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Above: Trigger assembly with five machined solid pins and ten retaining E-rings. Below: Same trigger assembly with five SPIROL Coiled Pins.

Coiled Spring Pins
Application: Air Rifle Trigger Assembly

The trigger assembly of an air rifle was composed of a housing, safety lever, three internal mechanisms and the trigger itself.  All of the parts were held in place using five machined solid pins, each of which was retained by two retaining E-rings, one in each end.  Four of the pins shared the same Ø3mm diameter but had three different lengths.  Adding the remaining Ø5mm pin, the customer had to keep a stock of four different pin sizes and two retaining E-ring sizes for their assembly.  The process of manually installing the five pins and ten retaining E-rings was time consuming, and all attention had to be paid to avoid installing the wrong length pin in any of the holes.

SPIROL's Engineering Department studied the application and found that Coiled Pins would provide an excellent alternative to the machined solid pins.  Due to the Coiled Pins being self-retaining, the retaining E-rings could be eliminated, and the length of all four Ø3mm pins could be standardized to one length that was shorter than the existing solid pin.  Similarly, the length of the Ø5mm pin could also be reduced by almost 2mm allowing the use of a Coiled Pin from our standard range, which was readily available.

The recommended Light Duty Coiled Pins are designed with enhanced flexibility, and the significantly reduced insertion force facilitates the installation process as well as future disassembly for maintenance purposes.  Light duty pins provide this flexibility while maintaining high strength in proportion to the materials in which they are installed.  The phosphate and oil finish provided corrosion protection as well as a grey/black color to match the larger assembly.  Requiring only a slight adjustment in hole sizes, the use of Coiled Pins in this application solved all the problems that the customer was facing, and provided the following benefits:

•    Replacement of 15 components (5 pins and 10 retaining E-rings) with 5 self-retaining Coiled Pins
•    Replacement of 6 different item numbers (4 pins and 2 retaining E-rings) with a single item number reducing purchasing complexity and inventory management
•    Elimination of the risk of wrong length pin installation in any of the holes
•    Elimination of machined pins with formed pins reducing individual pin component cost
•    Simplification of the assembly process reducing labor costs and increasing productivity
•    Easy automation of the pinning process to further reduce labor in high volume.

Our staff of engineers will review your application needs and work with your design team to recommend the best solution.  One way to start the process is to select Pinning Applications in our Optimal Application Engineering portal.

Many other applications can be reviewed in the private area of our web site.  In addition to application examples, registered users gain access to convenient online services and information not available on our public website.  To gain access, Register now.