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1. (WO1989000249) LOCKABLE, PIN-RETAINING COUPLING
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LOCKABLE, PIN-RETAINING COUPLING
DESCRIPTION
The present invention generally relates to
couplings for use with load-lifting devices and safety 5. restraints such as cables, chains, and ropes and, more partiuclarly, is concerned with a loc able,
pin-retaining coupling which remains securely locked
until released, and once released is held in the
released position without regard to its orientation to

10. the vertical, and in which the component parts are not subject to disassembly and subsequent loss.
The ability to transfer a load from a lifting
device such as a hoist or derrick or crane without
concern for the loss of component parts of the coupling

15. device is important in industrial settings such as
factories and quarries, and in construction.
Similarly, individuals requiring tethers tu safety equipment while engaged in hazardous sports or
occupations such as mountain climbing or window washing

20. require a coupling which is easily and quickly
operable, without fear of losing parts, without fear of either uncoupling during use or closing and becoming
coupled before being attached to the necessary
equipment.
25. Present couplings in use take the form of elongated links which close either by latching upon pins or close by means of a threaded nut, and are subject to being
distorted or sprung out of shape while in use, thus
making the locking or securing portions of these
30. couplings inoperable. The couplings become unsafe
under these circumstances.
Other couplings are held together by threaded nuts which require the use of wrenches and which often vibrate loose while in use.
In one general type of coupling the pin is simply
held in position by a cotter pin or clamp which often
becomes lost in usage. In another general type, pin 5. ' locking means have been complex and uneconomical to
manufacture or otherwise are overly bulkly and
undesirable in use.
U.S. Patent 4,068,960 discloses a clevis and pin
style coupling which remains latched in the closed 10. position.
It is therefore highly desirable to provide an
improved coupling and an improved locking means for a
load bearing pin.
It is also highly desirable to provide an improved 15. coupling having a pin, a clevis and a retractable latch to hold the pin in position.
It is also highly desirable to provide an improved coupling having a pin, clevis and a brake restraining
the movement of the pin wihtin the clevis when the pin 20. is in other than a fully engaged position.
It is also highly desirable to provide an improved coupling having a clevis and a pin with stops which
prevent the pin from being removed from the clevis.
It is also highly desirable to provide a relatively 25. simple, economical and safe locking means for a load
bearing pin.
It is also highly desirable to provide an improved coupling having a clevis and a pin with both a latch to prevent inadvertent opening of the coupling and a brake 30. to prevent inadvertent movement of the pin within the
clevis.
It is also desirable to provide an improved
coupling with these features by economical, maintenance free and readily available mechanical means with a
minimum of mechanical parts and with a minimum of
fabrication required on the parts in a mechanically
simple structure which is convenient to use.
5. it is also highly desirable to provide an improved coupling which may be coupled and uncoupled by
untrained users, conveniently, without the use of
tools.
It is also highly desirable to provide a coupling 10. which when open will remain open despite its
orientation and will not be closed prematurely due to
the force of gravity.
It is also highly desirable to provide an improved coupling and load bearing pin assembly which has all of 15. the above-identified features.
It is an object of the invention to provide an
improved coupling and an improved locking means for a
load bearing pin.
It is another object of the invention to provide an 20. improved coupling having a pin, a clevis and a
retractable latch to hold the pin in position.
It is yet another object of the invention to
provide an improved coupling having a pin, clevis and a brake restrainig the movement of the pin within the 25. clevis when the pin is in other than a fully engaged
position.
It is still another object of the invention to
provide an improved coupling having a clevis and a pin with stops which prevent the pin from being removed 30. from the clevis.
It is yet another object of the invention to
provide a relatively simple, economical and safe
locking means for a load bearing pin.

It is still another object of the invention to
provide an improved coupling having a clevis and a pin with both a latch to prevent inadvertent opening of the coupling and a brake to prevent inadvertent movement of 5, the pin within the clevis.
It is yet another object of the invention to
provide an improved coupling with these features by
economical, maintenance free and readily available
mechanical means with fabrication required on the parts 10. in a mechanically simple structure which is convenient to use.
It is still another object of the invention to
provide an improved coupling which may be coupled and
uncoupled by untrained users, conveniently, without the 15. use of tools.
It is yet another object of the invention to
provide a coupling which when open will remain open
despite its orientation and will not be closed
prematurely due to the force of gravity.
20. It is still another object of the invention to
provide an improved coupling and load bearing pin
assembly which has all of the above-identified
features.
In the broader aspects of this invention there is 25. provided a lockable, pin-retaining coupling comprising a clevis having a bore extending therethrough and a pin slidably positioned within the bore. A brake restrains movement of the pin within the bore. Stops adjacent
opposite ends of the pin prevents the pin fror being 30. removed from the bore.
OH THE DRAWINGS
The above mentioned and other features and objects of this invention and the manner of obtaining them will become more apparent and the invention itself will be
better understood by reference to the following
description of the embodiment of the invention taken in conjunction with the accompanying drawings wherein:
5. Figure 1 is an assembly drawing showing the clevis, its two legs, the pin inserted in the fully closed
position, and a slidable latch body in the second leg;
Figure 2 is an end view of the sσond leg taken
substantially along line 2-2 of Fig. 1 showing the 10. latch body in its latched position;
Figure 3 is an end view of the second leg like Fig. 2 showing the latch body in its unlatched position;
Figure 4 is a fragmentary cut-away view partially
in cross-section of the pin and clevis showing details 15. of the pin in the fully opened position;
Figure 5 is a fragmentary sectional view of the pin and clevis showing details of the collar, the collar
receptacle, and the pin's groove;
Figure 6 is an enlarged view of the detail shown in 20. Figure 5, again in cross section, illustrating the
co-operation of the collar, the pin groove, and the
collar receptacle in the fully opened position;
Figure 7 is a bottom plan view of the latch body;
Figure 8 is a side view of the latch body shown in 25. Figure 7 from one side;
Figure 9 is a side view of the latch body shown in
Figure 7 from the other side;
Figure 10 is a sectional view of the latch body
taken substantially along the section line 10-1 of 30. Figure 7;
Figure 11 is a cut-away view partially in
cross-section of the second leg of the clevis showing release of the spring biased rod which holds the latched body in the fully latched position;
Figure 12 is a cut-away view of the first leg
detailing the braking action of the pin's surface, the collar, and the collar receptacle;
5. Figure 13 is a sectional view of the collar taken
substantially through the collar's axis and
perpendicular to the collar's plane; and
Figure 14 is a detail, cut-away view of one
specific embodiment of the collar.
10. The invention provides a coupling to be used for
attaching loads n a readily transferable manner to
lifting devices such as cranes, hoists, and derricks.
There is likewise provided a coupling to be used with
safety equipment by those in sports and industry such

15. as mountain climbers and window washers. The coupling may be readily and safely utilized without regard to
the level of the mechanical ability of the users, and
without the requirement of tools or equipment for
releasing or engaging the coupling. The coupling
20. comprises a pin and clevis, the clevis having first and second legs, each of the legs having a bore
therethrough, the bore being co-axial and having
cylindrical surfaces, the bores being adapted to
slidably receive the pin, the pin having first and

25. second ends and first and second stops at the
respective ends, the pin having a cylindrical surface, the second leg having a latch, the latch holding the
pin in position within said bores of the first and
second legs when the latch is engaged with the pin, the

30. pin being retractable from the bore of the second leg
when the latch is not engaged with the pin, a brake,
the brake restraining movement of the pin within the
bores, the stops preventing the pin from being retractable from the bore of the first leg. A groove
in the second end of the pin cooperates with the
latching mechanism when the coupling is in the coupled position and cooperates with the retainer when the pin 5. is in the fully opened position. A collar contained
within a receptacle in the first leg's bore is wedged
between the face of the groove and opposite face of the receptacle.
The collar may be of a common stretchable material 10. such as either a polymer or a coiled spring, being
stretched about the pin. In the restraining position
the retainer occupies the groove at the end of the pin.
An advantage to use of this collar is that it
contacts the groove about the groove's circumference 15. rather than at a single point as does the retaining
means of U.S. Patent 4,068,960. Another advantage to
the use of the collar is that a wide variety o sizes
are commercially available. Depending upon the spring constant desired and the coefficient of friction of the 20. collar's surface, a manufacturer has a wide latitude in selecting collars for different sizes of pins. The
collar acts as a brake, preventing the pin's moving to the fully opened or to the fully closed position until the user is ready. It has been possible for a
25. conventional pin to accidently slip fully open due to
the force of gravity pulling the pin downward. It
likewise has been possible for a pin to close itself,
due to gravity. This tendency of couplings to either
open or close before the operator is ready is .ot only 30. annoying but is also a safety hazard. Those relying
upon the coupling as a safety device frequently have
only one hand available for use in operating the
coupling, and thus would appreciate the braking feature of the claimed invention which keeps the pin from
accidently opening or closing and which does not
require the use of both of the operator's hands to
maintain the fully opened position. The braking action 5. of the collar upon the pin's surface likewise allows
the pin to be only partially opened, thus keeping the
coupling in contact with existing attachments to
chains, ropes, cables, and the like, all without fear
that the pin might accidentially fully open allowing

10. everything to fall.
The braking effect of the collar may be altered by varying the spring constant of the collar, by selecting a collar whose surface finish has a greater or lesser
coefficient of friction, and by specifying that surface

15. finishes on the pin and the walls of the collar
receptacle be either smoother or rougher, thereby
changing the coefficient of friction on the surfaces.
In some embodiments it is possible to design the
components such that the collar rolls along the pin's

20. surface while in other designs it is possible for the
collar to slide along the pin's surface.
Referring to Figure 1, a two legged clevis 10 is
shown having a first leg 12, a second leg 19, and a pin 30. Pin 30 is shown in the fully closed position.
25. Latch body 48 is shown, as is spring-biased rod 72
preparatory to depression by a pencil point.
Referring now to Figures 4 through 6, pin 30 is
shown in the fully retracted position, being fully
withdrawn from the second leg 19 of the clevis 10, and

30. held in place by retainer 35 comprising collar 28,
contained within groove 38 and disk-shaped collar
receptacle 16 within pin 30 and bore 26,
respectively. Receptacle 16 comprises spaced-apart walls 17, and a cylindrical face 18 disposed between
walls 17. Bore 26 extends through first and second
legs 12 and 19. Bore 26 has a cylindrical surface
27. Collar 28 has a toroidal surface 29.
5. Pin 30 has a cylindrical surface 31 and a first end 32 on which is a first stop 34, which in a specific
embodiment may be an enlarged knob. Retainer 35
cooperates with second pin end 36 on which is located a second stop 37 comprising groove 38 and shoulder 40. 10. As is detailed in Figure 6, groove 38 and shoulder 40 define ramp 42. Ramp 42 has an incline 43 and a
base 44. Base 44 encircles pin 30 to form neck 45.
Head 46 is formed on second pin end 36 by shoulder
40. In a specific embodiment not shown ramp base 44

15. may be a single point at the intersection of incline 43 with shoulder 40.
Collar 28 is shown encircling neck 45 and wedged
between shoulder 40 and opposite receptacle wall 17.
Pin 30 is disposed within bore 26, pin suface 31 being

20. slidable with bore cylindrical surface 26.
Collar 28 is a non-compressible, but expandible
toroid having a surface 29. In a specific embodiment, collar 28 may apply a radial force to neck 45. Disk- shaped collar receptacle 16 has a major diameter such

25. as to accommodate fully collar 28 when collar 28 has
been forced about pin surface 31 when pin 30 is in
other than the fully opened position. Receptacle walls 17 are separated by bottom face 18 sufficiently to
accommodate the axial thickness of toroidal collar 28.

30. The radial distance from cylindrical surface 27 of bore 26 to face 18 of receptacle 16 may be equal to or greater than the axial thickness of collar 28, and the
distance in the same direction from pin surface 31 to base 44 of ramp 42 may be from about one-quarter to
about three-quarters of the axial thickness of collar
28. By maintaining these dimensions there will exist a clearance betwen collar 28 and face 18 which allows 5. collar 28 to operate frictionally against only one of
walls 17, shoulder 40, ramp 42, pin surface 31 and bore surface 27 and either free from interference with face 18 or in engagement with face 18. Face 18 may be
conveniently shaped to accommodate collar 28 and both

10. face 18 and walls 17 may be spaced to engage collar 28 when collar 28 is on pin surface 31 if additional
frictional forces are required. In one specific
embodiment, face 18 is cylindrical in cross-section.
Face 18 may also take the form of a fillet or a
15. V-shaped groove in other specific embodiments not
shown. Collar 28 and those surfaces engaging collar 28 can also be provided with friction-increasing surfaces if desired.
Groove 38 profiles neck 45 and encircles the second

20. end 36 of pin 30. Groove 38 has a shoulder 40 plunging downward and a ramp 42 comprising incline 43 and base
44. Ramp base 44 may have a width equal to or greater than the axial thickness of collar 28 as illustrated in Figure 6. In other specific embodiments not shown,

25. incline 43 abuts shoulder 40 directly and base 44 will be a single point turned on end 36. Ramp 42 encircles pin 30 and acts to stretch collar 28 outwardly about
pin surface 31 when pin 30 is moved toward the closed
position and away from the fully opened position. In

30. operation, collar 28 is urged outwardly and is
stretched upon surface 31 as shown in Figure 12.
Collar 28 is held between walls 17. Being thus
contained, collar 28 acts upon pin surface 31 either frictionally or by a rolling action to brake the motion of pin 30 within bore 26, being thus restrained from
motion relative to pin 30.
Figure 13 is a sectional view of collar 28 showing 5. toroidal surface 29. Figure 14 is a cut-away view
showing one specific embodiment of collar 28 where the toroid is a coil 33.
Braking action of brake 14 is created by the action of collar 28 on receptacle 16 and the spaced apart

10. walls 17 of the receptacle 16, and pin suface 31.
Collar 28 frictionally engages at least one of the
spaced apart walls 17 and is stretched about pin
surface 31 to create brake 14. In a specific
embodiment, collar 28 may engage face 18 and/or both

15. walls 17. Collar 28 applies radial force to surface 31 of the pin while being retained in receptacle 16.
Friction sliding movement between collar 28 and pin 30, and between collar 28 and receptacle walls 17 and/or
face 18 restrains movement of pin 30 through bore 26.

20. Pin surface 31, face 18 and the receptacle walls 17 may have their surface finishes varied to be either
smoother or coarser depending upon the coefficient of
friction desired. Likewise, the surface 29 of collar
28 may be varied to alter its coefficient of
25. friction. Thus, tailoring of the components may be
achieved such that collar 28 either rolls or slides
along pin surface 31.
Collar 28, because of its encircling character,
provides uniform resistance across surface 31 of pin

30. 30, as opposed to existing couplings utilizing a single point retaining means, which because of its very nature concentrates pressure at a single point promoting
scratching and scoring of the pin. Collar 28 also acts to center pin 30 within bore 26 allowing ease of
operation when compared with existing single point
devices which tend to urge the pin against one side of the bore only, making for difficulty in alignment.
5. Figure 1 shows pin 30 in the fully closed
position. At the first end 32 is a first stop 34,
shown in one specific embodiment as being enlarged and in the form of a knob. When pin 30 has been fully
closed in clevis 10, first stop 34 prevents pin 30 from

10. further movement and acts to locate pin 30 such that
latch body 48 can engage second pin end 36. As shown
in Figures 1 and 11, latch body 48 has projecting
tracks 64 which complement channel slots 22 located in second leg 19 of clevis 10.
15. Figures 1, 2, 3 and 7 through 11 show the structue of latch body 48 to contain an inner-surface 52, an
outer-surface 50, projecting tracks 64, and slot 54.
Slot 54 has an open, circular first end 56 which
accommodates head 46. Latch 66 comprises latch body 48

20. which, in addition to having outer 50 and inner
surfaces 52, is guided by upper and lower projecting
tracks 64. On latch body 48 an overhang 62 exists in
the region between inner surface 52 and undercut
portions 58 and 60 of slot 54. Projecting tracks 64

25. extend from latch body 48 in the form of a "T". Tracks 64 complement upper and lower transverse channel slots 22 positioned within second leg 19. Inner surface 52
has a slot therein. An open region of the slot 56
accommodates head 46 of pin 30. Overhang 62 is
30. complementary with neck 45 on second end 36 of pin
30. Overhang 62 engages second pin end 36 when latch
body 48 is in the latched position and prevents pin 30 from being retracted from second end 36 of clevis 10.

Overhang 62 disengages second pin end 36 when latch
body 48 is in the unlatched position allowing pin 30 to be retracted from second leg 19 of clevis 10.
In operation, as latch body 48 slides, the
5. undercut, longitudinal central portion 58 moves over
shoulder 40, over head 46, and comes to rest with
undercut, disk-shaped second end 60 of slot 54 cupping neck 45 of pin 30. Overhang 62 cups neck 45 and
latches pin 30 in the fully closed position. Hole 70

10. accommodates a spring biased rod 72 in order to lock
latch body 48 and prevent it from accidentally moving
from other than the fully latched position. Rod 72 may be depressed by any convenient, common instrument, such as the pencil point shown in Figures 1 and 11. The

15. second leg 19 and latch 66 are also disclosed in U.S.
Patent No. 4,068,960 and that disclosure is
incorporated hereby by reference.
In one specific embodiment shown in Figures 2 and
3, latch body 48 contains recess 68, which recess
20. accommodates detent 24 in order to prevent the removal of latch body 48 from second leg 19. Second leg 19 has a detent 24 which allows latch 66 to travel slidably
from the latched position to the unlatched position.
Detent 24 holds latch body 48 within second leg 19

25. preventing loss. Detent 24 may be of any conventional and well known designs such as a set screw, key or
pin. In specific embodiments not shown, latch body 48 may be urged into the latched position by a
conventional spring.
30. Because of the grave safety dangers involved in a
coupling's inadvertently coming loose, the present
invention employs three redundant safety measures.
Before opening, spring biased rod 72 must be depressed. While being depressed, latch body 48 must
be withdrawn, and finally pin end 30 must be axially
urged toward the open position against action of brake 14.
5. Furthermore, because of the action of brake 14 the coupling mentioned will not accidently close itself,
even when pin 30 is oriented in an upright position
subject to gravitational forces downward. When in th
fully open position an axial force must be imparted to

10. pin 30 sufficient to force collar 28 outwardly on ramp 42. Even then the aforementioned action of brake 14
prevents pin 30 from dropping into the closed
position. Brake 14 has the additional safety advantage of preventing pin 30 from accidentally sliding and

15. pinching a user's hand between enlarged end 34 and
first leg 12.
The disadvantage of conventional couplings which
employ safety devices which are either threaded or of a hook and latch nature, which safety devices are
20. subjected directly to load bearing forces, is that over time stresses deform the safety features. This
disadvantage is overcome by the instant invention.
Groove 38 only comes in contact with collar 28 and
latch body 48, neither of which is subjected to load

25. bearing forces. Likewise, rod 72 has its only contact with hole 70 of latch body 48, and is never subjected
to load bearing stress.
While there has been described above the principles of the invention in connection with a specific coupling

30. device, it is to be clearly understood that this
description is made only by way of example and not as a limitation to the scope of the invention.