View Full Version : Summary of Safety Harness

Katherine Rudolph
12-17-1998, 08:10 AM
Several months ago I posted a request for insight into safety harnesses
for posture testing. Here is the (tardy!) list of the replies. Thanks
to all those who replied!

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Katy Rudolph, PhD, PT Ph: 617-353-5463
Department of Biomedical Engineering fax: 617-353-5462
Center for BioDynamics krudolph@bu.edu
Boston University
44 Cummington Street
Boston, MA 01887

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Bryan Kirking

If you decide to build your own frame, check out 80/20 Inc. at
www.fwi.com/8020. We have used them before to build smaller frames. The
results look pretty cool, too.

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Tom Kernozek, Ph.D.

We have the Lite Gait by Mobility Research in our lab. We have similar

Here is their phone number, web and e-mail address:
Mobility Research www.litegait.com; e-mail MoRe@LiteGait.com
phone: 1-800-332-WALK

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Scott Colby

Here in the Duke University Sports Medicine Department we have purchased a
free standing frame with a harness support suspended from it which we use
with our treadmill for rehabilitation purposes. The name of the device
which we purchased is called Pneu-Weight and it is manufactured by Quinton

Their Home Office:
3303 Monte Villa Parkway
Bothell, WA 98021-8906
Voice Mail: 800/426-0337 ext. 13940
Fax: 206/402-2009

Our regional contact:
Paul Trodd
Fitness Regional Manager
Phone and Fax:

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Ben Heller

As part of my PhD work at the University of Strathclyde, I constructed a
trapeziodal frame from 25mm square cross-section steel tubing, 1.2mm wall
thickness, with a full-body mountaineering harness suspended from the
Apex. I have all the design calculations which showed failure at 6KN, I
allowed a safety factor of 5, limiting a subject's weight to 120Kg.

We used a quick-release knot, to allow the subject to be lowered to a
chair once the frame had arrested his fall.

The frame was designed for ambulatory work, and so had casters that sprung
out of the way when it was loaded, allowing rubber feet to lock the frame
(the kick-stool principle).

two of the side-members of the frame were chains, to allow wheelchairs to
be pushed in and out easily. The frame could be folded for
storage/transport - the longest member was 2.85m.

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Li-Shan Chou

You can check the following paper, which described the design and test of
an overhead harness system. "An overhead harness and trolley system for
balance and ambulation assessment and training", Arch Phys Med & Rehabil
74: 220-223.

We, at Mayo, also constructed a safety harness system in the Motion Lab.
It consists of a 6 meters long black anodized aluminum rail with a 6-wheel
sliding carriage attached to the ceiling. The carriage is then connected
with a fall-arrest full-body harness by a shock absorber and a strap with
adjustable length.

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Peter F. Meyer

I think you should be able to attach your harness to the ceiling above.
The concrete floor is 4.5" thick. It seems to me you have several options.

1) Bolt the harness to the floor above. This could be done with a HILTI
gun, which can shoot threaded studs into concrete. B&G has some that will
shoot 1/4", I am not sure if they have one for 3/8". You can get one at
a rental place if necessary.

2) Clamp the harness to a steel beam with a beam clamp- pick some up at
home depot. The above options will likely require permanent removal of
the ceiling tiles and grid to avoid interference.

3) A better option would be to run steel angle, or better yet, pipe across
the area of interest, just below the ceiling tile. Attach the pipe to the
beams with beam clamps and threaded rod just like you would hang piping.
For extra insurance, attach 3/16 wire rope to the pipe hangers near the
pipe, and clamp the rope to the beams so that they form an angle of about
30 degrees or so. All that would show through the ceiling is the pipe, the
bottom of the hangers, and a bit of wire rope. Since the clamps can be
removed, the whole set up would be removable. A plumber could whip it up
for you easily.

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Julie Harvey

Co-workers of mine just purchased a device for "un-weighting" elderly
subjects while they walk on a treadmill. It was made by Biodex. I can
check with them on the name of the device if you need me to. Hope that

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Steve Wolf

Have you contacted either NeuroCom or Chattecx to see how
they construct their uprights and crossbars from which a harness
can be suspended?

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Michael J. Worden, H/FI

Quinton Instrument Company makes such a harness - their number is
425-402-2000 or 800-426-0337 ext 2440 (sales)

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Qi Liu

Have you heard about UNSTRUT? This company's products work like heavy
Erector toy. They have all kinds of parts. You need to do is to assemble
them together. They have office in bay area. I am not sure whether they
have office in Boston. The harness system in our lab is made of UNISTRUT.
We do fix the beam on the ceiling. Their corporate phone number is
1-800-521-7730 or 313-721-4106.

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Eric Oussoren

Contact Biodex Medical Systems Inc and speak to Marvin Maskowitz.
Tel.: 516-924-9000

They have a free standing frame on castors. P/No.: 945-450.

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Cameron D. Grant Email. C.Grant@LaTrobe.edu.au or TSU@LaTrobe.edu.au

You may find it useful to talk with companies about fall arresting
harnesses (for people working in high places etc.) They can also fill you
in on the requirements for anchor points for your job. In Australia, the
anchor points for fall arrest is 15Kn (yes 1.5 ton!). We've just put a
grid into the roof of our movement lab, and this is what was needed
(admittedly it is a 5m high ceiling). We haven't looked at harnesses for
elderly, but will at some stage soon (also some sort of rail system so
that they can walk along a pathway), so I'll be interested in what you
find. I imagine that harnesses that are comfortable to wear, fit, and
still work will be a big ask, especially for the elderly. I look forward
to seeing your summary... Good luck

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Rodger Kram e-mail
WWW http://socrates.berkeley.edu:80/~rkram/

don't waste your money. unless you have too much! Go to EMS (Eastern
Mountain Sports) on Comm. Ave. (i used to live in Boston) and buy a rock
climbing harness (about 45$) then find a local distributor of UniStrut
Products. they make all the brackets, conduit holders etc. that you have
in most all buildings. what you want is Telespar. this is square steel
tubing with holes already drilled. if you want to see Telespar, look at
what supports a typical street sign (stop, yield etc.).

you want the 2 inch size. it can be cut to size. design a cube frame and
connect the corners of the cube with an overlapping tri joint such that
any two struts are connected by one bolt (3 bolts per corner)

send me your fax # if interested and i can fax you a drawing. telespar is
about 3$/foot.

we use this for treadmill running partial body weight support
(hypo-gravity) system regularly. it will definitely support a person

it is free standing.

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Steven E. Irby

Karen L. Harburn, PhD. of the Western University of Ontario, Canada,
published a description of their system in Arch Phys Med Rehabil Vol 74,
February 1993, pp220-223. It was entitled 'An Overhead Harness and Trolly
System for Balance and Ambulation Assessment and Training." A free
standing frame is described and a photo is included in the publication.
Dr. Harburn was most helpful over the telephone as well.

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Mr J.P. Tayler

I'm not actually a BiomechL subscriber but my wife is, and she wondered
if I could help.

A friend of mine tested climbing harnesses to destruction on a
free-standing framework as part of some research in the 80's. He built a
box-frame from builder's scaffolding poles, and then put a cross bar on
the top. He then clipped 2 large devices called maillons - a heavy-duty
screw-together linkage for joining chains - to the cross piece and then
suspended a line to which he attached the harnesses. I would suggest
approaching REI (the outdoor outfitters)in the US for information about
harnesses, MEC in Canada, or maybe Troll who manufacture harnesses in the
UK. Troll definitely have an active research science division and they may
be able to offer valuable advice/help.

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Al Finch

I have a free standing supporting tethering system in my laboratory. It
is called the Conva-Lift and it is FDA approved and patented by Numerical
Concepts in Terre Haute, IN. I have used the system for about 4 years in
developing procedure protocols for active traction and unweighted gait or
unweighted partial squats. It is a pneumatic system that dynamically
adjusts in order to keep the same exact foot weight during the gait cycle.
It will handle a 400 lbs patient easily from a wheel chair. It has a 12ft
circle footprint and uses air pressure at 80-120 psi that may come from a
conpressed air cylinder or small compressor. The subject walks in a 12 ft
dia circle while tethered from a pneumatic boom.The unweighted gait
creates a similar forceplatform pattern but just lighter. I published the
results in the International Society for Biomechanics in Sports
proceedings at Amherst (1994),Thunderbay(1995),and Madeira(1996). The
system really works great, I have finished examining its effects on
healthy and individuals with chronic low back pain and we are now ready to
evaluate its effectiveness on a convalescent population. Please contact
me if you desire any further information.

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David L. Jaffe

We have a Biodex unweighing system. It is an overhead system supported by
wheels. It costs about $3600 and comes with one vest (you may need
additional sizes). It has a pulley system - you can actually lift the
subject off the ground. A load cell measures how much the subject has
been unweighed.

I was unable to find a reference to this unit on the Biodex website:


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