IMPROVEMENTS IN DYNAMO ELECTRIC MACHINES
Year: 1885

page_text: I MICHAEL HOLROYD SMITH, of Halifax, in the County of York, Mechanical
and Consulting Engineer, do hereby declare the nature of my said invention for
"IMPROVEMENTS IN DYNAMO ELECTRIC MACHINES," to be as follows:-
The object of this invention is, the construction of machines propelled by, or for
generating electric currents, and so as to avoid consequent poles, wasted energy in
the field magnets, or the sparking of the brushes, and also to ensure thorough
saturation of the magnets, and intensity of the field, safety position of the
commutators, ready, and safe reversal of the machine, though each commutator has.
but one pair of brushes, compactness of machine, so as to render it specially
applicable for tram car work.
Machine for purpose aforesaid, constructed according to this my said invention
comprise, two "horse shoe" or bridge shaped electro magnets, so placed and wound,
that the south pole of one magnet, is opposite the north pole of the other, making
two seperate magnetic fields, in which two seperate armatures revolve attached to a
spindle, passed through them, having the commutators in the middle or between
the armatures, the bearings or journals of the spindle being at the outside.
Segmental brackets are held by tongue, and by groove, turned in the inner faces
of the pole pieces, and within these brackets, are split annular rings, provided with
lugs and screws, so that the said rings can be contracted, and moved, or expanded
and held, firmly in position, the rings move together, being connected by parallel
bars or rods, two of the latter are insulated, and carry curved springs, free to turn
on the said bars or rods. The springs are balanced, and span the coinmutatois, the
free ends being connected by adjusting screws. At or near the centro of these
springs, vertical brushes are held, constructed of sheets of copper, or copper wire,
placed radially, to the commutators, and at right angles, or obliquely to the axis
thereof, and by reason of the construction of the brushes as aforesaid, it is
immaterial in which direction, the armatures rotate-and their direction of motion,
may be changed at will, by slacking the adjusting screws, before mentioned, and
altering the lead of the brushes. When used as a motor the rotation of this
machine, may also be reversed, by changing the direction of the current.

page_text: the springs 19 may be balanced by adjustable weights 21 as shewn on plan Fig. 7-
The said springs 19 span the commutators and the pressure of the brushes is
regulated by the insulated adjusting screw 22 alone as shewn at Figs. 6, 14, and 15
or combined with springs, Figs. 11, 12, 13-At or near the centre of the springs 19
and connected thereto are the brushes 16 constructed of sheet copper or copper
wire or other suitable material and placed in some cases radially to the commu-
tators 6, 7, and at right angles to the axis as illustrated by Figs. 6, 11, 12, 14, 15,
and in some cases at an angle with the axis see Fig. 8, in some tangental with the
commutators see Fig. 13 in which case the lay of the brushes 23 is self actingly
changed by the direction in which the commutator 6 revolves and adjusted by the
tilting movement of the brush holder 29° upon its axis 25 whereon the angled or
bevelled end of either brush is brought to bear upon the commutator 6 (according
to the direction of rotation of the armature) the adjusting screws 26 being so set
as to admit the necessary amount of motion of the brush holder 20 to ensure the
bovelled ends of the brushes laying fairly upon the commutator 6 the brush
holder 29 being carried by the rings 13 and adjusted by spring and screw 27 as
previously described.
To facilitate the rocking or tilting movement the back of the brush holder 29
is formed wedge shape and rests against the flat side of a half round pin 28 held
in the frame 29 by means of the half round cotter pin 30, Figs. 13, 16, in order to
prevent the brush holder 29 falling out or being carried round, it is provided with
lugs 31 through which the half round pin passes.
Fig. 11 consists of a comb or strip of springy metal 19 fitted with small
renewable blocks 32 of solid copper or other metal each finger 19 of the comb
having a separate regulating spring 27.
In Fig. 12 stronger plates 19 are employed and the brush is held in a metal
box 34, and is adjusted by a spiral spring 35 behind or by a bow spring 36 see
Fig. 15.
In Fig. 14 the elasticity of the brush 16 is dependent upon the spring holder 19
one end being held firmly the other end being slotted to allow of the necessary
movement, the pressure is regulated by the adjusting screws 37, 37, 37.
When used as a motor the rotation of this machine may be reversed by changing
the internal coupling (or direction of the current).
Having now particularly described, and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is
1. The construction arrangement and combination of parts constituting the
improved electric generator or motor as herein fully described and illustrated by
annexed drawings.
2. The parts as constructed and combined for holding regulating and adjusting
the brushes as illustrated by drawings, Figs. 6, 7, 8, 11, 12, 14, 15.
3. The automatic reversing brush constructed, operated, and operating, as herein
fully described and illustrated by Figs. 13 and 16.
Dated this 5th day of November 100%