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I claim:
1. A lifting clamp for articles such as steel plates comprising:
a clamp body including a pair of spaced side plates, said body defining a
slot through said side plates to receive an article to be lifted, said
slot being laterally enlarged inwardly of its open outer end,
a pair of opposed jaws mounted on pivot pins connected to said body on
opposite sides of said slot adjacent said open end of said slot with said
jaws having convex gripping surfaces facing inwardly from the opposite
sides of said slot, each of said pivot pins being perpendicular to said
side plates, one of said jaws being a gripping jaw pivotally mounted for
opening and closing movement relative to the other jaw and the other jaw
being a cam jaw,
a shackle mounted for guided movement in said clamp body and adapted for
connection to a lifting force,
link means connecting said shackle to said gripping jaw to close said
gripping jaw when a lifting force is applied to said shackle, said link
means and said gripping jaw forming an assembly,
locking means having a manually operated handle pivotally mounted outside
of said clamp body and a spring between said side plates connected to said
assembly, said spring being tensioned by rotation of said handle to urge
said gripping jaw toward its closing position and released by reverse
rotation of said handle to free said gripping jaw to move to its open
position,
said cam jaw being unconnected to said shackle and mounted for free pivotal
movement about its pivot pin with its convex gripping surface extending
eccentrically above its pivot pin to be cammed inwardly in the slot into
closer gripping relation with said gripping jaw in response to a downward
load on said convex gripping surfaces, and
said clamp body extending laterally outwardly from said slot past said cam
jaw to completely enclose the outer surface of said cam jaw opposite its
gripping surface and said clamp body being relieved to enlarge the side of
said slot above the pivot pin for said cam jaw so that the upper end of a
plate engaged between said jaws can pivot around said cam jaw while
maintaining gripping contact with the convex gripping surface of said cam
jaw and without engaging said side of the slot.
2. A lifting clamp as recited in claim 1 wherein an auxiliary lock means is
mounted on the clamp body to be engagable with said handle to latch said
handle against inadvertent movement from its position urging said gripping
jaw to closing position.
3. A lifting clamp as recited in claim 2 wherein said auxiliary lock means
is spring biased to be manually releasable to free the handle for reverse
rotation.
4. A lifting clamp as recited in claim 2 wherein said auxiliary lock means
is shiftable to a position where it is deactivated from latching said
handle.
5. A lifting clamp as recited in claim 2 wherein said auxiliary lock means
comprises a pin reciprocally mounted in a pocket within the clamp body,
said pin being spring biased to extend outwardly of the body for
engagement with said handle in latching said handle.
6. A lifting clamp as recited in claim 5 wherein said pin is mounted in a
separate pocket provided between said side plates.
7. A lifting clamp as recited in claim 5 wherein said clamp body side
plates have bolts extending therebetween on opposite sides of said shack
and said pocket for said pin is formed within one of said bolts.
8. A lifting clamp as recited in claim 5 wherein said pin has a latching
detent engagable with a shoulder in said pocket by depressing and rotating
said pin to hold said pin fully within said pocket to deactivate said pin
from latching said handle.
9. A lifting clamp as recited in claim 5 wherein said handle has an
inclined cam surface on the handle portion which initially engages said
pin to cam the pin into said pocket as the handle is moved to its full jaw
closing position and said handle has a notch into which said pin extends
when the handle is in its full jaw closing position.
10. A lifting clamp as recited in claim 1 wherein said cam jaw is mounted
on said clamp body for limited pivotal movement.
11. A lifting clamp as recited in claim 10 wherein both of said jaws have
gripping teeth extending transversely of the jaw surface which is to grip
the article to be lifted.
12. A lifting clamp as recited in claim 10 wherein the gripping surface on
each jaw is curved at a smaller arc on the portion located furthermost
inwardly of said slot through said side plates.
13. A lifting clamp for articles such as steel plates:
a clamp body including a pair of spaced side plates, said body defining a
slot through said side plates to receive an article to be lifted,
a pair of opposed jaws mounted on opposite sides of said slot, one of said
jaws being a gripping jaw pivotally mounted for opening and closing
movement relative to the other jaw,
a shackle mounted for guided movement in said clamp body and adapted for
connection to a lifting force,
link means connecting said shackle to said gripping jaw to close said
gripping jaw when a lifting force is applied to said shackle, said link
means and said gripping jaw forming an assembly,
primary locking means having a manually operated handle pivotally mounted
outside of said clamp body and a spring between said side plates connected
to said assembly, said spring being tensioned by rotation of said handle
to urge said gripping jaw toward its closing position and the tension
released by reverse rotation of said handle to free said gripping jaw to
move to its open position, and
auxiliary lock means mounted on the clamp body to be engagable with said
handle to latch said handle against inadvertent movement from its position
urging said gripping jaw toward closing position.
14. A lifting clamp as recited in claim 13 wherein said auxiliary lock
means is spring biased to be manually releasible to free the handle for
reverse rotation.
15. A lifting clamp as recited in claim 13 wherein said auxiliary lock
means is shiftable to a position where it is deactivated from latching
said handle.
16. A lifting clamp as recited in claim 13 wherein said auxiliary lock
means comprises a pin reciprocally mounted in a pocket within the clamp
body, said pin being spring biased to extend outwardly of the body for
engagement with said handle in latching said handle.
17. A lifting clamp as recited in claim 16 wherein said pin is mounted in a
separate pocket provided between said side plates.
18. A lifting clamp as recited in claim 16 wherein said clamp body side
plates have bolts extending therebetween on opposite sides of said
shackle, and said pocket for said pin is formed within one of the bolts
connecting said side plates together to form the clamp body.
19. A lifting clamp as recited in claim 16 wherein said pin has a latching
detent engagable with a shoulder in said pocket by depressing and rotating
said pin to hold said pin fully within said pocket to deactivate said pin
from latching said handle.
20. A lifting clamp as recited in claim 16 wherein said handle has an
inclined cam surface on the handle portion which initially engages said
pin to cam the pin into said pocket as the handle is moved to its full jaw
closing position and said handle has a notch into which said pin extends
when the handle is in its full jaw closing position. |
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Claims |
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Description |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to clamps for lifting articles such as steel plates
and more particularly to such clamps having a locking device to retain the
clamp jaws in either an open or closed position.
2. Description of the Prior Art
U.S. Pat. No. 2,654,630 discloses a clamp, comprising a clamp body having a
slot to receive an article to be lifted. A jaw is provided on each side of
the slot adjacent the outer open end of the slot. The gripping jaw is
movable between open and closed positions relative to the other jaw which
is generally fixed. The movable jaw is operated by a shackle connected to
the movable jaw by a force multipling linkage.
The clamp body includes a pair of spaced side plates. Mounted on the inside
of the side plates is a pivotal locking plate operated by a handle located
outside the side plate. A heavy tension spring connects the locking plate
to the linkage which extends between the shackle and the movable jaw. By
rotation of the locking handle to a closed position, the spring exerts a
heavy closing force on the movable jaw. At the same time however, the
spring tends to cant the pivot pin connecting the locking plate to the
handle to a position inclined relative to its normal axis. This causes a
heavy operating action which makes the lever difficult to operate.
It has been found that some clamps tend to permit a plate being lifted to
engage a portion of the slot of the clamp in swinging back and forth such
that the plate tends to "walk out" of the slot and its engagement with the
clamp jaws.
Also in clamps, in their use, there could be a danger of the operating
handle striking an object while the steel plate is being lifted which
releases the handle to its open position, thus running the danger of the
steel plate becoming released from the clamp during the lifting operation.
SUMMARY OF THE INVENTION
Generally, the invention relates to a lifting clamp which comprises a clamp
body including a pair of spaced side plates. The body defines a slot
through the side plates to receive an article to be lifted, this slot
being laterally enlarged inwardly of its open outer end. The pair of
opposed jaws which are arcuate in shape are mounted with one jaw on each
opposing face of the slot. A shackle is mounted for guided movement in the
clamp body and has a lifting connection to apply a lifting force with the
shackle being connected by a link to the gripping jaw which is movable
between open and closed positions. The opposite clamping jaw is also
mounted to be movable for limited pivotal movement.
A locking means having a manually operated handle pivotally mounted on the
outside of the clamp body, has a spring tension created by rotation of a
handle to urge the gripping jaw to its closed position, and release the
spring tension by reverse rotation of the handle to move the gripping jaw
to its open position.
The manually operated handle additionally has an auxiliary lock which is
manually operated to latch the handle against inadvertent or unintentional
movement of the handle from its position urging the gripping jaw to a
closed position. This auxiliary lock is spring biased to latch the handle
by mere movement of the handle into the position urging the gripping jaw
toward closed position. The auxiliary lock is manually depressed to
unlatch the handle. Also the auxiliary lock may be constructed to remove
it from its normal position for latching the handle when the use of the
auxiliary lock is not desired.
A primary object of the present invention is to provide an improved lifting
clamp of the general type disclosed in Renfroe U.S. Pat. No. 2,654,630,
having an easily operated locking mechanism and a slot enlarged at its
inner end remote from the outer open end of the slot to obtain better and
safer lifting conditions where the jaws are arcuate and movably mounted on
the opposite sides adjacent the open end of the slot.
It is also a principal object of this invention to provide an improved
lifting clamp with an easily operated mechanism and an auxiliary lock to
latch the primary locking mechanism against inadvertent release.
Another object of this invention is to provide an auxiliary lock to latch
the above mentioned locking mechanism which can be deactivated and held
deactivated from its normal position where it latches the handle of the
primary locking mechanism.
Other advantages of this invention will become apparent from the following
disclosure taken in connection with the accompaning drawings wherein
preferred construction of embodiments of the invention are set forth by
way of example.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an elevational view showing the lifting clamp of the invention
from the side carrying the manually operated handle in its latched closed
position.
FIG. 2 is a view similar to FIG. 1 but showing the handle released for the
gripping jaw to be moved to open position.
FIG. 3 is a sectional view taken on line 3--3 of FIG. 4, showing how the
movable arcuate jaws and laterally enlarged slot permit a plate being
lifted to swing back and forth.
FIG. 4 is a side elevational view of the clamp.
FIG. 5 is a side elevation of the clamp taken from the opposite direction
of FIG. 4.
FIG. 6 is a sectional view taken on line 6--6 of FIG. 3.
FIG. 7 is a sectional view taken on line 7--7 of FIG. 2.
FIG. 8 is a sectional view taken on line 8--8 of FIG. 2.
FIG. 9 is a partial elevational view of an alternative embodiment showing
the auxiliary lock, latching the handle of the primary locking mechanism.
FIG. 10 is a view taken on line 10--10 of FIG. 9.
FIG. 11 is a view of a further alternative embodiment for the auxiliary
lock to enable it to be deactivated when its use is not desired.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
As shown in FIG. 1 the clamp 10 has its locking mechanism latched by an
auxiliary spring biased locking pin in the position where the jaws of the
clamp are urged to hold an article being lifted such as plate P. FIG. 2
shows the clamp 10 with the locking mechanism unlatched from the auxiliary
spring biased locking pin and the mechanism moved to the jaw opening
position where the two jaws of the clamp are moved apart from the clamp to
be ready to receive an article to be lifted.
The clamp 10 has a body made up of two side plates 11 and 12, these are
best shown in FIGS. 4 and 5 and in section in FIG. 6. The pair of side
plates 11 and 12 are secured in spaced relation to each other by a pair of
connecting bolts 14 and 16. Each bolt has a spacer tube 18 and 20,
respectively surrounding the bolt and establishing the appropriate spacing
between the pair of side plates of the clamp body. These bolts are located
near the top of the clamp body as best shown in section in FIG. 3. It will
be noted that bolt 14 has a conventional nut 22 threaded thereon to hold
the side plates in spaced relation. Nut 14 also has a conventional head as
appears in FIGS. 1 and 2. On the other hand the bolt 16 has a conventional
nut 24 threaded thereon but as shown in section in FIG. 7, it has a
tapered head fitting in a tapered hole in plate 12 for the head of the
bolt 16 to be flush with the outer surface of plate 12. This head of bolt
16 is provided with an allen wrench socket 26 to facilitate holding the
bolt while nut 24 is being threaded and tightened thereon. This flush
mounting of bolt head 16 has a purpose that will be apparent from the
subsequent description. As shown in FIG. 3, the side plates 11 and 12 are
also secured together by means of a bridging member 28. This bridging
member is welded to the inside of plate 11 and inside of plate 12 to
firmly hold the lower ends of the clamp side plates in appropriate spaced
relation. In addition to the bridging plate 28, a member 30 is also welded
to the inside of the plates and provides a stop for the small cam jaw.
Again as shown in FIG. 3, the combination of the bridging member 28, the
member 30 provide a stop pocket 32 to limit the rotation or movement of
the small cam jaw as will be described hereinafter.
A pair of jaws are pivotally mounted between the side plates 11 and 12.
Thus movable arcuate gripping jaw 34 is mounted on a pin 36. This pin 36
extends through apertures formed in the side plates 11 and 12 and is held
loosely in the side plates of the clamp body by retaining pins 38, as
shown in FIGS. 4 and 5.
The jaw 34 has a series of teeth 40 formed on its arcuate gripping surface
as shown in FIGS. 1 and 3. These teeth 40 extend transversely across the
width of the jaw 34 and in combination with the arcuate configuration of
the gripping surface provide an improved grip for the article, such as
plate P, being lifted. The arc of the gripping surface carrying teeth 40
is not the arc of a circle but rather has a lesser curvature toward its
lower end, as shown in FIG. 1, and a sharper curvature as its nears the
upper end of the gripping surface on jaw 34. This has an advantage in that
as the jaw moves into gripping engagement with an article, such as plate
P, the downward movement tends to drive the teeth 40 more firmly into the
surface of the article being lifted.
The other smaller camming jaw 42 is pivotally mounted at the opposite side
of the slot 44, the slot 44 being formed in the side plates of the clamp
body to receive the article to be lifted. It will be noted that the slot
44 is laterally enlarged at its inner most area as shown at 46, whereas,
it has a narrower entrance way adjacent the outer end of the slot 44. This
lateral enlargement 46 has an advantage in that it enables a plate being
lifted to rock back and forth without engaging the sides of the slot which
can have a tendency for the plate or article being lifted to "walk out" of
the clamp slot. The characteristic of such swinging movement of an article
such as plate P is illustrated in the different positions of the plate
shown in FIG. 3 where the solid line position shows one swinging position
of the plate and the phantom line showing illustrates the motion of the
plate were it to swing in the opposite direction.
Cam jaw 42 mounted on one side of the slot 44 is pivotally supported on pin
48. This pin 48, like pin 36 that supports gripping jaw 34, is mounted in
apertures formed in the side plates 11 and 12 of the clamp body and held
in this position by retaining pins 50. Like the gripping jaw 34, the
smaller cam jaw has teeth 52 formed on the outer arcuate gripping surface
of such jaw. The gripping surface carrying teeth 52 on cam jaw 42 is also
not an arc of a circle but rather has at its lower outer end a lesser
curve, as shown in FIG. 1.
As best shown in FIG. 3, the upper rear portion of cam jaw 42 has a squared
end segment 54. This segment fits in the pocket 32 formed between bridging
plate 28 and member 30. As shown in FIG. 3, the relation of the squared
segment 54 on jaw 42 to the pocket 32 on the clamp body is such that the
jaw 42 is restricted to a limited pivotal movement on pin 48, this
movement being shown as a maximum of 5 degrees from pivoting in one
direction engaging one portion of the pocket 32 to full pivoting in the
other direction engaging another portion of the pocket 32.
In practice better holding occurs with the combination of the teeth and the
formed gripping surfaces which have in the case of both jaw 34 and jaw 42
a larger radius of curvature near the outer end of the jaw leading into a
smaller curvature at the upper end within the laterally enlarged portion
46 of the slot 44. When the clamp is placed in operation to lift an
article, the small camming jaw 42 tends to pivot down as the gripping jaw
34 moves into engagement with the opposite side of the article being
lifted. With this downward camming the jaw moves to a point where it is
slightly tilted and the smaller radius curvature carrying teeth 52 on jaw
42 cams in for a more firm gripping of the surface of the article being
lifted.
A shackle 60 having a large opening 62 adapted to receive a conventional
lifting hook at the end of a hoisting cable is mounted to extend into the
body of the lifting clamp between side plates 11 and 12. This shackle 60
is supported in a pair of grooves 64 formed on the opposite inner sides of
the plates 11 and 12. These grooves 64 extend vertically and the shackle
carries a pin 66 at its lower end. This pin extends beyond the width of
the shackle 60 and engages within the grooves 64, as shown in FIG. 6, to
enable upward and downward movement of the shackle 60 in carrying out
action to open and close the clamp by pivoting gripping jaw 34 on its
mounting pin 36.
The shackle is connected to the gripping jaw 34 by link means formed by a
pair of flat link bars 68, which are best shown on FIGS. 4 and 6. These
link bars 68 are pivotally engaged with the shackle pin 66, as shown in
FIG. 6, and extend downwardly between the side plates of the body within
the lifting clamp to be engaged by pin 70 with the end of jaw 34 remote
from the pivot pin 36 which holds the jaw pivotally between the side
plates 11 and 12. The flat spaced link bars 68 are disposed on opposite
sides of the lower end of the shackle within the clamp body defined
between side plates 11 and 12. They extend downwardly within the body and
by way of their connection to jaw 34 by means of pin 70 they transfer
lifting force from the shackle through pin 66. The shackle 60 is movable
vertically in the clamp body by the sliding action of shackle pin 66 in
the slots 64. The slots limit the nonrotational movement of shackle pin 66
to a vertical path. The shackle at its upper end has the lifting
connection formed by the large opening 62 as previously mentioned.
When the clamp is mounted on a plate which is in a horizontal position with
the movable jaw on top of the plate, application of lifting force to the
opening 62 causes the shackle to pivot and engage the spacing sleeve 20
which serves as a fulcrum thereby causing the shackle to raise the shackle
pin 66 in the slots 65 and apply a closing force to the jaw 34 in the
manner fully described in U.S. Pat. No. 2,654,630.
To an extent the structure heretofore described is known in the prior art.
The unique arcuate configuration of the jaws with differing curvature arcs
in different portions and the laterally enlarged configuration of the slot
provided by both of the clamp body sideplates 11 and 12 contribute to
better gripping as well as safer gripping. With the limited pivotal
movement of the cam jaw 42 restricted in its movement by the pocket 32
formed by plate 28 and member 30, improved clamping action is achieved in
grasping and firmly holding an article being lifted such as a plate P.
At least one of the flat link bars 68 has a shoulder 72. Protruding pawl 74
is rotatably mounted fixed on a pin 76 within the body of the lifting
clamp between plates 11 and 12. The pin 76 has a manually operable handle
78 which is disposed on the outer side of the side plate 12 to be
accessable to the lifting clamp operator. When the handle 78 is moved to
the position as shown in FIG. 2, the protruding pawl 74 engages the
shoulder 72 on one of the flat link bars 68 to hold the principal gripping
jaw 34 in the open position, as shown in FIG. 2. In that position there is
no closing force on the movable jaw 34 which is permitted to remain fully
open and the engagement of the protruding pawl 74 with the shoulder 72
locks the clamp in the open position. If desired, in heavier clamps, a
pawl 74 may be mounted on each of the ends of the pin 76 to engage both of
the connecting link bars 68.
The pawl 74 also carries a pin 80 which is eccentric to the rotating shaft
76 with which the pawl rotates and to which the handle 78 on the exterior
of the clamp body is secured. The pin 80 is engaged by a tension spring 82
which has its other end connected to a pin 84 fastened to the lower end of
link bar 68. The pin 84 extends between the two link bars 68 to be engaged
by the lower end of spring 82 as best shown in FIG. 5. When the handle 78
on the exterior of the clamp is disposed in the position shown in FIG. 2,
the spring 82 is relaxed or not under tension. In this condition the clamp
jaws are open and the pawl 74 engaged with the shoulder 72 on the link
bars 68 to hold the clamp jaws open.
Spring 82 is tensioned between pin 80 eccentric with the axis of rotating
pin 76 and pin 84 fixed to the link bar 68, as shown in FIG. 3. When this
action takes place the tensioning of the spring acts to pull the main
gripping jaw 34 to a closing position, as shown in FIGS. 1 and 3. In that
position the two jaws are brought toward one another and a plate or other
article to be lifted, located between the jaws, will be grasped by the two
jaws and held. The greater the force added to the shackle 60 acting
through the link bars 68 will transmit further force to bring the two jaws
together.
The limited pivotal movement of the small camming jaw 42 along with the
transverse teeth 40 and 52 on the two jaws, has two advantages which
should be noted. First of all as previously mentioned, the force tending
to raise the clamp through shackle 60 against the weight of the article or
other item such as plate P being lifted, tends to cam both of the jaws 34
and 42 downwardly so that the shorter radius arcs at the upper ends of the
jaws will tend to grip in even tighter. As previously mentioned, the
lateral enlargement in the slot 44 at 46 also permits the plate to swing
and therefore avoid the plate tending to "walk out" of the slot. This, as
also previously mentioned, is illustrated in the positions of the plate
shown in FIG. 3. A further benefit of having the small camming jaw mounted
for limited pivotal movement is that with the rather enlarged teeth on
both of the jaws, the clamp could be slammed together in a way that would
tend, over at least a period of use, to damage the bitting quality of the
teeth on the two jaws. However, with the camming jaw 42 mounted for
limited pivotal movement the teeth tend to mesh together and adjust so
that they don't come together at the points which might damage the teeth
on one or both of the jaws were the clamp to be slammed to a closed
position on a frequent basis.
When the handle 78 is rotated to the position shown in FIG. 1, an important
feature of the invention is provided by an auxiliary spring biased locking
pin to hold the locking mechanism which in turn presses the jaws toward
closing position and is actuated by manually manipulated handle 78. It can
occur in the lifting operation with an article such as plate P gripped
between the teeth of the jaws of the clamp, that in raising the plate with
the handle 78 exposed on the outside of the lifting clamp body, this
handle can engage and be moved from the clamp closing position, as shown
in FIG. 1, to the clamp opening position, as shown in FIG. 2. Although the
continued weight of the article between the jaws will most likely retain
the jaws in their closed position despite release of the locking mechanism
to the position of FIG. 2, there remains the danger of the jaws either
moving open or releasing their solid grip with the obvious danger of the
article being lifted disengaging from the jaws and the clamp. To avoid
this consequence and as an added protection, an auxiliary spring biased
locking pin is provided on the clamp body to engage with the handle 78 and
retain it positively in the position shown in FIG. 1.
The jaws 42 and 34 while they are shown in a form that have arcuate
surfaces carrying the teeth 40 and 52, respectively, it is possible that
and to be understood that these jaws might instead be made, one or the
other of them, with a more or less spherical or semispherical curvature
for gripping an article to be lifted.
It will be noted that the eccentric location of the pin 80 on pawl 74 and
the relationship of the pawl, as shown in FIGS. 1 and 2, relative to the
spring and its connection at its lower end to pin 84 on the link bar 68
gives an over center spring connection such that the tension of the spring
shown in FIGS. 1 and 3 urges the handle 78 toward its locked position
where the pawl 74 engages the sleeve member which is described
hereinafter. Thus, there is a requirement for some force to move the
handle 78 from the position of FIGS. 1 and 3 over the center axis of pin
76 to release it to the open jaw position, shown in FIG. 2.
There are several different embodiments for the construction and location
of the spring biased auxiliary locking pin which positively holds the
handle 78 in the jaw closing position. Also one embodiment is provided
where the pin may be depressed and rotated to engage its detent and hold
the pin fully retained in the clamp so that the auxiliary locking means is
effectively deactivated.
Turning to the configuration of handle 78 which is mounted on rotating pin
76 that controls the movement of pawl 74 within the body of the lifting
clamp, it will be noted that the handle 78 is provided with a notch 86.
This provides a pocket in which the auxiliary spring biased locking pin
extends to positively lock the handle 78 in the position shown in FIG. 1.
In addition to the notch 86, the underside surface of the handle 78
immediately adjacent the notch 86, is provided with an inclined cam
surface 88. Cam surface 88 is provided so that in moving the handle 78 to
the closed jaw position the cam surface 88 will act to move the locking
pin inwardly so that it may then spring outwardly back into the notch 86
to perform the holding function for the pin, as will be described
hereinafter. This cam surface 88 is best shown in FIG. 10 of the drawings.
In one embodiment the auxiliary spring biased locking pin is formed and
mounted in a separate pocket, provided between the side plates 11 and 12
of the lifting clamp. This particular embodiment is shown in section in
FIG. 8 which is taken on line 8--8 of FIG. 2. An alternative embodiment is
shown in section in FIG. 10 wherein the auxiliary locking pin is mounted
within one of the bolts forming a part in securing the side plates 11 and
12 together as part of the clamp body. A third embodiment is shown in FIG.
11 where the detent for deactivating the auxiliary locking pin is
illustrated whereby by pressing the pin inwardly and turning it through an
arc of 90 degrees, the pin may be held completely within the clamp body
and thus the auxiliary locking pin feature will not be present when it is
not desired or needed. In this condition the colored end of the auxiliary
locking pin will be displayed in the manner as hereinafter described.
Referring to FIG. 8, a separate sleeve 90 is provided mounted in apertures
formed in the side plates 11 and 12 of the clamp. This sleeve 90 is
provided with a cover or end cap 92. A spacer tube 94 extends between the
inner surfaces of the plates 11 and 12 to dispose them in the desired and
appropriate spacial condition. A set screw 96 may be provided to extend
through spacer tube 94 and threaded into sleeve 90 to fix the elements in
proper position. A ring 98 is mounted within sleeve 90 and held in
position by one or more screws 100. A pin 102 carried by a shaft 104 is
disposed within sleeve 90 to project outwardly beyond the surface of clamp
side plate 12. The outer end of pin 102 is intended to engage within the
pocket 86 of manually operable handle 78. Also this outer end of pin 102
is to be cammed inwardly as the handle 78 is rotated, this camming being
achieved by the cam surface 88 on the underside of the handle 78. The pin
102 and shaft 104 on which it is carried, are retained against removal or
displacement out of the pocket formed by sleeve 90 by a retainer 106. This
retainer fits in a groove on the end of shaft 104 and engages with ring 98
to keep the pin 102 from leaving the pocket formed by sleeve 90. A spring
108 acts on the underside of pin 102 and against ring 98 to bias the pin
102 outwardly of the pocket formed by sleeve 90 with retainer 106
preventing the spring from expelling the pin 102 from sleeve 90.
In operation, the movement of handle 78 pivoting about the axis of pin 76
brings the notch 86 into engagement with pin 102. The cam surface 88 on
the underside of handle 78 cams the pin inwardly within the sleeve 90 to
move it to the phantom position shown in FIG. 8. Then as the handle 78
moves further the pin enters the notch 86 in the handle 78 and the pin
under the force of spring 108 is expelled outwardly to move into the notch
to securely hold the handle in the latched position. To release the handle
it is merely necessary to manually depress the pin 102 back into the
pocket formed by sleeve 90 against the urging of spring 108 and thus
release the handle where it can be rotated to the position such as shown
in FIG. 2.
In the embodiment of FIG. 8, the pin 102, acting as an auxiliary spring
baised locking pin for the handle 78, is mounted in its own separate
pocket apart from the part and other members used in constructing the
clamp. In FIG. 10 a very similar embodiment is illustrated, but in this
embodiment one of the bolts such as bolt 16 and spacer 20, as shown in
FIG. 7, is constructed to have a pocket for the pin with the pin as an
auxiliary locking means mounted within this bolt. Thus, using numbers
comparable to those shown in FIG. 7, the bolt 116 and spacer 120 are
secured in place by a nut 124, these components acting as mechanical
connectors for the upper portion of the side plates of the lifting clamp
in the same manner as bolts 16, spacer 20 and nut 24. The head of bolt 116
is tapered to fit in a tapered hole as in the case of bolt 16. The end of
the bolt 116, which is flush with the outer surface of plate 12 may have
spaced recesses 126. The recesses 126 can simply be engaged by a spanner
wrench to hold the bolt during the period that the nut 124 is being
tightened up in assembly of the clamp body.
The embodiment of FIG. 11 is quite similar to that of FIG. 10. The locking
pin 202 is mounted within a bolt forming a part of the connecting means
for the side plates 11 and 12 in the same manner as in FIG. 10. Likewise a
spacer is used between the plates and the body bolt is held by a nut at
the end thereof. Unlike FIG. 10, the bore forming a pocket for locking pin
202 extends completely through the bolt with an end of the shaft 206
carried by the pin 202 extending into the opposite end of this bore. This
shaft 206 within bolt 216 may have an appropriately colored end 204 which
will be exposed when the pin 202 is projected entirely within the bolt and
the colored end 204 is exposed at the opposite end in the dotted line
position, shown in FIG. 11. The shaft 206 on pin 202 carries a detent 208,
which is in the form of a pin extending transversely through a bore within
shaft 206. In the normal operative position for the locking pin 202 this
detent 208 will rest against the ring 210 under the influence of spring
212. A split sleeve 214 engages around the shaft 206 rearwardly and on the
opposite sides of the pin 202. The detent 208 may slide between the split
halves of sleeve 214 and then the pin 202 rotated to position it in the
location shown in Phantom in FIG. 11. To facilitate rotation of the pin
202, it is provided with a screwdriver slot 218 at its outer end whereby
to deactivate the auxiliary locking pin a screwdriver may be inserted in
the slot, the pin pressed in and then turned through 90 degrees to locate
detent 208 in pockets at the ends of the split sleeve 214. In this
position the detent 208 will hold the pin 202 within the pocket formed in
bolt 216 and the auxiliary locking means will be effectively deactivated
or inoperative until the screwdriver slot 218 is again engaged and the pin
pressed in and rotated 90 degrees to free the detent 208 for movement back
through the and between the halves of sleeve 214 to the position shown in
FIG. 11.
If desired, the limited pivotal movement of the smaller cam jaw 42 may be
omitted although there are advantages with the limited pivotal movement
for this jaw 42, as previously described.
There have been illustrated and described what are considered to be
preferred embodiments of the invention. It will be understood however,
that various modifications may be made by persons skilled in the art
without departing from the scope of the invention which is defined solely
by the appended claims.
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