Wrap Spring Clutch Design?
Wrap Spring Clutch Design?
(OP)
Can anyone help me to determine the relationship between the slip torque of a wrap spring clutch and the pre assembly interfence of the spring internal diamter and the hub.
I'm trying to determine the sensitivity of the clutch slip torgue to manufacturing tolerances.
Cheers
Justin
I'm trying to determine the sensitivity of the clutch slip torgue to manufacturing tolerances.
Cheers
Justin





RE: Wrap Spring Clutch Design?
I used one as a torque limiter in a spacecraft mechanical actuator. I selected this type because it gave very consistent slip characteristics over a very wide temperature range. The interference fit limits were determined thru a development test. We controlled the fit to extremely close tolerance by honing the spring ID to match the pin at assembly. Fortunately, we were only building half a dozen units, so this approach was practical for us.
As for a more analytical method, I can only recommend taking a look at the formulas for helical compression springs. Helical compression spring coil diameters grow in a similar fashion under load.
Good luck,
Terry
RE: Wrap Spring Clutch Design?
A more direct approach is to test it. Create samples with various interference and test.
If you are referring to slip in the driving direction, wrap spring clutches usually don't. They typically drive until the spring pulls apart or the internal member crushes.
RE: Wrap Spring Clutch Design?
RE: Wrap Spring Clutch Design?
Isrealkk, could you let me have the formula? The book's out of print and hard to find here in the UK, it's available from amazon etc but on a 2-4 week lead which is too late...
The clutch design is simply two bars pushed into the ends of helical spring. Torque requirement in 0.1 - 0.2Nm CW and locked CCW. Max diameter on the mechanism is 8mm, length ~ 30mm
Justin
RE: Wrap Spring Clutch Design?
Managed to source a paper from The Institute of Spring Technology, Sheffield UK with the calculations I need.
Justin
RE: Wrap Spring Clutch Design?
I am also looking for information on wrap spring clutch design. In my case the the spring is located on the inside of the driving and driven rings and engages in the unwinding mode. My need to to achieve consistency in time to engagement as the motion to be transmitted is very small and variations can nullify the motion.
Could ypu let me know which is the paper you sourced from the Institute of Spring Technology. This will cut down my time to identify what I need.
Thank you
JohnMLouis
RE: Wrap Spring Clutch Design?
The information was difficult to find but there are two sources that I found useful.
The info from IST was the most relevent for my application.
It is a paper imaginatively titled 'The Spring Clutch' by C.F Wiebusch, New York, from the Journal of Applied Mechanics, September 1939. I have the paper in .pdf form.
Another source which is more to your application maybe:
www.ses.
Hope this helps!
RE: Wrap Spring Clutch Design?
I too am looking for info on designing wrap spring clutches. I haven't been able to source 'The Spring Clutch' paper from IST or the Journal of Applied Mechanics (I could only get papers back to 2000). Can you tell me how you went about getting it?
Thanks!
RE: Wrap Spring Clutch Design?