Ratchet and pawl design
Ratchet and pawl design
(OP)
I'm trying to design a ratchet and pawl to fit in a compact space ~40mm diameter and handle +200 ft-lbs or torque. Can anyone point me to some good references?
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Ratchet and pawl design
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Ratchet and pawl designRatchet and pawl design(OP)
I'm trying to design a ratchet and pawl to fit in a compact space ~40mm diameter and handle +200 ft-lbs or torque. Can anyone point me to some good references?
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RE: Ratchet and pawl design
Go buy a 1/2" ratchet, take it apart, and copy it.
Mike Halloran
Pembroke Pines, FL, USA
RE: Ratchet and pawl design
How he will know that it can handle 200 ft-lbs of torque?
RE: Ratchet and pawl design
RE: Ratchet and pawl design
I'd start off by pulling apart the ratchet mechanism of a torque wrench rated at 200 ft-lbs or better.
Ron Volmershausen
Brunkerville Engineering
Newcastle Australia
http://www.aussieweb.com.au/email.aspx?id=1194181
RE: Ratchet and pawl design
I should have said, copy the geometry, and scale it up to use the space available.
Mike Halloran
Pembroke Pines, FL, USA
RE: Ratchet and pawl design
RE: Ratchet and pawl design
RE: Ratchet and pawl design
For ratchets see https://sdp-si.com/eStore/Direct.asp?GroupID=473
RE: Ratchet and pawl design
Before I _write_ 'looks about right', I run a few numbers.
Yes, any engineer should be able to calculate the forces and the stresses. Even I can do that.
I suggested copying a successful design so you start with _geometry_ that's about right.
I've seen lots of projects fail, yes including from homebrew ratchet designs, because a designer was too proud to copy, or at least do some intelligent comparative anatomy and reverse engineering.
OR, if you're intending to use a bunch, see if someone like J.H.Williams would be willing to tool up and supply your ratchet assembly as a component.
Mike Halloran
Pembroke Pines, FL, USA
RE: Ratchet and pawl design
RE: Ratchet and pawl design
I don't trust them so much anymore. The examples in textbooks are set up so the numbers come out nice, and rarely consider other than obvious details. The examples in other books are usually optimized to demonstrate the basic principles at hand, but the authors and artists probably never faced commercial realities, and they are primarily authors and artists, not engineers and designers.
That's part of why I usually take broken stuff apart before I toss it, and sometimes take new stuff apart right after I buy it.
Open up a couple of commercial ratchets, and you'll see what I mean; they won't look much like those sdp-si parts.
Mike Halloran
Pembroke Pines, FL, USA
RE: Ratchet and pawl design
RE: Ratchet and pawl design
Here's some other references:
http://b
http://b
You can get greater torque capacity by using multiple pawls instead of a single pawl, but the multiple pawls must be capable of equal load sharing under all conditions to be effective. So the assembly and manufacturing of a ratchet with multiple pawls would require much greater precision (and thus cost).
RE: Ratchet and pawl design
The first link in your post is a copy from Mechanical Linkages and Mechanical Controls by Nicholas P. Chironis 1965 Page 144 "Ratchet Layout Analyzed" by Emery E. Rossner.
RE: Ratchet and pawl design
RE: Ratchet and pawl design