This invention relates to an improved boom for a crane. Cranes presently known in the art have normally a boom of a fixed length the weight of the load to be liffeel by the was depended upon the Axed length or the bovun.
Such noolcs are held co the boom through hook plates rigidly held to the boom at said predetermined locations. A disadvantage associated with such a known construction is that the boom is of a fixed length.
An object of this invention is to propose an improved construction of a boom for use with a crane.
Another object of this invention is to propose a boom of an adjustable length which is efficient.
Still another object of this invention is to provide a boom having liner provided between the extensions of the boom so as to minimize the wear and tear of the extensions.
According to this invention there is provided a boom for use with a crane comprising a mein boom housing of a fixed length having a distal and proximal end, at least a first retractable boom disposed at the distal end of said main boom housing, said retractable boom cerrying a hook block with a hook, charcterized inthat liner provided between said retractable boom and housing
In accordance with this invention the boom has at least a first retractable boom disposed within the distal end of said main boom housing. the retractable boom has a part permanently extending beyondsaid distal end of the main boom housing, said
extended part having a load carrying hook.alternatively, and in the instance where two or more retractable booms are provided, the first retractable booms are provided, the first retractable bomm may or may not be provided with a load carrying hook, in the
instance where the load carrying hook is not provided with the first retractable boom, said retractable boom may then not have a permanently extended part. these
features are as such known in the art and do not constitute inventive features of this invention.
boom of the present invention comprises a main boom housing having a first retractable boom disposed at the distal end of said main boom housing. Aliner is
provided between said first retractable boom and main boom housing. A third retractable boom is provided within said second retractable boom. a hook plate or block carrying a hook provided with said third retractable boom. The first and second retractable boom are actractable by a hydraulic motive source, the third retractable boom being actuated by
pulley and rope system.
An improved boom for use with a crane according to a preferred embodiment of this invention is herein described and illustrated in the accompanying drawings wherein:-
Fig.1 shows the sectional view of the boom.
Referring to the drawings particularely fig.1 the boom has a main/mother boom 1 having a first extention 2 disposed therein slidably. A second extention 3 is disposed within the first boom 2
In accordance with this invention the boom has at least a first retractable boom disposed within the distal end of said main boom housing. The retractable boom has a part permanently extending beyond said distal end of the main boom housing, said
extended part having a load carrying hook. alternatively, and in the instance where two or more
retractable booms are provided, the first retractable booms are provided,the first retractable boom may or may not be provided with a load carrying hook, in the instance where the load carrying hook is not provided with the first retractable boom, said retractable boom
may then not have a permanently extended part. These features are as such known in the art and do not constitute invention features of this invention.
slidebly. Furthet a manual extension 4 having a hook 5 secured at the distal end thereof is disposed within the second extention 3. These features are as such known in the art. and do not constitute the inventive features according to this invention.
Specifically according to this invention and as shown in Fig. 1 liners 6 & 7 are provided between the mother boom 1 and first extension 2 of the boom. Similarly liner 8 is prcivided between the first extension and second extension of the booms. Also liner 9 is provided in between the second extension and third extension of the boom so as to provide a smooth functioning of the extensions and to avoid the wear and tear of the extensions during the operation of the crane.

WE CLAIM;
1. An improved boom for a crane comprising of a main boom housing of a fixed length having a distal and proximal end, first retractable boom disposed at the distal end of said main boom housing, said retractable boom carrying a hook block with a hook, haracterized in that liner provided between said retractable boom and housing.
2. An improved boom for use with a crane substantially as herein described and illustrated.