This invention relates to an improved boom for use with a crane.
Cranes present. 1 y known in the art have normally a boom of a fixed length. Due to such a fixed length of the boom, hooks are provided along different lengths of the boom depending upon the weight of the load to be lifted by the crane. A rope adapted to be operated by the operator is provided to adjust the height of the hook block with respect to the distal end of the last extension of the boom™
The main disadvantage of the boom known in
the art is that operator has to operate a plurality of levers to adjust the length of the rope during the
operation of the crane. Some time either the boom or the hook. block is damaged and same time the rope is
broken due to mis operation of the levers by the operator u n k n o w i. n q 1 y .
Therefore the main object of this invention
is to propose an improved construction of a boom for use with a crane.
A n a t h e r o b j e c t o f this invention i s t o propose an improved boom provided with automatic rope a d ;i u s i; i. n q m e a n B »
According to this invention there is provided
a boom for use in a crane comprising a single or plurality of extensions retractable within the mother
boom or main jib, a hook block being secured to the distal end of the last extendable member,, rope means
being provided ta adjust the height of the hook block characterised in that, a pully beinq provided at the
proximal end of last but one extension for facilitating the passing of said rope therethrough so as to adjust
the length of the rope with respect to the distal end of the last extension automatically.
In accordance with this invention a boom for use with a crane comprises single or plurality of extensions disposed in the mother boom of the crane operated by the hydraulic means provided therefor, A hook block is secured with the distal end of the last ex I R'l'H.U'b I e member „ A rope means are provided for adjusting the height of the hook block with respect to the distal end of the last extendable member.
Specifically according to this invention a pully is provided at the proximal end of the last extendable
member for passing the rope tberetnrouqh and such that. to adjust the height erf the hook block with respect to
the distal end of the? extendable boom automatically.
A boom for use in a crane according to a
preferred embodiment is herein described and illustrated
in the a c r: o m p a n y i. n q ci raw i n q s w h e r e i. n :
Fig. 1 shows the exploded plan view of the boom;
Referring to the drawings the boom has a mother boom MB having a first extendable member B.1.
adapted to the disposed therein. A second extendable member B2 having a manual extendable member B3 disposed
therein movably is provided within the first extendable member Bl such that to be displaced outwardly by the
hydraulic means provided with the crane,, These features are as such known in the art and do not constitute
i. n v e n t i v e f e a t u r e s „
Specifically,, according to this invention
means consisting of polli.es are provided with the proximal end of second extension to facilitate the
passing of the rope therethrough such that to adjust the
height: of the hook block automatically during the operation of the crane as both the extendable members
i.e.., second member and manual extension are extended simultaneously only and the height at which the work is
to be done is adjusted by retracting the second hook and the length between the distal end of the manual
ex tension and the hook block remain constant,,

WE CLAIM:
1. A boom for use in a crane comprising a sinqle or"
plurality of extensions retractable within the mother booiii or main jib,, a hook block being secured to the
distal end of the last extendable member, rope means being provided to adjust the height of the hook block
characterised in that a pully being provided at the proximaJ end of last, but one extension for facilitating
the passing of said rope therethrough so as to adjust the length of the rope with respect to the distal end of
the last extension automatica11y.
2. An improved boom for use with a crane substantially as herein described and illustrated,,