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Introduction
Franz Hermle & Sohn have produced clock movements for over 80 years in the
Federal Republic of Germany. Franz Hermle founded the company in 1922 as a
manufacturing facility for clock components and movements. During the occupation
of Germany following the World War 2 most of the original production equipment
was dismantled and removed from the Hermle factory. By the 1950’s the company
was able to procure new equipment and resume full-scale production. Since that
time Hermle has become a leading contender on a global scale in the clock making
industry.
In 1977 Hermle saw a need to open a plant in the United States of America.
Amherst, Virginia was selected as the home for this modern manufacturing
facility. This new plant has become one of the most efficient clock making
plants in the industry. The plant in Amherst uses the name Hermle Black forest
Clocks to distinguish itself from the parent company.
Hermle clock movements have been designed with the clock maker who will service
them in mind. In all probability they are among the easiest movements in the
world to service. Once the basic principles of operation set forth in this
manual are understood, this knowledge can easily be transferred from one
movement to another. The ready availability of parts and replacement movement
offers a wide range of options to clock makers servicing Hermle products and to
the customers they serve.
Some of the factors that cause Hermle movements to lend them to being easily
serviced, replaced, repaired or restored lie in the very rational way that every
movement has been designed:
All Hermle movements operate on the same principles.
Different models with variations in escapements, striking, chiming mechanisms
and special features are all placed on basic movements that can be counted on to
operate in the same manner as other Hermle movements do.
A rational system has been used to categorize Hermle movements into groups. Once
the principles of operation have been mastered for one movement, the variations
can be identified and dealt with quite easily. These groupings make it easy to
order parts and replacement movement when they are required.
Hermle spare parts and replacement movement are readily available through supply
houses supporting the clock making trade. These are identified in spare part
lists published by the factory.
This service information is a continuing effort on the part of Franz Hermle &
Sohn and Hermle Black Forest Clocks to assist those individuals who service
their clock movements all over the world.
Service, Repair,
Restore or Replace ?
Service
The clock maker is often called on to deliver a new clock and put it in
operation. In other instance, he may be asked to locate the cause of a minor
malfunction and correct it. The latter can occur both on new clocks that have
just been put into operation as well as those that have been working for several
years. If extensive disassembly and correction of wear problems is not required
and the problem can be solved by placing a component in its correct position or
by lubricating it, these are considered routine actions and rarely require that
the movement be removed from the customer’s home to accomplish them. Except as a
matter of convenience, it is rarely necessary to remove the clock and take it to
the shop to perform routine service functions.
Repair
Repair is generally accepted as meaning that the movement has a worn or broken
component that requires attention before the clock can be expected to render
reliable service. This may involve extensive disassembly of the movement to gain
access to the part needing attention. In other instances repairs can be
performed on components outside the plates in an expedient manner. Essentially
then, repair is accomplished to solve one or more specific problems, may or may
not involve a considerable amount of time, and may or may not require the
complete disassembly of the movement. If the movement does require disassembly,
a proper cleaning should be considered as it will improve the reliability of the
movement and is in the best interests of both the customer and the clock maker.
Restoration
Some customer may prefer to keep the original movement intact for sentimental
reasons even after the time involved and the labor costs have been explained to
them. Restoration is normally meant to include complete disassembly of the
movement and giving detailed attention to all of the component parts that are
likely to have been affected by wear, oxidation or other factors that would
affect its reliability. Specifically then, a properly restored Hermle movement
should have the appearance and reliability of a new one. As every component must
be removed and disassembled completely, a proper cleaning must always be a part
of the restoration process.
Replacement
During the course of performing a service or repair operation it may be
discovered that the whole movement is so badly worn or damaged that it is in the
customer’s best interest to replace it entirely. Replacing a movement in a
modern clock with one of the specifications is an entirely acceptable procedure
and should not be confused with the undesirable act of destroying an antique
clock by substituting an improper movement. One advantage to replacing the
movement is that the cost of labor and the cost of the movement can be computed
quickly and accurately in most cases.
Servicing Hermle
Movements
Timekeeping Problems
When a relatively new clock refuses to run:
(1) Check the clock to identify any obstructions such as the pendulum contacting
the case.
(2) Check for indirect causes of friction such as the pendulum leader binding in
the crutch.
(3) Check for friction caused by gummy oil or drying of the lubricants in the
time train, especially in the escapement area. If the movement is found to be
dry of lubrication remove the gummy oil residues with a sharpened piece of peg
wood so the train is free. Lubricate the movement.
(4) Check the stability of the clock. Floor clocks are likely to stop if they
are sitting on a soft carpet. To cure this problem a stable platform can be
constructed under the clock or it can be secured to the wall.
(5) Check the beat and ensure the automatic beat adjusting mechanism is in good
operating order.
(6) Check for wears which might warrant the repair, restoration or replacement
of the movement.
Servicing Chiming and Striking Failures
(1) As in the time train, friction or obstructions are the major causes of
chiming and striking failures.
(2) Check for obvious obstructions to the hammers to include the position of the
shutoff device.
(3) Check to ensure cables and chains are not binding or caught.
(4) Check the lubricant in the chiming or striking trains. If it has dried out,
remove the residues with a sharpened piece of peg wood and lubricate.
Repairing Hermle
Movements
A movement requiring repair usually has excessive wear, may have a component
that requires replacement or might have a condition that must be corrected
before the clock can be expected to operated reliably. Unless a repair is being
accomplished on an easily accessible component, the movement will usually have
to be removed from the case.
In most instances repairs accomplished outside the movement plates can be done
without removing the clock from the customer’s home. If work must be
accomplished between the plates, it is best to do this in a shop environment and
to perform a complete cleaning while the movement is disassembled. Repairs to
the time train
Damage to the self-adjusting beat setting mechanism is best accomplished by
replacing the complete assembly.
As in servicing, the greatest cause of repair problems will center on the pivot
holes and the sliding surfaces. If the movement has to be completely
disassembled it is advisable to service the center shaft assembly. Slip the clip
off and clean the old residues away. If the dissembled clocks are to be cleaned,
leave this assembly apart until all of the components have been dried,
lubricated and are ready for reassembly.
Check chains and cables to ensure they are capable of operating correctly. If a
chain has been overstressed and the links have opened these must be closed and
brought back to their normal shape. Consider replacing the complete chain or
cable if it has been damaged.
Damage to the escapement signals that it is best to remove the unit and replace
the damaged parts in an environment where a suitable test run can be conducted
and the required adjustment are accomplished.
Chime and Strike Repairs
In a dusty environment it is possible for the star wheel to cut into the lifting
tab that activates the chime hammer. Replacing this assembly is the most
expedient means of solving this problem. Minor repairs can be accomplished by
smoothing the face of the tab with a file to ensure the star wheel teeth cannot
get caught in the groove.
Damaged lifting surfaces on the chime drum are best dealt with by replacing the
complete assembly, as are damaged hammers and levers.
Restoring Hermle Movements
Restoration is normally understood to mean that the movement is going to be
completely disassembled, a complete cleaning is to be accomplished and all
problems caused by wear or damaged are to be corrected.
Every component that is not riveted or permanently joined should be removed
during the restoration process. This allows the cleaning solutions to reach
every surface of each component part. Once every part of the movement has been
cleaned, a meticulous inspection must be made of each component. Look for signs
of wear and fractures that might cause problems in the future. Reject any part
that does not appear capable of providing reliable service and replace it with a
new one.
Return worn pivots to a round and smooth condition. If it appears that nickel
plating has broken away from the pivots on older movements, it is best to
replace the wheel assembly. Bush each pivot hole that has any possibility of
harboring nickel residues.
Inspect each pivot hole for wear. If metal has worn away from the plate or the
pivot shows signs of wear, it is best to bush the hole. Smooth all wear tracks
out of each sliding surface. If grooves have been cut in lifting surfaces it is
best to replace the component or restore the metal that has been worn away in a
respectable manner.
The movement should be assembled, lubricated and test run for a reasonable
length of time. At the end of the restoration process the movement be should
have a respectable cosmetic appearance and should be capable of performing all
of its functions in a reliable manner.
Replacing Hermle Movements
The repair technician can recommend the option of replacing a Hermle movement
with full confidence. Hermle can supply an exact replacement or an improved
model with the same or better capabilities than the original in almost every
instance. There are several advantages to replacing a worn or damaged movement.
When mechanical movements operate over a number of years it is unusual for wear
to concentrate in only one or two locations. There are always the obvious wear
points such as pivot holes in locations receiving a great deal of stress or
shock. There are tracks that form in sliding surfaces and in the pallets. The
cumulative combination of this wear is often difficult to deal with
economically. This is especially true when a movement must be disassembled
several times to correct the problems that are not immediately obvious and do
not become apparent until after the clock fails to work reliably during the test
run.
Many customers and competent technicians share reluctance to replace a clock
movement. This reluctance may stem from a well-founded belief that this practice
is wrong and should not be engaged in. Without a doubt, it is not a good
practice to change movements in antique clocks or in special timepieces that
will lose their value if they are altered. However, changing the movement in a
modern production line clock does not have a negative effect on its value.
Conversely, if a clock of this nature has been put in good running order its
value will probably be much higher. A hundred years from now this may not be the
situation with the same clock.
When the cost of a replacement movement and the amount of time it will take to
install is known, a very accurate estimate can be given to the customer. Unless
the customer is firm n keeping the clock in its original condition for
sentimental reasons it is best to recommend the replacement of a worn modern
movement rather than engaging in restoring it. It is usually in the best
interest of both parties to do so.
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