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Патент USA US3037267

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June 5, 1962 ’
A. R. _sToKEs
3,037,258
DRILL COLLAR CLAMP
Filed June 23. 1960
4 sheetsfsheet 2 _
F/GZ
BY
ATTORNEY
June 5, 1962
‘
Filed June 23, 1960
3,037,258
A. R. sToKl-:s
DRILL COLLAR CLAMP
4 Sheets-Sheet 3
F rl@ 7
ALV/N RSTOKES
INVENTOR.
En?
AT TO F_ìNEY
June 5, 1962
V3,037,258
' A. R. s‘roKEs ‘
DRILL COLLAR CLAMP
Filed June 25, 1960
4 Sheets-Sheet 4
F/G. 8
23
d@ 42
52 ì 54
25A
50
29
FIG. /O
46
F/Gl/
A LV/N RSTOKES
INVENTOR.
BY Il Í/
A TTO R N E Y
Unired States Patent
nnte ,_
3,037,258
Patented VJune 5, 1962
2
l
Yet another object of this invention is to provide a
clamp of the above characteristics that may be easily
3,037,258
Alvin Ray Stokes, 3131A». Coolidge St., Borger, Tex., as
DRILL COLLAR CLAMP
and quickly adjusted in effective diameter to adapt it for
use with a wide range of sizes of pipe and the like.
signor of lìfty percent to Jimmie Blanks, Borger, Tex.
Filed June 23, 1960, Ser. No. 38,146
8 Claims. (Cl. 24-249)
The above and other objects and advantages of the in
vention will be apparent during the course of the follow
ing description of the invention, throughout which de
scription reference is made to the accompanying draw
This invention has to do with well drilling tools and
ings which form a part of the description, wherein like
has particular reference to an improved clamp. This
clamp is of particular use to prevent the dropping of 10 numerals are employed to designate like parts, and in
which:
_
cylindrical tools such as drill pipe, drill collars, and the
FIGURE 1 is a plan view of a preferred embodiment
like during their manipulation at a rotary table.
of the invention in operative position about a drill pipe,
In drilling wells by the rotary method, power to rotate
such pipe being shown in section;
the drill bit is transmitted from the power source at the
surface to the bit by means of pipe known as drill pipe.
Such drill pipe is made in lengths of 20 to 4() feet. As
FIGURE 2 is a diagrammatic side elevational viewrof
the clamp of the invention in operative position on a
pipe supported in the slips of a rotary table;
the well is drilled deeper, joints or lengths of such pipe
FIGURE 3 is a diagrammatic side view of the handle
are added to the string already in the drill hole and the
assembly 69 of the invention as seen along direction in
drilling is thus continued at greater depth as the pipe
works its way downwards. The drilling bit, in normal 20 dicated by arrow III of FIGURE l;
FIGURE 4 is a diagrammatic side View of the arm
usage, becomes worn to a point at which such must be
71 as seen along the direction indicated by arrow IV of
replaced. Thereupon, the whole drill string is withdrawn,
FIGURES l and 2;
the bit is replaced and the components of the drill string
FIGURE 5 is a cross-sectional View takenI along the
then are assembled, length by length, and lowered into
'
`
the well with the new bit attached thereto. Withdraw 25 plane V'-V" of FIGURE 4;
FIGURE 6 is a side view of t-he jack body 89' as seen
ing and installing drill strings thus necessitates several
along the line indicated by arrow Vl of FIGURE 1;
operations and manipulations of the separate joints or
FIGURE 7 is a diagrammatic partly sectional view
lengths and their associated collars, whereby the entire
of jack 70;
_
drill string is supported in the hole on slips in the rotary
FIGURE 8 is a diagrammatic sectional view through
table while further joints or strands are removed from 30
intermediate link 25A, along plane VlIIL-VIIP’ of FIG
or added to the string thus supported. This repeated
URE l0;
sequence of movement of the drill string, holding the
FIGURE 9 is a perspective view of intermediate link
string and removal and replacement of the lengths of
25A;
pipe forming the drill string, while supporting the drill
pipe is a difficult, physically tiring operation. It is also 35 FIGURE l0 is a front View of intermediate link 25A;
nerve-wracking as it involves the employment of sub
and
'
FIGURE 1l is a diagrammatic perspective representa
tion of the mechanism for holding handle 111.
hazards of accident to personnel and equipment.
The clamp made according to the present invention,
In these manipulations of the drill string and the com
ponent thereof for running in and removing drill strings, 40 shown generally as 29, comprises a plurality of like in
stantial manpower on the rig and there are substantial
production strings, etc., slips provided in the rotary table
for support of the drill strings during these operations
termediate pivotally connected links, 25A, 25B, 25C, 25D,
25E, ZSF, ZSG, 25H, 251, and 25], in a link assembly
frequently fail to obtain an effective grip on the string
which they are purposed to support. Such failure may
allow the pipe, liner, or other object being supported to
necting the ends of the link assembly 21 to hold it en
gaged about a pipe, collar or other generally cylindrical
21 and means 22 for releasably and conveniently con
item 2‘3. The like intermediate elements of the link as
fall into the well, necessitating expensive time-consuming
sembly 21 are generally shown in U.S. Patent 2,301,625.
The clamp of this invention forms a substantially an
nular structure for fitting about a pipe or cylindrical
According to this invention, there is provided a clamp
adapted for such circumstances of repeated cycles of at 50 object 23. In accordance with this invention, such may
be readily varied as to its length or diameter to lit pipe
taching and clamping on such pipe for only short inter
and like objects varying greatly in diameter. rThe inter
vals followed by release of such pipe, i.e., a device for
fishing operations for its recovery as well as endangering
personnel by the falling of such heavy equipment.
proved clamp that may be conveniently, quickly, and
mediate links, 25A-25l, are preferably identical. The
number of such links employed depends on the size of
the pipe being handled as described in U.S. Patent 2,301,
625, page 3, left column, lines 42-57. At one side of
body 29 each intermediate link, as 25A, has a horizon
tally projecting annular lug or eye 30 that is provided
with a vertical cylindrical opening 31. At the other side
of shoulder, collars and recesses.
lug or eye 30 may have a stop projecting from its pe
quickly clamping and subsequently quickly releasing
such clamp.
A general object of this invention is to provide a con
venient as well as practical, effective, and dependable
clamp.
Another object of this invention is to provide an im
55
controllably engaged about the pipe, drill collar or other 60 of each intermediate link body, as 29, is a horizontally
projecting fork 32 comprising two vertically spaced an
object, at a point above the rotary table and which clamp
nular ears or lugs, 33 and 35, adapted to receive the
is adapted to reliably and controllably engage down
eyes as 30, of adjacent links, as 25B, and having verti~
against the slips or other parts at the rotary table »to
cal openings 37 for registering with opening (correspond
prevent the falling of the pipe or similar object in the
ing to 31) 37 of such eyes. Hinge pins pass through the
event the rotary table slips fail to support the pipe or
openings 31 and l37 of the thus ñtted together eyes and
similar object.
yokes to releasably and pivotally connect such inter
Another object of this invention is to provide a clamp
mediate links. The upper ends of the pins 39 have heads
of the above characteristics that is also operable to quick
which prevent downward movement of the pins and
ly and conveniently and controllably obtain a depend
cotter keys are passed through openings in the lower por
able, positive grip on the pipe, drill collar, liner, or the
tions
of such pins to prevent their displacement. Each
like, even when such presents a smooth surface devoid
3,037,258
3
riphery or edge for cooperating with the adjacent link
body to limit the outward pivoting of the links relative to
each other. Such eyes and yokes are quite thick and
able from the housing 96. Housing 96 pivots on a ful
crum pin 97 and is pivotally attached through yoke 98
and pin 99 to a slot in the head of a pump piston 100,
heavy to have the strength required for the above-de
which pump piston seats in pump piston chamber 101.
scribed service.
The body 29 of each intermediate link, 25A-J, has a
guideway 41 which is designed to receive and mount a
The pump piston chamber connects via one-way valve
102 and passage 103 to ram piston chamber 105. The
ram piston wall 106 forms one wall of the hydraulic ñuid
reservoir chamber 107. A ñller port 108 is provided
slip, as 42.
The rear face of the guideway is sloped
downwardly and inwardly, i.e., toward the axis of the
pipe 23. In each of said links, grooves, 43, are provided
in the side wall of the guide body and open into said
guideways. Slips, as 42, are carried by each of the
intermediate links, 25A-J. These links are wedge ele
ments thicker at their top than at their bottom. These
slips each operate in a guideway provided therefor. The
slope of the back, 46, of each guideway is the same as
for reservoir 107. The reservoir chamber connects via
passage 103 to control valve 109. Control valve 109
alternatively provides communication either between
the reservoir chamber 107-via one-way valve 110-to
pump piston valve chamber 101, or valve 109 provides
for communication of reservoir chamber 107 and cham
ber 105 via channel 103 from the ram piston chamber.
Valve 109 is controlled by handle 111. Handle 111 is
the slope of the back of the slip. The biting face, 47,
provided with snap acting lock plates 112 and 113,
of each slip is thus held in a substantially vertical posi
mounted on adjustment plate 115 affixed to the pump
body housing 89.
tion (i.e., parallel to the pipe 23) regardless of the exact
height of that slip relative to the link body, 29, or its 20 Bourdon guage 114 connects to channel 103 and pro
radial distance from the center of the axis of the pipe,
vides a visual indication to the operator of the pressure
23, the outer surface of which pipe, 23, such slip is de
in the ram cylinder. rIThis serves to notify the operator
signed to contact and thereby hold. The opposite sides
when the slips have been brought to adequate contact
of each slip have tongues as 48 that project into the
with the pipe 23 or other object held by the clamp 20.
grooves 43 provided at and connected to the sides of 25 This also provides for indication of any decrease in pres
the guideways. These grooves guide the slips and hold
sure to notify the operator of slippage of the clamp or
them in proper orientation by engagement with the rear
leakage in the hydraulic system and permits same to be
face of the guideway. Teeth 39 of the face 47 effectively
promptly corrected. The lock plate 112 is shown in
grip the pipe 23 when such teeth contact the surface of
operative position in FIGURE l1 whereat it holds the
such pipe.
30 handle 111 while lock plate 113 is therein shown in the
Each of the slips are yieldably held in place by springs
position whereat it permits movement of the handle 111.
49 acting on shoulder 50 in groove 51 of link body 29
on each link. The lug 52 on the slip contacts the other
end of the spring. The slips are further held in place
by cotter pins 54 as shown in the drawing and as de
scribed in U.S. Patent 2,301,625, page 2, right column
Thereby means are provided for avoiding any accidental
release of the pressure in the ram cylinder.
The valve 102 comprises a spring 120 and ball 121.
. The elongated cylindrical valve chamber 122 is provided
at the radial end with a taper for a lock ñt of the ball
lines 49-58.
therein. The longitudinal axis of this chamber is di
The link assembly is provided with two handles, 55
rected along a radius of a pipe 23 so that the valve will
and 69. Handle 55 has substantially the same construc
close more tightly when the pipe revolves about its longi
tion as the handle 35 in the aforo-mentioned U.S. Patent 40 tudinal axis, and the clamp 20 is attached to said pipe
2,301,625. This handle has apertured slots 36A and
shown in FIGURES 1 and 2. This relation of the valve
36B which lit the assembly 21 and are held in place
components prevents leaking in valve 102 during pro~
by the pins 40A and 40B, respectively.
tracted periods of revolution of the drill pipe. The ram
Handle 69 comprises a bracket 73, which tits slidably
piston 93 has a sealing portion 1.13 provided with con
over one end of the link 25F. The bracket 73 is pro
ventional packing elements 116. Such packing elements
vided with openings 76A and 76B which register with
are also found at 1‘17 in the pump piston chamber 101.
the holes for the pin 77. Pin 77 passes through the open
The upper portion of the piston 93 is threaded to per
ings corresponding to 3‘1 and 38 in the intermediate link
mit the seating therein of »the threaded portion 127 below
25F. The head 79 on the pin 77 and a lower cotter pin,
the ram head 129.
as 80, hold such pin in place.
rI`he handle 69 is formed of sturdy steel to provide
permanent minor adjustment of the length of the piston.
for the weight and other stresses to be borne thereby.
A yoke 81 is provided at the other end of the handle 69;
this yoke comprises two lugs, 82 and 83, each provided
with a circular eye therein, 82A and 83A, respectively.
This yoke is joined by a cylindrical pin, 85, to a tongue
87 on the jack, 70. The pin 85 passes through the eyes
A lock nut 130 provides for semi
The connecting arm 71 at its lock end has locking lug
131 provided with an eye 132 which `freely tits between
the interior surface of the lugs 90 and 91. The cylin
drical pin 92 passes through the eyes of lugs 90 and 91
and tits into the corresponding circular eye 132 in lug
131. The above fit of the lugs limits the motion of the
arm 71 relative to jack 70 to rotation about the axis of
of lugs 82 and 83 as well as eye 86 on tongue 87; this
the locking pin 92. The shaft 133 of connecting arm 71
tongue slidably fits between lugs 82 and 83 and coop
is, in the preferred embodiment, provided with a flat
erates therewith to prevent twisting of the jack relative 60 upper surface 135 and a flat lower surface 136. The
to the handle. The pin 85 joins the handle and jack so
sides, 137 and 139, of the shaft may be threaded as shown
that the relative motion between the jack and the han
in FIGURES 4 and 5 (in lieu of the smooth cylindrical
dle is limited to rotation about the longitudinal axis
surface therefor shown in FIGURE l), and a lock nut
of the pin 85.
140 provided therefor as an extra safety feature when
Shoulder 88 of the jack, further limits the clockwise 65 the clamp 20 is to be kept in a fixed clamped position
rotation of the jack 70 about pin 85 and yoke 81.
on a revolving pipe, as 23, for a long interval of time.
The jack, 70, comprises a housing 89, a tail end lug
Such threads, open at their top and bottom, permit ready
87 and two front lugs, 90 and 91, which form a yoke.
and complete cleaning by a brush or flushing with sol
The lugs 90 and 91 are each provided with a circular
vent. The clamp 20 is diagrammatically shown in FIG
eye, 90A and 91A, respectively, for a cylindrical remov 70 URE 2 in its operative position about a vertical pipe 23,
able lock pin 92 provided with retainer chain 94 to
which pipe is supported by cores, as 118, in a jacket 119
housing 89. A longitudinally movable ram 93 is pro
therefor in a conventional `rotary table 124.
vided in the housing andv is actuated through a hydraulic
A yoke is formed by lugs, 141 and 142, at the other
mechanism below described by an arm 95 seated in a
end of shaft 133. These lugs each lhave a cylindiical
pivotlly movable arm housing 96. The arm 95 is remov 75 eye (143 and 145, respectively). A pivot pin, 146, cylin`
3,037,258
5
drical in section, fits into said eyes. This pin 146 also
passes through a circular eye of the lug of the end link
53 and so completes the connection of the link assem
bly 211 formed by similar intermediate links, 25A-J, end
link 53, and bridging link 150. The bridging link 150
has a body 15‘1 provided with a guideway 152 shaped
as guideway 41 above described for receiving and mount
ing a wedge shaped slip, 153, therein. Such slip 153
is replaceable with above described wedge shaped slip
element 42. Link 150 also has, at one side thereof, a lug
substantially identical with the lug 30. The bridge arm
72 is firmly connected'on to the other side of said body
151 and is provided with a yoke formed of a base 1156
and two lugs, 157 and 159. The base 156 is spherically
cupped at 160 to receive the hemispherical head 129 of
the ram 93. The lower surface 161 of the lug 157 and
the upper surface 162 of lower lug 159 are smooth and
quickly tightening such a link assembly for use even dur
ing the short cycles of tightening and loosening required
in the replacement of drill bits in a drill string as well
as for longer periods of attachment to the drill pipe.
lt is to be noted that the tension across the con
nection arm 71 is transmitted to pin 77 substantially
directly; thereby the tension developed by the jack 70
is applied relatively evenly from pin 146 to pin 77 in
a counterclockwise direction and from pin 146 to pin 77
in a clockwise direction. Further, the tension developed
by the jack is also distributed relatively evenly over the
slips and links, 25E, ZSG, and 15€); between pin 77
and bridging arm 72. The ram piston 93 moves much
more rapidly than does a screw actuated connection de
vice for a given motion of an operator. The force ap
plied to the links and the slips carried thereby is, how
ever, entirely adequate to provide the force of contact
needed between the slips and the pipe to prevent the
flat so as to slidably iit over surfaces 135 and 136. The
motion of pipe through those slips. Additionally, such
bridge arm surface 163 lying adjacent shaft surface 137
is smooth and curved to i'lt such latter surface and, also, 20 lower adequately operable pressures achieved by the de
vice of this invention concomitant on readily controlla
rounded at its front and rear to permit the bridge arm
ble force of contact of the slips and pipe avoids damage
72 to move smoothly over such shaft surface when in
to the pipe and slips and jamming `of the clamp as re
contact therewith. Thus, bridging arm 72 mechanically
supports link 150 on arm 71.
sults from the excess forces provided by the uncon
The spacing of such surface 163 from the body 151 25 trolled slower, inconvenient tightening of a screw. The
tightening provided by the device of this invention avoids
is sufficiently small-_through use of a short base 156-so
stress localization due to mal-distribution of the tensile
that such surface 163 does not interfere with the move
stress.
ment of the arm 72 while the yoke is sufficiently long to
A spring 171 between bridging arm 72 and jack 70 is
perform the function herein described for the arm 72.
The above ñt of the yoke of the bridging arm is di 30 also provided to facilitate release of the tension of the
rected to and provides that, in manipulation of the de
vice during the opening and closing the group of link
assemblies, as 251-7', ZSG, and 150, to the right of pin 77
link elements about the pipe, as 23, following opening
as shown in FIGURE l will, while freely movable as
the disconnection of the connecting element 22.
The links, 25A~l, are each about 3 inches from center
above described, have the above-described mechanical 35
support whereby to conveniently remain coplanar with
the handle 69, jack 70, and connector arm 71. It will be
noted that the locking action of the slips depends on a
definite contact of the pipe surface with such slips. Such
of valve 109 to discharge hydraulic fluid from the ram
piston chamber 105 to the reservoir 107 and so facilitate
of eye 31 to center of eye 37. Variation in the diam
eter of the pipe 23 to be accommodated by clamp 20 of
this invention is accomplished by addition or subtraction
of one such link per each inch diameter change as the
slips are held as by the springs 49 above described in 40 pins holding such links, as 39, are only removably held
in place by cotter pins. A jack 70v with a 1/2 inch
their retracted positions. Unless there is a tight ñt pro
diameter pump portion of about l inch travel and l
vided on the pipe surface the slips will lose their holding
inch diameter ram piston with a ll/z inch travel pro
power. When there is a large gap between slips a pipe
vides, with an 18 inch long handle 95, entirely adequate
intended to be held by a group of such slips moves to
force to provide the force of contact needed between
ward the largest space between the slips; this results in
an unequal distribution of weight on the various links 4.5 pipe surface and slip surface on 81/2 inch outside diam
eter pipe. Bridge arm 72 and link 53 can be brought
and slips and a consequent jamming of the pipe on some
as close as desired by shortening shaft 133 and thereby
links (usually those closest to the largest space between
more closely approximating slips 153 and 179. There
the links), while other links are then not functionally
by, according to this invention, such slips (153 and
active. Accordingly, this invention provides a device
that reduces the maximum spacing between the links. 50 179) are brought together so that the distance therebe
tween does not exceed the distance between other slips
Further, during tightening of the device of this invention
the stress applied to the pipe is equalized between the
as 169 and 154.
According to this invention, the removable pin 92
(which may, if desired, be provided with a cotter pin
It is thus seen that, according to this invention, there 55 as shown in FIGURE 2) is conveniently, permanently
retained near to the jack body 89 by chain 94. Bridging
is provided a device that minimizes the maximum space
arm 72 is held by spring 171 to the head 129 of ram
between slips. More specifically, it reduces the space be
piston 93; thus link 150 and jack 70 are arranged to be
tween slips as 179 and 153 to less than that of the length
manipulated as one unit during opening and closing of
of the connecting means therefor. This is done, accord
ing to this invention, by a link assembly that provides 60 the clamp 20. Thus, the assembly 20 is rapidly ‘and
various links sub-assemblies, as 25A-J as well as 150
and 5-3.
conveniently made operative merely by pivoting the arm
71 about pin 146 and dropping pin 92 into the hole
ate of ends of the member, 72, for connecting and dis
90A provided therefor.
connecting the link assembly. In a preferred embodi
Opening of the clamp of this invention from its opera
ment such intermediate links (as 153 and ZSF) are sup
ported by the connecting member 71. Still a further 65 tive position is similarly quickly accomplished. Loosen
ing of clamp 20 from its operative position (Shown in
feature of this invention is the provision of the meter
FIGURES l and 2) is accomplished merely by turning
«114 which indicates when the slips are making adequately
valve handle 111; tightening of clamp 20 is quickly
forceful contact with the pipe to be supported thereby.
and controllably effected by pumping handle 95.
Thus the operator is able »to immediately and conveniently
correct his operation of the clamp, by notice of such 70 In use of the clamp 20 of this invention, Áthe clamp is
provided with the proper number of links 25A-J for
automatic indication of adequacy of contact of slip and
gripping the pipe 23, drill collar, or other such item.
pipe notwithstanding the wear of the pins and slips and
The clamp is then opened easily by removing pin 92
other parts, variations in manufacture, and skewed loca
and wrapped about a diametral section of the pipe a
tion of the clamp 20 on the pipe 23 during use thereof.
According to this invention, a device is provided for 75 convenient working distance above rotary table 124.
oriented functioning slips, eg., 169, 154, 153, intermedi~
3,037,253
7
S
Links 150 and 53 are approXimated to each other, arm
supporting said one end link on said rigid element of
72 is pivoted about the longitudinal axis of pivot pin
146, shaft 133 passes into the yoke formed by lugs 157
and 159, locking lug 131 smoothly slides between lugs
90 and 91, and locking conveniently available pin 92 is
dropped into place. Clamp 20 is then tightened and
whereby the slips on the end links are closer together than
the ends of the means for connecting the like intermediate
links said pivotal connections and means for pivotally
the slips thereof are then positively, conveniently and
controllably brought into contact with the surface of the
nected elements substantially in only one plane.
said connecting means intermediate the ends thereof,
connecting allowing rotation of all said pivotally con
3, In a clamp comprising a multiplicity of like inter
pipe 23, the valve 109 having been previously turned
mediate links, two end links, means for pivotally connect
to the locking position (the position at which valve 109 lO ing the links to form a continuous assembly with the end
connects reservoir 107 and pump piston chamber 101),
links at the ends of the assembly, means on the end links
by pumping handle 95 until indicator 114 indicates the
for connecting the ends of the assembly whereby the as
pressure in ram piston chamber 105 has reached that
sembly may be arranged around a pipe or like object, and
providing a reliable, yet non-damaging grip on the pipe by
a shiftable gripping slip for each link, the improvement
the slips of the clamp. The positive engagement of the
which comprises that the means on the end links comprise
slips as 42, 169, 153, 154, 179 on the item held thereby,
a connecting means with a rigid portion, such connecting
as pipe 23, holds the clamp thereto.
If the means, as
118, purposed to grip the pipe when making up or
disconnecting the drill string as above described should
fail the clamp 2t) attached to pipe 23 moves downward
ly therewith until it contacts the slips 113 or other part
of table 124; then the slips of the clamp 20 of this
invention, said clamp having been attached as above
described, having been positively engaged with the pipe
means being pivotally attached at one of its ends to a link
intermediate said end links and, at its other end to one
end link at the ends of said assembly, said connecting
means comprising a tightening means, said tightening
means being permanently and pivotally connected to said
intermediate link and being connected to indicating means,
said indicating means being responsive to the force de
veloped by said tightening means, and said rigid portion
surface move downwardly with the walls of said pipe 25 of said connecting means mechanically supporting the
and are, due to the slope of the back, as 46, of the
other end link on said connecting means intermediate
guideways, as 41, then each forced into a tighter grip
the ends thereof said pivotal connections and means for
on said pipe surface. 'Ihe slips, as 42, thus reliably
pivotally connecting allowing rotation of all said pivotallyl
and tirmly engage the pipe and prevent its fall further
connected elements substantially in only one plane.
into the well. The pipe thus held by the clamp 20 30 4. linl a clamp comprising a multiplicity of like inter
of this invention is then raised for further operation by
mediate links and two end links pivotally connected to
passing lifting clamps under the links, as 25A-I, lifting
form an assembly adapted to be arranged around a pipe
on the handles as 55 or 69, or when lifting clevises are
or like object, means for joining the ends of said assembly
provided in lieu of pins as 39, as is within the scope of
to hold the assembly around the object, at least one of said
this invention, by lifting the clamp and pipe therewith.
“ means being detachable from the link assembly, and a
It is to be understood that the forms of the invention
spring loaded slip on each link for gripping the object,
herewith shown and described are to be taken as pre
the improvement which comprises that the means for
ferred examples of «the same and that various changes
joining the ends of the assembly comprises a pivotally con
in shape, size and arrangement of parts may be resorted
nected series of elements, said series being attached at
to without departing from the spirit of the invention or 40 one end thereof to a link intermediate said end links and
the scope of the subjoining claims. Having thus de
scribed tlie invention, I claim:
l. In a clamp comprising a multiplicity of like inter
mediate links and two end links, means for pivotally
connecting the links to form a continuous assembly with
the end links at the end of the assembly, means for con
necting the ends of the assembly whereby the assembly
may be arranged around a pipe or like object, and shift
able slips carried by each link for gripping the object,
the improvement which comprises that «the means for I
connecting the ends of the assembly comprises a con
necting means with a rigid portion, such connecting means
nearer to one end link than the other and, at its other
end to said other end link, said connecting means com
prising a rigid portion, said connecting means also com
prising a tightening means being permanently and pivotal
ly connected to said intermediate link, said tightening
means being connected to indicating means, said indicating
means being responsive to the force developed by said
tightening means, and rigid bridging means connected
to said one end link and to said tightening means and
supporting said one end link on said rigid portion of
said connecting means intermediate the ends thereof,
whereby the slips on the end links are closer together
than the ends of the means for connecting the like inter
mediate links said pivotal connections and means for
being pivotally attached at one of its ends to a link
intermediate said end links and, at its other end, to one
end link at the end of said assembly, said connecting 55
pivotally connecting allowing rotation of all said pivotally
means comprising `a tightening means, and means me
connected elements substantially in only one plane.
chanically supporting the other end link on said rigid
5. A device as in claim 4 wherein, in the operating
portion of said connecting means intermediate the ends
position thereof, the tightening means exerts compressive
thereof.
2. In a clamp comprising a multiplicity of like interme 60 force on the bridging means towards said other end link.
6. In a clamp of the character described comprising a
diate links and two end links, means for pivotally connect
multiplicity of like intermediate and two end links, means
ing the links to form a continuous assembly with the end
for detachably pivotally connecting the links to form a
links at the ends of the assembly, means for connecting the
continuous series assembly adapted to be engaged around
ends of the assembly whereby the assembly may be ar
ranged around a pipe or like object, a shiftable gripping 65 objects, each link being proportioned to increase the ef
íective diameter of the assembly a given amount whereby
slip for each link, the improvement which comprises that
the clamp may be used on objects of larger and smaller
the means for connecting the ends of the assembly com
diameter by increasing or decreasing the number of links
prises a pivotally connected series of elements, one of
in said assembly, a gripping slip shiftably vertically on
said elements being rigid and elongated, said series being
attached at one end thereof to a link intermediate said end 70 each link, and movable inwardly upon downward shift
ing, spring means urging the slips upwardly, and means
links and nearer to one end link than the other and, at
for releasably connecting the ends of the assembly to hold
its other end, to said other end link, said connecting means
the slips in initial gripping engagement with the object
comprising a tightening means permanently and pivotally
including a member pivotally secured to one end of the
connected to said intermediate link, and means connected
assembly, the improvement which comprises that such
to said one end link and to said tightening means and 75 member pivotally secured is one of a pivotally connected
3,037,258
9
series of rigid connecting elements, said series being at
tached at one end thereof to a link intermediate said end
links and nearer to one end link than the other and, at
10
end of which ram contacts said bridging means, a valve
chamber between said ram piston chamber and said pump
piston chamber provided with a one-way valve permitting
ñow toward said ram piston chamber, said chamber being
its other end to said other end link, said connecting means
longitudinally elongated in the direction of passing from
comprising a iiuid actuated tightening means permanently
the periphery to the center of said objects about which
and pivotally connected to said intermediate link and
said plurality of links are adapted to be engaged, said
operatively connected to means indicating the pressure of
valve containing an inlet orifice, an orifice blocking means,
such Huid, and rigid bridging means connected to said one
and a spring, said spring urging said oriñce blocking means
end link and to said tightening means and supporting said
one end link on one of said rigid portion of said connect 10 toward said oriiice in a direction away from the center of
said object, whereby said valve serves to maintain opera
ing means intermediate the ends thereof, whereby the
tive pressure in the ram piston chamber on rotation of
slips on the end links are brought closer together than the
said device when said device is operatively connected to
ends of the means for connecting the like intermediate
said object about which said plurality of links are adapted
links said pivotal connections and means for pivotally
connecting allowing rotation of all said pivotally con 15 to be engaged.
nected elements substantially in only one plane.
References Cited in the tile of this patent
7. A device as in claim 6 wherein in the operating
UNITED STATES PATENTS
position thereof the tightening means exerts compressive
force on said bridging means towards said other end link.
883,630
Dunn _______________ __ Mar. 31, 1908
8. A device as in claim 6 wherein said ñuid actuated 20 1,104,579
Thorsby ______________ __ July 21, 1914
tightening means is located in one of said pivotally con
nected series of rigid elements, said means comprising a
2,301,625
2,406,607
Johnson ______________ __ Nov. 10, 1942
Jensen ______________ __ Aug. 27, 1946
984,592
63 8,250
France ______________ __ Feb. 28, 1951
Great Britain __________ ___ June 7, 1950
housing which includes a ram piston chamber, a llluid I
FOREIGN PATENTS
reservoir chamber, a pump piston chamber, and valve
chambers, a movable ram in said ram piston chamber 25
being slidably located in said ram piston chamber and one
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