Excavating – Cable-operated – Scoop or bucket
Reexamination Certificate
1999-05-13
2001-04-03
Pezzuto, Robert E. (Department: 3671)
Excavating
Cable-operated
Scoop or bucket
Reexamination Certificate
active
06209234
ABSTRACT:
FIELD OF THE INVENTION
THIS INVENTION relates to improvements in the rigging by which to support the bucket of a dragline excavator and parts therefore.
BACKGROUND ART
Dragline excavators are commonly employed in tasks such as the removal of overburden in preparation for open cut coal mining. In these, a bucket capable of scooping typically 50 cubic meters of soil is actioned off a boom, which might be typically 50 meters in length. The draglines are sold rated at a particular suspended load for operating purposes. The suspended load is the total of the weight of the load of overburden picked up, the weight of the bucket, and, additionally, the weight of the rigging which supports the bucket off the boom and couples to it to enable its action, the rigging being the assembly of elements and cable by which the bucket is suspended and operated.
The design of dragline rigging is well settled. It has remained in common use, largely unchanged, over a substantial number of years. The assembly supporting the bucket off its lifting cable, and interlinked with the drag line bucket, is typically an array of linkages between a hoist socket and a trunnion link, respective elements being interconnected by swivel pins of the like. The bearing surfaces between these elements wear over time, and they require regular servicing. Normally the dragline excavator is operated continuously, being shut down only every two to three weeks for a matter of hours, typically eight, in which to effect servicing. The down time represents a significant operational cost and management seeks to minimise it. Servicing the wear points is pre-planned. An inspection of expected wear points is made during a short stoppage, some days before a service is expected. This enables acquisition of what replacement parts might be needed in preparation for their being installed.
Either or both of a reduction in weight of the rigging, or the down time taken in servicing it, will have a significant impact on the overall economics of drag line operation.
OBJECT OF THE INVENTION
It is an object of the present invention to effect improvements in the rigging by which to support and/or control the bucket of a drag line excavator, in particular to the upper rigging with a view to one or more of a reduction in rigging weight, a reduced inventory of parts, or a reduction in down time at servicing the dragline rigging. Various other objects and advantages will hereinafter become apparent.
OUTLINE OF THE INVENTION
The invention achieves its object in provision of a dragline rigging adaptor by which to support a dragline bucket in which there is an equalizer encircling means at a first end and first and second connection points, substantially at a second end, at which to fit a dragline bucket and a dragline dump block. The dragline rigging adaptor may have an equalizer shaped with a substantially concave surface at which the equalizer encircling means engages, in use. The dragline rigging adaptor may have its load bearing surface in the upper segment of the equalizer encircling means hard faced. The dragline rigging adaptor may be formed with the hard facing extended substantially over the length of the upper half of the equalizer encircling means. Additionally the load bearing surface of the equalizer may be hard faced.
The invention provides in a particular form dragline rigging by which to support and operate a dragline bucket having a hoist line equalizer with an upper weight bearing surface at which to take the load of the bucket, and a link member with an equalizer encircling means, dragline bucket support pins and dump block pins. The dragline rigging ideally has its mating surfaces of the hoist line equalizer and the encircling member may be rounded in a complementary fashion to permit relative angular movement whilst maintaining contact over a sufficiently extended surface area to optimise load bearing and wear. These mating surfaces are ideally hard faced.
The mating surfaces of the hoist line equalizer and the encircling member may be rounded in a complementary fashion to permit relative angular movement whilst maintaining contact over a sufficiently extended surface area to optimise load bearing and wear as the parts swivel and pivot in use.
Use of the above defined encircling member advantageously reduces the number of links and pivot pins deployed in suspension and operation of the bucket. Additionally, the encircling member has the advantage of effecting a weight reduction over the weight of the equivalent prior rigging, typically from a prior 2 tonne assembly to around 1.0 tonne equivalent in respect of the present proposal. This reduction can enable a potential increase in the bucket capacity to move more overburden over a year, effecting a saving typically of the order of $750,000 per annum. The reduction in pieces and material from the prior style upper rigging can reduce the cost of the new equivalent component over the older upper rigging by a figure of the order of $10,000. A further advantage arises in a reduction of the number of pins whose bushes need replacing. This work is not without hazard and its reduction has its benefits.
REFERENCES:
patent: 4791738 (1988-12-01), Briscoe
patent: 5992061 (1999-11-01), Fleck et al.
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