Hydraulic shovel with hoisting hook

Details Hydraulic shovel with hoisting hook Hydraulic shovel with hoisting hook

2001-05-24

2003-05-27

Underwood, Donald W. (Department: 3652)

Material or article handling

Vertically swinging load support

Shovel or fork type

C414S694000, C414S912000

Reexamination Certificate

active

06568898

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a hydraulic shovel provided with main boom, stick boom, bucket or other operation machine and, especially, to a hydraulic shovel ensuring the operation efficiency or the security during the crane work using a hoisting hook.
2. Description of the Related Art
Conventionally, the hydraulic shovel has been used for earth and sand excavation, transportation or various other operations. A hydraulic shovel
1
′ shown in
FIG. 12
comprises a travel body
2
′, a revolving frame
3
′ mounted on the travel body
2
′ to be rotatable about the vertical axis, and an operation machine
4
′ fitted to the revolving frame
3
′. The operation machine
4
′ comprises a main boom
6
′ vertically rising and descending by a not shown main boom cylinder attached substantially to the center of the revolving frame
3
′, a stick boom
8
′ vertically swinging by a not shown stick boom cylinder attached to the main boom
6
′ taking the distal end of the main boom
6
′ as fulcrum, and a bucket
11
′ vertically swinging by a not shown bucket cylinder attached to the stick boom
8
′ through a pair of right and left links
10
′ taking the distal end of the stick boom
8
′ as fulcrum.
In addition to a not shown engine loaded near the rear section of the revolving frame
3
′, a variable capacity type pump (not shown also) driven by the engine, and a plurality of command valves (not shown also) driving a plurality of operation cylinders of the operation machine
4
′ by selectively supplying hydraulic oil discharged from the variable capacity type pump are provided. The command valve is connected in correspondence to the operation cylinder of the operation machine
4
′. A plurality of not shown command levers for changing over independently the plurality of command valves are disposed in an operator cabin
3
a′
disposed at a position shifted to the right or to the left from the front center of the revolving frame
3
′.
A bottom section of the main boom cylinder is attached to the revolving frame
3
′, and a piston rod thereof is attached to the main boom, and the main boom
6
′ vertically rises and descends by this main boom cylinder. A bottom section of the stick boom cylinder is attached to the main boom
6
′, and a piston rod thereof is attached to the stick boom
8
′. The stick boom
8
′ swings vertically by the stick boom cylinder taking the distal end of the main boom
6
′ as fulcrum. A bottom section of the bucket cylinder is attached to the stick boom
8
′, and a piston rod thereof is attached to the link
10
′ between the stick boom
8
′ and the bucket
11
′, and the bucket
11
′ vertically swings by the bucket cylinder attached by means of the pair of right and left links
10
′. The hydraulic shovel
1
′ excavates the ground surface to a desired depth, transports excavated earth and sand to the dumping position and dumps the same.
On the other hand, there is a hydraulic shovel
1
′ capable of crane work in addition to earth and sand excavation, transportation and the like. This kind of hydraulic shovel has, as shown in
FIG. 12
, a hoisting hook
12
′ for lifting/hanging a load, fixed swingably to the back face side of the stick boom
8
′ through a link attachment fixing pin
11
b
′ of the bucket
11
′, and provides the distal end of the stick boom
8
′ with a crane function. In order to prevent the bucket
11
′ and the hoisting hook
12
′ from interfering during the crane work, the bucket cylinder is extended to the maximum excavation position of the bucket
11
′, stopped at a state where the scooping face side of the bucket
11
′ is most retracted to the stick boom
8
′ side, and the crane work is performed by the hoisting hook
12
′ with this stopped posture.
In addition, a hydraulic shovel provided with another crane mechanism is disclosed, for example, in Japanese Utility Model Publication No. 58-11826. According to the hydraulic shovel disclosed in this Publication, a pair of winches are provided on the back of a main boom. A pair of first pulleys are supported by an stick boom support shaft for supporting rotatably the distal end of the main boom and a stock boom, while a pair of second pulleys are supported by the stick boom top pin. Two wires of respective winch are led inside the main boom and stick boom, wound around respective first and second pulleys, wound around a pair of third pulleys supported by a bracket of the hoisting hook, and the distal end of the wire is fixed to the stick boom. The hoisting hook is hung and supported at the stick boom bottom side through the wire, and the hoisting hook moves vertically by taking in/out the wire by the winch.
In order to prevent the bucket and the hoisting hook from interfering during the crane work, the bucket cylinder is retracted to the maximum dumping position of the bucket while being maintained at a posture where the bucket is most damped to the stick boom back side, and the crane work is performed by the hoisting hook with this posture. When the hoisting hook is not in use, the hoisting hook is hung and engaged by a hanging bar disposed inside a forked section of the stick boom by taking up the wire by the winch, and the hoisting hook is housed in the stick boom forked section.
During excavation or transportation of earth and sand, with the hoisting hook housed, the main boom cylinder and stick boom cylinder are operated to swing vertically the main boom and stick boom respectively and, at the same time, the bucket cylinder is operated for nodding the bucket vertically at the distal end of the stick boom. The hydraulic shovel excavates the ground surface to a desired depth, transports excavated earth and sand to the dumping position and dumps the same.
Generally, the conventional hydraulic shovel operates the main boom in the rising direction by elongating the main boom cylinder, and operates the main boom in the descending direction by retracting the same. Even when the main boom is erected, as the gravity center of the operation machine comprising main boom, stick boom and bucket is positioned forward of the equipment, an effort in the retraction directing for descending the main boom is applied to the main boom cylinder, thereby generating a hold pressure at the bottom side thereof at all times. Therefore, if a hydraulic oil hose connected to the main boom cylinder bottom side is broken by an external force, the hold force by the main boom cylinder is lost, and the main boom swings suddenly in the descending direction. Ordinarily, a fall prevention valve maintaining the inner pressure of the bottom side of the main boom cylinder is fitted in order to avoid this sudden swinging.
Moreover, the hydraulic shovel swings the stick boom downward by elongating the stick boom cylinder taking a linkage section with the main boom as fulcrum, and swings the stick boom upward by retraction operation. For example, during the transition from excavation to dumping operation, if a hydraulic oil hose connected to an oil chamber in the head side of the stick boom cylinder is broken by an external force, the hold pressure by the stick boom cylinder is lost, and the stick boom swings suddenly downward with the bucket. It is a common practice that a fall prevention valve is fitted to the head side of the stick boom cylinder in order to avoid this sudden swinging.
During the excavation of earth and sand, the main boom cylinder and stick boom cylinder are operated to swing the main boom and stick boom up and down respectively, and at the same time, the bucket cylinder is operated to nod the bucket at the distal end of the stick boom. An operation range of the distal end of the stick boom section of this time is within a rotation range from the vertical posture of the stick boom as it swings downward, t

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