US 2036771 A
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TUBULAR POLE Filed Dec. 13, 1935 Patented pr.. 7, 1936:I
UNITED STATES PATENT OFFICE Application December 13, 1933, Serial No. 702,214 In Germany December 15, 1932 2' Claims.
This invention relates to a tubular pole composed of several elements consisting each of a conical tube section of sheet steel. The invention consists in that the tube sections of sheet 5 steel are of elliptic cross section and have on the inner side and on the outer side a weather-proof and stiffening coating and that the tapering of the cross section from the lower to the upper end of each element is such that the lower end of l every following element can engage over the upper end of the preceding element with av short length and that every following element can be completely inserted into the preceding element for transporting purposes. It has become known l from U. S. A. Patent 1,932,671 to employ pointed tube sections of elliptic cross section. According to this patent the tube sections are covered with concrete on the inner side and on the outer side and only the ends of the elements are constructed 20 so that they can be slipped the one over the other, the concrete cover having to be subsequently completed at the joints. These elements are heavy and fragile and it was not possible to insert them the one into the other for transporting 25 purposes. It has been found that tube sections with a weatherproof and stiffening coating possess a resistance which is not less great than that of the concrete covered tube sections, but are capable to withstand higher bending stresses and 30 are more practical and cheap in every respect.
Merely the lowermost elements have in particular instances concrete covers in order to better protect the portion of the pole embedded in the ground against corrosion and that portion closely above the ground against intentional damaging.
The concrete cover on the lowermost element or elements is, however, carried out in such a manner that the following element need only be slipped on and that no subsequent completing of the outer is necessary. The coating on the tube elements consists of metals or enamel and the surface of this coating especially on the joints is made irregular and painted with a. soft and 45 hardening mass in order to attain a very solid connection of the elements the one with the other. For improving the appearance of the elements and for further stiffening the same longitudinal grooves are pressed into the wall.
50 An embodiment of the invention is illustrated by way of example in the accomp-anying drawing in which:--
Fig. 1 shows in longitudinal section the lower portion of a pole.
55 Fig. 2 is a cross section on line II-II of Fig. 1.
Fig. 3 is a longitudinal section on line III- III of Fig. 1 on a larger scale.
Fig. 4 shows in longitudinal section on smaller scale a pole composed of three sections.
Fig.v 5 is a cross section on line V-V of Fig. 4 5 on a larger scale.
IIhe tubular pole according to the invention is erected from tube sections al, a2, a3 of sheet steel about 2 mtrs. long. The tube sections taper in upward direction andl are of elliptic cross` section. The conicity of the individual elements is such that every following element can be slipped with its lower end for a short length over the upper end of the preceding element and so that every following element can be completely inserted into the preceding element for transporting purposes. As may be seen from the drawing the lower end of each element telescopes over the upper end of the preceding element a distance approximately equal to the largest diameter of the pole at the juncture of the two sections.
It has been found that this amount of telescoping is suflicient to render the pole strong and rigid and yet economical to manufacture because of the small -amount of metal used in the overlap. The wall of the elements has on the inner side and on the outer side a weatherproof and stiifening coating b of zinc, lead, copper, enamel or the like. This coating is rendered irregular by a suitable method particularly at those portions which are slipped the one over the other, these irregularities of the coating being formed by impressions or indentations c so that the accurate fitting of the ends to be slipped the one over the other is not impaired. Prior to the putting together of the individual elements the irregularities of the coating are made smooth by painting with a soft and hardening mass, such as water glass, varnish, fine mortar and the like. 'Ihe solidified mass ensures a very strong con- 40 nection of the telescoped portions. For further stiifening the wall of the elements may have longitudinal grooves d, as shown in Figs. 4 and 5. These grooves extend prefer-ably only between the joints of the elements and improve the appearance of the same. rThey may, however, extend over the whole length of each element and do not impede in any way the telescoping of the elements.
The uppermost element a3 (Fig. 4) is prefer- 50 ably filled with a light mass, such as wood cement easy to be drilled for screwing in supporting means, such as insulator supports e. The individual elements are so light and handy that one man can carry the elements of a whole pole if they are inserted in each other and he can erect the pole with the aid of climbing irons and a suitably light lifting crane. Poles of smaller size may be put together when lying on the ground and they can be raised and erected by one man. For special cases, i. e. if the ground is bad and the pole particularly high, the l'owermost element or the lowermost elements may have a concrete cover. Such an element is less corroded by the ground than an element without concrete cover and offers better protection against intentional damaging. The concrete cover is provided on the inner and outer sides of the tube section of sheet steel. The outer concrete cover is thickened on the upper end of the element and an annular gap h is provided in this thickened portion around the sheet steel wall a so that the bare lower end of the next following tube section can be slipped into this annular gap on the tapered top end of the lowermost tube section. The annular gap is then lled with a tough and weatherproof material, such as liquid tar or asphalt. If a second concrete cover tube section is placed on the lowermost tube section, the lower portion of the wall of the following element has no concrete cover so that it can be slipped on like a bare tube element.
l. A tubular pole composed of pole elements, each of which consists of an upwardly tapered steel sheet wall of elliptic cross section, each element tapering from its lower to its upper end in such a manner that every following element can be slipped with its lower end a short length over the upper end of the preceding element and can be completely inserted into said preceding element, and a stiffening and weatherproof coating on the outer side and inner side of the sheet metal wall of each element, the surface of this coating particularly on the portions of the elements to be placed the one over the other being roughened and painted with a soft and solid hardening substance filling out the irregularities.
2. A tubular pole composed of pole elements each of which consists of a sheet steel walll of elliptic cross section and tapering in upward direction, the wall of the lower elements of the pole having a concrete cover on the inner and outer side, the outer concrete cover thickened at the upper end, this thickened portion of the ooncrete cover having an annular gap extending around the sheet metal wall and adapted to receive the lower bare portion of the next following element, this annular gap being lled with a weatherproof tough substance, the tubular wall of each element tapering from its lower to its upper end in such a manner that the lower end of every following element can be slipped for a short length over the upper end of the tubular wall of the preceding element and that each following element can be completely inserted into the preceding element except the concrete covered elements.