Collapsible Mast

Scientific American
31 December 1910

A Portable Collapsible Mast

An Ingenious Device For Many Uses

A German inventor has devised a very ingenious construction of masts made of steel bands running lengthwise of the mast and transverse connecting members for holding the steel bands together to form a tubular structure of square or polygonal cross section. Our illustrations show several forms of this new mast, together with very original mechanism employed for erecting the mast and for taking it down.

While the general principle is the same for all sizes and types of masts, there are certain differences in construction, according as the masts are to be portable or stationary. The small cut at the left shows a portable mast, before erection, and on our front page other cuts show stationary masts, two of them in course of construction, and the third finished.

Portable masts are made in heights varying from 6 to 130 feet, with either four or six steel bands of best quality, their width being either 1-1/4, or 2-1/2, or 4 inches. The bands are wound on four or six drums, as the case may be. For very small sizes ( up to 17 feet ) spring drums are used, and the mast is pushed up or down by means of two wheels the teeth of which fit into corresponding holes in the two opposite bands. For larger sizes, the drums are rotated by means of cranks, and the raising of the mast is effected by means of a hoisting device of various forms. In most cases, the hoisting device is operated by one or more cranks, which control either friction wheels engaging opposite bands, or toothed hoisting wheels engaging opposite bands, or toothed hoisting wheels which fit into holes of some of the bands. With a mast comprising four bands, two are operated in this manner, while a six-band mast has three of its bands engaged by toothed hoisting wheels.

In the case of portable masts, the transverse connecting members consist of plates or frames arranged to surround and brace the tube formed by the longitudinal steel bands. When the mast is completely collapsed these numerous plates are stacked one upon the other ad thus occupy very little space. The uppermost plate is secured to the top of the mast, and the other plates are held together loosely by ropes or other flexible connections, so that the plates will be raised successively and automatically as the mast is extended upward by turning the cranks. A small ladder may be attached permanently to the plates to enable a person to climb up or down readily. In the illustration a seat for the person is carried by the upper end of the mast; instead of this, there is provided sometimes a rotary table with a chair and a stand for holding a telescope.

Stationary masts on this principle are made in heights from 50 to 250 feet, and over, with four or six steel bands up to 11 inches wide and up to 1/5 inch thick. The masts are raised by means of simple hoisting devices, which for the smaller sizes are operated by levers rocked up and down as shown on this page; for larger sizes the hoisting device is operated by cranks, as shown on the front page. Instead of being permanently connected with the steel bands, as in the portable masts, the hoisting device is detachable, so that the same hoisting device may be used to erect different masts successively. In fact, the manufacturers will rent the hoisting device to their customers. The steel bands are not wound on drums, but simply coiled upon themselves for convenience in storing and shipping. Their edges have teeth or projections which interlock, and in some cases they also have perforations in the center. Instead of connecting plates, two-part clamps are employed, these being applied individually as the structure rises, and drwn tight by means of screws to hold the steel bands together. The clamps may be formed with steps to facilitate climbing the mast. Stationary masts are set with a suitably prepared foundation, and are generally braced by guy wires. The top of the mast may carry an extension made of steel tubing.

These masts are used for a great variety of purposes, as supports or carriers for electric lamps or searchlights, for wires or cables, as antennae for wireless telegraphy, as extensible ladders, as flagpoles, as observation posts, signal masts or semaphores, for cranes and derricks, posts for scaffolds or buildings, etc.

Among the advantages of the new masts the manufacturers mention in the first place the great strength of the structure, combined with light weight. The safety of the masts is very great since all joints are longitudinal, and transverse joints are avoided; even in the case of overloading the mast will not break, but simply bend, and the construction is therefore exceedingly durable. The parts required for erecting the masts are shipped readily, as they can be divided into a number of parcels, none of which will be very bulky. Even the coiled steel bands for the stationary masts need not exceed 5 feet in diameter. the parts are not heavy, so that they may be readily handled and transported.

All parts of the finished masts are easily accessible, thus facilitating inspection and repairs. The masts may be put up and taken down readily and in very short time in any kind of weather ( wind, ice, etc. will not interfere ) by a small working force, from one to three men being sufficient, and these need not be skilled workers. In the case of portable masts, the time required for erection or taking down is only a few minutes; even with stationary masts, the time is very short, comparatively, four hours being sufficient for the erection of a mast 100 feet high.

The portable form of the invention presents obvious special advantages for purposes of rescue work, for firemen, and railroads, where it will be valuable on account of the quick erection of the mast, its ready transportability, and the fact that in the collapsed state it may pass through places where it could not be brought fully erected. For the same reasons, it will find ready use in the army and navy for reconnoitering purposes, signaling, carrying searchlights, periscopes, torpedo nets, sheds for dirigible balloons and for aeroplanes, etc. The portable mast may be mounted on a truck, and in this form will provide a very convenient addition to the equipment of a fire department or army. The hoisting device may be operated by a motor, thus saving time and labor in extending and collapsing the mast.

Telescopic Lifting-gear

Load - handling appliances. - Comprises a telescopic tubular mast for lifting and other purposes, in which the sections are raised progressively by a flexible steel band and are automatically locked in the extended position. Fig. 2 shows a detail view, and Fig. 3 is a sectional elevation of the apparatus. The tubes are raised by a band a which is stepped to correspond with the various diameters of the tubes so that it always fits the diametrical section of each tube and is thus kept rigid. The band is wound on a drum l and passes between two rolls h, i the drum being driven from the roll i by chain gearing k. Projections on the rolls engage with perforations in the band and keep it central. Each tube is locked, until the one inside it has been raised, by a pin d carried by a lever b the lower end of which is actuated by the shoulders on the band a and thus the tubes are released in turn. As the tubes are extended each section is locked to the next by a split clamp q which is tightened by an arm o actuated by a pin m on a fixed bracket n. When the band is lowered, the sections are released in order as they come down, so that the band is always rigid in the tubes. In a modification, the band a may be tapered instead of stepped.

I, EARL NITSCHKE, Engineer, of 43, Waldemarstrasse, Berlin S.O. 26, Germany, do hereby declare the nature of this invention and in- what manner the same is to be. performed, to be particularly described and ascertained in and by the following statement:

In known telescopic lifting gear it has been proposed to extend the tubular sections by means of a jointed rack passing up the inside and wound on a drum.

Now according to my invention the tubes are operated by means of a steel band which is preferably stepped to correspond in width to different sections of the telescope so that it always fits the largest sectional dimensions of the different tubes.

My lifting gear can be employed for lifting loads of all kinds, people, antenna for radiotelegraphy. projectors, and also as a mast for signalling purposes, phototelegraphy, and the like.

Some illustrative embodiments of my invention are represented by way of example in the accompanying drawings, wherein : -

Figure 1 is a vertical section through part of my lifting gear, three different forms of the steel band being indicated therein;

Figure 2 is a vertical section showing means for guiding the steel band and mechanism for securing the tubes;

Figure 3 is an elevation, partly in section, showing the lifting gear with the tube elevating and fixing devices, and

Figure 4 shows the automatic fixing device in elevation.

Referring to the drawing, the telescopic tubes 1,2, 3,4 are driven positively by the steel band a wound on a drum (Figure 3) being guided by two press rolls h pressed together by a screw i and driven upwardly or lowered by turning the crank-handle g secured to one of the rolls, which roll is geared to the drum by a chain k. The band is kept most rigid and most suitable for raising loads when it occupies the entire section of the tubes, as shown at f in Figure 1, but is also sufficiently rigid when it is cut tapered, as shown at u, and occupies the largest section of the tube at places, whereas, when the band has rectilinear, parallel sides as shown at viz, and therefore its breadth is only equal to the section of the top telescope tube, it must be made correspondingly thicker.

I prefer to use a steel band which is recessed or shaped step-like as at f, fills the entire diametral section of the tube, and thus cannot move out of position, such a band being able, although relatively weak, to lift considerable loads, namely i acts in the tube like a rigid connecting-rod.

In order that the steel band may always have its shoulders in the tubes suitable for the same, the tubes must not be raised or lowered irregularly, but in order.

The tubes are elevated in order by means of the spring-pulled pawl b (Figure 2) pivoted on tube 3 ; this pawl carries a pivoted pin d which can enter into the tubes 1, 2,3 and thus lock the same; the pin d is withdrawn the thickness of a tube by the shoulders f of the rising band coacting with the pawl, whereby one tube is released after another.

The tubes are caused to descend in order by the spring shackles or clamps Q (Figures 3 and 4) in a manner as previously used in telescopic apparatus for wireless telegraphy and these clamps are automatically released by the pin m, of the bracket n, by which the shackles are automatically tightened as the tubes are elevated. The construction and operation of the shackles will be readily understood from Figures 3 and 4 ; the top ends of the tubes are slotted and each carries a shackle q, whilst, the largest tube carries a support or bracket n carrying a pin m. A bolt s having on the right a head and on the left a nut passes through the ends of each shackle ; outside one end of the shackle is secured a block p having a slanting face through which bolt s passes, and loose on the latter is an arm o having a projection r with a slanting face which corresponds to the slanting face on the block p. When the shackle is locked the arm o is opposite, the pin m , so that when the tube 2 for example moves upwards, the shackle q is tensioned and the inner tube is fixed, whereas when the tubes descend till they are unlocked, at the moment when one tube abuts on the head of another.

In order to keep the band always in the middle of the rollers I provide a row of perforations in the band (Figure 2), into which the teeth w provided in the middle of the rollers enter.

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