Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
lZS24~
Tackle mechanism
This invention relates to a tackle mechanism
for lifting, lowering and pulling loads, comprising
one or more clamp jaw pairs disposed in a housing
and having clamp jaws for a continuous cable, the
clamp jaws being operable by way of clarlp levers
-and comprising clamp jaw carriers for the clamp
jaw pairs, and an actuating mechanism for the opening
and closing movement of the clamp jaw pairs.
Known tackle mechanisms having two clamp jaw
pairs reciprocating in opposite clirections are
usually so cons'ructed that the cable is clamped
as in a vice having parallel clamp jaws. Parallel
guidance of the clamp jaws is obtained by articulating
each clamp jaw on the opening and closing mechanism
at two points as considered in the cable direction.
This mechanism may consi.st of parallelogram levers,
bell cranks or levers with S-shaped closing cams.
- The fact that the cable on the load side of a
contacting clamp jaw pair is in every case thinner
than on the side remote from the load, i.e. because
it undergoes transverse contraction through the
traction, results in the parallel clamp jaws exerting
excessive pressure on the cable and excessive
stress on the corresponding clamp lever pair near
`~ S~24~
the load-remote end. On the other hand, the clamp
lever pair on the load side is always subjected
to less loading. Given a small cable diameter
of up to about 15 mm the transverse contraction
of the cable is small but on the other hand the
elastic deformation of the opening and closing
mechanism is relatively considerable so that the
lack of uniformity of the pressure on the cable
hardly takes any adverse form. In the case of
lQ larger cable diameters, however, the non-uniform
pressure frequently results in local pitting.
Consequently, there is considerable cable and clamp
jaw wear during load lowering. In addition, there
is no proof of parts of the opening and closing
- 15 mechanism being secure against fracture.
Another known tackle mechanism comprises two
automatic gripper blocks provided ~ith clamp jaws,
one of these blocks alternately clamping and driving
the cable while the other block slides freely along
the cable. For safety reasons it is desirable
for the two blocks or their clamp jaws to be subjected
to different wear. This ensures that one gripper
block al~ays operates reliably. To ensure uneven
wear, two different gripper blocks or gripper blocks
with different clamp jaws are used. The di~ferent
3~
. .
construction of the clamp jaws can be obtained
in various ways, e.g. by different lengths, by
using different materials, by different cable grooves,
or the like. In one embodiment, one of the clamp
jaws can slightly incline just one of the two gripper
blocks with respect to the longitudinal axis of
the other clamp jaw. The object of this is to-
make the wear of this block or its clamp jaws less
than the wear of -the clamp jaws of the other block,
so that the other block wears more quickly, thus
ensuring alternate replacement. Alternate replacement
means that one of the two blocks is intended always
to operate reliably. These steps do not decisively
affect the above problems concerning obtaining
uniform wear at both clamp jaws, and the known
steps on the contrary point in an opposite direction.
The object of the invention is to provide
a tackle meehanism for lifting, lowering and pulling
loads of the kind referred to hereinbefore, which
is dist.inguished by uniform cable clamping and
reduction of eable and elamp jaw wear at both jaws.
To this end, in a tackle mechanism of the
kind referred to, aecording to the invention, at
least one of the two clamp jaws of each clamp jaw
pair is pivotally mounted on a pivot disposed transversely
~Z5~'3~
of the cable directionl and the pivotally mounted
clamp jaws are articulated at least at one end
on the associated clamp levers and the associated
clamp jaw carriers each have a corresponding aperture
for the pivots for the clamp jaws. According to
another embodiment, in which again at least one
of the two clamp jaws of each pair is pivotally
mounted on a pivot disposed transversely of the
direction of the cable, the invention teaches,
with lndependent significance, that the pivotally
mounted clamp jaws are articulated at least at
one end on the associated clamp ~aw carriers and
the associated clamp levers each have a corresponding
aperture for the pivots for the clamp jaws.
According to the teaching of the invention, the
pivotally mounted clamp jaws can assume either
a parallel or oblique position to the associated
co-acting jaw depending on the particular phase
of movement and the load at any time, so that the
transverse contraction resulting from application
of the traction and the transverse compression
of the cable produced by the effect of the clamp
jaw biasing force, can no longer result in excessive
pressure near the load-remote end of the clamp
jaws. - In the case of manually operated tackle
` lZS~4~1
-- 5
mechanisms, the weight and price play an important
part. The tackle mechanism according to the invention
allows increased material stressing as a result
of distinct load conditions by a statically well-
defined construction. The number of components
can thus be reduced and this in turn reduces the
~weight and price compared with the known parallel
guidance of the clamp jaws. In addition, wear
on the cable and clamp jaws is reduced with increased
1~ safety against fracture, so that the tackle mechanism
according to the invention is also distinguished
by considerable cost-effectiveness to the user.
These are the main advantages of the invention.
Further features essential to the invention
are indicated hereinbelow. According to a preferred
embodiment of the invention, the two clamp jaws
of each pair are mounted pivotally. The pivots
for the pivotally mounted clamp jaws may be constructed
as push-in or pull-out bolts, so that it is a simple
matter to fit and dismantle the.pivotally mounted
clamp jaws. The introduction or removal of a
cable transversely of the cable direction is rendered
possible as a result of the easy removal of the
pivotally mounted jaws. According to the invention,
the pivotable jaws are mounted pivotally in each
i;~5Z~
.
-- 6
case between two opposite clamp levers or clamp
jaw carriers and hence positioned for symmetrical
stresses. Finally, the pivotally mounted clamp
jaws can be constructed as slender and in every
case resiliently yielding clamp jaws, so that optimized
distribution of transverse pressure at the cable
is obtained in addition to pivotability, due to
the resilient yielding feature.
Accord:ing to the invention, the clamp lever
action can be on a decreasing scale as in the parallelo-
gram type c:Lamp mechanism. Alternatively the
clamp lever action may be progressive as in the
bell crank mechanism. Finally, the clamp lever
ation can be substantially proportional to the
closing travel as in the closing cam type mechanism.
In every case substantially uniform transverse
press~lre is always obtained on the associated cable.
The invention will be explained in detail
hereina~ter with reference to the drawing illustrating
just one exemplified embodiment
Fig. 1 shows a tackle mechanism according
to the invention in diagrammatic side elevation
with pull levers articulated on the clamp levers
at the top.
Fig. 2 is a detail of the subject shown in
~ZSZ4~1
-- 7
Fig. l having a pivotally mounted clamp jaw with
external clamp levers and internal clamp jaw carriers.
Fig. 3 is an exploded view of the subject
of Fig. 2.
Fig. 4 is a modified embodiment of the subject
of Fig. 2, in which the l:wo clamp jaws are pivotally
~mounted with external clamp jaw carriers and internal
clamp levers.
Fig. 5 is an exploded view of the subject
of Fig. 4.
Fig. 6 is a modifiecl embodiment of the subject
of Fig. 1 having two clamp lever pairs with a point
of articulation at cable height ~a = 0) and
pivotally mounted coacting jaws.
Fig. 7 is a vert cal section on the line A-
B through the subject of Fig. 6.
Figs. 8 to ll are diagrams showing ~he clamp
jaws acting on the cable during the lifting and
lowering of a load.
-~ lZ~Z4~:1
-- 8
The drawings show a tackle mechanism for lifting,
lowering and pulling loads, comprising a plurality
of, namely two, pairs of clamp jaws 2 disposed
in a housing 1 and comprising clamp jaws 5, 6 for
a continuous cable 7, the jaws being operable via
clamp levers 3, 4, and also comprising clamp jaw
carriers 8, 9 for the clamp jaw pairs 2 and an
actuating device lO for the openlng and closing
movement and the reciprocating movement or the
clamp jaw pairs, l.e. clamp jaws 5, 6~ The clamp
jaw carriers 8, 9 are articulated with the clamp
jaw pairs 2 on ^ockers ll. The latter are articulated
on the housing l. The pivot axes 12, 13 of the
clamp jaw carriers 8, 9 and rockers l]. are arranged
in axis-parallei relationship to one another and
transversely of the cable direction. The cable
jaw carriers 8, 9 are constructed as bearing cheeks
or bearing levers for the clamp jaws 5, 6 and clamp
levers 3, 4. The clamp jaw carriers 8, 9 are
respectively suspended from a front and rear rocker
11 as considered in the cable direction. The
rockers 11 of each clamp jaw carrier 8, 9 are disposed
parallel to one another. The rockers ll may be
constructed as two-armed members in which case
the clamp jaw carriers 8, 9 are suspended in each
~2r~
case between the -two arms. The pivot axes 13
of the rockers 11 are formed by transverse connecting
bolts of the housing 1, which is frequently made
in two parts.
The clamp jaws 5, 6 of each pair 2 are articulated
by means of the clamp levers 3, 4 on pull levers
15 of the actuating mechanism 10. Closing springs
16 are disposed between the pull levers 15 and
the associated clamp jaw carriers 8, 9.
The pull levers 15 of the actuating mechanism
10 can be pivoted on the clamp levers 3, 5 of the
clamp jaw pairs 2 at the top or bottom or else
at the top and bottom alternately and are also
articulated on an actuating lever 17 of the actuating
mechanism 10. The pivot axis 12 between one clamp
jaw carrier 8, 9 and a rocker 11 is provided as
a point of engagement for a reverse mocion lever
18 of the actuating mechanism 10.
At least one of the two clamp jaws 6 of each
pair 2 is pivotally mounted on a pivot 23 extending
transversely of the cable direction. According
to the invention, both clamp jaws 5, 6 of a pair
2 may be pivotally mounted. The pivots 20 of
the pivotally mounted clamp jaws 5-and 6 are in
the form of push-in or pull-out bolts.
~z~
-- 10 --
According to one e~emplified embodiment, the
pivotally mounted clamp jaws 6 are articulated
at one end on the associated clamp levers 3 while
the associated clamp jaw carriers 8 each have a
corresponding aperture 19, e.g. of kidney shape,
for the pivots 12 of the clamp jaws 5. - According
to another e~emplified embodiment, the pivotally.
mounted clamp jaws 6 are articulated at one end
on the associated clamp jaw carriers 8 while the
associated clamp levers each have an aperture 19,
e.g. a kidney-shaped aperture, for the pivots 20
of the clamp jaws 5. It is also possible for
the pivotable clamp jaws 5, 6 to be mounted each
to pivot between two opposite clamp levers 3, ~
or clamp jaw carxiers 8, 9. The pivotally mounted
clamp jaws 5, 6 are constructed as slender and
hence resilient].y yielding clamp jaws.
The tension on the pull levers 15 and on the
cable 7 in the embodiment shown in Figs. 1, 2 and
4 forms a force couple spaced by the amount a.
Corresponding counter-acting forces must be taken
by guide means, preferably the rockers 11. Their
points of articulation on the clamp jaw carriers
8, 9 are therefore situated far apart, i.e. in
accordance with the spacing b. - If a construction
lZ~
-- 11 --
is embodied as shown in Fig. 4, the guides have
to take only the deadweight of the clamp jaw pairs
2, because the points of articulation of the pull
levers 15 are at cable height and hence a = 0.
If two clamp lever pairs 3, 4 are articulated,
the pull levers 15 can in fact provide stabilization
of the clamp jaw pairs 2 in the direction of the
cable. Only one introduction point c is then
required to ensure accurate alignment of adjacent
clamp jaws pairs 2.
Referring to Fig. 8, when a load is lifted,
the top clamp jaw pair 2a slides on the cable 7
with a subsequent engagement action, the clamp
jaws 5, 6 being pressed resiliently into contact.
The bottom clamp jaw pair 2b clamps fast and lifts
the load, its clamp jaws 5, 6 being pressed agalnst
the cable 7 by lever action. Referring -to Fig.
9, the top clamp jaw pair 2a clamps fas-t and lifts
the load, while the clamp jaws 5, 6 are pressed
against the cable 7 by lever action. On the other
hand, the bottom clamp jaw sliding on the cable
7 engages subsequently and its clamp jaws 5, 6
are only resiliently pressed against the cable
7.
Referring to Fig. 10, the top clamp jaw pair
~z~
- 12 -
2a carries half the load for lowering and is clamped
fast against the cable 7 by lever action, and the
load is lowered. The bottom clamp jaw pair 2b
also carries half the load and is clamped fast
by lever action, but allows the cable to continue
to slide with a braking effect during the subsequent
engagement action. Referring to Fig. 11, the
top clamp jaw pair 2a engages subsequently and
carries half the load, i.e. is clamped by lever
action and allows the cable 7 to slip through with
braking effect. The bottom clamp jaw pair 2b
also in turn carries half the load and is clamped
by lever action, but the load is lowered.
According to another embodiment of the invention
of independent significance, in which again at
least one of the two clamp jaws 5, 6 of each pair
2 is pivotally mounted, the pivotally mounted clamp
jaws 5, 6 are subjected to the action of a yoke
transversely of the cable direction. In this
embodiment, therefore, the pivotal mounting of
the clamp jaws 5, 6 can be obtained by means of
a tilting type joint, a support in the form of
a rubber block, or the like.
