Improvements in Impact Tools.
Year: 1899

page_text: Date of Application, 14th Feb., 1899-Accepted, 18th Mar., 1899
COMPLETE SPECIFICATION.
Improvements in Impact Tools.
I, THOMAS HENRY PHILLIPS, of St. Davids, in the County of Delaware, State
of Pennsylvania, United States of America, Mechanical Engineer, do hereby
declare the nature of this invention and in what manner the same is to be per-
formed to be particularly described and ascertained in and by the following
statement:
My invention relates to impact tools such as rock drills, and has reference
more particularly to the valves and valve controlled passages of the tool and to
the rod packing devices carried by the cylinder front head.
The objects of my invention are to avoid excessive wear and friction in the
steam chest to provide for a variable stroke of the piston; to overcome the
inertia of a heavy single valve and thereby insure a quicker and more sensitive
action of the valve mechanism to employ interchangeable valves; to cushion
the rear stroke of the piston so as to prevent it from coming into injurious con-
tact with the back head; to prevent cushioning of the forward stroke, so as to
insure an uncushioned blow; and to regulate the speed and time of travel of
the valve by which the flow of motive fluid to and from the forward end of the
cylinder is governed; without effecting the flow of motive fluid to and from the
rear end of said cylinder to reduce the wear on the rod packing, to avoid trouble
and delay, caused by jarring loose of the nuts such as are sometimes used to
hold in place the glands of the stuffing boxes; to prevent the glands from
falling out of position; and to provide for drawing the glands up evenly so as
to uniformly compress the packing when desired.
I will describe my invention with reference to the accompanying drawings of
which Figure 1 represents a longitudinal sectional elevation of an impact tool
constructed according to my invention; Figure 2 is a plan of the same with the
valve chest and valves in section; Figure 2ª is an enlarged sectional view of
one of the valves, Figure 3 is a transverse section on the line - Figure 1;
Figure 4 is a view of the underside of the valve chest structure shewing the
passages formed therein; Figures 5, 6, 7 and 8 are diagrams illustrating suc-
cessive positions of the piston and the position of the valves corresponding
therewith; and Figures 9, 10 and 11 are diagrams illustrating modifications of
part of my invention.
1 represents the cylinder of the tool containing an elongated piston compris-
ing a forward head 2, a rear head 3 and an intervening grooved or chambered
portion 4, the piston rod 5 passing through a stuffing box carried by the cylinder
front head 6 which will be hereinafter referred to.
The rear head 7 of the cylinder has the usual ratchet mechanism connected
with a spirally grooved bar 8 which engages with a nut or projection inside the
piston so that the latter will be partially turned on its axis on each backward
stroke. This mechanism forms no part of my present invention and may be
similar to any of the forms ordinarily employed.
The valve chest 9 is securely bolted to the top or side of the cylinder 1 and
contains two valve chambers arranged side by side, one of these chambers con-

page_text: taining a valve 10 and the other a precisely similar valve 11. Each of the
valves 10 and 11 is a spool-like structure consisting of a stem, with projecting
flanges or heads 12 and 13 at the opposite ends, and a central flange 14 between
the ends, the annular, space between the heads 12 and 14 of each valve com-
municating with the forward end of the chamber in which the said valve works
through a passage 15 of contracted diameter in the valve stem and said space
also communicates with the rear end of the chamber in which the valve works
through a like contracted passage 17 in the valve stem.
Each end of each valve chamber is enlarged in diameter for the reception of
a washer 19 which closes the end of that portion of the valve chamber in which
the valve reciprocates, rubber or other elastic material 20 being interposed
between this washer and the end cap 21 of the valve chest so as to provide an
elastic backing for the washer.
'
The annular space between the heads 12 and 14 of cach valve is in constant
communication with a steam inlet passage 22 which has a threaded opening at
each side. of the valve chest so that a steam supply pipe can be connected to the
said chest at either side, and in like manner, the annular space between the
heads 13 and 14 of each valve is in constant communication with an exhaust
passage 23 which likewise has a threaded opening at each side of the valve
chest for the reception of an exhaust pipe. The threaded openings which are
not in use are suitably plugged.
Between the inlet and exhaust passages of the valve chest are two passages 24
and 25 the passage 24 communicating with the chamber containing the valve 10
and the passage 25 communicating with the chamber which contains the valve 11
and said passage 24 being also in communication through a passage 26 with the
rear end of the cylinder 1 while the passage 25 is in communication through
a passage 27 with the front end of said cylinder.
The cylinder 1 contains a U-shaped passage 28 the ends of which communicate
with the interior of the cylinder the said passage being also in constant com-
munication with the exhaust passage of the valve chest through a passage 29.
The forward end of the chest containing the valve 10 is in communication
with the interior of the cylinder through a passage 30 formed partly in the
cylinder and partly in the valve chest and the rear end of the said valve chest
is also in communication with the interior of the cylinder through a passage 31.
The rear end of the chamber containing the valve 11 is in communication
with the passage 26 of the cylinder through a passage 32 formed partly in the
cylinder and partly in the underside of the valve chest, and the forward end of
the said valve chamber is in communication through a passage 33 on the under-
side of the valve chest with the chamber containing the valve 10 this communi-
cation being at a point in the said chamber between the rear end of the same
and the exhaust passage 23.
The operation of the tool is as follows:-
Supposing in the first place, the parts to be in the position shewn in Figures 1,
2 and 5, that is to say, the piston at the rear end of its stroke, the valve 10 at
the rear end of its stroke, and the valve 11 at the forward end of its stroke.
Motive fluid which I will refer to as steam is entering the valve chest' by the
steam inlet passage 22 through the forward space of the valve 10 and the
passages 24 and 26 to the rear end of the cylinder and steam is escaping from
the forward end of the cylinder through the passages 27 and 25 the rear space
of the valve 11 and the exhaust passage 23. Steam can always enter each end
of each valve chamber from the steam passage 22 through the passages 15 and 17
in the valve stem and the movement of each valve in its chamber is caused by
cutting off the escape of steam from one end of said valve chamber and at the
same time permitting the escape of steam from the opposite end of said valve
chamber.
!
The valves are retained in the position shewn in Figure 5 owing to the fact
that there is full steam pressure exerted on the front end of the valve 10 because

page_text: the passage 30 is closed by the forward head 2 of the piston while the rear end
of the chamber containing the said valve 10 is open to the exhaust through the
passage 31, the central groove of the piston and the passages 28 and 29 and the
rear end of the chamber containing the valve 11 is open to the full pressure of
steam in the passage 26 as well as to that which enters through the passage 17
in the valve stem, while the front end of the said chamber is open to the exhaust
through the passage 33 and the rear space of the valve 10. This continues
until the piston moves forward in the cylinder to the position shewn in Figure 6
that is to say, until its rear head 3 closes the passage 31 and the front head 2
uncovers the passage 30.
There being now a free escape of steam from the chamber in front of the
valve 10, and the escape from the rear end of said chamber being cut off,
the valve 10 by the accumulation of steam at its rear end is moved forward to
the position shewn in Figure 6 so as to cut off the supply of steam to the rear
end of the cylinder and open the said rear end of the cylinder to the exhaust,
and at the same time the rear head of the valve 10 cuts off the exhaust of steam
from the front end of the chamber containing the valve 11, by reason of the rear
head of the valve 10 being interposed between the opening of the passage 33 and
the exhaust passage 23. As the steam exhausts from the rear end of the
cylinder the pressure in the passage 26 and in the rear end of the chamber
containing the valve 11 is reduced and is finally overcome by the pressure in
the front end of the said chamber whereupon the valve 11 is moved rearward
as shewn in Figure 7 so as to open communication between the front end of the
cylinder and the steam inlet passage 22 through the front space of the valve 11,
and the passages 25 and 27.
Owing to the delay in the movement of the valve 11, however, the admission
of steam to the forward end of the cylinder does not take place until an appreci-
able time has elapsed after the opening of the rear end of the cylinder to the
exhaust, by the movement of the valve 10, hence the piston has moved forward
in the cylinder to the full extent necessary to cause the tool to deliver its blow
before steam enters the forward end of the cylinder.
An uncushioned blow is the result, and time has been allowed for the exhaust
from the rear end of the cylinder, and back pressure is thus avoided on the
retraction of the piston.
As the piston moves rearwardly the valves retain the position shown in
Figure 7 until the said piston reaches the position shown in Figure 8 that is to
say, until the front head 2 closes the passage 30 and the rear head 3 opens the
passage 31. Escape of steam from the rear end of the chamber containing the
valve 10 being thus permitted and escape of steam from the front end of said
chamber being cut off, the valve 10 moves rearwardly again, admitting steam
to the rear end of the cylinder, and opening to the exhaust the front end of the
chamber containing the valve 11, so that the pressure of live steam against the
rear end of the said valve will immediately effect the forward movement of the
same, thus opening the forward end of the cylinder to the exhaust, this admission
of steam to the rear end of the cylinder and exhaust from the front end, being
effected at such a point in the rearward travel of the piston, that ample cushioning
of the rear stroke is provided for, and injurious contact of the piston with the
rear head of the cylinder is prevented.
By thus using two valves, one controlling the flow of steam to and from the
rear end of the cylinder, and the other controlling the flow of steam to and
from the front end of the cylinder, and by making the movement of the latter
valve dependent upon the previous movement of the former, I positively insure
the attainment of the uncushioned forward stroke, and cushioned back stroke,
of the piston, the use of the two valves also enabling me to make each valve so
light that it has less inertia, and thus is more sensitive than a single heavier
valve. Each valve, moreover, being free to turn and perfectly balanced, exces-
sive wear and friction are avoided, and both valves being 'precisely alike, the

page_text: substitution of one for the other by an ignorant or careless attendant cannot
affect the working of the tool.
Variable stroke of the piston is also provided for, since it will be apparent
that the tool will be operative so long as the forward stroke permitted is sufficient
to cause the forward head of the piston to uncover the passage 30 and the rear
head to cover the passage 31, the back stroke in this case being correspondingly
limited, hence the piston will simply reciprocate with a short stroke in mid
position a longer stroke being provided for by moving the cylinder rearwardly
on its supporting structure.
Secured to the front end of the cylinder is a split and separable front head or
casing 6 held together by transverse bolts 36-37 and having at the inner end a
split and separable plug 38 which fits into the forward end of the bore of the
cylinder, the forward end of said casing being internally threaded for the recep-
tion of an external thread upon a gland or follower 39 which is likewise, by
preference, split and separable so that it can be readily applied to the piston
rod 5. A mass of packing 40 is interposed between the inner end of this
gland 39 and the plug 38, so that by screwing up the gland this mass of packing
can be compressed to the desired extent, the pressure being exerted evenly
throughout the mass instead of unevenly as is sometimes the case when the gland
or follower has projecting ears acted upon by independent tightening devices
one of which can be screwed tighter than the other. The forward end of the
split casing 6 is slotted, as shown in Figures 2 and 3 so that this portion_can,
by the action of the bolts 37, be caused to bind tightly upon the gland or
follower 39 and thus lock the same in position after adjustment. In case, how-
ever, there should be any loosening or backing off of this gland, the complete
release of the same from the casing 6 is prevented by the engagement of an
external shoulder 41 upon the gland, with an internal shoulder 42 in the casing,
so that under no circumstance can the gland drop from the casing and fall into
the hole which is being drilled, an accident which sometimes happens when the
ordinary gland with studs and nuts is employed, and which is likely to cause
such jamming of the drilling tools in the hole as to make their withdrawal
difficult and sometimes necessitate their abandonment.
It will be observed that the packing is arranged close to the joint between
the cylinder and the front head, that is, as close as possible to the piston, where
there is the least vibration of the piston rod, and consequently the least wear
upon the packing, so that the latter will remain in good condition for a longer
time than is the case with packing arranged more or less in advance in the front
head where the vibration of the piston rod is more appreciable.
When it is desired to repack the stuffing box, this can be readily effected by
removing the nuts from one or other of the ends of the longitudinal bolts 35,
by which the opposite heads are secured to the cylinder, and then sliding the
head 6 forward on the rod 5, until the plug 38 can be freed from engagement
both with the cylinder and the head, the parts of the plug being then separated
so as to permit access to the interior of the stuffing box.
After the latter has been re-packed the parts of the plug can be re-applied to
the rod and the head 6 again secured in position.
The casing 6, plug 38, and gland 39 are made in split and separable halves,
because it is preferable in this class of tools to forge from one piece of metal
the piston rod and the chuck in which the shank of the drill steel is clamped,
the chuck as well as the piston being of greater diameter than the rod, so that
the latter cannot be passed longitudinally through the plug or gland. When the
rod is keyed or otherwise detachably secured to the piston or chuck, the split
construction of the parts through which the rod passes, need not necessarily be
adopted.
The use of the passages 15 and 17, in the valves for maintaining constant
communication at each end of each valve chamber with the live steam passage,

page_text: is not essential to the proper carrying out of my invention as the same end can
be attained by the use of passages in the valve chest, as for instance, the
passages 15 and 17" shown in Figure 9, in fact the maintenance of constant live
steam communication with each end of the chamber containing the valve 11 is
not necessary, as steam, may if desired be conducted to and from the opposite:
ends of the said chamber, solely through the medium of the passages 32 and 33
under control of the valve 10, and the entrance of live steam to the forward end
of the chamber containing the valve 10 may be effected by permitting a slight
clearance between the forward head of the said valve and the chest, instead of
by a passage through the valve. These modifications are illustrated in Figure 10.
The construction shewn in Figures 1 and 2 however, is preferred as it permits
me to use snug fitting valves, and renders the valves interchangeable.
The rear end of the chamber containing the valve 11 may if desired, like the
front end, communicate directly with the chamber containing the valve 10, as
shown for instance at 32 in Figure 10 instead of communicating indirectly
through the medium of the passages 24 and 26, as shown in Figures 5 to 8 the
end to be attained being the placing of the said passages 32 and 33 in com-
munication with the live steam and exhaust passages of the chest alternately,
or the alternate closing of each passage and the opening of the same to the
exhaust, and the construction shown in Figures 1, 2 and 4 being adopted simply
for convenience, as it avoids the formation of complicated passages in the valve
chest, which would otherwise be required.
The advantages of my invention (so far as they arise from the use of two
light, independent and easily operated valves, one for controlling the flow of
steam to and from the front end of the cylinder and the other for controlling
the flow of steam to and from the rear end of the cylinder) may be attained,
even if the movement of the front end controlling valve is not dependent upon
the previous movement of the rear end controlling valve.
In the structure shown in the diagram Figure 11, for instance, the passages 32b
and 33b lead directly to the cylinder, the termination of the passage 33b, being
some distance in advance of that of the passage 31, and the termination of the
passage 32 being some distance in advance of that of the passage 30, so that
both sets of passages will be controlled by the piston.
If this construction he employed the movement of the valve 11 will follow
that of the valve 10 on the forward stroke of the piston, so as to obtain the same
results of uncushioned blow, and free rear exhaust which arise from the pre-
ferred construction shown in Figures 1 to 8, but the movement of the valve 11,
will in this case, precede that of the valve 10 on the back stroke of the piston,
hence as compared with the preferred construction, there will be an earlier cut
off of the steam from the front end of the cylinder, and consequent lessened
lifting power, decreased rear travel of the piston and a lighter blow.
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 combination in an impact tool, of a cylinder, a reciprocating piston
contained therein a valve chest having inlet and exhaust passages for the motive
fluid, and two valves each in its own chamber and each operated by the pressure
of the motive fluid, one valve controlling the flow of motive fluid to and from
the rear end of the cylinder, and the other valve controlling the flow of motive
fluid to and from the front end of the cylinder substantially as herein before
described.
2. The combination in an impact tool, of a cylinder, a reciprocating piston
contained therein, a valve chest having inlet and exhaust passages for the
motive fluid, and two valves, each in its own chamber one valve controlling the
flow of motive fluid to and from the rear end of the cylinder and the other valve
controlling the flow of motive fluid to and from the front end of the cylinder,

page_text: the movement of the front end controlling valve, being governed by and follow-
ing the movement of the rear end controlling valve, substantially as herein.before
described.
3. The combination in an impact tool, of the cylinder a reciprocating piston
therein, a valve chest having inlet and exhaust passages for the motive fluid,
and two valves, each in its own chamber one of the said valves controlling the
flow of motive fluid to and from the rear end of the cylinder, and the other
valve controlling the flow of motive fluid to and from the forward end of the
cylinder, the movement of said rear end controlling valve being governed by
the movement of the piston, and the movement of the said front end controlling
valve being governed by, and following the movement of the rear end controlling
valve substantially as herein before described.
4. The combination of the cylinder, a reciprocating piston therein, a valve
chest having inlet and exhaust passages for the motive fluid, two valves, each
in its own chamber, a passage leading from the first valve chamber to the rear
end of the cylinder, a passage leading from the second valve chamber to the
front end of the cylinder, each passage, by the movement of its controlling valve,
being placed in communication alternately with the inlet and exhaust passages
of the chest, and passages for admitting motive fluid to and exhausting it from,
the opposite ends of each valve chamber, the said passages being so arranged
that on the forward movement of the piston in the cylinder, the first valve will
be moved so as to open the rear end of the cylinder to the exhaust, and the
second valve will be subsequently moved, so as to open the front end of the
cylinder to the inlet, substantially as herein before described.
5. The combination of the cylinder, a reciprocating piston therein, a valve
chest having inlet and exhaust passages for the motive fluid, two valves, each in
its own chamber, a passage leading from the first valve chamber to the rear
end of the cylinder, a passage leading from the second valve chamber to the
front end of the cylinder, each passage, by the movement of its controlling
valve being placed in communication alternately with the inlet and exhaust
passages of the chest, and passages for admitting motive fluid to and exhausting
it from the opposite ends of each valve chamber the said passages being so
arranged that on the forward movement of the piston in the cylinder, the first
valve will be moved so as to open the rear end of the cylinder to the exhaust,
and the second valve will be subsequently moved, so as to open the front end
of the cylinder to the inlet, and on the rearward movement of the piston in the
cylinder, the first valve will be moved so as to open the rear end of the cylinder
to the inlet, and the second valve will be subsequently moved so as to open the
front end of the cylinder to the exhaust, substantially as hereinbefore described.
6. The combination of the cylinder, a reciprocating piston therein, a valve
chest having inlet and exhaust passages for the motive fluid, two valves each in
its own chamber, a passage leading from the first valve chamber to the rear
end of the cylinder, a passage leading from the second valve chamber to the
front end of the cylinder, each passage, by the movement of its controlling valve,
being placed in communication alternately with the inlet and exhaust passages
of the chest, passages leading from the opposite ends of the first valve chamber
to the cylinder so as to be controlled by the piston, and passages leading from
the opposite ends of the second valve chamber to the first valve chamber, so as
to be controlled by the valve in the said chamber, substantially as herein before
described.
7. The combination of the cylinder, a reciprocating piston therein, a valve
chest having inlet and exhaust passages for the motive fluid, two valves each in
its own chamber, a passage leading from the first valve chamber to the rear end
of the cylinder, a passage leading from the second valve chamber to the front
end of the cylinder, each passage, by the movement of its controlling valve,
being placed in communication alternately with the inlet and exhaust passages

page_text: of the chest, passages leading from the opposite ends of the first valve chamber
to the cylinder so as to be controlled by the piston, passages leading from the
opposite ends of the second valve chamber to the first valve chamber, so as to be
controlled by the valve in the said chamber, and passages whereby motive fluid
is continuously admitted to the opposite ends of the said first valve chamber,
substantially as hereinbefore described.
8. The combination of the cylinder, a reciprocating piston therein, a valve
chest having inlet and exhaust passages for the motive fluid, two valves each
in its own chamber, a passage leading from the first valve chamber to the rear
end of the cylinder, a passage leading from the second valve chamber to the
front end of the cylinder, each passage, by the movement of its controlling
valve, being placed in communication alternately with the inlet and exhaust
passages of the chest, and passages leading from the opposite ends of the first
valve chamber to the cylinder so as to be controlled by the piston, passages lead-
ing from the opposite ends of the second valve chamber to the first valve
chamber, so as to be controlled by the valve in the said chamber, and passages
whereby motive fluid is continuously admitted to the opposite ends of each valve
chamber, substantially as hereinbefore described.
9. The combination of the cylinder, a reciprocating piston therein, a valve
chest having inlet and exhaust passages for the motive fluid, two valves each
in its own chamber, a passage leading from the first valve chamber to the rear
end of the cylinder, a passage leading from the second valve chamber to the
front end of the cylinder, each passage, by the movement of its controlling valve,
being placed in communication alternately with the inlet and exhaust passages
of the chest, passages leading from the opposite ends of the first valve chamber
to the cylinder so as to be controlled by the piston, passages leading from the
opposite ends of the second valve chamber to the first valve chamber, so as to
be controlled by the valve in the said chamber, and passages in the valves,
whereby each end of each valve chamber is continuously in communication
with the motive fluid inlet passage, substantially as hereinbefore described.
10. The combination with the cylinder, piston and piston rod of an impact
tool, of a stuffing box casing having an internal shoulder, and a gland for com-
pressing the packing, the said gland having an external shoulder situated inside
of the shoulder of the stuffing box casing, and adapted to engage therewith to
prevent removal of the gland, substantially as herein before described.
11. The combination with the cylinder, piston, and piston rod of an impact
tool, of a split and separable stuffing box casing having an internal shoulder,
and a gland or follower contained within the said casing, and having an
external shoulder located inside of the shoulder of the stuffing box casing and
adapted to engage therewith, substantially as herein before described.
12. The combination with the cylinder, piston, and piston rod of an impact
tool, of a split and separable stuffing box casing slotted at the forward end, a
gland screwed into the said casing, and transverse bolts whereby the slotted
portion of the casing is confined to the said gland, substantially as herein before
described.
13. The combination with the cylinder, piston, and piston rod of an impact
tool, of a split and separable stuffing box casing having an internal shoulder.
and a split and separable gland or follower fitted to the said stuffing box and
having an external shoulder for engaging with that of the casing, substantially
as hereinbefore described.
14. The combination with the cylinder, piston, and piston rod of an impact
tool, of a stuffing box casing having an internal shoulder, a gland or follower
having an external shoulder located inside of the shoulder of the stuffing box
casing and adapted to engage therewith, and a plug at the inner end of the
said stuffing box casing, substantially as hereinbefore described.
15. The combination with the cylinder, piston, and piston rod of an impact
tool, of a stuffing box casing having an internal shoulder, a gland or follower

page_text: having an external shoulder situated inside of the shoulder of the stuffing box
casing, and adapted to engage therewith, and a split and separable plug at the
inner end of the said stuffing box casing, substantially as herein before described.
Dated this 14th day of February 1899.
JOHNSONS & WILLCOX,
47, Lincolns Inn Fields, London, W.C., Agents.