Note: Descriptions are shown in the official language in which they were submitted.
1238897
DRILL BITS WITH CONE RETENTION MEANS
BACXGROUND OF THE INVENTION
~IELD OF THE INVENTION
1 This invention relates generally to drill bits con~
nectable to the lower ends of rotary drill strings for use in
drilling oil and gas wells as drilling mud is circulated
downward through the string, out the bit, and upwardly within
the annulus between the string and well bore so as to remove
cuttings therefrom. More particularly, it relates to im-
provements in drill bits of this type having cones which are
mounted for rotation about thrust bearings which extend in-
wardly from the lower ends of legs which depend from a shank
at the upper end of the bit body which is attached to the
drill string.
In conventional bits of this type, the cones are
releasably retained or hel~d on the thrust bearings by locking
balls or split metal rings received within races and matching
recesses formed in the inner and outer cylindrical bearing
surfaces of the cone and journal bearing, respectively. More
particularly, means are provided for inserting or removing
these retaining parts so that the cones may be replaced or
repaired from time to time. However, the locking balls and
rings are subject to frequent breakage due to high temper-
atures from uneven wear due to very high thrust loads on the
cones, thus requiring frequent replacement of the entire bit
body. Also, the races and recesses for the balls and rings
~ 1 ~
- ` ~Z3889~
1 reduce the bearing areas of the cone and journal bearing as
well as the strength of the cones by reducing their thickness
in the area of the races and recesses.
To compensate for this loss of journal ~earing area,
bits of this type are often provided with "nose" bearings in
the form of cylindrical projections on the ends of the jour-
nal bearings which are received within cylindrical bearing
surfaces in the inner ends of the cone recess. This, how-
ever, inherently reduces the end areas of the cones and jour-
nal bearings available for carrying thrust on the cone.
It's also conventional practice to lubricate the
bearing surfaces between the cone and journal bearing by
means of a lubricant introduced through an opening in the
body into a reservoir leading to the surfaces. The lubricant
is normally contained by means of electameric O-rings which
surround the journal bearing surface to form a rotary or
dynamic seal between it and the cone. More particularly, the
lubricant is preferably maintained at well pressure to pre-
vent the intrusion of well fluid by means of a "compensator"
at the opening to the reservoir. However, these seal rings
are highly susceptible to failure due to the high pressures
and temperatures present in the well, particularly when dril-
ling with oil base muds, thus requiring that the drill string
be pulled to replace them when the lubricant which is lost.
Even then, if the seal rings have failed, foreign substances
in the drilling mud may get between and seriously damage the
bearing surfaces.
~23~1~97
1 Bits of this type are often made up of separate for-
gings each comprising a section of the shank and a leg on
which a journal bearing is mounted, and welded to adjacent
sections along the inner and outer edges of their adjacent
sides, because of their locations, these welds are difficult
to form, particularly along the inner edges of the sections.
Also, the welded side edges of the shank portions of the sec-
tions require substantial preparation prior to the forming of
threads thereon for connecting the shank to the lower end of
the drill string.
The cones of bits of this type which are used to
drill in rock or other hard formations often have carbide
inserts mounted in rows along high wear areas of the cone.
Conventionally, these are press fitted into cylindrical holes
in the outer side of the cone. To securely hold the inserts,
the holes must be of substantial depth, which of course lim-
its the diameter of the journal bearing about which the cone
rotates.
SUMMARY OF THE INVENTION
_
An object of this invention is to provide a bit of
this type in which the cones are held or retained on the
journal bearings by means which does not limit the cylin-
drical bearing areas between them, and, more particularly
which eliminates the need for "nose" bearings and thus pro-
vides greater thrust bearing areas.
- 3 -
lZ3~ 97
l Another object is to provide a bit of this type in
whiGh lubrioant is caused to circulate betwe~n ~he bearing
surfaces of the journal bearing and cone, and thus maintained
at a cooler temperature as the cone rotates about the bearing
during drilling.
Another object is to provide a bit of the type de-
scribed which makes it possible to accomplish both of the
above described objects by a compact arrangement which re-
quires substantially no modification of the overall shape and
size of the thrust bearings and cones.
A further object is to provide a bit of this type in
which lubricant is contained between the bearing surfaces of
the journals bearings and cones in such a manner as to re-
quire less repair or replacement of the seals therebetween,
and, more particularly, without dynamic elastomeric seals.
Yet another object is to provide such a bit having a
simple and inexpensive arrangement for insuring that foreign
substances will not intrude between the lubricated bearing
surfaces, even upon failure of the seals intended to contain
the lubricant.
A still further object is to provide a bit of this
type in which the body is of a construction which is simpler
to assemble, and which requires no special preparation for
the shank threads, then the above mentioned bit body con-
structions.
3LZ3~397
Still another object is to provide a bit of this
type in which carbide inserts for the cones are installed
in holes in the cone which are of less depth, so that the
journal bearings may be made of correspondingly greater
diameters.
These and other objects are accomplished, in
accordance with the illustrated embodiment of the present
invention, by a drill bit of the type described in which
a chamber formed between walls of the journal bearing and
cone is filled, filled with liquid from which air has
been displaced to provide a liquid lock which holds the
cone on the journal bearing. As a consequence, and as
previously mentioned, the cylindrical bearing surface
of the journal bearing and cone need not to be interrupted
by recesses to receive balls or split rings. Furthermore,
because of this larger bearing area between the journal
bearings and cone, it is not necessary that the journal
bearing have a "nose" bearing, as might otherwise be
required. As also previously mentioned, this in turn
makes it possible to devote at least substantially all
of the adjacent end surfaces of the journal bearing and
cone to absorbing thrust loads.
3L238~97
Thus broadly, the invention contemplates a rotary
tool which comprises a supporting body, a tool member
supported for rotation on the supporting body, means forming
a chamber between the walls of the supporting body and
S tool member, a liquid filling the chamber from which air
has been displaced, and means sealinq the chamber. The
sealing means includes a means on the tool member and
the supporting body sealing therebetween,and the chamber
is sealed to prevent leakage of air in or liquid out of
the chamber to form a liquid lock which holds the tool
member on the supporting body while permitting relative
rotary movement between the tool member and supporting
body and preventing any substantial longitudinal movement
between the tool member and supporting body.
DESCRIPTION OF T~E PREFERRED EMBODIMENT
In the illustrated and preferred embodiment of the
invention, the body has conduits which connect each chamber
with the exterior of the body, each conduit having an out-
wardly facing seat intermediate its ends, and a plug is
threadedly connected to each conduit outwardly of the seat.
- 5a -
~238~397
1 More particularly, the plug has a vent port therethrough with
a seat on its inner end about the port, and a closure element
is disposed between the seats to close the vent port and the
conduit as the plug is moved inwardly to displace liquid
which fills the chamber. Thus, the closure element is held
off the seat on the plug by means of a needle or the like
extending through the vent port so as to permit liguid to
pass outwardly therethrough as the plug is threaded inwardly
within the conduit. As also illustrated, each cone has a
shaft which is inserted within a recess in the journal bear-
ing as the cone is fitted over the bearing and the chamber is
formed between the outer end of the shaft and the inner end
of the recess with which the conduit connects. As a result,
the liguid lock is formed between each cone and journal bear-
ing without within the normal combines of the bearing's ex-
terior dimensions.
In accordance with another novel aspect of the pre-
sent invention, first passageway means extends longitudinally
between the cylindrical bearing surfaces of each journal
bearing and the recess in the cone which fits over the bear-
ing are connected with the second passageway means and which
extend between adjacent ends of the journal bearing and cone
recess, and means including a pump means connecting with the
passageway means and is provided for circulating the lubri-
cant therethrough in response to rotation of the cone. More
particularly, the second passageway means are formed on op-
posite faces of a thrust bearing between the ends of the
12388g7
l journal bearing and cone recess and connecting with an an-
nular recess between the cone recess and the outer diameter
of the thrust bearing with which the first passageway means
connect.
As illustrated, the above mentioned shaft on each
cone which extends into a recess in the journal bearing has
an enlarged inner end which forms an annular pump chamber on
the inner end of the enlarged end opposite the chamber on the
opposite outer end thereof which is filled with liquid to
form a liquid lock holding the con on the journal bearing,
and a helical vance is fixed to on of the shaft and cone
recess to displace lubricant in the pump chamber in response
to rotation of the cone. Preferably, and as illustrated, the
passageways of the first passageway means are formed in the
upper side of the journal bearing, and thus away from the
lower side which carries the load from the cone. More parti-
cularly, the first passageways of the first passageway means
are enlarged intermediate their ends which connect respec-
tively with a supply port connecting with the exterior of the
bit body and the aforementioned annular recess so as to form
a heat sink, which, in combination with the circulation of
the lubricant within the passageways, lowers to a consider-
able extent the temperature of the lubricant. More particu-
larly, in the illustrated and preferred embodiment, the shaft
which extends into the recess in the journal bearing to form
the pump chamber passes through a central opening in the
thrust bearing and has means thereon which fits closely with-
1~38897
1 in the hole in the thrust bearing to hold it centered as well
as openings therein connecting with the pump chamber with the
second passageways formed in opposite faces of the thrust
bearing.
In accordance with another novel aspect of the pre-
sent invention, the lubrioant is contained between the bear-
ing surfaces of each cone and journal bearing by means which
includes a generally triàngularly shaped groove in the corner
of the cone about the outer end of its recess, a seal ring of
elastarmeric material in the corner of the recess, and a ring
of carbon graphite or other suitable composite refractory
metal disposed between the seal ring and inner end of the
cylindrical surface of the journal bearing, the graphite ring
and journal bearing having sealing surfaces which are curved
about approximately soo so as to maintain sealing engagement
between them despite some longitudinal misalignment of the
cone and journal bearing. More particularly, annular pads of
deformable material are held between adjacent sides of the
recess and the graphite ring to insure that the seal ring and
graphite ring rotate with the cone, whereby the seal ring of
is static and then much less prone to failure than dynamic
seals formerly used for this purpose.
The bit body includes an upper body section adapted
for connection to a drill string having a shank with a bore
in one end, and hollow legs depending from the lower end of
the shank, to connect the bore of the shank with its open end
so that drilling ~luid circulating downwardly through th~
123889~
1 drill string may be jetted through a jet nozzle in each leg
toward the lower areas of the bit. The body also includes
lower sections which are connected to the lower end of the
shank and to one another in side by side relation and with
the jet nozzle legs extending between them. More
particularly, each lower body section includes a depending
leg having an inwardly extending journal bearing therein to
receive a cone for rotation thereabout. In this manner, the
bit may be assembled without having to make difficult weld
along the inner edges of the adjacent segment~ of the bit
body, and since it is not necessary to weld along the shank,
without having to prepare the shank prior to threading the
same for attachment to the lower end of the drill string.
As illustrated, the upper ends of the lower body
sections have interfitting parts which are closely received
in a lower extension of the shank bore to hold them against
lateral displacement, and a plug is disposed across and seal-
ed within the bore extension above the lnnerfitting parts to
divert drilling fluid into the nozzle legs.
Each of the cones which is rotatable about a journal
bearing has carbide inserts which are mounted about the outer
side of the body for cutting the bottom of a well bore as the
cones rotate with and relative to the body of the bit. More
particularly, in accordance with still another novel aspect
of the present invention, each such insert is mounted has a
conical surface on its inner end which is adapted to fit
closely within a conical inner end of the hole in the outer
_ g _
~Z3889~7
1 side of the body and is held within its hole by a brazing
material which forms a bond between their conical surfaces.
Nore particularly, a preformed pellet of the brazing metal
which is shaped to fit closely within the conical end of the
hole is heated and an electrical potential is passed from the
insert to the pellet of the cone to cause the pellet to soft-
en and then be brazed to the conical surfaces of the hole and
insert as the inner end of the insert continues to be moved
into the pellet. More particularly, each such insert has a
vent passage which permits gas to escape from the pellet as
it is brazed to the cone and insert.
Lubricant is supplied to the bearing surfaces of the
cone and journal bearing by means which includes a reservoir
for the lubricant leading to the first passageway means, an
opening in the body which connects the reservoir with the
outside of the body, and a piston which is sealably slidable
in the reservoir and which is urged towards the reservoir by
well fluid. In accordance with another novel aspect of the
present invention, and as compared with the prior art, a
charge of gas intermediate the piston and lubricant in the
reservoir is maintained at a pressure some what higher than
that of the ambient well fluid. More particularly, a means
is formed in the piston to permit the charge to be injected
into the space between the piston and the reservoir upon
filling of the reservoir with liquid and movement of the
piston into the body opening.
-- 10 --
~;~38~9'7
1 BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings, wherein like numerals are used
throughout to indicate like parts:
Fig. 1 is a vertical sectional view of a bit con-
structed in accordance with the present invention and having
the upper threaded end of its shank connected to the lower
end of a rotary drill string;
Fig. 2 is a vertical sectional view of the upper
section of the body of the bit of Fig. l removed from con-
nection with the lower end of the drill string;
Fig. 3 is a lower end view of the upper body section
of Fig. 2;
Fig. 4 is a side view of one of the lower sections of
the body of the bit, removed from connection with the upper
body section, prior to assembly of the cone on the journal
bearing thereof, and with the thrust bearing and shaft on the
cone for fitting within the recess in the recess in the jour-
nal bearing being shown in exploded positions with respect to
the bearing;
Fig. 4A is an enlarged cross sectional view of the
shaft, as seen along broken lines 4A--4A of the exploded
portion of Fig. 4;
Fig. 5 is an end view of the journal bearing, as seen
along broken lines 5-5 of Fig. 4;
Fig. 6 is a view of the outer face of the thrust
bearing shown in the exploded portion of Fig. 4, and as seen
along broken lines 6-6 thereof;
-- 11 --
123~89~
1 Fig. 7 is an enlarged detailed cross sectional view
of the seal assembly between the outer end of the cone recess
and the inner end of the journal bearing, as indicated by the
encircled portion designated by the number "7" in Fig. l;
Fig. 8 is a vertical sectional view of the lower body
sections of the bit, when connected to one another, but with
the cones removed therefrom for purpose of illustration;
Fig. 9 is a view of the lower end of the assembled
lower body sections of Fig. 8;
Fig. 10 is a cross sectional view of the lower body
sections, as seen among broken lines 10-lO of Fig. 1, and
showing the extension of the nozzle legs of the upper body
between adjacent sides of the lower body sections;
Fig. 11 is an enlarged sectional view of the plug in
the conduit of the bit body leading to the liquid lock cham-
ber, as shown at number "11" in Fig. 1, and illustrating the
vent port and closure member therethrough;
Fig. 12 is a further enlarged sectional view of the
annular recess between the outer end of a journal bearing and
the inner corner of a cone recess in which it is received, as
seen at number "12" in Fig. 1; and
Fig. 13 is an enlarged sectional view of a hole in
the outer surface of a cone, and a carbide insert as it is
moved into the hole for engaging the body of brazing metal
therein.
- 12 -
~Z3~38~37
l With reference now to the details of the above des-
cribed drawings, the overall bit, which is indicated in its
entirety by reference character 20 in Fig. 1, comprises a
body at 21 which includes a shank 22 having a threaded upper
end 23 connected to the lower end of a drill string DS and
having a bore 24 in its upper end forming a lower continu-
ation of the bore through the drill string. The upper body
22 of the drill bit body also includes three hollow legs 25
which depend from the lower end of the shank in generally
equally spaced apart relation to connect the bore 25 in the
shank with their open lower ends. A jet nozzle 27 is releas-
ably mounted within the lower end of the hole 2~ through each
leg so that drilling mud which is circulated downwardly
through the drill string may be jetted toward a desired area
of the bit.
The bit body 21 also includes three lower sections 27
which are connected to the lower end of the shank and to one
another in side by side relation, with the nozzle legs 25
extending between the sides of the upper ends adjacent body
sections 27, as best shown in Fig. 10. More particularly,
each such lower section 27 of the bit body has a depending
leg 28 and a generally inwardly and downwardly extending
journal bearing 29 thereon and about which a cone 31 is rota-
table. ~he upper end of each section 27 has a neck portion
32 which, together with the neck portions of the other lower
body sections, forms a cylindrical boss which fits closely
with a lower extension 33 of the bore 24 o~ the shank. More
- 13 -
1 particularly, shoulders 34 on the upper ends of the lower
body sections are adapted to abut the lower end 35 of the
shank, and the adjacent outer end edges of the shoulders and
lower end of the shank are chamfered to receive a peripheral
weldment 36 connecting the lower body sections to the upper
body section. As best shown in Fig. 10, the outer edges of
the adjacent inner ends of the sides of the lower body sec-
tions are also chamfered to receive a longitudinal weldment
40 between them.
As shown in Figs. 9 and 10, the outer ends of the
sides of the adjacent lower body sections are flared at 37 to
form a recess 38 extending lengthwise thereof to receive the
nozzle legs 25 between them, and the lower ends 41 of the
upper portions of the lower body sections are disposed above
the cones 31 received on the journal bearings. Holes 42 are
formed in the abutting sides 39 for alignment with one an-
other to receive pins dowel pins 43 which hold the sections
in vertically side by side relation. Thus, during assembly
of the bit body, two of the lower body sections 27 are moved
into interfitting relation by means of two vertically spaced
dowel pins received within aligned holes in their sides, and
the third body section is then moved into position by dis-
posing its holes 42 over the ends of the dowel pins on one of
the previously connected sections, the holes 42 between the
last connected and the other of the first two connected sec-
tions being empty.
- 14 -
~238897
l A plug 44 is disposed within the bore extension 33 of
the shank and has an "o" ring 45 carried thereabout for seal-
ably engaging the extension and thereby combine drilling
fluid within the bore 24 for flow into and through the hollow
nozzle legs 27. More particularly, and as shown in Fig. 1,
the upper side of the plug is generally conically shaped to
direct the flow of the drilling fluid evenly to the three
nozzles.
Each journal bearing pin has a recess 46 formed in
lO : its outer end to receive a shaft 47 threadedly connected to
the end of the recess 30 in each cone 31 as the cylindrical
surface of the cone recess is moved over the cylindrical
outer diameter of the journal bearing. An enlarged outer end
48 of the shaft 47 carries seal rings of 49 which are seala-
bly engageable within the recess 46 to divide it into an
inner annular chamber about the shaft between the inner end
of the head 48 and the end of the cone recess and an outer
chamber intermediate to the outer side of the head 48 and the
end of the recess 46 in the journal bearing.
More particularly, tlle end wall 50 of the journal
bearing recess connects with a conduit 51 leading to the
outer side of the shirtail of the leg 28 from which the jour-
nal bearing extends. As shown in Fig. 11, the outer end of
the conduit 51 is enlarged at 52 to form a seat about conduit
51 and threaded to receive a plug 53 which in turn has a vent
port 54 formed therethrough. More particularly, and as pre-
- 15 -
- ~23~897
1 viously described, a closure element in the form of a ball 55
is disposed between a seat on the inner end of the vent port
54 and the seat formed in the conduit 51.
The cone is held on the journal bearing over which it
fits by liquid which fills the outer chamber and from which
air has been exhau~ted upon displacement of the liquid
through the port in the plug 53 as it is moved inwardly with-
in the threaded conduit 52. As also previously described,
the ball 55 is held off the seat on the inner end of the vent
port by means of a needle (not shown) inserted through the
vent port as the plug is moved inwardly. Thus, liguid within
the chamber may flow past the ball and through the vent port
until the inner end of the ball is held tightly between the
seats on the plug and conduit following which the needle may
be withdrawn. Thus, air-free liquid is captured within the
chamber and the conduit which forms a liquid lock to hold the
cone on place on the journal bearing.
As shown in Fig. 11, the outer end of the plug 53 has
a noncircular recess to receive a suitable tool for moving it
into and out of the threaded end 52 of the conduit. When the
plug is in place upon filling of the outer chamber in the
journal bearing with liquid, a stopper 56 (see Fig. 1) may be
moved into place to seal off the outer end o the conduit in
the event there might be leakage past the plug. As shown in
Fig. 4, the outer end of the enlarged head of the shaft 47
also has a noncircular recess to receive a suitable tool for
connecting it to a cone.
- 16 -
~23~389~ .
1 More particularly, when the cone is held in place on
the journal bearing, a seal assembly 57 carried within a
groove on the outer end of the cylindrical recess 30 in the
cone sealably engages a sealing surface about the intersec-
tion of the inner end of the journal bearing with the inner
side of the leg 28 from which from which it extends. This
seal assembly, which will be described in more detail to
follow, seals off passageways through which lubricant is
circulated between the cylindrical bearing surfaces of the
journal bearing and its cone during rotation of the cone
about the journal bearing.
As previously described, a first set of passageways
through which the lubricant circulates are shown at 58 to
comprise recesses formed in the outer bearing surface of the
journal bearing and extending longitudinally in spaced apart
relation on the upper side of the bearing surface. More
particularly, each such passageway 58 connects intermediate
its upper and lower ends with lateral passageways 59 leading
to the pump chamber formed between the inner end of the en-
larged head 48 of the shaft 47 and the inner end of the re-
cess in the cone, and the outer ends of the passageways 58
are flat, as best shown in Fig. 5, to connect with laterally
extending second passageways 59 between the end of the jour-
nal bearing and the end of the recess in the cone and leading
to the opposite end of the pump chamber.
More particularly, a helical vane 60 is mounted about
the shaft 47 for rotation within the pump chamber, so that as
the cone rotates in a clockwise direction, as seen in a dir-
- 17 -
~238897
1 ection looking from the journal bearing downwardly, the lu-
bricant is caused to circulate downwardly through the pump
chamber, laterally outwardly through passageways between the
ends of the cone and recess and then upwardly through the
longitudinal passageways 58 for return through to the pump
chamber through the lateral suction passageways 59. More
particularly, and as shown, the longitudinal passageways 58
are deep intermediate their upper and lower ends to provide
heat sinks which further contribute to reducing the temper-
ature of the lubricant.
Lubricant is supplied to the above described passage-
ways and pump chamber form a reservoir 61 formed in the lower
body section 27 and connected to the upper end of one of the
passageways 58 by means of a vertically extending port 62
depending from the lower end of the reservoir and a downward-
ly and inwardly extending port 63 connecting with the upper
end of the middle passageway 58. Lubricant may be supplied
to the reservoir and the passageways through an opening con-
necting the port 63 to the upper shirttail of the leg 28, and
closed by means of a plug 64.
As shown in Fig. 1, the upper end of the reservoir 61
is closed by means of a piston 65 sealably disposed within
the reservoir and held down by means of a snap ring 66, and
is filled with lubrioant to a level below the lower open end
of the piston. A chamber 67 formed between the reservoir and
the lower side of the piston 65 is filled with nitrogen at a
pressure which is somewhat higher than that of the well fluid
- 18 -
lZ38~97
1 which acts against the upper side of the piston. The chamber
67 is adapted to be filled with nitrogen or other ~as through
a valve plug 68 extending through the piston 66 and closed,
upon filling, by means of a cap 69 across its outer end.
A thrust bearing 70 disposed between the lower end of
the journal bearing and the inner end of the recess of the
cone has a central hole 71 through which the shaft 47 on the
cone extends, and an outer diameter which is of somewhat
lesser diameter than the bearing surface of the journal bear-
ing and spaced from the inner diameter of the cone recess by
an annular passageway 72. More particularly, and as shown in
Fig. 12, the inner end of the cone recess has a curved outer
wall 73 and the corner of the journal bearing adjacent to its
inner end has a quarter round 74 so that, with the outer
diameter of the thrust ring 70 substantially aligned with the
reduced diameter inner end of the journal bearing, the pas-
sageway 72 permits the free flow of lubricant between longi-
tudinally extending passageways 58 between the cylindrical
surfaces of the journal bearing and cone recess and the lat-
eral suction passageways 59 between the inner ends.
As shown in Fig. 6, these laterally extending pas-
sageways 75 and 76 are formed in the opposite faces of the
thrust bearing and extend radially outwardly from the hole 71
to the recess 72 so as to permit lubricant to pass radially
either between the lower end of the journal bearing and the
opposite face of the thrust bearing or between the end of the
recess in the cone and the opposite face of the thrust bear-
-- 19 --
1238897
l ing. As shown, the passageways on opposite sides of the
thrust bearing are staggered in a circumferential sense.
The thrust bearing may be made of berrelium copper, or, if
desired, a composite refractory metal such as MoS2.
The thrust bearing is held in a position of alignment
with the longitudinal axis of the thrust bearing by means of
an enlargement 77 formed on the portion of the shaft 47 which
extends through the hole 71 in the thrust bearing. As shown
in Fig. 4, the mid portion of the enlargement 77 has an outer
diameter 78 which fits closely within the hole 71, and slots
79 are formed in the enlargement 77 to permit lubricant to
flow from the pump chamber into the hole 71 in the ~thrust
bearing and thus radially outwardly through slots 75 and 76
into the annular recess 72 and thus into the longitudinal
passageways 58. The thrust bearing 70 may be found to rotate
with the cone, and thus with respect to the journal bearing,
or alternatively may be held against rotation with respect to
the thrust bearing, so that the cone rotates with respect to
it.
The seal assembly ~7 is best shown in Fig. 7 to com-
prise an O-ring 80 of elastameric material disposed within a
triangularly shaped groove 81 formed at the intersection of
the inner diameter of the recess of the cone with the end of
the cone opposite a sealing surface about the intersection of
the journal bearing 29 extends. More particularly, the seal
assembly also includes a ring 82 of carbon graphite or other
composite refractory metal such as MOS2 disposed between the
- 20 -
1238897
1 O-ring 81 and sealing surface, and, as shown in Fig. 7, the
outer wall of the graphite ring and the opposite sealing
surface of the journal bearing against which it is sealably
engaged form quarter rounds which enable some misalignment of
the longitudinal axis of the journal bearing and cone without
damage to the seal assembly. The sealing surface is ground
and lapped to fit the graphite ring.
The seal assembly also includes annular pads 83 of
rubber of other deformable material disposed between the
sides of the groove and the oppositely facing sides of the
graphite ring 82 disposed opposite thereto. More particular-
ly, the pads are pressed between them to form a frictional
grip which prevents the ring 82 from rotating with respect to
the cone, and in turn prevents the seal ring 81 from rotating
with respect thereto. Consequently, a wear surface of the
seal assembly is formed of non-elastermeric material, and the
elastermeric ring thereof is static and thus less suscept-
ible to wear than would be a dynamic seal.
As shown in Fig. 13, at least certain of these in-
serts 90 mounted about the wear surfaces of the cone have
inner conical ends 91 adapted to be received closely within
the similarly shaped inner ends of holes in the cone. More
particularly, a pellet 93 of brazing material such as nickel,
which has a conical shape adapted to ~it closed within the
conical end 92 of the hole in which the insert is to be im-
bedded is adapted to be heated, and an electrical potential
is connected across the insert and the cone, with its posi-
- 21 -
~;~3~389~
1 tive end connected to the insert in its nega~ive end connect-
ed to the cone, so as to soften the pellel 93 as the lower
pointed end of the insert 91 is moved into contact therewith.
As the insert is then moved fully into the hole, the brazing
material and gases which it releases are permitted to escape
between the hole and the insert through one or more slots 94
formed in the side of the insert. As shown, the outer end of
the hole and an intermediate portion of the recess are formed
with surfaces above the conical portions which stabilize the
insert when brazed to the cone in the manner described.
From the foregoing it will be seen that this invent-
ion is one well adapted to attain all of the ends and objects
hereinabove set forth, together with other advantages which
are obvious and which are inherent to the apparatus.
It will be understood that certain features and sub-
combinations. This is contemplated by and is within the
scope of the claims.
As many possible embodiments may be made of the in-
vention without departing from the scope thereof, it is to be
understood that all matter herein set forth or shown in the
accompanying drawings is to be interpreted as illustrative
and not in a,limiting sense.
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