Motor vehicles – Frame
Reexamination Certificate
2000-07-20
2002-12-31
Dickson, Paul N. (Department: 3619)
Motor vehicles
Frame
C280S781000
Reexamination Certificate
active
06499556
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a revolving deck for an earthmoving machinery such as a minimal rear-swing radius hydraulic excavator.
2. Related Art
In the related art, there has been widely employed the so-called “minimal rear-swing radius hydraulic excavator” in which the swinging locus of the rear end portion of a revolving unit having vertically swinging equipment at its front portion is confined, as seen in a top plan view, within the width of left and right crawlers of a travel unit. This minimal rear-swing radius hydraulic excavator
30
will be described with reference to
FIGS. 12 and 13
.
FIG. 12
is a side view of the minimal rear-swing radius hydraulic excavator of the related art, and
FIG. 13
is a perspective view showing a revolving deck
33
of FIG.
12
.
Over a travel unit
31
, as shown in
FIG. 12
, there is revolvably mounted a revolving unit
32
. On the upper face of the revolving deck
33
or the base of the revolving unit
32
, there are mounted a cab
34
, a machine cab including an engine
35
a
and a hydraulic unit
35
b
, a counter weight
36
and so on. To the central front portion of the revolving deck
33
, on the other hand, there are swingably attached equipment
40
including a boom
41
, an arm
42
and a bucket
43
. These components of the equipment
40
are driven by a boom cylinder
44
, an arm cylinder
45
and a bucket cylinder
46
, respectively.
As shown in
FIG. 13
, the revolving deck
33
is constructed by forming a frame body
33
a
of a single circular plate and by welding a center bracket
33
b
for mounting the boom
41
and the boom cylinder
44
to the central front portion on the frame body
33
a
, and a rear bracket
33
c
for mounting the engine
35
a
and the counterweight
36
to the central rear portion, respectively. On the other hand, the frame body
33
a
is equipped at its left portion with a bracket
33
d
for mounting the cab
34
and at its right portion with a bracket
33
e
for mounting the hydraulic unit
35
b
and so on. To suitable portions of the frame body
33
a
, there are additionally welded a variety of brackets and reinforcing members. To the outer periphery of the frame body
33
a
, moreover, there are attached left and right revolving guards
37
and
38
by means of bolts
39
.
If the frame body
33
a
of the revolving deck
33
is made of the single plate, however, the plate thickness has to be increased to retain the rigidity thereby to invite a problem that the increased weight raises the cost. Since the left and right revolving guards
37
and
38
are attached by the bolts
39
, on the other hand, there is the problem that they fail to contribute to the strength of the frame body
33
a.
In order to solve these problems, there have been proposed several techniques in the related art.
As a first related art of the revolving deck for the hydraulic excavator, there is a technique of the revolving frame of a hydraulic excavator, as disclosed in Unexamined Published Japanese Utility Model Application No. 87455/1994, for example.
FIG. 14
is a perspective view showing the revolving frame of the Utility Model Application. In this Application, a frame body
51
, a fender
52
, a counter weight
53
, an oil tank
54
and so on are integrally cast.
As a second related art, on the other hand, there is a technique of a revolving frame of an earthmoving machinery, as disclosed in Unexamined Published Japanese Patent Application No. 88617/1998, for example. According to this Japanese Patent Application, as shown in
FIG. 15
, of a left side frame
62
forming part of the structure of a revolving frame
61
, a sectional shape of a rear frame portion
62
B for supporting a machine room
71
and so on from the lower side is made larger in the vertical (or height) direction than a front frame portion
62
A for supporting a cab
72
and so on from the lower side. Of individual overhanging beams
63
,
64
,
65
,
66
and
67
overhanging leftward and rightward from the central portion of the revolving frame
61
to the front frame portion
62
A and the rear frame portion
62
B, on the other hand, the front side overhanging beam
64
having its leading end side jointed to the rear frame portion
62
B is made to have a larger sectional shape.
However, the following problems are left unsolved in the related art described above.
The technique, as disclosed in Unexamined Published Japanese Utility Model Application No. 87455/1994, can have effects of a high rigidity and an improved assemblability for a small-sized machinery, because the frame body
51
, the fender
52
, the counter weight
53
and the oil tank
54
are integrally cast. For a medium- or large-sized machinery, however, the weight is drastically increased and also strength is required. As a result, difficulty is encountered in its manufacture, and the drive power required for the entire machinery is increased. Thus, problems arise in the fuel consumption, the performance of the machinery and the cost for its manufacture.
In the revolving frame disclosed in Unexamined Published Japanese Patent Application No. 188617/1998, on the other hand, the front portions of the front frame portion
62
A and a right side frame
68
, as seen in a top plan view, are located outside of the tail swing radius of the counter weight
73
so that they fail to conform with the so-called “minimal rear-swing radius type”. As a result, this failure may allow the revolving frame to contact with an obstacle at those overhanging portions.
SUMMARY OF THE INVENTION
In view of the aforementioned problems of the related art, the invention has an object to provide a revolving deck for an earthmoving machinery, which is shaped to have no contact with an obstacle within the tail swing radius of a counter weight and which has a structure of a high rigidity but not a large weight.
In order to achieve the object, according to a first aspect of the invention, there is provided a revolving deck for an earthmoving machinery, comprising: a main frame including a revolving unit mount portion and mounting a counter weight on its rear end portion; side decks arranged on the left and right sides of the main frame; and side frames disposed at the outer ends of the side decks, wherein the swinging locus to be drawn by the rear end portion of the counter weight is confined, as seen in a top plan view, substantially within the swing arc of the revolving deck. The revolving deck is formed, as seen in the top plan view, to be substantially within the width of a crawler, and the side decks are made of an integral skeleton structure including a plurality of overhanging beams jointing the main frame and the side frames.
According to the first aspect of the invention, the revolving deck is formed within the tail swing radius substantially equal to the counter weight so that it does not contact with an obstacle within this radius. Further, the revolving deck is given an integral skeleton structure in which the main frame and the side frames are jointed by a plurality of overhanging beams (or side decks), so that the weight can be made less than that of a single plate structure or a cast structure. On the other hand, even a medium- or large-sized hydraulic excavator can be easily manufactured with this simple structure so that its cost can be lowered. Because of the integral skeleton structure, moreover, many openings can be formed in the lower face of the revolving deck to improve the maintenance from the bottom of the deck.
According to a second aspect of the invention, the side frames of the first aspect are made to act as guards for protecting the overhanging beams and the main frame from an external force.
According to the second aspect, the side frames are made to act as the guards (or revolving frame guards) for protecting the overhanging beams and the main frame from external forces. As a result, these guards can provide reinforcing members for the frames to lighten the weight and reduce the number of parts so that the parts can be easily servic
Dickson Paul N.
Komatsu Ltd.
To Toan C
Varndell & Varndell PLLC
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