Traversing hoists – Boom or mast – Extensible by sliding sections
Reexamination Certificate
1998-12-22
2001-03-13
Brahan, Thomas J. (Department: 3652)
Traversing hoists
Boom or mast
Extensible by sliding sections
C414S918000
Reexamination Certificate
active
06199707
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a telescopic boom incorporating therein a telescopic cylinder; and, more specifically, to a telescopic boom mounted to a vehicle for high lift work.
BACKGROUND OF THE INVENTION
Known as a vehicle for high lift work is the one comprising a turntable mounted on a body, a telescopic boom axially supported by the turntable and adapted to perform operations such as extension/retraction and derricking, and a platform attached to the distal end of the telescopic boom. At the time of operation, this vehicle can derrick and extend the telescopic boom such as to move the platform to a desirable high working position, thus allowing workers to work there.
An example of the telescopic boom for such a vehicle for high lift work, as shown in
FIG. 19
, is constituted, in a telescopic fashion, by a proximal boom
909
a
mounted to the body (not shown) of the vehicle so as to be able to derrick, an intermediate boom
909
b
inserted into the proximal boom
909
a
so as to be able to extend and retract therein, and a distal boom
909
c
inserted into the intermediate boom
909
b
so as to be able to extend and retract therein. Thus constituted telescopic boom
909
incorporates therein a telescopic cylinder
921
which drives the intermediate boom
909
b
so as to make it extend or retract relative to the proximal boom
909
a
. The distal end portion of the cylinder rod
921
b
of the telescopic cylinder
921
is attached to the inside of the proximal end portion of the proximal boom
909
a
; whereas a cylinder tube
921
a
is attached, by way of a stationary shaft
923
extending laterally therefrom, to the inside of the proximal end portion of the intermediate boom
909
b.
At positions separated from the cylinder tube
921
a
by a predetermined distance, the stationary shaft
923
is provided with rotatable retraction sheaves
925
, each of which is wound with a retraction wire
935
, whose one end is fixedly attached to the inside of the proximal end portion of the distal boom
909
c
, whereas the other end is fixedly attached to the inside of the distal end portion of the proximal boom
909
a
. The distal end of the cylinder tube
921
a
is provided with two rotatable extension sheaves
927
, which are located on the inner side than the retraction sheaves
925
. Each extension sheave
927
is wound with an extension wire
937
, whose one end is fixedly attached to the inside of the proximal end portion of the proximal boom
909
a
, whereas the other end is fixedly attached to the inside of the proximal end portion of the distal boom
909
c.
Here, since one end of the retraction wire wound about each retraction sheave is connected to the distal boom, the one end extends obliquely with respect to the retraction sheave. Therefore, the thrust load caused by the retraction wires would act on the retraction sheaves, whereby there is a possibility of the retraction wires shortening their lives. A similar problem would also occur in the extension wires.
Also, the extension sheaves are disposed on the inner side than the retraction sheaves, and the extension wires wound about the respective extension sheaves extend over the upper side of the telescopic cylinder, such that one end of each extension wire is fixedly attached to the inside of the proximal end portion of the proximal boom. Therefore, when assembling the telescopic boom, the retraction wires and extension wires must temporarily be fixed separately from each other while being assembled, whereby a large amount of labor is necessary for the assembling operation of the telescopic boom, and it is difficult to adjust tensions of retraction wires and extension wires.
Further, in order to attain safety in operations by securing electric insulation between the platform and the body of the vehicle, the distal boom is formed with an insulating member. Since the extracting/retracting operation is effected such that the extension/retraction of the intermediate boom relative to the proximal boom and the extension/retraction of the distal boom relative to the intermediate boom are simultaneously performed with the same ratio, however, the telescopic boom as a whole must be elongated in order to secure an insulating distance (the amount of extension of the distal boom) which is required for the safe operation. As a consequence, there has been a problem that, depending on the installation conditions of the telescopic boom and vehicle, there is a possibility of workers on the platform receiving an electric shock when touching an electric wire or the like before securing the required insulating distance.
The distal end of the distal boom
909
c
is provided with a not-illustrated platform, which is equipped with a winch operable in response to a hydraulic pressure supplied thereto, an operating apparatus sending out a control signal to the vehicle in response to an electric power supplied thereto, and the like. Therefore, hydraulic hoses and electric cables (hereinafter referred to as “hose and the like”) for connecting the body of the vehicle and the platform to each other are disposed within the telescopic boom
909
. As shown in
FIG. 20
, the hose and the like
965
, with their one end being held on the upper face of the proximal end portion of the proximal boom
909
a
, extend toward the distal end of the telescopic boom
909
along the upper face of the proximal boom
909
a
. The hose and the like
965
are wound about a sheave
961
attached to the distal end portion of the distal boom
909
a
so as to turn around toward the proximal end, pass through the gap between the proximal boom
909
a
and the intermediate boom
909
b
so as to extend to the proximal end portion of the intermediate boom
909
b
, and are wound about a hose sheave
963
attached to the proximal end portion of the intermediate boom
909
b
so as to turn around toward the distal end again. The distal end portion of the hose and the like
965
passes through the distal boom
909
c
so as to extend to the distal end of the latter. As being thus routed, the hose and the like
965
can extend or retract together with the extending/retracting operation of the telescopic boom
909
.
Here, the hose sheave necessitates a hose separator for winding the hose and the like appropriately about the hose sheave such that they are separated from each other without becoming entangled, a stopper for keeping the hose and the like from dropping out of the hose sheave, and the like. Also, along with the extending/retracting operation of the telescopic boom, a repetitive motion of tension or flexure acts on the hose and the like, whereby there may be cases where the hose and the like repeatedly come into contact with the hose separator or the like, thus being worn out or damaged. Also, when an excess tension is applied to an electric cable, there is a possibility of its inner strands breaking. Further, there is a problem that, when the extension wire wound about an extension sheave is broken or drops out thereof, there is a possibility of the distal boom moving down toward the proximal end of the telescopic boom.
SUMMARY OF THE INVENTION
In view of such problems, it is a principal object of the present invention to provide a telescopic boom which is easy to assemble.
It is another object of the present invention to provide a telescopic boom in which tensions of its retraction and extension wires are easy to adjust.
It is a further object of the present invention to provide a telescopic boom which can keep the lives of the retraction and extension wires from decreasing.
It is another object of the present invention to provide a telescopic boom which can secure the electric insulation thereof and thus is excellent in safety.
It is a further object of the present invention to provide a telescopic boom in which, even when an extension wire is broken, for example, there is no possibility of its distal boom moving down toward the proximal end of the telescopic boom.
It is another object of the present invention to provide a telescopic boom which does
Ebara Tomomasa
Hayakawa Yoichi
Nagao Makoto
Suzuki Takuo
Tsuriya Michito
Brahan Thomas J.
Kabushiki Kaisha Aichi Corporation
Usher Robert W. J.
LandOfFree
Telescopic boom does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Telescopic boom, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Telescopic boom will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2525041