Improvements in Switches for Controlling and Regulating_Double or Compound Electric Motors, especially applicable to Traction or Marine Propulsion.
Year: 1890

page_text: Date of Application, 18th Aug., 1890
Complete Specification Left, 19th May, 1891-Accepted, 18th Aug., 1891
PROVISIONAL SPECIFICATION.
Improvements in Switches for Controlling and Regulating_Double
or Compound Electric Motors, especially applicable to Traction
or Marine Propulsion.
1, ALFRED JAMES JARMAN of No. 158 High Street, Clapham in the County of
Surrey, Electrical Engineer do hereby declare the nature of this invention to be as
follows:-
My present invention relates to improvements in switches for regulating and
controlling double or compound electric motors according to the method forming
the subject of the Specification and drawings of Letters Patent granted to me,
dated July 30th, 1889, No. 12082. The objects sought to be attained are; first; to
prevent undue sparking, or the formation of an arc when the contact is broken by
moving the switch; second to reduce the effect of self induction, caused by
suddenly cutting a helix of many turns out of the electrical circuit; third; to
afford absolute security in working, independently of the care and skill of the
operator fourth; to generally improve the construction of such switches by
rendering them casier of access, increasing the insulation, and improving the
durability of the apparatus generally.
In carrying my invention into effect, I employ a cylinder of wood, or other
suitable insulating material, and mount it upon a spindle or shaft, which, however is
not connected to the conductors, nor is used as a conductor. Upon the circum-
ference of said cylinder 1 arrange metallic strips of varying lengths, corresponding
to the different contacts necessary for the proper regulation of the motors. I prefer
to employ two or more such strips for each contact, so as to provide an increased
area of conducting surface therefor. A mixture of powdered glass, slate powder,
and Portland cement is then moulded, plastered, or fitted upon the circumference of
the cylinder in such a manner as to fill up the intervening spaces between the
contact strips, and renders the surface of said cylinder perfectly even and true.
The cylinder, made up in this manner is mounted by means of the central spindle
or shaft, in a bracket or stand, having two ends cast upon or fitted thereto. A
series of contact tongues, preferably made of hard drawn copper, or an alloy of
copper with any other suitable metal, are attached to the bracket, and insulated
from it and from each other. The ends of said tongues are made sufficiently
nassive for carrying the maximum current without heating, and are placed so as to
bear upon the surface of the cylinder, and connect any two or more of the contact
strips thereon, the necessary pressure being afforded by the tension of the springy
part of the tongues. The number, arrangement, and connections of the tongues
and strips, are such that the various contacts forming the connections described in
my Specification No. 12082 of 1889, may be performed during a part of one
revolution of the cylinder, and are duplicated, in order that the same variations may
take place in the same order when the motors are revolving in the opposite
direction. may also modify the arrangement of these contacts and connections to
cut out of, or include in the circuit, in series or parallel, any suitable number of
layers in the differential field magnet winding, which is termed by me, "gamut
winding."
At the upper end of the spindle which carries the cylinder, and attached to the
bracket, I provide a quadrant or dial, upon which the different positions of the
switch are marked for the guidance of the operator. A square, or equivalent
formation of the end of the spindle admits of a lever or handle being fitted to it,
but so as to be removeable under certain conditions. Said handle or lever has an
ndex or pointer attached, and the boss in passing over, and fitting the spindle
extends slightly below the dial plate, which is recessed underneath and furnished

page_text: with a radial slot, through which a pin in the lower part of the boss, may pass, and
freely turn in the recess when the handle is in position. Said slot is placed so that
the index or pointer must point to zero, indicating that all the contacts are broken,
before the handle can be placed upon the spindle, or removed from it, thus affording
absolute security, independently of the carefulness of the operator.
At the lower end of the spindle aforesaid I firmly attach a disc, in the circum-
ference of which is cut angular slots or recesses, the number and position thereof
corresponding to the various contacts, and a catch, with an angular head is fitted
with either a spiral or a plate spring so as to engage with either of the angular
slots in the disc, thus retaining the switch at any point from motion resulting from
vibration or the like, yet offering but little resistance to the movement of the
handle or lever by the operator.
The whole apparatus is enclosed in a suitably shaped case, which may be made
of insulating material throughout, or may be coated with an insulating substance
internally, to prevent short circuiting, or accidental electric contact being established.
As a further preventative measure, I prefer to attach a plug or strip of insulating
A door or
material to the back of each of the contact tongues before described.
doors in the side or sides of the case afford a means for access to the interior, and
a cap may be placed over the top when the handle is removed for the better
exclusion of dirt and moisture.
]
may modify this arrangement of the complete switch as hereinbefore described
by placing the contact tongues, or equivalent spring contacts upon the cylinder,
and the corresponding contact strips upon the interior surface of the bracket or the
case, the other portions of the apparatus comprised in my invention remaining
the same.
In some cases of application, it is necessary to place the switch in a horizontal
position, while the dial plate and handle is conveniently placed near to the operator.
In such cases I use auxiliary shafts or spindles, connected by bevil gearing of equal
pitch and number of teeth or cogs, so that the movement of the handle with the
index, and the cylinder is synchronous, although these may be placed a considerable
distance apart. The safety check and locking device hereinbefore described may
be adapted to this modification.
The formation of a perfectly true and even surface upon the cylinder or case, by
filling up the spaces between the contact strips with insulating compound is most
important, since in such switchies as hitherto made, a distinct break has occurred
when a strip passed one of the tongues, and an are frequently formed to the
deterioration of the working surface and also detriment to the efficiency of the
switch. By the arrangement of the contact strips according to my invention
entirely obviates this disadvantage, and the rubbing of the slightly rough surface
of the intervening insulation keeps the contact surface of the tongues clean.
I do not, however, in carrying out this portion of my invention confine myself to
the particular ingredients hereinbefore mentioned, but may use other suitable
substances or materials for effecting the same objects.
Dated this 5th day of August 1890.
FREDK. WALKER,
11, Furnival Street, Holborn, London, E.C., Agent for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Switches for Controlling and Regulating_Double
or Compound Electric Motors, especially applicable to Traction
or Marine Propulsion.
I, ALFRED JAMES JARMAN of No. 158 High Street Clapham in the County of
Surrey, Electrical Engineer do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and ascer-
tained in and by the following statement :-
My invention relates to improvements in switches for regulating and controlling

page_text: Hombre of compound electric motors according to the method forming the subject of
the Specification and drawings of Letters Patent granted to me, dated July 30th
A.D. 1889 No. 12082. The objects sought to be attained are; first, to prevent
undue sparking or the formation of an arc when the contact is broken by moving
the switch, second, to reduce the effect of self induction caused by suddenly cutting
a helix of many turns out of the electrical circuit; third, to afford absolute security
in working, independently of the care and skill of the operator; fourth, to generally
improve the construction of such switches by rendering them easier of access,
increasing the insulation and improving the durability of the apparatus generally.
In order that my invention may be the better understood, I have appended the
accompanying two sheets of drawings in which
Figure 1 Sheet 1 is a vertical section of the improved switch,
Figure 2 a plan of the top plate,
Figure 3 a transverse section on the line A B Figure 1 and
Figure 4 an elevation of a contact tougue, shewn detached Figure 5, Sheet 2
being a diagram of the connections.
In carrying my invention into effect I employ a cylinder A of wood or other
suitable insulating material and mount it upon a spindle or shaft B, which is not
connected to the conductors, nor is used as a conductor. Upon the circumference
of said cylinder I arrange metallic strips «; of suitable lengths, corresponding to
the different contacts necessary for the proper regulation of the motors. I prefer
to employ two or more such strips for each contact, so as to procure an increased
area of conducting surface therefor. A mixture of powdered glass, slate powder,
and Portland cement is then moulded, plastered or fitted upon the circumference of
the cylinder A in such a manner as to fill up the intervening spaces 6 between the
contact strips a, and render the surface of said cylinder perfectly even and true.
Said cylinder A, made up in this manner is mounted by means of the central
spindle or shaft B in a bracket C, having two ends D and E cast upon, or fitted
thereto. A series of contact tongues e preferably made of hard drawn copper or
an alloy of copper with any suitable metal, are attached to the bracket, and
insulated from it and from each other. The ends of said tongues are made sufficiently
massive to carry the maximum current without heating and are placed so as to
bear upon the surface of the cylinder and connect any two or more of the contact
strips thereon, the necessary elastic pressure being afforded by the tension of the
springy part of said tongues. The number, arrangement and connection of the
tongues e and strips a are such that the various contacts forming the connections
described in my Specification No. 12082 of 1889 may be performed during a part
of one revolution of the cylinder A, and are duplicated in order that the same
variations may take place in the same order when the motors are required to operate
in the opposite direction, as shewn by the diagram Figure 5. I inay also modify
the arrangement of these contacts and connections to cut out of, or include in, the
circuit, in series or parallel, any suitable number of layers in the differential field
magnet winding which is termed by me, "gamut winding."
22
At the upper end of the spindle B, carrying the cylinder A I provide dial F,
shewn more particularly by the plan view Figure 2, upon which the different
positions of the switch are marked for the guidance of the operator. A square, or
an equivalent formation d of the end of the spindle B admits of a lever or handle H
being fitted to it, so as to be removeable under certain conditions only. Said
handle H has an index or pointer g attached, and the boss in passing over the end d
and fitting the spindle B, extends slightly below the dial plate F, which is recessed
underneath and furnished with a radial slot through which a pin e, fixed to the
boss, passes, and which freely turns in the recess when the handle is in position.
Said slot e is so placed that when the index g points to zero, indicating that all the
electrical contacts are broken, the handle H can only be placed upon or removed
from the spindle B, thus affording absolute security independently of the carefulness
of the operator. At the lower end of the spindle B I firmly attach a disc I in the
circumference of which is cut angular slots or recesses, or circular recesses as shewn,

page_text: the number and position thereof corresponding to the various contacts. A plunger h
with an angular or circular head is fitted to work freely within a suitable recess i
in the bracket C, and caused to engage with the recesses upon the circumference of
'the disc I by the compression of a spiral or other spring, thus retaining the switch
at any desired point of contact from being moved by vibration or the like, yet
offering but little resistance to the movement of the handle or lever H by the
operator.
The whole apparatus is enclosed in a suitably shaped case J which may be made
of insulating material throughout, or may be coated with an insulating substance
internally to prevent short-circuiting or accidental electric contact from being
established. As a further preventative measure I may also attach a plug or strip
of insulating material to the back of the contact tongues c to prevent contact with
the case .I. A door or doors in the side or sides of the case J afford means for
access to the interior and a closing cap or cover may be placed upon the top when
the handle H is removed, for the better exclusion of dirt and moisture. I may also
modify the construction of the contact tongues a by employing a moveable or
adjustable contact & Figure 4, which may be adjusted by means of a set screw to
any degree of pressure or may be removed for renewal without disturbing the
tongue c.
I may modify the arrangement of the complete switch as hereinbefore described,
by placing the contact tongues c or equivalent spring contacts upon the cylinder,
and the corresponding contact strips upon the interior surface of the case J, or
bracket C, the other portions comprised by my invention remaining the same.
In some cases of application it is necessary to place the switch in an horizontal
position while the dial plate and handle is conveniently placed near to the operator.
In such cases I use auxiliary shafts or spindles, connected by bevil gearing, in
which the wheels are of equal pitch and the number of the teeth or cogs is the
same, in order that the movement of the handle and index upon the dial plate
corresponds exactly with the contacts made by the movement of the cylinder A,
although this part of the apparatus may be placed at a considerable distance away
from said handle. The safety check and locking device hereinbefore described may
also be adapted to this modification.
The formation of a perfectly true and even surface upon the cylinder or case, by
filling up the spaces between the contact strips a with insulating compound is most
important, since in such switches as hitherto made a distinct break has occurred
when a strip passed one of the tongues and an arc frequently formed, to the
deterioration of the working surfaces, and detriment to the efficiency of the switch.
By the arrangement of the contact strips according to my invention, this
disadvantage is entirely obviated and the rubbing of the slightly rough surface of
the intervening insulation keeps the contact surfaces of the tongues clean. I do
not, however, in carrying out this part of my invention confine myself to the
particular ingredients hereinbefore mentioned but may use other suitable substances
or materials for effecting the same objects.
In Figure 5, Sheet 2, I have shewn a preferred method of coupling a compound
motor by means of a pair of switches as herein described, arranged to be operated
The
alternately by moving the handle or lever from one side to the other.
secondary cells, or other batteries, A A¹ are coupled in series as shewn, and the
connections 2, 12, 11, 10, 9, 8 and 2, 8, 9, 10, 11, 12 from the motor B correspond
to 5, 7, 4, 3, 13 and 13, 3, 4, 7, 5, on the motor C, the switches D D' operating
each side in a similar manner.
Figure 6 shews the arrangement of the connecting strips upon the barrels of the
switches or the cases thereof, which are coupled together in the manner shewn-
14 joining 3, 13 joining 18, and so on as shewn by the connecting strips or wires
which may be covered by the insulating material hereinbefore described.
I do not wish to claim any method of coupling or connecting the motors, and
therefore do not describe the various connections in their relation to said switch the
construction of which forms the subject of my invention.

page_text: Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed I declare that what I
claim is:
First. The construction and arrangement of parts constituting a switch for
regulating a double electric motor, substantially as herein described and shewn.
Second. In a switch as referred to in the preceding claim, the method of, and
means for producing a smooth surface on the cylinder A or case K substantially as
described and partly shewn by Figure 1 of the appended drawings.
9
Third. In a switch as above referred to, the construction and use of a safety
device comprising a pin e and slot in combination with a handle H index and
dial plate F, substantially as herein described and shewn by Figures 1 and 2 of the
appended drawings.
Fourth. In an improved switch the construction and use of adjustable and
removeable contacts & substantially as herein described and shewn by Figure 4 of
the appended drawings.
Fifth. In a switch the construction and use of a locking device, comprising a
notched disc I and spring plunger substantially as herein described and shewn by
Figures 1 and 3 of the appended drawings.
Dated this 16th day of May 1891
FREDK. WALKER,
11, Furnival Street, Holborn, London, E.C., Agent for the Applicant.