Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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A D~EDGER CHAIN JOINT
The present invention relates to a joint for a chain
such as used for example in a dredger, wherein successive links
and/or buckets are pivotally inter-connected.
In general, the successive buckets of a bucket dredger
are interconnected through links. The buckets with links run over
a polygonal bottom tumhler and a polygonal top tumbler, the top
tumbler serving for the drive, and the bottom tumbler being
disposed at the bottom of a bucket ladder. The dredging operations
are controlled by means of the dredging ladder. The top and bottom
tumblers are mounted on parallelly extending shafts, the pivot pins
of the link bearings being parallel to these shafts. Mostly, each
bucket is connected through two pairs of links to the preceding
bucket and likewise by means of two pairs of links to the next
bucket, the pivot pins at one side of the bucket always being co-
extensive. Such a construction is described inter alia in Dutch patent
application 75,05387 of O. & K. Orrenstein & Koppel AG published
12th November 1975. In i~ use i5 made of cylindrical bearing faces
in the shape of a bearing bushing of bearing material that is
disposed more or less fixedly in a bore in a lug of a bucket, the
bearing bushing being adapted for sliding movement relative to a
pivot pin. A link is mounted on the pivot pin on opposite ends
thereof. These links are connected to a next bucket.
In view of the substantial wear occurring in practice,
and the noise during operation going therewith, it is proposed in
said prior Dutch application to provide the bearing on either side
with a resilient diaphragm which is vulcanized both to an inner
ring and to an outer ring in order to prevent leakage of lubricating
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oil. The inner ring is secured to the pivot pin and the outer
ring is fixed in a bore in the lug. The pivoting movements
between the lug and the links as they pass the top and bottom
tumblers has to be taken up ~y de~ormation of the resilient
diaphragm. It is the object of the present invention to provide
an improved dredger chain joint construction of the above described
type.
~ In accordance with the present invention there is
- provided a bearing construction for a dredger chain, wherein two `~
1~ bearings are disposed co-axially and wherein each bearing comprises
an outer bearing bushing disposed in a lug, while on eithe~ side
of the lug there is mounted a link on a pivot pin, upon which is
; mounted an inner bearing bushing having a convex outer surface, the
outer bearing bushing being mounted in a bore in the lug and
being provided with a corresponding internal concave bearing face.
Although, theoretically, cylindrical bearings will be
sufficient for a bucket dredger chain, it has surprisingly been
; found in practice that the use of a spherical joint construction
results in a substantial reduction of the wear and hence an
increase in the lifetime and a reduction of the noise during
operation. Such a bearing may be provided in known manner with
lubrication, and use may be made of bearing sealings, such as
sleeves, cupped washers, diaphragms, strings and other resilient
packing constructions.
It has furthermore been found that it is effective
to mount the convex bearing bushing on the pivot pin with a
clearance of about lmm. In spite of this clearance, it has
turned out in practice that the relative movements occur sub-
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stantially between the convex and the concave bearing bushings,
while the relativ~ly large clearances facilitate assembly and
disassembly of the bearing. ~or the bearing sealing, use may ~e
made of a double lip packingl V-shaped in cross-section, which is
mounted on a mounting sleeve or a ~earing ring and is contiguous
with a separate retaining sleeve in the lug, against which the
concave outer ring is mounted. For the supply of lubrication~ said
lug may accommodate an oil reservoir which is designed preferably
eccentric.
Further features of the in~ention will be apparent from
the following description o~ an embodiment according to the
present invention, given by way o example, with reference to the
accompanying drawing.
The single figure shows partly in cross section a bearing
construction according to the present invention.
A relatively heavy lug l is connected to a dredger bucket,
not shown, by a connecting portion diagrammatically indicated by
2; this may be for instance a supporting rib of a bucket. Lug 1
accommodates a bearing comprising a cylindrical pivot pin 3 having
a head 4 and a cotter hole 5. On either side of lug 1 there is
present a link 6, 7, which links may be connected either to a lug
on a next dredger bucket or may be integral with a next dredger
bucket. On the pivot pin there are disposed two stepped mounting
sleeves 8, on the outer surfaces o~ which there is disposed a double
lip packing or cupped washer 9, V-shaped in cross-section. It will
be noted that with this construction at least two lips are present
between the exterior and the bearing interior, so that any
difference in pressure is equalised in a corresponding number of
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steps. Between the collars of sleeves 8 there is disposed an
inner bearing bushing 10, the outer ~ace of which is convex or
spherical. Said convex inner bearing bushing 10 is accommodated
in two outer ~earing bushing portions 11, each having a corresponding
concave internal ~earing face r whîch portions, after being applied r
are indussoluble interconnected to ~orm an outer bearing bushing.
Retaining sleeves or rings 12 bear against the outsides of said
outer bearing bushing. ~he inner face of each ring 12 functions
as a sealing face of the respective cupped washer 9: the rings
may be secured w;th a specific pre-tension in the lug 1 or be
fixed in a different manner. O-rings 13 are disposed in grooves
of sleeves 8, on the one hand to prevent leakage of lubricant
present in the bearing r and on the other hand to prevent water
and/or dirt from penetrating into the bearing. Sleeves 8 are
mounted with a relatively large clearance o~ about 1% of the pin
diameterr in this embodiment about lmm on pin 3 r the links
being mounted with a oorresponding clearance. Furthermorer there is
shown a lubricant reservoir 14 formed by a central circumferential
groove in lug 1. Said groove is eccentrically disposed such that
at the location where the greatest forces are exertedr the
least quantity of material has been removed~ Finally the bearing
is retained by a retaining ring 15 on pin 3 r which may be secured
by means of a cotter r not shown r in cotter opening 5.
It is observed that on each side of a bucket there are
disposed at least two of such co-extensive bearings. By
removing the cotter r the links can be easily removed from the
pin 3, while the pin itself can be withdrawn from the sleeves 8.
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~fter this, the bearing can he entirel~ removed from the bore of
lug 1. The large and heavy parts, such as lug 1 and links 6 and
7, are provided with simple cylindrical bores, and the pin, too,
has a simple cylindrical shape. Only the lighter bearing, mounting
5 and retaining sleeves are of convex or concave, or of stepped,
configuration. If desired, the entire ~earing may be mounted in
the lug of the bucket in the workshop, while the bearing pins 3
and possibly the links need only ~e mounted during the assembly
on a dredger.
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