IMPROVED MEANS FOR INDICATING THE HEATING OF BEARINGS IN STEAM ENGINES AND OTHER MACHINERY
Year: 1880

page_text: PROVISIONAL SPECIFICATION left by Henry William Wimshurst at the
Office of the Commissoners of Patents on the 2nd December 1880.
HENRY WILLIAM WIMSHURST, of Thicket Road, Upper Norwood, in the County
of Surrey.
"IMPROVED MEANS FOR INDICATING THE HEATING OF BEARINGS IN
STEAM ENGINES AND OTHER MACHINERY."
The practice which at present obtains of testing the temperature of bearings by
the sense of touch is open to serious objection by reason of the danger and the
liability to error attending the operation.
The object of my Invention is to provide a sure means for attracting attention
to the bearings so soon as they are heated beyond the desired limit.
This I effect by availing myself of the well known qualities of certain metals and
other substances, such as an alloy of bismuth, lead, and tin, or solid paraffin, which
substances melt at comparatively low temperatures.
I form a plug or stopper of fusible metal, such as is above mentioned, or of
its equivalent, which will melt, say, at 150° Fahrenheit, more or less, according to
the proportions of the alloy used, and I cause such plug or stopper to be inserted
in or attached to any convenient part of the journals or working parts of the engine
which are liable to get heated by friction.
Against this plug or stopper cause one end of a weighted bell crank lever or a
spring to bear in such a manner that directly the desired limit of temperature
is overstepped, the plug by its fusion or fracture will liberate the said lever or
spring and allow it to act upon a gong, operate a steam whistle, establish electrical
contact, or give any other desired indication that the bearings are heated improperly.
By these means the attention of the engineer in charge of the mechanism will be
instantly arrested, and he will be enabled to stop his engines and cool and lubricate
the bearings before any harm is done.
In some cases a loop of cord or wire may be passed over the fusible plug or
stopper, and be connected by its other end to a lever, spring, or electrical signalling
apparatus; the melting or fracture of the plug or stopper causing such mechanism
to be set in action immediately the string or wire is liberated:
This arrangement would allow of any undue heating of the bearings being
instantly indicated in the captain's cabin, or in other convenient spots at some
distance from the machinery.

page_text: A supply of such fusible plugs or stoppers. being kept at hand it will be possible
to put the safety indicator into working order by simply screwing or knocking a
fresh plug into the bearings.
In cases where the temperature in which machinery is being run is not very
high, it will be possible to dispense with the use of fusible plugs of metal, and
instead thereof to employ a tube of solid paraffin or its equivalent to retain in
tension a cord or wire attached to a lever or spring, such lever or spring being
allowed to act directly the paraffin in the tube (which may be mounted in any
convenient manner on the bearing) has melted and liberated the end of the cord or
wire.
A tube filled with mercury or other fluid capable of rapid expansion under heat
may be arranged so as to liberate a spring or establish electrical contact on any
desired temperature being indicated, or advantage may be taken of the unequal
expansion of different metals to attain similar results.
If desired the steam supply may be automatically cut off by a simple arrange-
ment of levers or pulleys connected with the cord or wire.
It is obvious that other well known substances which melt at between 100° and
400° Fahrenheit will answer my purpose equally well.
In some cases it will be possible to dispense with the use of weighted levers,
springs, and other similar contrivances for giving the alarm signals, as the mere
fusing and dropping of a short rod or bar of the metal as above described may
serve to sufficiently indicate the heating of the bearing and attract the attention of
the engineer.