The Enhanced Safety and Ergonomics of the Front Loading Arbor
The Enhanced Safety and Ergonomics of the Front Loading Arbor
This document explains how the Front Loading Arbor resolves the hazards associated with the
traditional rod arbor.
The counterweight system is essential machinery in a theatre. First introduced in Austria in
1888, the system is to be found in virtually every significant theatre built in the 20th century.
From the beginning, there have been hazards associated with the counterweight system.
Operating Hazards
The arbors of any counterweight system must, by intent, be loaded and off-loaded with
counterweight bricks on a show-to-show basis.
The stack of bricks required for a given production may vary from as few as 80 pounds to more
than 2,000 pounds. The ANSI standard1 permits a maximum brick weight of 33 pounds.
Therefore, if a production needed a 2,000 pound counterweight, 60 bricks weighing 33 pounds
each would have to be loaded onto the arbor. And removed when the production ends. Some
productions could require the loading and off-loading of 40,000 to 50,000 pounds.
The adding and removing of the bricks has been hazardous from the beginning.
Building Hazards
OSHA2 standards 3 require compliant handrails4 at elevated work surfaces. A loading gallery of
a counterweight system is an elevated work surface. However, a compliant handrail system
makes the use of a standard rod arbor difficult, if not impossible to use safely. Therefore, they
are often omitted.
The Front Loading Arbor
Operating hazards reduced or eliminated by the Front Loading Arbor include:
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The loader no longer has to twist his back while moving a counterweight brick
The loader no longer reaches beyond the safety of the loading gallery to load a brick
With a storage bench, the loader can bend rather than stoop to do the work
Repetitive motions are reduced
Bricks can be held closer to the body as recommended by ergonomic guidelines
The risk of falling is reduced by changing the way the work is done and by the
inclusion of a compliant safety rail on the loading gallery
1
ANSI E1.4 – 2009 Entertainment Technology Manual Counterweight Rigging Systems
Occupational Safety and Health Administration
3
The Occupational Safety and Health Standards: D: Walking – Working Surfaces 1910.23
Guarding floor and wall openings and holes.
4
Ibid, paragraph (e)
2
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Easier to Handle and More Ergonomic
The Front Loading Arbor allows the loader to load and off-load bricks more quickly, easily and
safely. The loader can use two hands on the brick until it is safe to release the brick - either
securely in the arbor or safely on the brick storage bench.
The old rod arbor requires that the loader remove one hand from the brick for an amount of
time. And that moment is while the brick is tipped precariously on the arbor.
Figure 2: Although difficult to discern in this image,
the loader is working on his knees as he adds a
brick onto an old rod arbor. Note how he must
work to the bottom and to the back of the arbor. He
must steady himself with one hand while holding a
33 pound brick in the other while loading. The
details of this step of loading will vary from theatre
to theatre, but the essence of the operation remains
the
same.
See
YouTube
video
at:
https://youtu.be/KpSe23R97Yc
Figure 3: To load an old rod arbor, the loader must
sit with legs dangling over the gallery, while he
bends into the arbor-well to load and off-load
bricks. In some instances, a loader might find it
faster to actually step off of the gallery and into the
arbor well. This is done; it is not admitted to those
outside of the ‘group’. See YouTube video:
https://youtu.be/TcDckmv1kLM
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Figure 2: When loading the Thern 'Brickhouse' Front
Loading Arbor, the loader is able to work standing and
can hold the brick firmly in two hands for the entire
operation. In this installation, the owner decided to
reuse existing bricks rather than using Thern bricks.
Reusing bricks will save money if budgets are limited.
Figure 4: A loader works comfortably and
loads bricks into their Front Loading
Arbors while he is standing upright. See
YouTube
video
at:
https://youtu.be/m5DDqtdvA94
The Enhanced Safety and Ergonomics of the Front Loading Arbor
The Front Loading Arbor Works with a Compliant Safety Rail
The Front Loading Arbor allows for a compliant safety rail without impeding the work of
loading or off-loading counterweight bricks.
Loading of an old rod arbor is made difficult – even unsafe – by a compliant safety rail on the
arbor side of the loading gallery. Therefore, they are often omitted or altered with noncompliant chain.
Figure 7: With a Front Loading Arbor the loader can
work over or under the rails of a compliant safety rail
system without difficulty, simply by bending at the
knees.
Figure 8: With the old rod arbor, the loader must
work on hands and knees, twisting his back while
holding bricks weighing as much as 33 pounds.
1200 pounds
Figure 3: A compliant safety rail presents no obstacle to
loading and off-loading bricks from this installation of
front-loading arbors at Louis and Clark Community
College in Godfrey, Il.. Bricks are on a storage bench.
Figure 6: Often a non-compliant railing system is
purposely installed. This is an example of one of the
better railing systems. The loaders will unlatch the
chains when loading and off-loading. For a time before building codes required them - safety rails
were omitted completely.
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Work with Less Stooping and Bending
The Front Loading Arbor allows the loader to do most of his work on the balls of the feet. He is
required to only bend slightly at the waist or to stoop to load bricks.
1200 pounds
The old rod arbor will require that the loader work on her hands and knees for a portion of the
loading. And to twist her back while holding bricks that weigh 20 to 33 pounds.
Figure 9: With the Front Loading Arbor, the loader
merely has to bend slightly at the waist to pick bricks
from the storage shelf. He has easy access to the most
convenient shelf of the front-loading arbor. He is
protected by a compliant safety rail.
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Figure 10: A storage shelf does not make sense for a
rod arbor, as the shelf holds the bricks too high while
the loader is working on hands and knees (as in
Figure 8). Thus, when the loader is loading the last of
the arbor, he must pick the bricks from the floor of
the catwalk. Seldom does the loader stoop, rather he
bends at the waist.
The Enhanced Safety and Ergonomics of the Front Loading Arbor
Elimination of Spreader Plates and Locking Collars
The Front Loading Arbor does not have spreader plates.
The old rod arbor – to be used correctly – has the active safety components of spreader plates.
We often find them defeated. The reason that they are defeated is that they are an annoyance to
use.
Figure 11: The spreader plates are of one half-inch
thick plate to comply with the requirements of the
Department of State Architects in California. The
resistance to using the spreader plates properly is
greater in this instance.
Figure 13: The spreader plate of this old rod
arbor may or may not be in the proper location,
but the locking collar is definitely not in the
proper location. It should be at the top of the
stack.
Figure 12: The spreader plate and the locking collars
of this old rod arbor are tied off to the arbor top in an
attempt to get them out of the way. This is more
common than one might hope.
Figure 14: The Front Loading Arbor does
not need spreader plates. The shelves
prevent the sides from spreading and
provide convenience for loading.
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Handles on the Bricks
The Front Loading Arbor may be purchased with its own bricks, which have a handle that
makes grabbing the brick faster, easier and more secure.
Yet – if budgets are limited - the Front Loading Arbor can be used with existing rod arbor
bricks. Although not a convenient as the special bricks, the standard brick can be held securely
with two hands for the entire process of loading or off-loading.
Figure 15: Pallets of custom bricks being delivered.
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Figure 16: Old rod arbor bricks for recycling.
The Enhanced Safety and Ergonomics of the Front Loading Arbor
Short List of Installations of Front Loading Arbors
Allen Theatre
Texas Tech University
Lubbock, TX
Bouldin Auditorium
Bethel College
Bouldin, TN
Conexus Arts Centre
City of Regina
Regina, SK
Eisenhower Auditorium
United States Military Academy
West Point, NY
Fulton Chapel
University of Mississippi
Oxford, MS
Hartman Theatre
SUNY Plattsburgh
Plattsburgh, NY
Hatheway Hall
Louis and Clark Community College Godfrey, IL
K.R. Williams Theatre
Winston-Salem State University
Winston-Salem, NC
Kings Cross
University of the Arts
London, UK
Levoy Theatre
Millville, NJ
Manatee Performing Arts Center
Manatee Players, Inc.
Bradenton, FL
Meek Auditorium
University of Mississippi
Oxford, MS
Northern Alberta Jubilee Auditorium Province of Alberta
Edmonton, AB
Plainwell Performing Arts Center
Plainwell, MI
Plainwell High School
Southern Alberta Jubilee Auditorium Province of Alberta
Calgary, AB
Theatre Department
Edmonton, AB
McEwan University
Thomas R. Proctor HS
Utica, NY
York Theatre
City of Vancouver
Vancouver, BC
Zellerbach Hall
University of California – Berkeley Berkeley, CA
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