Pin detents and friction rings are the most common mechanisms by which the anvil of an impact wrench holds the sockets in place. Each one has its pros and cons and has its fans and detractors.
In this article, I will tell you all about them so that you can choose the most suitable holding mechanism for your needs.
Difference Between Hog Ring vs Detent Pin
Electric and pneumatic percussion tools such as impact wrenches and impact drivers generate a lot of vibration during their operation. Under such conditions, a friction ring or a pin detent mechanism is used to secure the socket on the tool.
Here’s how they work..
Friction Ring (Hog Ring)
This coupling method uses one or several stacked steel rings on the end section of the anvil’s square drive. They are a little wider than the internal part of the socket.
When a socket is placed onto the impact wrench’s anvil, the friction ring shrinks, but since it is made from an elastic metal like spring steel, it will push against the socket’s wall to recover its original shape, holding the socket in place.
When the impact wrench is working, it causes the hog ring to expand, improving the socket’s grip and preventing it from slipping off the anvil while in use.
Friction rings are usually C-shaped, and depending on the tool’s make and model, they are installed over an o-ring which helps them to expand further, increasing the ring’s force and making sockets to be installed easier into the tool.
To remove the impact socket, you just have to pull it hard, and it will break loose.
Pin Detent Mechanism
This method uses a slighter complex mechanism. The anvil has a spring-loaded pin or small ball, also called spring-loaded ball detent, to hold the socket in place. As the socket slides into the anvil, the ball or pin is pushed inside the anvil, and when it reaches a hole in the socket’s wall, the spring pushes the ball or pin through the hole, locking it in place.
Removing the socket by bare hand is almost impossible; the spring is pretty strong, so a tool like a thin screwdriver or a nail is needed to push the spring-loaded ball down to remove the socket. It’s important to notice that the impact socket you get has a hole for this purpose.
Friction Ring or Pin Detent: Which is Better?
An impact wrench with a friction ring works best when you need to swap the sockets often. It is suitable for low to mid torque applications such as lug nut removal.
The detent pin system is safer as the spring-loaded pin retainer holds the socket very securely.
Friction Ring Pros and Cons
- Ease of Use: Friction rings make installing and removing sockets easy; they don’t require as much force as pin detents.
- Simple operation: They don’t require extra tools to remove the sockets from the hog ring anvil, and the job can be done simply by hand.
- Speed: Unlike the detent pin anvil, you don’t need to align the hole on the socket and pin. You can put the socket on all four ways.
- Practicality: Friction rings are ideal for jobs requiring multiple sockets or people who do different tasks all day long and need to switch sockets many times a day.
- Compatibility: They can be used with all kinds of sockets; it’s not necessary to use special sockets.
- Durability: Friction rings and the o-ring (when they have it) wear out much faster than detent pins which usually last as long as the tool.
- Maintenance: They require frequent inspection and may have to be potentially replaced several times during the tool’s lifespan.
- Consistency: As the detent ring or hog ring wears, the tool loses its ability to hold the sockets in place safely.
- Holding Limitations: Not all friction rings can hold sockets during hard vibration from the impact mechanism and when subjected to high-torque applications. That’s why many high-torque impact wrenches use anvils with pin detents.
Pin Detent Pros and Cons
- Highly Strong Grip: They provide an extremely secure grip on sockets, making the detent pin anvil mechanism ideal for working on scaffolds or other height jobs where losing the socket could be dangerous for other workers and people passing by.
- High-Torque Capability: Detent pins can hold sockets in place even under incredible amounts of torque and vibration.
- Durability: They are tough and should have the same lifespan as the impact wrench. They don’t require maintenance.
- Consistency: They don’t lose their capacity to hold sockets safely in place with time.
- Impractical: You might need an additional hand tool is required for socket removal and sometimes installation, making them impractical for jobs that require multiple sockets. The process of installing and removing sockets can be tedious.
- Hard: Installing and removing the sockets require more force than friction rings.
- Compatibility Issues: Some impact sockets don’t bring detent pin holes.
- Unfixable: Although they shouldn’t break, if they do, you must replace the anvil because power tools manufacturers don’t sell spare parts for these mechanisms.
If you work on the ground most of the time and work on jobs requiring multiple sockets, I would advise you to choose the friction ring holding system. It’s very practical, and for automotive jobs, for example, you would never have to use so much torque that it exceeds the gripping force of a friction ring.
On the other hand, if you work on trucks or fastener that needs extremely high torque, you use your impact wrench for jobs that don’t require changing the sockets often, or if you work on high grounds, pin detents are the best choice for you.
Something interesting to notice is that you can get anvils of each type for most impact wrench brands and models. So, if you are uncomfortable with your tool’s holding mechanism, you can swap the anvil along with the holding mechanism.
Just make sure that you get the anvil that suits the size of your impact wrench.
David Castillo is an automotive industry expert specializing in vehicle electronics and stand-alone fuel management systems. He has over 20 years of experience and owns a car repair garage and tuning shop.
David still runs his shop but is now more focused on pre-purchase car inspections and writing for FinePowerTools.