U.S. patent number 3,586,195 [Application Number 04/786,200] was granted by the patent office on 1971-06-22 for digging and lifting device.
Invention is credited to Osmano Beltrami.
United States Patent |
3,586,195 |
Beltrami |
June 22, 1971 |
DIGGING AND LIFTING DEVICE
Abstract
A digging and lifting device having a bucket lifted by a pair of
arms, each of which is on turn connected to the vehicle body
through two connecting rods pivoted at one end and at an
intermediate point thereof. The arms are in such a manner parallely
controlled by an articulated quadrilateral so to impart to the
bucket a substantially vertical path. In addition, a pair of
articulated parallelograms maintain the bucket parallel to itself
while being lifted and a movable ballast provides to limit within
an acceptable range the equipment gravity center shiftings during
the bucket operation.
Inventors: |
Beltrami; Osmano (Ravenna,
IT) |
Family
ID: |
11140556 |
Appl.
No.: |
04/786,200 |
Filed: |
December 23, 1968 |
Foreign Application Priority Data
|
|
|
|
|
Feb 7, 1968 [IT] |
|
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12472/68 |
|
Current U.S.
Class: |
414/707;
414/715 |
Current CPC
Class: |
E02F
3/308 (20130101); E02F 3/3405 (20130101) |
Current International
Class: |
E02F
3/28 (20060101); E02F 3/34 (20060101); E02F
3/42 (20060101); E02f 003/62 (); E02f 003/42 () |
Field of
Search: |
;214/770,140,773,774,775,776,142 ;37/103,117.5 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Forlenza; Gerald M.
Assistant Examiner: Oresky; Lawrence J.
Claims
I claim:
1. A lifting device preferably for loose materials and in
particular a digging and lifting device equipped with a standard or
grabbing bucket of the type mounted on self-propelled industrial
vehicles or the like and comprising material lifting means, arm
means by which said material lifting means is provided with first
and second ends and an intermediate portion therebetween, a first
connecting rod having first and second ends, said first end of said
first connecting rod being pivotally connected to the vehicle frame
at a first point, said second end of said first connecting rod
being pivotally connected to said arm means in said intermediate
region, a second connecting rod having first and second ends, said
first end of said second connecting rod being pivotally connected
to said vehicle frame at a second point, said second end of said
second connecting rod being pivotally connected to said arm means
at said second end of said arm means, said first and second points
and the pivot connections be between said arm means and said first
and second connecting rods forming vertexes of an articulated
quadrilateral, said first connecting rod being moved in a direction
opposite to the direction of movement of said arm means, wherein
said material lifting means follows a substantially vertical
preestablished lifting path wherein said first connecting rod being
acted upon by a lifting jack, said jack being pivotally connected
at one end to an intermediate point of said first connecting rod
and at the opposite end to the vehicle body.
2. A device according to claim 1, wherein said lifting jack is
connected to said first connecting rod at approximately the middle
thereof.
3. A device according to claim 2 wherein said lifting jack is
provided with a relatively short-stroke motion.
4. A lifting device preferably for loose materials and in
particular a digging and lifting device equipped with a standard of
grabbing bucket of the type mounted on self-propelled industrial
vehicles or the like and comprising material lifting means, wherein
arm means by which said material lifting means is provided with
first and second ends and in intermediate portion therebetween, a
first connecting rod having first and second ends, said first end
of said first connecting rod being pivotally connected to the
vehicle frame at a first point, said second end of said first
connecting rod being pivotally connected to said arm means in said
intermediate region, a second connecting rod having first and
second ends, said first end of said second connecting rod being
pivotally connected to said vehicle frame at a second point, said
second end of said second connecting rod being pivotally connected
to said arm means at said second end of said arm means, said first
and second points and the pivot connections between said arm means
and said first and second connecting rods forming vertexes of an
articulated quadrilateral, said first connecting rod being moved in
a direction opposite to the direction of movement of said arm
means, wherein said material lifting means follows a substantially
vertical preestablished lifting path, and comprising means for
shifting the pivot means formed at the connections of the first
ends of said first and second connecting rods, and said vehicle
frame, said means consisting of a plurality of holes aligned on the
vehicle body and adapted to accommodate pivot pins.
5. A lifting device preferably for loose materials and in
particular a digging and lifting device equipped with a standard or
grabbing bucket of the type mounted on self-propelled industrial
vehicles or the like and comprising material lifting means, wherein
arm means by which said material lifting means is provided with
first and second ends and an intermediate portion therebetween, a
first connecting rod having first and second ends, said first end
of said first connecting rod being pivotally connected to the
vehicle frame at a first point, said second end of said first
connecting rod being pivotally connected to said arm means in said
intermediate region, a second connecting rod having first and
second ends, said first end of said connecting rod being pivotally
connected to said vehicle frame at a second point, said second end
of said second connecting rod being pivotally connected to said arm
means at said second end of said arm means, said first and second
points and the pivot connections between said arm means and said
first and second connecting rods forming vertexes of an articulated
quadrilateral, said first connecting rod being moved in a direction
opposite to the direction of movement of said arm means, wherein
said material lifting means follows a substantially vertical
preestablished lifting path, and comprising means for shifting the
pivot points formed at the connections of the first ends of said
first and second connecting rods and said vehicle frame, said means
consisting of hydraulic shifting means by which respective point
pins are shifted within seats provided on the vehicle frame.
6. A lifting device preferably for loose materials and in
particular a digging and lifting device equipped with a standard or
grabbing bucket of the type mounted on self-propelled industrial
vehicles or the like and comprising material lifting means, wherein
arm means by which said material lifting means is provided with
first and second ends and an intermediate portion therebetween a
first connecting rod having first and second ends, said first end
of said first connecting rod being pivotally connected to the
vehicle frame at a first point, said second end of said first
connecting rod being pivotally connected to said arm means in said
intermediate region, a second connecting rod having first and
second ends, said first end of said connecting rod being pivotally
connected to said vehicle frame at a second point, said second end
of said second connecting rod being pivotally connected to said arm
means at said second end of said arm means, said first and second
points and the pivot connections between said arm means and first
and second connecting rods forming vertexes of an articulated
quadrilateral, said first connecting rod being moved in a direction
opposite to the direction of movement of said arm means, wherein
said material lifting means follows a substantially vertical
preestablished lifting path, said first ends of said first and
second connecting rods being provided with respective pivot pins,
said respective pivot pins being eccentrically and adjustably
attached to the vehicle frame.
Description
BACKGROUND
This invention relates to a device for lifting preferably loose
materials, and in particular to a digging and lifting device of the
type comprising a grabbing or excavating bucket. In more detail,
the present invention relates to the field of power shovels as
fitted on tractors or like tracked, half-tracked, wheeled or like
self-propelling means, which comprise a standard bucket adapted to
be driven upwardly along a soil escarpment that is being formed, or
a grabbing bucket. In either cases, said bucket is lifted to dump
the soil or other excavated material onto transport means, which
may be e.g. a tipper or like truck.
As already well known, the digging and lifting devices of the type
above described generally comprise an arm, or a pair of arms,
adapted for supporting the bucket and having their opposite ends
pivotally connected with a stationary pivot point, which is usually
located at the highest possible level on the vehicle body in order
to attain the greatest possible lifting height with the smallest
possible arm length.
However such an arrangement results in many drawbacks from both
viewpoints of digging sharpness and of dump easiness, as well as
from the viewpoint of physical and mechanical balance of the whole
digging equipment. Amongst such drawbacks which will be fully
described later on a prominent one is that the curved path of a
conventional bucket does not allow an easy formation of suitable
and convenient soil escarpments, e.g. vertical or substantially
vertical escarpments, while on the other hand the bucket is
brought, at the upper end of its path, into a position which is
approximately above the vehicle or at any rate--unless very long
and thus expensive and hardly controlled arms are utilized--very
near to vehicle. As it can be readily appreciated, when the bucket
lies in such a position, the dumping of soil or like materials onto
a truck becomes very difficult and can be effected only onto the
end thereof and not onto the middle section, as it would be
obviously convenient and desirable.
A further drawback inherently caused by said curved path of
conventional buckets is represented by the highly erratic positions
taken by the center of gravity of digging equipment in the course
of lifting operation, which results in undesirable instability of
the equipment and in heavy wear of load-bearing transmission
elements. Moreover, large variations occur both in the required
lifting power--which results in the necessity to have a prime mover
proportionally overdimensioned--and in the bucket lifting speed,
which varies according to different positions taken by the axis of
the lifting jack or jacks in respect to the fixed pivot point at
which the arm is pivotally connected to the vehicle.
The above and further drawbacks of the already known digging
equipments are obviated by the device according to the invention,
which also provides novel and advantageous features for said
digging and lifting means. The device according to the invention is
essentially characterized in that the arm or each arm by which the
bucket or like lifting means is supported is pivotally linked to at
least one pair of connecting rods which are on turn pivotally
connected to the vehicle frame in such a manner as to form an
articulated quadrilateral therewith, being said articulated
quadrilateral arranged in such a manner as to constrain the bucket
or like means to follow a preestablished lifting path, different
from an arc of circle and in particular to follow the contour of a
rational soil escarpment, as well as to dump the lifted material
from an advantageous position. In particular, two bucket supporting
arms, located substantially parallel with each other on either side
of vehicle, may be provided, each arm being controlled by a pair of
connecting rods, parallel to connecting rods of the opposite arm,
which are pivotally connected to the arm at the end opposite to
that carrying the bucket and at an intermediate point of the same,
the connecting rods being in turn pivotally connected to the
vehicle body.
In order to take full advantage of a path opportunely calculated
for the operations to which the device is designed, each pair of
connecting rods is pivotally connected with the related arm in such
a manner as to bring about, in each position thereof, a
compensation of the deviations from a substantially vertical path
which would be suffered by the bucket when the supporting arm
thereof swings on its pivotally connected end, as stationary
maintained; such compensation is obtained by shifting said arm end
in an opposite direction by the action of said related pair of
connecting rods. Thus, an advantageous path can be obtained, having
an initial portion close to the vehicle, a substantially vertical
middle portion and an end portion allowing to have the material to
be dumped under the most convenient conditions.
The previously specified features of this invention will be now
described in full detail, along with further inventive features as
shown by the device embodying the invention, with reference to
preferred embodiments thereof as shown in the accompanying
drawings, being both description and drawings given as not
restrictive examples of the range of the invention.
DRAWINGS
FIG. 1 diagrammatically shows the conventional means by which the
motions of a bucket can be controlled.
FIG. 2 diagrammatically shows the means according to the invention
by which the motions of a bucket are controlled.
FIG. 3 is a side view of a first embodiment of the device according
to the invention, in a tracked power shovel fitted with a standard
bucket.
FIG. 4 is a plan view of power shovel of FIG. 3.
FIG. 5 diagrammatically shows a device according to the invention,
by which the bucket is kept parallel to itself while being
fitted.
FIG. 6 shows a second embodiment of a power shovel with a grabbing
bucket and a movable ballast adapted to compensate the gravity
center shiftings as caused by the bucket travel.
PREFERRED EMBODIMENTS
Referring now to FIG. 1, it diagrammatically shows drive means for
an arm 10 by which a grabbing bucket 11 is lifted. Such arm 10 is
connected to a pivot point 12, firmly secured to the tracked
vehicle body and is operated by a jack 13 which on turn is
pivotally connected at 14 to the arm 10 and at 15 to the tracked
vehicle body, in such a manner that any point of the bucket 11,
e.g. the pivot point 16, is compelled to travel along a path 17,
consisting of an arc of circle. Such curved path necessarily
results in the formation of a soil escarpment 18 which is inclined
with respect to the vertical plane. Said escarpment shape is not
presently accepted, since vertical or nearly vertical escarpments
are preferred, being such escarpments retained by the successive
application of soil supporting means. Moreover, the bucket 11, when
in its fully lifted position 11', is usually too close to vehicle
body and thus a dump of material onto the middle section of a truck
or similar transport means is not possible. It would be possible to
prevent such drawback by providing a sufficiently long arm 10,
which however is more expensive, more difficult to control and in
addition requires also greater continuous power ratings of lifting
means; consequently, the general trend is directed toward a
decrease of arm length. Due to such restrictions, imposed upon the
size of arm 10, the pivot point 12 thereof usually needs to be
located at an inconveniently high level in order to allow the
bucket 11 to be raised to a sufficient height for a convenient
dumping, without requiring a too large extension of piston rod of
hydraulic jack 13.
Further ill-effects of the already known drive means are to be
traced back to the shiftings of the equipment gravity center in
respect to a vertical plane when the bucket is being lifted, which
results in a marked instability of the equipment, as well as in
heavy wears of the load-carrying transmission elements, which are
subjected to variable stresses owing to a varying weight
distribution while the equipment is in operation. In addition, a
widely variable lifting force is required in the known drive means
between the lowest position of the arm 10 and the highest position
10' thereof, which results in an excessively variable lifting rate
when a constant extension rate of the piston rod of jack 13 is
maintained, due to different positions taken by the axis 14, 15 of
said jack 13 in respect of the arm pivot point 12.
The above drawbacks are wholly prevented or at least reduced by the
driving means according to the invention, substantially as shown in
FIG. 2, wherein only one lifting arm is diagrammatically shown, as
in FIG. 1.
As shown in FIG. 2, such arm 20 for lifting the bucket 21 has not
its end 22 directly connected to the body of a vehicle, being said
end pivotally connected instead to a first connecting rod 23 which
is on turn pivotally connected at 24 to the tracked vehicle or the
like. A second connecting rod 25 is pivotally connected at 26 to
the vehicle body and at 27 to an intermediate point of arm 20, the
latter connecting rod being preferably acted upon by a hydraulic
jack 28 connected thereto at 29 approximately at the middle of
connecting rod 26 and pivotally connected to the vehicle at 30.
As it can be readily appreciated, said driving means for the bucket
21 allow to have the bucket 21 moved along any suitable path, by
suitably positioning the pivot points of the connecting rods 23 and
25, and in particular along a path by which due account is taken of
the previously specified factors, whereby ensuring the equipment
operation under the best conditions. Thus, a soil escarpment 31
very close to a vertical plane can be obtained, while at the same
time the bucket can be brought into a dump position 21' in which it
is suitably spaced from the vehicle body without need of increasing
the length of arm 20, but on the contrary with the possibility of
reducing this length due to the action of connecting rod 23.
Amongst the various advantages, the following ones are to be
emphasized: the pivot points 24, 26 and 30 can be kept in such a
low position on the vehicle that no supporting frame is needed; the
arm can be lifted with nearly constant power input and speed; and
finally a lifting can be performed without having the equipment
gravity center to undergo an unnecessarily large shifting. It is
clear that by connecting the connecting jack 28 to the middle of
connecting rod, a relatively short-stroke movement is obtained.
Such a short-stroke movement permits use of a sturdier lifting arm
or jack than is employed with prior art devices.
An arrangement of connecting rods 23, 25 in respect of arm 20
similar or substantially similar to that as shown in FIG. 2 is
particularly advantageous for the attainment of the above stated
purposes. In fact, such an arrangement gives the possibility to
accomplish a suitable compensation of deviations from a
substantially vertical path to which the bucket would be subjected
should the pivot point 22 be kept stationary. Such compensation is
brought about as a consequence of a shifting of pivot point 22 in
an opposite direction, caused by the combined action of connecting
rods 23 and 25. In particular, the pivot point 22 will tend to move
backwards to a position 22", in the course of a first portion of
the bucket path, which substantially corresponds to the portion of
path which would shift the bucket outwardly should the pivot point
22 be kept stationary. Then, the pivot point 22 is shifted from the
position 22" in an opposite direction, until attaining its final
position 22', whereby to compensate the inward deviations to which
the bucket 21 would be subjected (i.e. from the position 21" to
position 21') should the pivot point 22 be kept stationary.
The above feature allows in a rather easy manner a substantial
vertical bucket path to be maintained along its whole travel; any
deviation from said vertical path, which could possibly be
considered as desirable can be easily obtained by a suitable
shifting of the pivot points 24 and 26. It is to be observed that
the above stated advantageous feature is obtained due to the fact
that in the lowest position of arm 20 the pivot point 26 of
connecting rod 25 is higher than the axis of said arm, whereby in
the course of lifting operation a position is attained wherein the
axis 26--27" of connecting rods 25 is parallel to axis of the arm
20" which position defines the point wherein an inversion in the
shifting direction of the pivot pint 22 occurs.
Referring now to FIGS. 3 and 4, a description will be given of a
first embodiment of the drive mechanism already examined with
reference to FIG. 2 as embodied in a power shovel equipped with a
standard bucket. Said shovel is fitted on a tractor 40 movable on
tracks 41 and 42, and its digging and lifting motions are performed
by two arms 43 and 44, to which the bucket is connected at the
pivot points 46 and 47. Each arm 43 and 44, which are kept always
parallel with each other, is pivotally connected to its opposite
end 48 and 49, respectively, to a first connecting rod 50 and 51
respectively, that is on turn pivotally connected to the fixed
pivot point 52 and 53 respectively on the tractor frame 54. Further
connecting rods 57, 58 located misaligned in respect of related arm
are pivotally connected at one end to intermediate points 55, 56 of
arms 43, 44 and at the opposite end to the pivot points 59 59a on
the tractor frame. Fast with said further connecting rods 57, 58
are two plates 60, 61 to which a pair of lifting jacks 64, 65 are
pivotally connected at 62, 63, being the opposite ends of said
jacks pivotally connected at 66, 67 to the tractor frame. The
operation and advantages of above stated lever arrangement have
been already described with reference to FIG. 2, so that it will be
sufficient only to state that, when a standard bucket it utilized
as in this case a substantially vertical path such as that
indicated by the reference number 68 can be obtained by the pivot
point arrangement shown in said FIG. It is to be observed that the
bucket 45, when in its final position as shown with dash-and-dot
lines lies at a relatively large horizontal distance from the
tractor body, whilst it is very close thereto in its lowest
starting position.
The path 68 can be modified at the convenience both in the
manufacturing stage e.g. by an arrangement of pivot points
different from that shown in the figures, and while the equipment
is in operation, by the provision of means allowing said pivot
points to be shifted steplessly or along a row of preestablished
positions. Said means may be in the form of a row of holes provided
in the tractor frame wherein the pivot points can be conveniently
arranged or--as stated in more detail later on--of a combination of
guides and control means for said pivot points, or finally--as
shown in FIG. 3--by having the pivots 52 and 59 and the pivot
points on the other side of the tractor corresponding thereto
eccentrically secured to the frame, whereby said pivots can be
forcibly moved along a circumference having a suitably selected
diameter, as e.g. the circumference 69 and 70.
Fitted on the bucket supporting arms 43 and 44 are means adapted to
control the bucket motions in respect of the related pivot points
46 and 47. Such means may consist of a pair of hydraulic jacks 71,
72 located parallel to related arm and each acting through a
leverage system as shown in FIG. 3, which consists of two levers
72, 73 pivotally connected to each other as well as to the arm 43
and to the bucket 45, the lever 72 being also pivotally connected
at 74 to the extensible piston rod 75 of jack 71. It is thus
possible to obtain a tilting bucket as shown in the upper section
of FIG. 3, as well as, by suitably controlling the jack 71, a
compensation of the successive inclinations of arms while being
lifted, whereby to keep the bucket 45 always parallel to itself.
This latter result can be also attained through mechanical means
(as shown in FIG. 3) that consist for each arm 43 of a lever 76 and
of an angle bar 77, pivoted at 48 and hinged at 78 to said lever 76
and at 79 to a further lever 80 that is directly secured to the
fast end of jack 71. By such design, as diagrammatically sown in
FIG. 5, the above stated compensation can be easily obtained and
the bucket is always kept parallel to itself without necessity of
utilizing the jack 71 which may be considered to this purpose as a
rigid and inextensible rod.
The device utilized for keeping the bucket 45 always parallel to
itself while being lifted is diagrammatically shown in FIG. 5,
being in said diagram utilized the same reference numerals of FIG.
3 with the addition of arms 77' and 77" of angle bar 77, the pin 81
by which the lever 76 is hinged to tractor frame and the pin 82 by
which the lever 72 is hinged to arm 43. Moreover, the assembly
consisting of rod 80, jack 71 and related rod 75 is
diagrammatically shown by a single rod 71--80. Referring now to
said FIG. 5, it can be observed that two articulated parallelograms
are formed by the assembly of said rods, i.e. a first parallelogram
consisting of rods 76, 77', 50 and the line through the points 52
and 81, and a second parallelogram consisting of the rods 77",
71--80, 72 and 43. It will be therefore obvious that in the course
of motions caused by the connecting rod 50, the first articulated
parallelogram is forced to keep the side 77' always parallel to
itself, since said side 77' must remain parallel to the line
through the two fixed points 52 and 81. As the lever 77' maintains
its orientation, the lever 77" correspondingly maintains its own
orientation, being rigidly connected to the former one in such a
manner as to move always parallel to itself. Thus the opposite side
72 of the second articulated parallelogram will remain always
parallel to itself too and to lever 77", whatever the motions of
arm 43 may be. Referring again to FIG. 3, it is obvious that due to
the existing connection, when the lever 72 is kept always parallel
to itself the bucket 45 will also be kept parallel to itself while
being lifted.
A second embodiment of this invention is shown in FIG. 6. This
embodiment relates to a grabbing bucket 100 fitted on a tractor 101
mounted on wheels 102, 103 and 104, 105, the bucket being operated
on either tractor sides (only the tractor side shown in the figure
will be considered in the following description) by an arm 106
pivotally connected at 107 with a first connecting rod 108. Said
rod 108 is on turn connected at a pivot pint 109 with the vehicle
frame, being said arm pivoted at 110 to a second rod 111, that is
pivotally connected at 112 with the vehicle frame. Pivotally
connected at 113 with said lever 111 is a jack 114 which on turn is
pivoted at 115 and with which a compensating jack 116 is
associated, this latter jack being pivotally connected at 117 with
the vehicle frame and at 118 with the rod 111. Pivotally connected
at 119 with the outer end of arm 106 is a bucket 100 operated by
the jack 120 which is pivoted at 121 on the gusset 122 welded to
arm 106 and pivotally connected at 123 with the bucket gusset 124.
In this latter case the successive inclination of movable arm is
compensated by conveniently operating said jack 120, which
automatically provides through the drive mechanism by which the
jack 116 is operated to keep the bucket always parallel to itself
while being lifted; however, as an alternative, recourse may be
made also to previously described mechanical means.
With the considered grabbing bucket it is particularly important to
have a bucket path with a lowermost position very close to tractor
and an uppermost position as far as possible therefrom. Such a path
can be easily obtained as shown at 125 through the means according
to the invention and in particular by the arrangement of levers and
pivot points as shown in FIG. 6 wherein 126', 126", 126'"... are
the arcs of circumference along which the point 123 can be caused
by the jack 120 to travel around the rotation center 119 in the
different successive positions of the latter while the bucket is
being lifted.
Even in the latter embodiment the shape of path 125 can be modified
by the previously specified means adapted to change the position of
pivot points and in particular of pivot points 109 and 112. In the
latter embodiment two elongated slots 127, 128 within which the
pivots 109 and 112 can be suitably shifted under the control of
jacks 127' and 128' or the like are provided. In such a manner, as
in the preceding case, it is possible to have the whole space of a
plane extending between two limiting paths covered by a point of
the bucket, thereby hereby adapting the bucket to different
applications each time as required.
In the presently considered case, wherein a bucket path rather
different from the vertical one is required, proportional shiftings
of the equipment gravity center will obviously occur while the load
is being lifted. To prevent the ill effects which would be caused
by such shiftings of the gravity center in respect of vertical
plane wherein it originally lies, means are provided which are
suitably shifted while the bucket is being lifted, thereby
maintaining said gravity center within an acceptable range about
its initial position. Such means may consist of movable ballast
130, as shown in FIG. 6, pivotally connected at 131 with the
tractor frame in a position opposite to that of bucket in respect
of the equipment gravity center. Said movable ballast is pivotally
connected at 132 with a controlling rod 133 adapted to shift
outwardly or inwardly the ballast according to bucket motions,
thereby displacing the ballast gravity center and hence the
equipment gravity center in such a manner as to substantially
equalize the bending moments, as caused by the ballast and by the
bucket in respect of a fixed point on the tractor body. Said rod
133 which is guided in its intermediate position by the connecting
rod 134 pivoted at 135 and 136 is advantageously controlled by the
motions of connecting rod 111, through the lever 137 which has one
end secured thereto and the opposite end pivotally connected at 138
to said control rod 133. In such a manner, a displacement of
ballast 130 is obtained, which corresponds to the angular motion of
lever 111 and thus to bucket liftings and substantially to the
outward shiftings thereof.
It is understood that, while the invention has been disclosed with
particular reference to digging equipments, it can however be
applied also to all other equipments wherein a lifting is generally
required along a path more or less different from an arc of
circle.
Obviously many modifications and changes of the present invention
are possible in the light of the above teachings. Therefore, it is
to be understood that the invention is not limited to the details
specifically described and illustrated, and that within the scope
of the appended claims it may be differently practiced.
* * * * *