Re: Shuttlelocks
Stan LaCount
Description
Collection
Title:
Re: Shuttlelocks
Creator:
Stan LaCount
Date:
10/9/2000
Text:
As I have field tested a couple of these for the last 5 years, I thought I
would pass the following on to any who might be interested in a report on
shuttle locks from a design engineer's perspective:
One of the problems facing us is that so many of the vendors carry the same
style or mechanism which they have copied from some other manufactures
mechanism. One common type is constructed of a cylindrical housing of
delrin that incorporates a smooth pin and an adjustable tilting washer that
locks it; I won't name any one supplier (there are several ). To release
the suction sleeve pin, a segmented white plastic button screwed (blind) to
an aluminum plunger through a blue anodized ferrule on the medial side is
pushed. If a piece of the sleeve, sock, pant/belly button lint, or trash
gets caught in the mechanism it will lock it on. Roll the suction sleeve
down, insert finger, the end of a tooth brush or some similarly shaped
object, you get the release suction picture, and pull the residual out.
From here, it may be possible to twist the distal end and pull out the
sleeve near the pin reinforcement cup. It ain't easy but I've always
managed to clear the foul without destroying anything. Another cause for
the pin unlocking failure in this mechanism is the tendency to over tighten
the small allen screw adjustment for the tilting washer for a more secure
fit. If it is too tight it may not release. Interestingly, sand and
seawater don't seem to be a problem for this lock if you wash it out with
fresh water afterwards. The relative wear is usually in the pin and has to
be replaced about every 9 months. If the tilt washer is worn, it's a bear
to disassemble but can be done. It rotates during it's life and forms a
concentric wear pattern that always provides a fairly sharp edge. If a new
pin doesn't fix it, I'd replace it at this point. It is a little tall also,
about 3/4 or more. I don't recall seeing one with a euro 4 hole mtg plate
and the removal and installation methodology is a little awkward. The
plastic operating push button is designed to be segmentally broken or
cleaved to desired protrusion length but this feature also causes it to
break-off in use and it drops out often unnoticed when the medial side is
contused. Until replaced, the only way to donn the leg again is to insert a
screw and pry the lock out to engage it again. The endolite dynamic
response foot adjusting knob tool is the same size thread and will work in a
pinch.
All in all, it's a very novel device, fairly reliable and a maintenance free
lock in general but dangerous in failure. The leg will suddenly slip off
going down the stairs or suspended over a ladder and has no safety pin or
other fail safe modes. This happens if the adjustment is too loose or the
pin is worn. Frankly, there could be some culpability in a lawsuit
somewhere, hmmmm.
PDI makes a fairly safe euro 4 hole reliable locking device in a black
plastic. It employs a steel wedge plunger that engages a toothed pin
similar to a Narwhale's horn in appearance. The steps are fairly coarse and
it can click in service (noisy). The hardened OS plunger, being more
brittle than the SS pin, can chip and rust and does so immediately
especially considering the galvanic cell between the dissimilar metals. It
also can be taken down and repaired but again, this is probably not cost
effective. The push mechanism is a little more robust and it is a fairly
safe lock but again there is no secondary safety in failure.
There is one other fairly new device that bears mentioning. This type uses
a geared cog that engages an annular grooved pin. Ossur and a few copy cats
have developed a machined aluminum euro 4 hole lock that looks very
promising. This gear looks to be mild steel and I'd like to see it made of
monel, ss or bronze but in addition to simply holding the leg on, it also
will adjust the sleeve tension. It would be hard to jam the mechanism by
lint or sock material because to unengaged, one only pushes against a spring
to slide the spline gear laterally out of the pin grooves. It disassembles
for maintenance easily and the gear should probably be cleaned and lightly
greased every 6 months or so. This lock might be worth maintaining and
costs more initially. It looks to be the most reliable and has a very low
profile, about a half inch. There are a lot of variations in this style but
most are made of metal bodies. I would think that sand and seawater are
contraindicated for this lock. Perhaps we could see it in titanium with a
bronze gear soon?
At any rate, there are many variations on a theme out there and none are
perfect. Have you considered a lanyard locking system?
Stan LaCount PRE
----- Original Message -----
From: Braceon CPO < <Email Address Redacted> >
To: < <Email Address Redacted> >
Sent: Monday, October 09, 2000 10:05 PM
Subject: Shuttlelocks
> With all the different shuttlelocks on the market, any feedback on which
are
> most widely used....least complicated...easy fabrication....durable..few
> mechanical problems?
> I have had a few patients get stuck in their lock overnight!
> Thanks
> B.Raceon
>
> ********************
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> message.
>
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> questions, send e-mail to the moderator
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>
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> related to Orthotics and Prosthetics.
>
> Public commercial postings are forbidden. Responses to inquiries
> should not be sent to the entire oandp-l list.
********************
To unsubscribe, send a message to: <Email Address Redacted> with
the words UNSUB OANDP-L in the body of the
message.
If you have a problem unsubscribing,or have other
questions, send e-mail to the moderator
Paul E. Prusakowski,CPO at <Email Address Redacted>
OANDP-L is a forum for the discussion of topics
related to Orthotics and Prosthetics.
Public commercial postings are forbidden. Responses to inquiries
should not be sent to the entire oandp-l list.
would pass the following on to any who might be interested in a report on
shuttle locks from a design engineer's perspective:
One of the problems facing us is that so many of the vendors carry the same
style or mechanism which they have copied from some other manufactures
mechanism. One common type is constructed of a cylindrical housing of
delrin that incorporates a smooth pin and an adjustable tilting washer that
locks it; I won't name any one supplier (there are several ). To release
the suction sleeve pin, a segmented white plastic button screwed (blind) to
an aluminum plunger through a blue anodized ferrule on the medial side is
pushed. If a piece of the sleeve, sock, pant/belly button lint, or trash
gets caught in the mechanism it will lock it on. Roll the suction sleeve
down, insert finger, the end of a tooth brush or some similarly shaped
object, you get the release suction picture, and pull the residual out.
From here, it may be possible to twist the distal end and pull out the
sleeve near the pin reinforcement cup. It ain't easy but I've always
managed to clear the foul without destroying anything. Another cause for
the pin unlocking failure in this mechanism is the tendency to over tighten
the small allen screw adjustment for the tilting washer for a more secure
fit. If it is too tight it may not release. Interestingly, sand and
seawater don't seem to be a problem for this lock if you wash it out with
fresh water afterwards. The relative wear is usually in the pin and has to
be replaced about every 9 months. If the tilt washer is worn, it's a bear
to disassemble but can be done. It rotates during it's life and forms a
concentric wear pattern that always provides a fairly sharp edge. If a new
pin doesn't fix it, I'd replace it at this point. It is a little tall also,
about 3/4 or more. I don't recall seeing one with a euro 4 hole mtg plate
and the removal and installation methodology is a little awkward. The
plastic operating push button is designed to be segmentally broken or
cleaved to desired protrusion length but this feature also causes it to
break-off in use and it drops out often unnoticed when the medial side is
contused. Until replaced, the only way to donn the leg again is to insert a
screw and pry the lock out to engage it again. The endolite dynamic
response foot adjusting knob tool is the same size thread and will work in a
pinch.
All in all, it's a very novel device, fairly reliable and a maintenance free
lock in general but dangerous in failure. The leg will suddenly slip off
going down the stairs or suspended over a ladder and has no safety pin or
other fail safe modes. This happens if the adjustment is too loose or the
pin is worn. Frankly, there could be some culpability in a lawsuit
somewhere, hmmmm.
PDI makes a fairly safe euro 4 hole reliable locking device in a black
plastic. It employs a steel wedge plunger that engages a toothed pin
similar to a Narwhale's horn in appearance. The steps are fairly coarse and
it can click in service (noisy). The hardened OS plunger, being more
brittle than the SS pin, can chip and rust and does so immediately
especially considering the galvanic cell between the dissimilar metals. It
also can be taken down and repaired but again, this is probably not cost
effective. The push mechanism is a little more robust and it is a fairly
safe lock but again there is no secondary safety in failure.
There is one other fairly new device that bears mentioning. This type uses
a geared cog that engages an annular grooved pin. Ossur and a few copy cats
have developed a machined aluminum euro 4 hole lock that looks very
promising. This gear looks to be mild steel and I'd like to see it made of
monel, ss or bronze but in addition to simply holding the leg on, it also
will adjust the sleeve tension. It would be hard to jam the mechanism by
lint or sock material because to unengaged, one only pushes against a spring
to slide the spline gear laterally out of the pin grooves. It disassembles
for maintenance easily and the gear should probably be cleaned and lightly
greased every 6 months or so. This lock might be worth maintaining and
costs more initially. It looks to be the most reliable and has a very low
profile, about a half inch. There are a lot of variations in this style but
most are made of metal bodies. I would think that sand and seawater are
contraindicated for this lock. Perhaps we could see it in titanium with a
bronze gear soon?
At any rate, there are many variations on a theme out there and none are
perfect. Have you considered a lanyard locking system?
Stan LaCount PRE
----- Original Message -----
From: Braceon CPO < <Email Address Redacted> >
To: < <Email Address Redacted> >
Sent: Monday, October 09, 2000 10:05 PM
Subject: Shuttlelocks
> With all the different shuttlelocks on the market, any feedback on which
are
> most widely used....least complicated...easy fabrication....durable..few
> mechanical problems?
> I have had a few patients get stuck in their lock overnight!
> Thanks
> B.Raceon
>
> ********************
> To unsubscribe, send a message to: <Email Address Redacted> with
> the words UNSUB OANDP-L in the body of the
> message.
>
> If you have a problem unsubscribing,or have other
> questions, send e-mail to the moderator
> Paul E. Prusakowski,CPO at <Email Address Redacted>
>
> OANDP-L is a forum for the discussion of topics
> related to Orthotics and Prosthetics.
>
> Public commercial postings are forbidden. Responses to inquiries
> should not be sent to the entire oandp-l list.
********************
To unsubscribe, send a message to: <Email Address Redacted> with
the words UNSUB OANDP-L in the body of the
message.
If you have a problem unsubscribing,or have other
questions, send e-mail to the moderator
Paul E. Prusakowski,CPO at <Email Address Redacted>
OANDP-L is a forum for the discussion of topics
related to Orthotics and Prosthetics.
Public commercial postings are forbidden. Responses to inquiries
should not be sent to the entire oandp-l list.
Citation
Stan LaCount, “Re: Shuttlelocks,” Digital Resource Foundation for Orthotics and Prosthetics, accessed November 24, 2024, https://library.drfop.org/items/show/215200.
