Keeping The Wheels
has a special place in our psyche: the incessant splashing of
water on the waterwheel, producing endless silent power; the rhythmic
rumble of wooden gears powdered white, trimmed with cobwebs, and
the singing of well-adjusted millstones grinding warm sweet-smelling
flour; the creaking of windmill machinery turned by the magic
of an invisible force, completely uncontrollable, yet harnessed
in the service of man for centuries; or the swish of a stationary
steam engine, the rhythmic rush of giant gleaming rods back and
forth, turning wheels silently with awesome power.
was built for a practical purpose: to provide a service or earn
a living. But engineering embodies ingenuity and so it moves ever
onwards, producing faster, more powerful, more efficient machinery.
What happens, then, to old machinery when it becomes obsolete?
The first problem is how to protect it.
Stretton Mill near Wrexham is a complete, traditional flour
mill owned by Cheshire County Council and operated by a small
employed staff trained by professional millwrights. The Mill
is open to the public during the summer months and mills flour
Much machinery is made of timber dating from the 18th and
19th centuries. Wooden machinery can often continue to work
safely, provided it is free of major defects and joints are
kept tight. Above right: Most
historic machinery contains plain bronze bearings which will
wear if not kept clean, dry, and continually lubricated.
enclosing machinery may not have been designed to be of great
architectural importance, being primarily functional in nature
and simply designed to support or protect the machinery and store
the product. But such buildings are visible elements of the landscape
and can become objects of great affection, acquiring both historic
interest and aesthetic value. Consequently, their treatment may
be subjected to historic value judgements, either independently
or as elements of the site as a whole.
being less visible, possibly less comprehensible, and perhaps
derelict-looking, may be undervalued. In the past this sometimes led
to notable cases in which a building became protected while its entire
purpose, its machinery, was lost. Listing or scheduling a building
confers protection on the whole building including all its fixtures,
and therefore all historic machinery which forms part of the building
is protected. But machinery has ancillary and detachable parts and
so it is vulnerable to gradual loss through theft for scrap or people hunting for souvenirs or spares. When machinery falls silent
it is thus vital to record and secure it by whatever means will
must be effectively excluded from the vicinity of working
machinery and properly supervised. Stationery machinery must
be immobilised, not just turned off, if visitors are permitted
to circulate nearby. Written operation and safety procedures
for staff must be developed and periodically reviewed.
If this cannot
be assured, it may be necessary to dismantle the vulnerable parts,
tag them, and remove them to a safer location. However, experience
has shown this is a risky course of action as memories fade, records
get lost, and components disappear, even in museums.
the machinery to working order is often a more sustainable solution.
But there are advantages and disadvantages.
of working use:
- It keeps the machinery intact. Most machines need to be
substantially complete to work, and many require important
ancillaries such as starting equipment, lubricants, lubricant
filters, spares, tools, and other items without which the
machine is not truly complete.
- It generates interest and so promotes care and maintenance
both of the machinery and the building in which it is housed.
- It may be able to earn its keep by carrying out its original
task and so contributing directly towards the cost of its care.
This is particularly true of vessels, vehicles, and mills.
of working use:
- Danger to staff and visitors: most historic machines were
built to be accessible for maintenance, so guards were fitted
only where absolutely necessary. As a result, most historic
machines do not forgive a careless approach, and the consequences
can be fatal.
- Wear and tear: most bearings involve one piece of metal
sliding over another, so a film of lubricant must be maintained
between them if wear is to be minimised. Despite this, wear
is inevitable and irreversible, and ultimately may determine
the life of a machine as non-renewable working parts become
too weak or degraded to operate safely.
- Damage: catastrophic failure or accident may render machinery
inoperable and ultimately irreparable.
- Cost: supervision, insurance, maintenance, fuel and other
consumables may all be expensive.
|Blagdon Pumping Station, a 'cathedral of steam'. Two
magnificent beam pumping engines by Glenfield and Kennedy
of Kilmarnock were installed in 1902 to pump Bristol's drinking
water. Still owned by Bristol Water Company over 30,000 visitors
a year visit on summer weekends. No. 9 An air vessel evened
out the surge of water delivered in three seconds by each
pump-stroke, and a 6m diameter 20 tonne flywheel kept the
Engine rotating a uniform 17rpm. The operational pumps are
now electric, but most of the original features have been
retained, including buildings, water mains, and cooling ponds.
of machinery in working condition is therefore inevitably a compromise.
It is vital to analyse the risks, and balance them against the
returns, always bearing in mind that the aim is long term preservation.
Wear may be
reduced by not making the machinery work as hard as it once did.
A stationary engine, for example, can 'tick over' with its driven
machinery 'off-load'. Likewise, a wind or watermill designed to
mill flour can demonstrate its modus operandi by rotating without
actually grinding grain.
speed and/or load of historic machinery reduces wear and risk
of damage, as well as the cost of fuel and consumables. However,
idling machinery often becomes neglected and poorly maintained,
and is often no less dangerous than when operating at full load
a course of action it is essential to carry out a thorough assessment
of the potential consequences, including what might go wrong and
the severity of the result, before examining how best to mitigate
or manage the risks. There is no ideal solution, but the most
comprehensive assessment can often be achieved by an experienced
specialist liaising with those caring for the machinery.
be taken of the limitations of the historic machinery:
- it may have been built of relatively weak materials which
could have deteriorated or contain hidden defects, and some
parts may be over-stressed, or become so in use
- access for inspection, cleaning, and maintenance may be
difficult or risky, and the machinery may be difficult to
start, run or stop.
- unknowns may include the history of use/misuse of the
machinery, and the condition of materials and internal parts.
of the risk-assessment should include:
- analysis of the hazards and measures to manage them, perhaps
incorporated into safety notes
- operation guidelines (including starting, operating and
- maintenance schedules (including cleaning, inspection,
lubrication and housekeeping). These should be written, adopted
by proprietors, issued to operatives, signed for by them and
backed-up by appropriate training.
timber components are rare and should be preserved wherever
possible. This wooden windshaft broke in a high wind and was
repaired with a steel sleeve.
SOME PRACTICAL ISSUES
It is essential that working machinery is under the control of
one competent person who is accorded and accepts full responsibility
for all aspects of the operation. (This is particularly necessary
where volunteers, who tend to function by consensus, are involved.)
Operation of complex machinery by 'committee' is dangerous, whereas
clearly devolved responsibility, enforced with a degree of discipline,
can enhance safety.
The knowledge and skills required to operate traditional machinery often
have to be re-learnt, putting the operator and machinery at risk.
Contact with others having expertise, and training if available,
are essential, and may be both legal and insurance requirements.
There should be an established written routine before starting
machinery for cleaning, lubricating, checking for obstructions
and freedom to rotate (where applicable). Bolts, nuts, cottars, wooden
teeth, etc, should be checked for tightness, covers and guards
secured, and stock prepared for processing (grain for milling
or water for pumping, for example). Working machinery must be
supervised continuously. Unfamiliar noises during operation, changes
in operating sounds, leaks and vibrations often provide warning
of a problem and must be investigated immediately, usually requiring
the machinery to be stopped. Working machines should be inspected
periodically by an expert, usually every six or 12 months.
Guards separate human and machine, protecting each from the
other. They should allow access for maintenance while offering
protection at two levels:
- to the operator who is expected to be familiar with the
machinery, skilled in its maintenance and reasonably attentive.
Localised guards or rails around particular hazards may suffice.
- to lay persons, that is to say everyone not trained and
authorised to approach the machinery. This may require more
comprehensive guarding, often at a distance from the machine,
or enclosures either to secure the people or the machines.
When the input of energy to a machine increases, or its driven-load
decreases, it speeds up and may become dangerous. There must therefore
be some form of speed-governing, which should be duplicated if
not 'fail-safe'. It should be remembered that, if the drive to
a governor fails (its drive belt breaks for example), an engine
will speed up, putting its flywheel and bearings at risk.
Machinery can only be stopped safely by cutting off its source
of power. Often the point at which this is carried out is remote
from the danger area, so additional measures may be needed, such
as remote cut-off devices or emergency alarms. Shut-off arrangements
should be backed-up if not 'fail-safe'. For example, what action
will be taken to stop a waterwheel if its sluice-gate won't close
fully due to intake of an underwater obstruction? Having a secondary
means of damming off the water, or lowering the millpond level, may
prevent serious consequences. Needless to say, the time to prepare
for such an emergency is before starting the machine.
Traditional 'plain' bearings comprise two materials sliding over
each other, separated by a thin film of lubricant, without which
the softer surface will wear. The lubricant is gradually lost
from the bearing, so must be replaced continuously. Automatic
replenishment is most effective and reliable, and usually
a justifiable addition to most machinery. Where lubrication points
are difficult or dangerous to access, they should be fed by pipes
from a safer location.
SCOPE OF PRESERVATION
is usually one of several components in a process system. For
example, a water or sewage pump is part of a system for moving
water from a lower to a higher level. If we define a machine as
'a mechanical or electrical device for carrying out a practical
task', then its reservoirs, culverts, and pipe-work may therefore
be considered to be part of the machine. However, for practical
reasons they are often excluded from the preservation process.
If we draw
the boundary a little closer to the machine itself, it may be
obvious that it is an assemblage of components in one place. This
definition may work well enough for an internal combustion engine,
but not where the fuel is burned externally, as in a steam engine,
for example. The boiler is an essential part of the engine but
may be sited in an adjoining building and become defined out
because of the difficulty of preserving or maintaining it, and
the costs involved.
is particularly acute with extended machines such as mine winders
and pumps, haulage equipment and transport systems. It is therefore
important to preserve as much of a working system as possible,
rather than focussing on isolated items of machinery.
It is one of life's
great pleasures to discover an industrial building and then
to find that it still contains its machinery. Even greater is
the pleasure of learning that the machinery is still cared for,
can operate, and can perhaps carry out its original function.
historic machinery the importance it deserves, and avoid the mistake
of preserving buildings without the machinery that gave them purpose.
article is reproduced from The
Building Conservation Directory 2006. It explores the issues to be considered where mills and other industrial archaeology can be kept in use.
GEOFFREY WALLIS CEng MIMechE FRSA is a founder and director of Dorothea
Restorations Ltd. Having started as a volunteer
in his student days, he now has 30 years' professional experience
in the conservation of historic mills, machinery and metalwork.
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