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Патент USA US2117810

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May 17, 1938.
E. B. Lr-:AR
Filed June 5, 193s
s sheets-sheet 1
May 17, 1938.
E. B. LEAR u
Filed June 3, 1936
3 Sheets-Sheet 2
May 17, 193s.
Filed June 5, 195s '
s sheets-sheet s
Patented May 17, 1938
Earl B. Lear, Detroit, Mich., assignor to Chicago
Pneumatic Tool Company, New York, N. Y., a
corporation of New Jersey
'Application June 3, 1936, .Serial No. 83,210
1 Claim.
The present invention relates to fluid pressure
operated percussive tools, such as rock drills, and
is concerned particularly with the throttle .and
(Cl. 121-40)
and associated ports, the valve being arranged
in the ori-position;
»distributing valves for such tools.
Among the objects of the invention are to
reduce the manufacturing cost and weight of a
rock drill and to insure positive hole cleaning.
Accordingly, a throttle Valve and a blower valve
are combined into a unitary structure so ar
ie ranged that each time the throttle valve is turned
on or off a stream of air is directed through the
bore in the drill steel to remove the detritus from
the hole. The throttle valve is so constructed
thatit closes the central exhaust port for the
l5 cylinder whenever the throttle valve is in either
the blowing or closed position to prevent the
admissionA of dirt through the exhaust port to
the cylinder bore.
A feature of the invention resides in fluid pres
sure means for holding the distributing valve
immovable against one of its seats to admit
compressed air to the rear end of the cylinder
bore from whence the air is conducted through
the hollow piston to the drill steel bore with a
Vminimum of leakage. The means for holding
the distributing valve in position comprises ports
in a manipulative throttle valve, one of which
admits live air lto one face of the distributing
valve and another of which exhausts the oppos
ingY face of the distributing valve.
Another object ofthe invention is the pro
vision of a distributing valve of the disc Atype
having means for centering the valve relative to
its seats and for prolonging the life of the valve.
The vdistributing valve is in the form of a disc
perforated to receive a bushing and'having a
hub adapted to fit the bushing and guide the
valve in its movement.
Other objects and features of the invention will
appear more clearly from the accompanying
`drawings and appended claim.
In the drawings which illustrat e one embodi
ment of the invention:
Fig. 1 is an elevation of a portion of a rock
drill ofthe sinker type, the throttle valve handle
being shown in drilling position;
Fig. 2 is a section through the plane indicated
by the arrows 2-2 in Figs. 1 and 6;
Fig. 3 is a view similar to Fig. 2 but partly in
elevation .and partly schematic and showing the
combined throttle and blower valve in blowing
Fig. 4l isa fragmentary schematic view show
ing two‘diiierentsections of the throttle valve
Fig. 5 is a View similar to Fig. 4 but with the
throttle valve> adjusted to the drilling position;
Fig. 6 is an end elevation looking from left 5
toward right in Fig. 1;
Fig. '7 is a cross-section as. indicated by the
arrows l-'I in Fig. 1, but with the throttle valve
in blowing position;
Fig. 8 is a fragmentary longitudinal section
showing the cylinder, piston and distributing
valve,- certain passages being, for convenience,
shown in simplified form;
Fig. 9 is a fragmentary longitudinal sectional
view on an enlarged scale showing the distribu 15
ting Valve and valve chest, and
Fig. 10 is a sectional view of the distributing
valve on the same scale as Fig. 9.
The rock drill illustrated in the drawings com
prises a cylinder II having a piston I2 recip 20
rocably mounted therein. The forward part of
the piston has a grooved extension I3 which
passes through a front cylinder washer I4
and into fluted engagement with an internally
grooved chuck nut I5 which is’keyed to a chuck
i6. The washer I4 forms a closure for the front
end of the cylinder. At the end of its forward
stroke the piston strikes the drill steel I1 having
a non-circular ñt with the chuck. The chuck
nut I5, chuck I6, and washer I4 are held in posi 30
tion by means of a iront head I9 which may be
fastened to the cylinder by any suitable means,
such asA elongated bolts I8 shown in Figs. l, 6
and '7.
The rear of the cylinder II is closed by a back
cylinder’washer 20 which cooperates with a valve
case 2l to form a housing for a distributing valve
22. A ratchet ring 23 is. positioned between the
valve case and a backhead 24, the backhead be
ing adapted to seat the heads Ißa of the bolts
I8. The backhead is provided with arms 25 for
supporting a grip handle 26. A plate 2l at the
rear end of the ratchet ring cooperates with the
backhead 24 to provide a lubricant reservoir. 28.
Any suitable means may be provided for ro* 45
tating the piston I2 step-by-step as it recipro
cates. As shown, the rotating mechanism com
prises a riiie nut Sil screwed to the piston, a rifle
bar _3l spirally splined to the nut, and pawls 32
carried by the head of the riñe bar and engageable
with the internally toothed ratchet ring 23. A
bushingf33, surrounding the rifle bar, provides a
support for valve 22.
The distributing valve 22 is shown most clearly
in Figs. 9‘and 10.
It comprises a disk portion.35 » 55
and a hub 3’6 integral therewith. The forward
face of the disc portion is a plane surface adapted
to rest on one or the other of the seats 31]c
and 311* formed on the member 20. Valve seats
313‘ and 317’ are ñat and angularly disposed relative
to each other so that the planes of the seats
diverge forwardly.
The seats have recesses 38]c
and 38T. A port 40 connects the recess 38T with
the rear end of the cylinder and a passage 4|
connects recess 38j with the front end of the
cylinder thereby to admit live pressure fluid al
ternately to opposite sides of the piston head I2.
The interior of the hub 35 is deñned by frusto
conical surfaces 36a and 351), the included angle
15 between such surfaces being equal to the included
angle between the seatsl 31j and 317’ so that the
interior of the hub embraces. the bushing 33 on
opposite sides when the disc portion 35 rests on
either seat. The upper edge 35e of the hub is
20 bevelled to iit the adjacent portion of the valve
chest 2|. The hub 36 guides the valve in its
movement, permits rapid tripping of the valve and
prolongs the life of the same. The hub also cen
ters the valve with respect to Vits seats and as
25 sociated passages and thereby insures an adequate
supply of pressure fluid with minimum leakage.
The valve 22 is free to be oriented about its axis
to distribute wear.
When the machine is conditioned for drilling,
the operation is as follows: Live air is admitted (by
throttle means hereinafter described) to a cham
ber 43 in the valve housing 253, 2i, the rear face
of the distributing valve 22 being exposed to pres
sure fluid in said chamber. Assuming the dis
35 tributing valve and piston occupy the position
shown in Figs. 8 and 9, live air passes around the
peripheral edge of the valve disc portion 35 over
the seat 31T and through recess 381“ and port 4|!
to the rear end of the cylinder, thereby forcing
the- piston l2 forwardly. The air in front of the
piston head I2 is vented through exhaust port 44
until the piston head has covered the exhaust
port. The piston continues moving forward un
der its momentum and delivers a blow to the drill
steel l1. Toward the end of the forward stroke
of the piston the valve is tripped to the position
shown in Fig. 2 by the combined action of a re
duction in pressure in the recess 38T caused by
the uncovering of the exhaust port 44, and the
building up of pressure at the front end of the
cylinder due to the compression of air trapped
in front of the piston head I2 which is trans
mitted to the recess 38]c by means of passage 4|.
After the valve has been tripped, live pressure
fluid from chamber 43 passes around the periph
eral edge of the distributing valve over seat 31j
and through recess 38j and passage 4| to the
front end of the cylinder || to force the pis
ton rearwardly. The air at the rear end of the
60 cylinder is first exhausted through port 44 and
then compressed aftery the piston head covers
the exhaust port. When the front edge of
the piston head uncovers the exhaust port, the
drop in pressure at the front end of the
65 cylinder causes a corresponding reduction in pres
sure in the recess 38f which, together with the
increase of pressure in recess 381", is effective to
trip the valve to the position shown in Fig. 9,
thus completing a cycle of operation.
It is desirable to provide means for blowing a
stream of live air through the drill steel I1 to
clear the bore hole of accumulated detritus. Ac
cordingly, the invention comprises a blowing ar
rangement which is operable whenever the throt
tle valve is turned on or 01T and which does not
require the manipulation of any device other
than the throttle valve.
The throttle valve 45, as shown in Fig. 7, is gen
erally of frusto-conical shape to fit a correspond
ingly shaped bore in a projection 46 on the out
side of the cylinder ||. A handle 41, having an
extension on the valve, is keyed thereto at 48 and
is retained by a nut 49 threaded on the extremity
of the throttle valve. A spring-pressed detent 50
carried by the handle is adapted to register with l0
any one of three depressions 5| on the cylinder
projection 46 for yieldingly locking the handle
and valve in selected position of adjustment. A
sleeve 53 threaded to the cylinder projection 46,
provides a retainer for an air supply hose 54 15
which communicates with recess 55 in the throttle
As shown in Figs. 3, 4 and 5, the live air recess
55 communicates with two- ports in the throttle
valve 45 adapted selectively to admit pressure 20
fluid to passage 51 leading to the supply chamber
4S in the distributing valve housing 20, 2|. One
of these ports 58 registers with passage 51 in the
drilling position and the other port 59 registers in
the blowing position. The throttle valve 45 has a 25
groove Eil out oi’ communication with the live air
recess 55 and positioned to connect the main ex
haust port 44 with the exhaust port 6| in the pro
jection 46 when the throttle valve is adjusted to
drilling position. A supplementary groove 60a 30
establishes communication between exhaust port
6| and a passage 63 leading to recess 38j in the
distributing valve housing 2l to vent the recess
when the throttle valve is adjusted to blowing 35
When the throttle handle 41 is in the drilling
position, shown in Figs. 1 and 2, live air is sup
plied to the distributing valve case 2| through
port 58 in the throttle valve and passage 51 in
the cylinder. At the same time the central ex 40
haust port 44 in the cylinder is vented through
groove 65 in the throttle valve. In order to stop
the operation of the machine, the throttle han
dle 41 must first be turned to the blowing posi
tion shown in Figs. 3 and 7. In this position, the 45
throttle valve supplies live air to the distributing
valve chamber 43 by means of port 59` and pas
sage 51. Simultaneously the central exhaust port
44 in the cylinder is closed by the throttle valve,
and the recess 38j, facing one side of the dis
tributing valve, is vented through cylinder pas
sage 63 and throttle valve -grooves 60a and 60.
The preponderance of pressure on the rear face
of that portion oi the distributing valve which
overlies recess 38j moves the valve to the position 55
shown in Fig. 9 and holds the valve against seat
31j to admit live pressure ñuid through port 40
to the rear end of the cylinder.
The pressure
fluid admitted through port 4|) drives the piston
forwardly until it is stopped by engagement with 60
the drill steel. Pressure ñuid in back of the piston
passes through the clearance between the splines
on the rifle bar 3| and riñe nut 30 and through
the interior of the hollow piston and drill steel to 65
blow the detritus from the bore hole. When the
valve handle 41 is adjusted to the off position, the
live air recess 55 in the throttle valve is cut off
from communication with the cylinder passages,
and the main exhaust port 44 in the cylinder is 70
closed to prevent the admission of dust to the
interior of the cylinder.
What is claimed is:
A fluid actuated rock drill comprising a cylin
der, a hollow piston reciprocating therein, a hol 75
low drill steel adapted to receive blows from the
piston, a distributing valve chest, passages leading from said chest to the respective ends of the
cylinder, a main exhaust port for the cylinder, a
supplementary exhaust port for the front end of
the cylinder, a fluid pressure supply chamber in
the valve chest, a distributing valve in the chest
valve, a manipulative throttle valve mounted
characterized in that said throttle valve
and housing are provided with selectively operable means for venting either exhaust port and
simultaneously closing the other exhaust port,
controlling communication between said supply
and the supply chamber in the distributing valve
chamber and said passages, a source of live pres
sure fluid, connections between said source and
said supply chamber, a housing for a throttle
and vice versa, and are provided with selectively
operable means for opening and closing the con
nections between the source of live pressure fluid
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