Improvements in Motive Power Apparatus, chiefly designed for Operating Dental Instruments.
Year: 1895

page_text: Date of Application, 29th Jan., 1895-Accepted, 2nd Mar., 1895
COMPLETE SPECIFICATION.
[Communicated from abroad by LOUIS THELESPHOR EBENS METHOT, of
No. 1128, Boylston Street, Boston; Massachusetts, United States of America,
Dentist.
Improvements in Motive Power Apparatus, chiefly designed for
Operating Dental Instruments.
I, HENRY HARRIS LAKE, of the Firm of Haseltine, Lake & Co., Patent
Agents, 45 Southampton Buildings, in the County of Middlesex, do hereby
declare the nature of this invention and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement:-
My invention has for its object to provide an improved machine by means of
It is fully
which tools, such, for example, as dental instruments may be actuated.
set forth in the following description, and its novel features are pointed out in the
clains which are appended hereto. I have shown the best form of my invention
now known to me in the accompanying drawings, in which
Fig. 1 is a side elevation.
Fig. 2 is a central lengthwise section of the tool-driver.
Figs. 3 and 4 are views of details hereinafter referred to.
I have shown my invention as embodied in a dental engine, and I will describe
the illustrated embodiment thereof.
In dental operations, the instruments employed usually require to be directed by
the hand of the operator, and with very great care. Their position requires
frequently to be changed. It is therefore important, in a dental engine, that the
power required to actuate the instrument be supplied properly, while at the same
time the strain or weight exerted upon the hand of the operator, and requiring to be
sustained by him, or overcome in effecting the necessary movement of the instrument
in use, must be reduced to a minimum. The strain, or weight, if possible, should
not exceed that of the usual hand-instruments, in order that the operator may not
be subjected to any unusual muscular strain. It is also essential that the mechanism
employed for operating the instrument be so constructed as to allow the utmost
freedom of movement, so that the instrument may be used in any, position, and also,
so that when not in use the whole device may be readily moved to a position where
it will not be in the way, and, when desired, may be readily swung into operative
position again. These objects I have attained by means of my present invention,
which is of simple construction, and will be readily understood from the following
description.
A pivoted supporting bracket is shown at 1, said bracket being provided with lugs 2
for the reception of vertical pivots 3, by means of which latter it is secured to
the projections 4 of the base 5, which last is secured by screws or other well-known
means to a wall or other support 6. The pivoted bracket 1 has an outwardly and
downwardly curved arm at the lower end of which is pivoted a lever 7, which may
be of wood or other suitable material and has depending from the short end thereof
an electric motor enclosed in a casing 8. The casing 8 is provided with an
upwardly projecting portion 9 by means of which the motor is suspended on the
lever 7 from a pivot 10, so that as the lever 7.swings, the motor and its case will
maintain substantially a vertical position. The shaft of the motor projects through
the case and is provided exteriorly thereof with one or more grooved driving

page_text: pulleys 11. The long end of the lever 7 is provided with guide pulleys 12, which
are grooved, and which serve as guide pulleys for the driving band 13. The
pulleys 12 are loosely mounted at each end of a suitable cross-piece or bearing 14,
the latter being formed with a socket or opening 141, which fits on the end of lever 7.
A loop or bight of the driving cord. 13 extends downwardly from the guide
pulleys 12 a sufficient distance to bring the tool which is to be operated in convenient
proximity to the work which is to be done, when the lever 7 is in a substantially
horizontal position. A suitable retaining device 122 secured to the outer end of
one of the journals on the cross-piece 14, is constructed and arranged to extend
across the grooved edges of the pulleys 12, 12, and serves to prevent the driving
cord from flying out of the grooves thereof. The mechanism by means of which
the tool or instrument is directly actuated, is shown more clearly at Fig 2, and
consists of a cylindrical casing 15 through which a spindle 16 passes. One end of
the casing 15 is exteriorly threaded to receive an internally threaded sleeve 17
upon which is loosely mounted a bracket 18 which supports the guide pulleys 19.
At the other end of the casing 15 a sleeve 20 is provided, which slides into the
end of the casing 15. and is held in place by frictional contact with said casing.
The sleeves 17 and 20 serve as bearings for the spindle 16, and the space inside said
casing 15 and around said spindle may be packed with an absorbent material, which
will hold a lubricant, so that the device may be used a considerable time without
additional lubrication. One end of the spindle 16 is provided with a head 21,
which is preferably of metal, or some heavy material, and which is rigidly secured
to the said shaft in any well-known manner, as by the use of a set screw 22. The
inner end of the head 21 is grooved as shown at 23 to constitute a pulley which
receives the loop of the driving cord 13. The employment of a relatively heavy
pulley or head 21 is advantageous because of the resulting momentum obtained.
The two portions of the driving cord 13 are passed between the pairs of guide
pulleys 19, which are journalled in the upper portion of the bracket 18, as shown
in Figs. 2 and 4, the said cord passing between one pair of said guide pulleys,
thence around the head 21 in the groove 23 therein, and thence between the pair
of guide pulleys on the opposite side of the bracket 18. The end of the spindle 16
which is nearest the sleeve cr bearing 20 is secured to a. flexible shaft 24, and
which is of well-known construction. The other end of the flexible shaft 24 is
secured to a short spindle 25, which is mounted in a sleeve 26, the end of said
short spindle 25 being shaped to engage the proximate end of the shaft 27 of the
tool-holder 28. The proximate ends of the sleeve 20 and the sleeve 26 are secured
together by means of a flexible connection 29, of similar construction to that of
shaft 24, and which serves to protect the shaft, while at the same time permitting
it to yield in any desired direction. The covering 29, which is of spiral wire, is in
turn covered with a layer of thin leather 30, or similar suitable material, which
serves as a protection and finish. The sleeve 26 is provided with a thimble 31, which
is screwed into said sleeve 26 and serves as a bearing for the short shaft 25.
spring-catch 32 is pivoted to the thimble 31 and serves to secure the tool-holder 28
in place, when it is slid into connection with the said thimble 31. The flexible
shaft 24, and all the parts connected therewith, including its covering, and the
sleeve 26, thimble 31, and the tool-holder 28, are old and well-known, and will not
require a more detailed description. -
A
The bracket 1 may be swung laterally, thus providing for the lateral movements
of the device, and through having the lever 7 pivoted to the support 1, provision is
made for the vertical movements thereof. The floating tool-driver shown in Fig. 2,
being suspended by means of a loop of the cord 13 from the guide pulleys 12, is
free to be swung in any direction at the end of the said loop. The long arm of the
lever 7 is so proportioned to the short arm thereof that the weight of the motor
and its case is just sufficient to balance the weight of the floating tool-driver
and its attached parts, so that if there were no friction at the pivot of the lever 7
said lever would assume naturally a horizontal position. There is preferably a
slight friction at the fulcrum of the lever 7, so that while the lever may be swung

page_text: freely vertically, it will stay at any point at which it may be left within a.
considerable distance of the horizontal position, and will not of itself return to a
horizontal position. The floating-tool-driver is so mounted and balanced in the
loop of the driving cord 13, that when the tool-holder 28 is removed therefrom or
when the weight of the tool-holder 28 is sustained by the hand of the operator, the
tool-driver will assume a horizontal position. It will therefore be seen that when
the operator is at work, there is no weight or strain whatever on the tool-holder 28.
which he holds in his hand, and he therefore is not subjected to any unusual strain
in the use of the machine. As the weight of the holder and floating tool-driver
which are shown in Fig. 2, may be comparatively slight, the driving band or
ccrd 13 will slip if the instrument becomes accidentally engaged in the napkin or
rubber in the mouth of the patient, thus stopping the tool and avoiding all danger
from accidental injury. The motor which is mounted in the case 8 is connected in
the well-known manner by means of wires with a source of electricity, and by means.
of a rheostat, the switch of which is operated by a foot-lever in convenient
proximity to the foot of the operator, so that the motor may be conveniently started
or stopped, or the speed thereof increased or decreased. The electrical connections,.
as also the rheostat and its operating switch are not shown, as they are of well-
known construction and are familiar to all skilled in the art.
When the tool or instrument is not in use, it may be instantly moved up to one
side out of the way. My device takes up no floor space, is compact and inexpensive,
and is so readily put into operation when required that a considerable saving is
effected in the time of the operator by its use.
It will be understood that for dental purposes the machine may be used to
operate a variety of dental instruments, which require to be rotated, as also to
drive brushes, grinding devices, and the like. It is therefore applicable to a large
variety of mechanical operations which are carried on by dentists and others, and
I do not desire to limit myself in the use of my invention to a dental engine, as many
mechanical operations which are carried on in connection with various industries
are very similar in character to the mechanical operations which are carried on by
dentists, and the device therefore, may be applied to a great variety of uses other
than those which come within the scope of a dentist's work.
Having now particularly ascertained and described the nature of the said inven-
tion, and in what manner the same is to be performed, as communicated to me
by my foreign correspondent, I declare that what I claim is :-
1. In combination, an electric motor, a driving band passing around a pulley
driven by the said motor, a guide around which said band passes after leaving the
said pulley and from which guide a loop of the band depends, a floating tool-driver
having a pulley engaged in the depending loop of the said driving band whereby
not only to rotate the said pulley but to sustain the tool-driver, and meaus for
supporting the said motor and guide and maintaining the parts in equipoise, the
motor counter-balancing the other movable parts, and vice versa, substantially as
described.
2. In combination, a lever, means for supporting said lever, an electric motor
supported from one end of the said lever and constituting a counter-balance for the
weight at the other side of the fulcrum of the said lever, a driving band or cord
passing around a pulley driven by the said motor a guide at the opposite end of
the said lever over which the said driving band or cord passes and from which the
latter depends in a loop, and a floating tool-driver having a pulley engaged in the
said loop, whereby not only to rotate the said pulley but to sustain the said tool-
driver, substantially as set forth.
3. In combination, a supporting bracket mounted with capacity for lateral
movement, a lever pivoted to the said bracket with capacity to move vertically
relatively thereto, an electric motor suspended from one end of the said lever, and
serving as a counter-balance for the weight at the other side of the fulcrum of the
lever, a driving band or cord passing around a pulley on the shaft of the said.

page_text: .
motor, guide pulleys at the opposite end of the said lever over which said driving
band or cord passes and from which the said cord depends in a loop, a floating
tool-driver comprising a spindle having a pulley engaged in the said loop whereby
not only to rotate the said pulley but to sustain the tool-driver, and a flexible
connecting shaft intermediate the said spindle and the tool which is driven thereby,
whereby the position of the tool may be changed while it is in operation,
substantially as set forth.
4. In combination, a lever, a motor applied to one end of the said lever, and
serving as a counter-balance for the weight at the other side of the fulcrum of the
lever, a driving band or cord passing around a pulley driven by the said motor, a
directing guide at the opposite end of said lever over which said driving band or
cord passes and from which the latter depends in a loop, a floating tool-driver
comprising a cylindrical casing, a spindle passing therethrough, a bracket journailed
on said casing, guide pulleys for the driving band or cord journalled on said
bracket, and a pulley fast on one end of the spindle and engaged in the depending
loop of the driving band or cord, the weight of said floating tool-driver being
equally disposed on each side of the point at which the driving band engages the
said pulley, whereby the said floating tool-driver is balanced on said driving band
and all weight or strain is removed from the tool-holder, substantially as set forth.
5. Mechanism constructed and operating substantially as set forth for supporting
and actuating a pendant tool-holder.
Dated this 29th day of January 1895.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.