Static structures (e.g. – buildings) – Striplike unit – reversibly flexible and rigid
Patent
1993-03-02
1994-09-20
Ridgill, Jr., James L.
Static structures (e.g., buildings)
Striplike unit, reversibly flexible and rigid
E04H 1218
Patent
active
053477707
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an improved extendible beam or column system, and in particular to an extendible mast for supporting an antenna, and also to an improved method of erecting same.
The invention-will have many applications, such as antenna support masts, ladders, booms or any other elongate rigid column member used as a support structure. However, the invention will be described in relation to antenna support masts, realising that the scope of the invention is not to restricted to this application.
2. Background Information
Antenna support masts or towers comprising a plurality of telescopic sections telescoped one within the other, and which are normally operated by means of a hand pump are well known and in common use for antenna systems required for field use, e.g. by army personnel. Such mast systems suffer from a number of disadvantages. They are relatively expensive and not very reliable in use due to the tendency of the telescoping sections to "stick" on the seals when raising or lowering them by means of the pump. This can slow down quite significantly both the erection and the pull-down time which in some situations, e.g. military operations, may be quite critical. Furthermore, the cables leading to the antenna are required to be carried externally of the tubular telescoping sections and hence are prone to damage both during use of the antenna and transportation thereof. A still further disadvantage is their relatively heavy weight which renders their handling more difficult.
It is the main object of the present invention to provide an improved extendible column or mast for supporting an antenna, especially for those used in the field, which obviates at least some of the aforementioned disadvantages, and in particular one which is able to be very quickly erected and pulled down, and which is able to be easily repaired in the field.
It is a further object of the present invention to provide an extendible mast which can be constructed so that it is less likely to fail during operation in adverse environmental conditions, e.g. heat, salt spray and dust in comparison to known mast systems of a similar type.
SUMMARY OF THE INVENTION
In one of its forms therefore, this invention provides an extendible column or mast assembly comprising a pair of elongate link chains arranged to interengage with one another so as to form a rigid mast or column, each said chain having a plurality of pivotally interconnected chain link elements, wherein each said link element of each said chain (apart from its leading and trailing link elements) is pivotally connected to a pair of adjacent said elements in its own chain by first and second spaced apart pivot means, said adjacent interconnected link elements having interfitting walls constructed and arranged to permit relative limited pivotal movement from an axially in-line position in one direction only and preventing pivotal movement in the opposite direction of said one direction from said in-line position, and wherein at least some of said link elements in said chains have abutment surfaces which, when the chains are interengaged, co-operate with one another to provide interlocking means for preventing relative movement in horizontal planes between link elements of one chain and adjacent link elements of the other chain, and chain drive means for interengaging the chains and for driving the chains, so interengaged, in an upwards direction to raise the rigid mast or column or in a downwards direction to lower the mast or column.
Preferably the chain links of each chain are moulded of high strength plastics material and are identical with one another. Depending on load requirements, the material can be a low-grade composite plastic or a carbon fibre composite.
Preferably, the drive means is contained in a portable base frame which can be easily transported in or on a vehicle and readily handled manually in the field.
The drive means may conveniently be a gear drive unit manually operated by a crank handle,
REFERENCES:
patent: 2554300 (1951-05-01), Hayakawa
patent: 3012635 (1961-12-01), Blain
patent: 4863418 (1989-08-01), Fillar et al.
patent: 4866893 (1989-09-01), McGinnis
patent: 5025606 (1991-06-01), McGinnis
Althoff Johannes J. W.
McDonnell Michael P.
Polytech Technical Services Pty. Ltd.
Ridgill, Jr. James L.
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