IMPROVEMENTS
Year: 1874

page_text: LETTERS PATENT to Seth Wyle Wilson, of Philadelphia, Pennsylvania,
United States of America, now of Lombard Street, in the City of
London, Civil Engineer, for the Invention of "IMPROVEMENTS IN
Sealed the 3rd July 1874, and dated the 6th January 1874.

page_text: Specification of Letters Patent bearing date the 13th December A.D.
1870, No. 3266.
An important part of the said apparatus is a contrivance for putting
on and releasing the brakes, and which consists chiefly of a friction
plate provided with electro-magnets in connection with a battery and an
armature plate. The friction plate is made fast on a shaft which also
carries a friction roller fitted to turn independently upon the said shaft
and rotated by contact with one of the axles. The armature in the form
of a flat circular plate is fitted on the hub of the said friction roller
and is provided with pins which enter holes in the same way, therefore
the said armature plate and roller will always rotate together while the
said armature plate is free to move endwise, so that it may approach or
recede from the magnet or friction plate. When the clectric circuit is
open the armature is not in contact with the friction plate and therefore
the aforesaid shaft remains stationary, but when the circuit is closed the
armature is attracted to the friction plate and held in contact with the
same, the shaft being caused to rotate and wind up the chain by which
the brakes are applied to the wheels.
According to my present Invention I modify the above apparatus
and provide a more efficient and economical electric clutch as follows,
that is to say, instead of having the electro-magnets arranged as above
described in combination with an armature fitted on the hub of the
friction roller I imbed the magnets in recesses or cavities made in the
said friction roller which must be of sufficient thickness to receive
magnets of suitable size. The wires from the battery are passed through
the back of the roller to the magnets; I prefer to employ four of these
electro-magnets but any desired number may be employed. A plate or
disc is fitted and made fast on the said shaft facing the magnets and
carries an armature plate connected to it by pins and holes which allow
it to approach and recede from the magnets as above described.
While the circuit is open the armature plate is not in contact with
the roller carrying the magnets, and therefore the said roller runs freely
on the shaft without imparting motion to the same, but when the circui
is closed the armature plate is drawn into contact with the said roller
and turns with it and thereby causes the said shaft to rotate and wind
up the chains which operate the brake shoes; or I may dispense with
the said chains and brake shoes and apply the retarding pressure direct

page_text: to the wheel in the following manner :-I arrange on the axle of the
railway carriage or wagon a clutch consisting of a thick circular plate or
block of cast iron or other suitable material. This circular block is made
concentric with the axle but is secured immovably to the carriage body
or frame; it is formed with deep cavities or recesses in which I imbed
electro-magnets connected by suitable wires with the battery as above
described. In combination with this circular block and upon the said
axle or shaft I place an armature plate connected to a circular plate
fixed on the wheel by pins and holes which permit the armature plate
to move endwise on the axle as above described so as to approach and
recede from the magnet block; or instead of having the armature plate
fitted to a plate fixed on the wheel it will be more convenient in certain
cases to fit a disc on the axle and fit the armature plate by pins and
holes thereon in combination with the fixed magnet block.
When the circuit is open the armature plate will remain out of
contact with the magnet block and the apparatus will remain inoperative,
but when the current is closed the said armature plate will be drawn
into contact with the magnet block and will be held by the same with
a pressure proportioned to the force of the electric current, and will
immediately or nearly so stop the rotation of the axle.
By these improvements the construction of the said apparatus is
greatly simplified and a much smaller quantity of wire will be required
for the coils of the electro-magnets, therefore the cost of the apparatus
will be materially reduced.