Sewing Machine Safety Clutch vs. Posi-Pin® Safety Shear

SKU: X-HT-300605



You’re sewing on your industrial sewing machine and accidentally sew over a metal zipper or snap, or you experience a thread jam. Suddenly, your machine is not working properly. A machine crash has just occurred. Some industrial sewing machines have what’s called a safety clutch mechanism. This mechanism is integrated into the hook drive shaft system that ultimately moves the hook to catch the loop of thread created by the needle's motion. But did you know there’s a better safety system out there that protects not just the hook but also the rest of the working machine parts past the balance wheel? In this blog, we’re going to explain what a common safety clutch is on industrial sewing machines and why the proprietary Sailrite® Posi-Pin® Safety Shear (Patent #7438009) is a better, safer alternative for your machine.

What Is a Safety Clutch?

A safety clutch is a mechanism that connects the rotary hook to the drive shaft in an industrial sewing machine. Power transfers from the motor to the drive shaft, engaging the rotary hook to complete stitches. The safety clutch is meant to be a fail-safe should you run into problems while sewing.

This system works well when you sew as intended. But what happens when something goes wrong? The most common ways you might pop the clutch is when you get a bird’s nest of tangled thread in the rotary hook or if a broken needle gets jammed in the hook. When either of these scenarios occurs, the needle bar still moves up and down but you won’t be able to pick up your bobbin thread. This is because a safety clutch only protects the rotary hook — part of the lower drive shaft — from damage. The upper drive shaft is still engaged and operational. The motor will still run and send power to other parts of the machine.

Why is this a problem? If the jam occurs anywhere other than the hook, the machine’s internal components can shift or break. This can happen if you hit something metal (a grommet or zipper) while sewing. You’ll throw the machine out of timing, which requires time and effort spent retiming and tuning the machine to get it operational again. You might even break something and require a sewing machine technician to replace the part.

That’s why the Posi-Pin Safety Shear is a much better solution to traditional industrial sewing machine safety clutches. It’s an incredibly fast and easy way to get your machine back up and running after a crash occurs. It provides an ultimate fail safe in the event of trying to sew something the machine is incapable of handling. The pin will break before the machine parts are stressed beyond their tolerances. Let’s learn more about the Posi-Pin and how this small but vital component is revolutionizing industrial sewing machine safety.

Posi-Pin Safety Shear: A Better Solution

Simply put, the Posi-Pin Safety Shear is a better alternative to a safety clutch system. The Posi-Pin is a sacrificial component that is designed to break at the shear point if you hit metal or sew over something you shouldn’t. With the Posi-Pin, nothing moves when the pin breaks. Both the upper and lower drive shafts stop moving, whereas with a safety clutch only the rotary hook stops moving. This protects your Sailrite sewing machine’s internal components. Patented by Sailrite, the Fabricator, Ultrafeed and Leatherwork Sewing Machines are the only machines with this technology.

This video shows what happens when a machine with a standard Safety Clutch crashes versus a machine with the Posi-Pin Safety Shear. Notice the standard Safety Clutch only stops the rotary hook (green) while the Posi-Pin stops the entire machine (green).

When a crash occurs, all you have to do is remove the broken pin, replace it with a new one, change your needle and continue sewing. Only very rarely do parts need to be checked for damage. On the Fabricator, you most likely just need to replace the Posi-Pin and install a new needle. On the Ultrafeed and Leatherwork machines, you also need to check the cap spring for potential damage.

This video shows the entire machine stops operating when the Posi-Pin breaks.

Pulling the Posi-Pin out also immediately stops machine operation, which is an excellent added safety feature for homes with small children or pets. With the Posi-Pin, you can disengage the balance wheel when winding bobbins, which further reduces wear and tear on the machine’s internal components.

In Conclusion

If you’re searching for an easy-to-operate, intuitive sewing machine that requires very little maintenance and troubleshooting, the Sailrite line of sewing machines is for you. Not only will you have the advantages of the Posi-Pin Safety Shear technology, but the machines also come with best-in-class warranties and the Sailrite customer support guarantee. You’ll receive one-on-one support for the lifetime of your Sailrite sewing machine. With hundreds of support videos, our well-trained customer service staff is here to answer any questions you may have about your machine.

Learn more about our powerhouse industrial straight stitch machine by visiting our Fabricator page.

Learn more about the portable Ultrafeed Sewing Machine visiting our Ultrafeed page.

Learn more about our entry-level hobbyist leather machine visiting our Leatherwork page.