Classifications

• • E—FIXED CONSTRUCTIONS
  • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
  • E02F—DREDGING; SOIL-SHIFTING
  • E02F3/00—Dredgers; Soil-shifting machines
  • E02F3/04—Dredgers; Soil-shifting machines mechanically-driven
  • E02F3/28—Dredgers; Soil-shifting machines mechanically-driven with digging tools mounted on a dipper- or bucket-arm, i.e. there is either one arm or a pair of arms, e.g. dippers, buckets
  • E02F3/30—Dredgers; Soil-shifting machines mechanically-driven with digging tools mounted on a dipper- or bucket-arm, i.e. there is either one arm or a pair of arms, e.g. dippers, buckets with a dipper-arm pivoted on a cantilever beam, i.e. boom
  • E02F3/302—Dredgers; Soil-shifting machines mechanically-driven with digging tools mounted on a dipper- or bucket-arm, i.e. there is either one arm or a pair of arms, e.g. dippers, buckets with a dipper-arm pivoted on a cantilever beam, i.e. boom with an additional link

Definitions

• This invention relates to mechanical handling apparatus of the general kind that includes a boom or jib movable by fluid-pressure operated means, which in this context usually means hydraulic means, but which also includes pneumatic means.
• Such apparatus may be static, such as a jib crane mounted on the ground or on a fixed structure, or mobile .
• mobile apparatus of the above kind include excavators and mobile cranes,- and cranes or other apparatus having a boom or jib and fitted to and/or carried by vehicles for transporting materials and/or equipment and/or other cargo.
• vehicles may be land vehicles such as trucks or construction equipment, or floating vehicles such as ships, barges, dredgers or pontoons used in civil engineering.
• the invention is particularly applicable (subject to the foregoing) to small excavators of up to 15 kW power.
• a typical conventional excavator is a mobile vehicle, having a chassis which carries a support structure arranged to be rotated about a vertical axis on the chassis, and a jib which is pivoted on the support structure so as to be raised and lowered with respect to the latter, sideways displacement of the jib being obtained by rotation of the support structure on the chassis.
• the jib typically consists of two booms articulated together, the main boom being pivoted on the support structure and the other, or outer, boom carrying a scoop or bucket. Relative movements of the bucket, the outer boom and the main boom are effected by hydraulic actuators of the conventional piston and cylinder type.
• the main boom is carried on a boom pivot which is in a fixed location on the support structure, and is raised or lowered by a boom actuator which is coupled at one end to a suitable point along the boom, the other end of the actuator being mounted on the support structure by a pivot which is again in a fixed location on the latter.
• actuator in this Application means a fluid- pressure operated actuating device, typically a piston- and-cylinder actuator or jack.
• An object of the present invention is to overcome this problem by increasing the angle of depression of the boom, without detriment to its angle of elevation.
• the invention aims to increase the depth to which the excavator can satisfactorily dig, without detriment to the range of loading-out heights at which it is capable of working.
• the document US-A-4, 393 , 607 describes a heavy-duty hydraulic excavator having a long boom consisting of three articulated sections, the lowest of which, described as a base boom, is raised and lowered by a boom actuator about a fixed boom pivot .
• the mechanism is arranged to enable the boom to be fully retracted and folded on the base of the excavator when the latter is travelling, so as to park the long boom in a compact, folded state.
• the mechanism includes a parking actuator pivoted to one end of a pair of rocking levers, which are themselves pivoted on the axis of the base boom. The other end of these levers carries the base pivot of the boom actuator.
• the boom In normal operations of digging, lifting and conveying spoil, the boom operates conventionally, with the parking actuator out of use and its associated levers stationary on the fixed platform of the machine.
• the parking actuator actually works in opposition to the boom actuator in order to achieve the required compact parking of the boom, and is activated by the operator when the boom is in a non-load carrying state.
• the arrangement does not aim to provide a means for continuously and automatically adjusting the position of the boom cylinder pivot with respect to the boom pivot whereby to increase the useful rotation of the boom when the machine is exerting a digging force or carrying a load.
• the two actuators have entirely separate hydraulic control systems.
• Another object is to improve the performance of the apparatus in terms of power utilisation throughout its work cycle, and generally to improve its mechanical efficiency.
• Another object is to achieve the above objects without intervention by the operator to that end, over the whole range of boom rotation, and with both the said actuators controlled from a single valved supply.
• the boom actuator is carried by an actuator pivot which is displaceable in a vertical plane by a second actuator as the boom is raised and lowered.
• mechanical handling apparatus having a boom and a boom actuator, for raising and lowering the boom about a fixed boom pivot, wherein the boom actuator is carried by an actuator pivot which is displaceable in a vertical plane by a second actuator as the boom is raised and lowered, characterised in that the second actuator is a variable-geometry actuator coupled to the boom actuator through coupling means such that the second actuator varies the line of action of the boom actuator and works in tandem with the latter so as to tend to increase the force applied in operation of the apparatus at the free end of the boom as the orientation of the boom tends to decrease the said force.
• Figure 1 is a simplified side view of a typical small excavator incorporating features of the invention
• FIG. 2 which is included for purposes of explanation and comparison, shows diagrammatically the arrangement of a main boom and boom actuator in a conventional small excavator,-
• the structure 14 also carries a fourth pivot 46, in a fixed location on the support structure.
• the rear end of the cylinder of a second (or “variable geometry") actuator 48 is mounted on the pivot 46.
• the piston 50 of this actuator is coupled, through a pivot 52, to the linkage 42.
• Both of the actuators 24 and 42 are controlled by the hydraulic control system of the excavator, and in this example they are both operated by the same hydraulic control circuit (which is not shown, but which is generally conventional) . Typically, these two actuators will be connected in parallel in that circuit.
• the apparatus is mobile (e.g. an excavator)
• the vehicle of which it consists, or (as the case may be) the vehicle on which it is mounted need not be a tracked vehicle. Skids or wheels, for example, may be used instead of tracks.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Mining & Mineral Resources (AREA)
• Civil Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Structural Engineering (AREA)
• Operation Control Of Excavators (AREA)

Applications Claiming Priority (3)

Publications (1)

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• 1995
  • 1995-04-21 GB GB9508116A patent/GB2299979B/en not_active Expired - Fee Related
• 1996
  • 1996-04-22 EP EP96910128A patent/EP0821751A1/de not_active Withdrawn
  • 1996-04-22 WO PCT/GB1996/000955 patent/WO1996033315A1/en not_active Application Discontinuation

Non-Patent Citations (1)

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