provements in Breast Drills
Year: 1898

page_text: Date of Application, 6th June, 1898-Accepted, 23rd July, 1898
COMPLETE SPECIFICATION
Improvements in Breast Drills
I, HERBERT JOHN HADDAN, of the Fum of Herbert Haddan & Co, of
18, Buckingham Street, Strand, London, WC, Civil Engineer, do hereby declare
the nature of this invention a communication to me from abroad by the Chicago
Pneumatic Tool Company, of Chicago. Illinois, in the United States of America,
and in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement. —
-
The invention relates to that class of rotary pneumatic drills, which are known
as breast-drills, being small, portable drills for comparatively light work, and
adapted to be held in the hands of the operator and pressed to the work by
pressure of his breast against a plate on the upper end of the drill, called the
breast-plate The invention has for its object the provision of a simple, smull,
compact, and highly efficient drill of this character, in which the drill shall be
driven by the piston of an oscillating cylinder mounted in the frame of the dull
and having its piston-1od connected to the crank of the drill shaft, as hereinafter
described in connection with the accompanying diawings, in which Figure 1
represents a front elevation of the dull, Figure 2 an approximately vertical
section, with the piston and crank in a different position from that shown in
Figure 1: Figure a horizontal section approximately on the line 3-3 of
Figure 2, and Figure 4a honzontal sectional detail approximately on the
line 4 of Figure 2
The same letters of reference are used to indicate corresponding parts in the
several views
The frame A of the drill, which supports the moving parts, and which is
preferably of substantially the form shown in the drawings, has journaled in
what may be called its forward side the vertical drill-shaft B which has inter-
posed in it a clank C, and at its lower end catiles a chuck or holder D for the
drill point This shaft B also has secured upon it beneath the frame A a hand-
wheel E, by which it may be tuined by hand in starting the drill or when other
occasion may require
Connected to the crank C of the drill shaft B is the forward end of the rod F
of a piston G fitting in a horizontal oscillating cylinder H which is provided at
its upper and lower sides with ti unnions I by which it is journaled in the
frame A The piston rod F extends entuely through the cylinder H and in its
rearward movement its rear end plays through a horizontal opening K in the rear
side of the frame A, Figures 2 and 3 The font and rear heads of the cylinder H
are provided with stuffing boxes L L' surrounding the piston-rod F
The trunnion I of the cylinder and the upper wall of the cylinder contain the
passages M N through which the motive fluid is alternately admitted to and
exhausted from the opposite ends of the cylinder, the passage N being shown in
dotted lines in Figure 2, and both passages in full lines in Figure 4 The horizontal
upper ends of these two passages M N open through the forward side of the
trunnion I, which latter constitutes the valve and co-operates with a curved
valve face O fitting against the forward side of the trunnion I, Figure 4, and

page_text: The
having opening through it the inlet port P which communicates with the supply
The valve
passage through which the motive fluid is admitted to the machine
face is formed in the present instance upon the rear end of a hardened plug R
fitted into the rear end of a casting S secured to the upper side of a frame A
and having formed in it the inlet passage Q, which passage Q connects at its
extreme forward end with a short passage or port T, Figure 4, communicating
with the threaded opening U into which is sciewed the usual nipple for the
reception of the flexible hose leading to the compressed air lesei voir
casting S also has formed in it the upper half of a vertical chamber S', whose
lower half V, is formed in the fiame A, as shown in Figure 2 Fitting in this
chamber is a throttle valve W controlling communication between the parts TQ
of the inlet passage, and provided with a vertical stem X extending upward
though and projecting from a reduced opening in the casting S When the
valve W is in its upper position, as in Figure 2, communication between the
parts TQ of the inlet passage 19 closed, and the supply of motive fluid thereby
cut off When the valve W is pressed downward to its limit of movement the
inlet passage will be opened and the motive fluid admitted to the dill As the
cylinder oscillates in its bearings the upper ends of the ports M N will be
alternately brought into communication with the inlet port P and the outer au,
to alternately adimit and exhaust the motive fluid to and from the opposite ends
of the cylinder, as usual
Secured to the upper side of the fiame A of the machine at its forward edge
is a vertical voke Y, Figure 1, whose upper end 18 connected by a brace Z with
the rear end of the frame A, Figure 2 Guided vertically in the upper end of
this yoke 18 a rod which has secured to its upper end the breast-plate B¹
heretofore referred to, Figures 1 and 2, and which carries at its lower end a
laterally projecting arm whose rear end fits in a notch or recess in the upper
end of the stem X of the throttle valve W, Figure 2 A spring D' presses the
rod A and parts caned by it upward, and normally holds them in position for
the throttle-valve to cut off the supply of motive fluid from the machine, but
when the drill is pressed to its work the pressure exerted against the breast-
plate B' will force the rod A downward and open the throttle and thereby admit
the motive fluid to the machine Whenever the pressure is relieved the supply
of motive fluid will be automatically cut off
The frame A has the laterally projecting handles E' E' secured to it, Figure 1,
which the operator grasps with his hands while he bears with his breast against
the plate B and presses the drill to its work
It is not essential that the throttle-valve shall be operated by the breast-plate
If desued a fixed breast-plate may be employed, and a separate handle or operat-
ing device for the valve be provided
Having now particularly described and ascertained the nature of this inven
tion and in what manner the same is to be performed, I declare that what I
claim 18.-
1 The herein described breast-drill, comprising a suitable frame, a crank-shaft
journaled therein, an oscillating evlinder mounted in said frame and having the
iod of its piston connected to the crank of said shaft, inlet and exhaust-ports
controlled by the oscillation of the cylinder, and a breast-plate upon said frame
for pressing the dill to its work
2 The herein described breast-drill, comprising a suitable frame, a crank-shaft
journaled therein, an oscillating cylinder mounted in said frame and having the
rod of its piston connected to the crank of said shaft and having inlet and exhaust
passages for the opposite ends of the cylinder formed in one of the cylinder
trunnions, and their co-operation with the supply and exhaust controlled by the
oscillation of the cylinder, and a breast-plate upon said frame for pressing the
drill to its work
3. The herein described breast-drill, comprising a suitable frame, a crank-shaft

page_text: Journaled therein, a hand-wheel fast upon said shaft, an oscillating cylinder
mounted in said frame and having the rod of its piston connected to the crank
of said shaft and having inlet and exhaust passages for the opposite ends of the
cylinder formed in one of the cylinder trunnions, and their co-operation with
the supply and exhaust controlled by the oscillation of the cylinder, and a breast-
plate upon said frame for pressing the drill to its work.
4 The herein described breast-drill, comprising a suitable frame, a crank-shaft
Journaled therein, an oscillating cylinder mounted in said frame and having the
rod of its piston connected to the crank of said shaft and having inlet and
exhaust passages for the opposite ends of the cylinder formed in one of the
cylinder-trunnions, and then co-operation with the supply and exhaust controlled
by the oscillation of the cylinder, a movable breast-plate mounted upon said
frame, a throttle valve for the inlet passage controlled by said breast-plate
5. The herein described breast-dill, composed of the frame A, the drill shaft B
Journaled in said frame and having the crank C interposed in it and the hand
wheel E secured upon it, the oscillating cylinder H provided with the
trunnions I J Journaled in the frame A and containing the piston G having its
rod F connected to the crank C, the trunnion I and upper wall of the cylinder
having the passages M N formed in them and co-operating at their upper ends
with the valve face O having the port P communicating with the inlet passage Q,
and the throttle valve W controlling the passage Q
6 The herein described breast-drill, composed of the frame A, the drill shaft B
journaled therein and provided with the crank C and hand-wheel E, the oscillating
oylinder H having the trunnions I J Journaled in the frame A, the piston G fitting
in said cylinder and having the piston rod F extending through the opposite heads
of the cylinder and connected at its forward end to the crank O, the passages M N
formed in the trunnion I and wall of the cylinder H for admitting the motive
fluid to and exhausting it from the opposite ends of the cylinder, said passages
co-operating at their upper ends with the valve face O having the port P opening
through it and connecting with the inlet passage Q, and the throttle valve W
controlling the passage
7 The herein described breast-drill, composed of the frame A, the drill shaft B
journaled therein and having the crank C and hand-wheel E, the cylinder H
having the trunnions I J journaled in the frame A and containing the piston G
having its rod F connected with the crank C, the trunnion I and upper wall of
the cylinder having formed in them the passages M N for admitting the motive
fluid to and exhausting it from the opposite ends of the cylinder, the casting S
secured to the upper side of the frame A and having fitted in its rear end the
hardened plug R having the curved valve face O fittang against the forward side of
the trunnion I and provided with the port P co-operating with the upper ends
of the passages M N and communicating with the inlet passage Q, and the
throttle valve W fitting in the vertical chamber V and controlling the passage Q
8 The herein described breast-drill, composed of the frame A, the drill shaft B
journaled therein, and provided with the clank C and hand-wheel E, the oscil-
lating cylinder H having the trunnions I J journaled in said frame and containing
the piston G having its rod F connected to the crank C, the trunnion I and upper
wall of the cylinder H having formed in them the passages M N co-operating
at their upper ends with the valve face O and with the port P communicating
with the inlet passage Q, the throttle valve W controlling said passage and
provided with the vertical stem X, the yoke Y secured to the upper side of the
frame A, the vertical sliding rod A¹ mounted therein, the breast-plate B¹ secured
to the upper end of said rod, and the laterally projecting arm & secured to its
lower end and engaging the stem X of the throttle valve W