-ball detent pin except in very specific applications.
Typically, when someone is referring to the “material” of a ball detent pin, they’re talking about the body of the pin. Ball detent pin bodies are most commonly made from low carbon steel (12L14/1215 or 1008/1018) or stainless steel (300 series). Medium carbon steels (1038) or alloy steels (1144, 4140, or 4037) can also be used if additional shear strength is needed. Materials with higher carbon contents can then be through-hardened (up to Rockwell C40) for even more shear strength. Detent pins should not be case hardened. The high hardness of the case impairs the ability to drill the hole for the ball. Additionally, in order to retain the ball in the pin, we “stake” material over the edges of the ball. Case hardened pins tend to chip rather than stake. While the main concern with detent pins is typically the body material, the material from which the ball and spring are made are important as well. Pivot Point utilizes 300 series stainless balls and springs in all of our detent pin designs in order to help guard against corrosion build-up that could bind those components and lead to pin failure. If utilizing a key ring on your detent pin, it’s typically going to be made from zinc plated spring wire, or 300 series stainless, to match the detent pin body.
Check out our video below showing how we manufacture our ball detent pins:
While SLIC Pins and Ball Detent Pins look similar, there are a host of differences. The Venn diagram below demonstrates the similarities and differences between these two labor-saving solutions:
Just ask – Pivot Point is happy to provide samples for testing. We often make samples to your specifications, or can find similar sizes for quick sampling. Visit: www.pivotpins.com to contact us.