US1746804A

US1746804A - Universal transmission tower

Info

Publication number: US1746804A
Application number: US338006A
Authority: US
Inventors: Percy H Thomas
Original assignee: Individual
Current assignee: Individual
Priority date: 1929-02-06
Filing date: 1929-02-06
Publication date: 1930-02-11
Anticipated expiration: 1947-02-11

Description

Feb. 11, 1930. P. H. THOMAS UNIVERSAL TRANSMISSION TOWER 3 Sheets-Sheet Original Filed Dec 31, 1926 INVENTOR Feb. 11, 1930. THOMAS 1,746,804

UNIVERSAL TRANSMISS ION TOWER Original Filed D60. 31, 1926 3 Sheets-Sheet 2 39 I6 9 a; 71 6a 39 b 31 m 5 7f] 9 20, 24 27 F'IEJO INVENTOR Feb. 11, 1930. THOMAS 1,746,804

Original Filed Dec. 51, 1926 5 She ts-sheet 3 1' November Patented Feb. 11, 1 930 STATES mesa-i PATENT GZ 'FEQE Pl-BCY I-I. THOMAS, OF UPPER IvIONTCLAIB, NEW JERSEY UNIVERSAL TRANSMISSEON TOWER The present case is an improvement on my Patent No. 1,616,932, entitled Improvements in universal transmission tower, dated February 8th, 1927.

My invention relates to supporting towers for electric transmission lines and particularly to towers of steel or other material of great rigidity and strength and offers a particularly rugged and economical structure.

I show a tower composed of elements which can be assembled in more than one relation to accommodate the construction to various conditions at the point of installation as will appear hereinafter.

This tower makes use of a number or" design principles shown in my Patent No. 1,616,931, entitled Transmission line towers for electric circuits, dated February 8th, 1927, and my application Serial No. 67,159, tiled 5th, 1925, Transmission line towers. V

I have shown in Figs. 1, 2 and 3 a form of tower with tour posts and transverse guys, located on level ground. Fig. 1 is an elevation taken looking along the line and toward the l ft in Fig. 3. The lacing in the posts 5*, 5 not shown for clearness. Fig. 2 is an end elevation taken looking toward the top of the sheet in Fig. 3, certain crossarm members i not being shown. 8 is a plan view of the left hand end of the tower as shown in Fig. 1.

Figs. 5 and 11 show certain details, espe cially a method for flexibly connecting a pair of posts to one end of the crossarm. Fig. 4: is an elevation of an extension 9 of the crossarm taken looking toward the top of the sheet in Fig. 3, and Fig. 5 is a plan of the same. Certain elements are shown partly or wholly by center lines and certain are not shown at all for purposes of clearness. Fig. 11 is a perspective view of the construction shown in Figs. 1 and 5, certain crossarm members being broken away for the purpose of clearness. This view is taken looking out from This application filed. February 6, No. 333 006.

the paper and from the left toward the right in Fig. 2 and from the upper lefthand corner of the sheet toward the end of the crossarm that is not shown in Fig. 3. In Figs. 1, 5 and 11 certain members at the end of the crossarm supporting the conductor 2 are not shown.

In Fig. 6 the same tower is shown located on ground sloping across the line making an inclination of 525% with the horizontal, this view being an elevation taken the same as 1. Fig. 7 is an elevation of the same tower taken looking across the line located on ground sloping both along and across the line. Figs. 8 and 9 are respectively an end view and a partial plan respectively of air ther form of tower made up of the same elements as the tower of Fig. 1 and having two posts only, but having both transverse and longitudinal guys. Certain parts are omitted for clearness.

Fig. 10 shows an elongated post for applicants tower, having an extension inserted at .ne middle.

in Figs. 1, 2, 3, t and 5, showing a tour post form of tower, 1 is a crossarm supporting six electrical conductors, 2, 2, and two

ground wires

3, 3. Insulator strings supporting the conductors are shown at l, l. The crossarm 1 is trained preferably of steel members such structural angles put together in the usual way. The crossarm may be supported by two pairs of

posts

5, 5 and 5 5" attached to the crossarm 1 at their upper ends, but spread apart lengthwise of the line at the lower ends. The posts may be supported on any

suitable foundations

6, 6 at the ground level, tripods being shown in the illustrations. lhese posts are so designed and connected to the cross that no material bending moment will be introduced in the posts by any movements of the crossarm within reasonable limits. The crossarm will normally be held firmly in )lace against all stresses acting on it, but should a foundation settle, or a connection stretch a little or the guys be tightened unevenly, there would be a certain movement of the crossarm but this would throw no bending stresses into the posts. This is important since bending stresses would be very severe on the posts.

Similarly the posts are so connected. to the foundations or the foundations are so designed that any angular movement of the posts corresponding to the limited movement 1 of the crossarm already described will not throw bending stresses into the post. The post may be hinged to the foundations as shown for longitudinal motion in Figs. 1 and 2 where the post is carried on a bolt 35, which in turn passes through the tops of the three angles 36 connected in the form of a tripod, with a base 37, or the connection may merely be designed for flexibility as for example, as shown for transverse motion in Figs. 1 and 2 also.

The crossarm is restrained from lateral motion by the transverse guys 7 and 8. Each of these guys is connected to an extension 9 fastened to the crossarm 1 and divides at the connector or equalizer 7 and 8 into two guy rods, 7 7 b and 8 8 respectively. These divided guy rods are connected to anchors or foundations near the bottom of the

posts

5 and 5 as shown. By this arrangement I secure the distribution of the stresses produced in the posts by the transverse pull on the crossarm and whenthe guys are connected directly to the foundations of the posts, as here shown,

" the weight of the tower and its load at each post is in opposition to any uplift on the guy. I further secure an attachment of the transverse guys 7 and 8 to the crossarm 1 in such a way that no bending in a plane perpendicular to the crossarm is produced and no bending stresses in the posts. This arrangement further serves to give an indication of the relative tightness of either pair of

guys

7, 7 or 8*, 8 for the connectors 7 and 8 will be pulled to one side if either guy of the pair is too tight. The guys 7 and 8 are attached to the extensions at a point on the central plane of the crossarm.

Longitudinal stresses on the crossarm whether due to conductors, ground wires, wind or other cause are taken up by horizontal components of the axial stresses in the posts, for these posts taking no bending have only axial stresses. The vertical components of the stresses in the posts due to horizontal longitudinal stresses on the crossarm are equal and of opposite sign and neutralize each other at the top. 7

All downward stresses including the weight of the crossarm are divided between the four posts according to the well known laws of mechanics. V

I have not shown the details of the particu lar framing of the crossarm or the posts and foundations for this will be evident to those are attached the posts 5 5 5, 5 and de tails of suitable connections between the posts and the crossarm. In these figures I have used center lines or gauge lines largely to represent the steel members which will usually be of structural steel angles. I have shown portions of angles in outline where this is necessary for clearness. Fig. 11 shows in perspective the same construction as Figs. 4 and 5, the same numerals being applied to the same members in all the figures. The crossarm is shown as extending backwardly and to V the right. The angles 33, the

plates

30, 30, 22', 23, 24; and

bolts

25, 26 and 27, forming the flexible connections between the posts and the crossarm are shown clearly. The

members

19, 20 are braces boltedto the flanges of the

angles

12, 13 and 17, 18.

Referring to Fig. 1, 10 is a strut or tie angle, being a part of the crossarm shown also in Fig. 3 and in Fig. 7. This is the member to which a ground wire may be connected when used. This member 10 connects the two main

crossarm chord angles

28, 28.

The post 5 is connected to the extension 9 by two

heavy bolts

25 and 26 acting as hinges between the crossarm and the post for motion of the crossarm transversely. In the post these bolts are carried by two pairs of

plates

30, 30, bolted or riveted to the

main angles

31, 31, of the post- 5 two angles being connected to one pair of plates. These

bolts

25 and 26 pass through holes in the

plates

22 and 23 which are part of the crossarm extension 9. this securing the posts to the crossarm in such a manner as to permit free motion of the crossarm transversely without putting bendmoment in the posts. This connection, however, is stifi against angular motion in the plane containing the axis of the post and the two

bolts

25 and 26. This stiffness is useful in steadying the crossarm against wind pressure along the line, which would otherwise overturn the crossarm. However, this wind pressure is only that acting on the mem bers abovethe plane of the angles 28, for stressin that plane is resisted by the posts by axial stresses, these posts having their axis meeting in the line of the centers of the members 10, see Fig. 4. The residual bending moment of longitudinal wind must be taken by the posts but will be so small as to be unobiectionable. The postis given a suitable cross sectional shape for this purpose.

The

plates

22 and 23 taking the stresses from the post are carried by two

angles

12 and 13 connecting to the plate 21 secured to the member at its center and the angles 16 and 17 connected at the point 29 (see Fig. 5) to the

angles

39, 39, which are extensions of the

angles

28, 28 and also to the angle 32' (see Fig. 1) from above. The

plates

22 and 23 are connected together by the angle 19, secured to the legs of the

angles

12 and 13.

The post 5 is connected to the crossarin extension 9 through the plate 2% by means of the bolt 2?, much in the same way as post 5., but a single bolt is used so that the connection may be flexible both transversely and longitudinally. The plate 2 1 and the bolt 27 are secured to the post at the center point of its top by two angles 33, which run across the post to transfer the stresses to the

plates

30, 30 and the main corner angles 31. The plate 24 is carried by the

angles

14 and 18 connected respectively to the plate 21 and to the

angles

16 and 17 and 32 at the point 29. The

plates

23 and 24 are connected together through the angle 20. It will be noticed that a transverse movement of the crossarm 1 will tend to bend the

plates

22, 23 and 2%, since they do not lie strictly in parallel planes. However, in practice this will be of no disadvantage because for any degree of motion likely to exist the amount of this bending will not be important and because the posts are free to rotate on their axes to a certain extent.

The angles 11 and connect the

plates

22 and 2% to the angles 28 at their point of connection to the ends of the member 10, securing the cross-arm against overturning.

There is advantage in using a connector or equalizer 3% at the point where the guys 7 8 and 7 8", cross as this supports these guys and gives a certain control of the clearance between the conductors 2 and the guys by determining the angle at which the guy 7 or 8 leaves the post top.

Turnbuckles or other length adjustment means 10 should be inserted in the guys at a sufficient number of points to permit adj i...t ment of stress and position for all guys.

Certain members have been omitted in these figures to clarify the drawings so that the construction may be clear, but they may easily be supplied by those skilled in the art.

This tower of Figs. 1, 2 and 3 may be used on sloping ground. If the slope is across the line, the posts may still be placed vertical and the guys readjusted as shown in Fig. 6. In this case the crossarm will be generally parallel to the surface of the ground. The clearance from the conductors to the guys will be somewhat affected but not seriously and in any case any desired clearance may be provided for by design. This use of my tower avoids the necessity of excavation of the ground on the high side or building up under the posts on the lower side on such sloping ground. This is often of very great advantage.

hen the ground slopes with the line the tower may be installed on the. actual surface of the ground as it lies throwingthe center line of the tower of]? the vertical and for reasonable slopes no material disadvantage re: sults. The stresses due to dead load are increased on the downhill posts but the stresses due to longitudinal load are decreased on this post, so that for reasonable angles no special construction is required. This condition is shown in Figure 7, in which the tower of Fig. 2 is shown on ground sloping both with and across the line, the ground under the back posts being the higher. In Figs. 6 and T the same posts are designated; by the same numerals as in Figs. 1, 2 and 3. In Fig. 7 some members have been omitted for the sake of clearness, but they may be readily supplied by those skilled in the art.

By this method of adjusting the tower to the slope of the ground I avoid much expense and diiiiculty in side hill extensions such as are required in many towers of the standard type.

In general I prefer to fabricate the posts in two parts, such parting being assembled and galvanized in the shop and the two being bolted together in the field, the separation be ing at or near the middle of the section being square at this point. In this case all four posts may be made of identically the same members, the top halves being assembled on the lower halves with the post 5 in a position at right angles to that for posts 5*. The

plates

30, 30 may be used in all post tops but the angles 33 must be added in post 5 to carry the bolt 27. i

There circumstances permit I may use two posts, for example, two posts 5 of Figs. 1, 2 and 3 in place of 4. In this case I add longitudinal guys 38, Fig. 8, connected to each post preferably at the middle point of the member 10 of the crossar-m corresponding. to. the member 10 of the Figs. 1, 2 and 3, these guys taking up longitudinal stresses. In this case the crossarm extension S) corresponding tothe extension 9- of Figs. 1, 2, 3. must be somewhat differently framed since there is but one post to be connected. Such framing need not here be shown as it involves no novel problems. The extension 9. is symmetrical about a vertical plane through the middle. of the crossarm.

This tower of Fig. 8 is shown in plan in Fig. 9, where similar parts are similarly numbered. One of the transverse guys for the structure of Figs. 8 and 9 is shown at 7, the other guy 8 being. similar but oppositely placed. The longitudinal guys 3.8 may to advantage make a small angle with the, center line of the transmission line to give a little support to the transverse guys and to improve the clearance from they conductors.

other members of the tower.

-As shown in the various figures, on account of the transverse flexibility of the connections between post 5 and the crossarm, and where four posts are used the flexibility in both directions of the connection between the post 5 and the crossarm, the structure as a whole may be subjected to sinking of foundations, irregularities of installition, stretching or improper adjustment, of guys, etc., without throwing undue stresses into the posts or V This is in contrast to the conditions in the standard four legged type of tower, wherein any yielding of foundations must cause serious strains in the rigid structure.

The present type of tower gives what might be called a universal structure which may be used for many sorts of sites and conditions as may be most convenient. Where ground space is important the arrangement of Figs. 1, 2 and 3 is suitable, while that of Figs. 8 and 9 is usually more economical:

where guys may be permitted. The arrange ment of Flgs. 8 and 9 is similar 1n many re spects to structures shown in my applications referred to. 7

It will be noted that certain elements, the more important parts, are the same in all uses Serial No. 67,159 and Patent 1,616,931 above ofthe tower, while certain other parts, large:

ly the connections, vary for different ground conditions and other causes. For example, both the upper and lower post sections are all the, same, also the crossarm is always the same, excepting the

extension

9 or 9 which in thissense is to be taken as attached to the crossarmrather thana part of it.

The material and form of the guy also re nains the same although the length varies. The connections, as for example the bolt hinges, are differently arranged for difierent embodiments also the guy connections and the guy lengths. This layout is favorable for economy for the special parts for the line as a whole are reduced to a minimum. Where the slopes of the ground are not uniform or where desirable for other reasons, I contemplate the lengthening of one or more posts to conform to the ground or other condi tions. This lengthening is accomplished preferably by inserting a length of post between the top and bottom elements above described. Such an extension piece is shown in Fig. 10, where the member 41 is inserted between the post top 42 and the post bottom 43 of the post 5*.

I claim as my invention:

1. A transmission line tower comprising a transverse crossarm carrying attachment points for conductor supports thereon, located in a plane of attachment, a foot on each side of the center under said crossarm and rigidly framed thereto, a single post under each of said feet taking downward axial loads and hinged to said foot to permit motion across the line while resisting overturning. of

said crossarm, means for restraining motion across the line consisting of'crossed ties connected to the points of connection between said feet and said posts and means for re-' tion across the line consisting of crossed ties attached at one end to the connection between the posts and the feet and at the other near the base of the opposite post and means for restraining longitudinal motion of said crossarm, said means being attached to said crossarm in said attachment plane.

3. A transmission line tower comprising a transverse crossarm carrying attachment points for conductor supports thereon, located in a plane of attachment, a foot on each side of the center under said crossarm and rigidly framed thereto, a single post under each of said feet taking downward axial loads and hinged to said foot to permit motion across the line while resisting overturning of said crossarm, means for restraining motion across the line consisting of crossed ties connected to the points of connection between said feet and said posts and means for restraining longitudinal motion of said crossarm, said means being attached to said crossarm. 7

4. A transmission line tower comprising a transverse crossarm carrying attachment points for conductor supports thereon, located in a plane of attachment, a foot on each side of the center under said crossarm and rigidly framed thereto, a single post under each of said feet taking downward axial loads and hinged to said foot to permit motion across the line while resisting overturning of said crossarm, means for restraining motion across the line consisting of crossed ties connected to the points of connection between said feet and said posts and means for restraining longitudinal motion of said crossarm, said means consisting of guys in pairs connected to said crossarm in the plane of said cable supports.

5. A conductor carrying crossarm having a horizontal truss for resisting longitudinal stresses, feet under said crossarm framed rigidly thereto on opposite sides of the center, a single post bearing axial stresses under each of said feet, hinged joints between said posts and said feet permitting freedom of motion only across the line, foundations under said posts, and m ans for restraining motion across the line consisting of crossed tension members secured at the top to the connecting points between said posts and said feet and at the bottom to said foundations.

6. A transmission line tower comprising a transverse overhanging crossarm, a single post supporting said crossarm on each side of the center and foundations under said posts, said posts being each provided at the top with two separated hinge joint bearings operating in one plane and at the bottom with a single hinge joint bearing operating in a plane at right angles to said first named plane.

7. A post in an articulated transmission line structure comprising a long column designed to take axial stresses, two hinged bearings at the top spaced apart in a direction along the line and a single hinged bearing at the bottom set at right angles to said first named bearings.

8. A post in an articulated transmission line structure comprising along column designed to take axial stresses, two hinged bear ings at the top spaced apart in a direction along the line and a single hinged bearing at the bottom set at right angles to said first named bearings, said post consisting of three members, an upper member and a lower member both having tapered main legs and a central member having parallel main legs connected to said members with tapered legs.

9. A transmission line tower comprising a transverse crossarm, carrying attachment points for conductor supports thereon located in a plane of attachment, two compressi-on members under said crossarm one on each side of the center, hinges on said crossarm to permit motion of the crossarm across the line, while resisting overturning of said crossarm, said hinges being located below said plane of attachment and means for restraining displacement of said crossarm longitudinally and transversely, the forces resisting transverse displacement being applied near said hinges.

10. A transmission line tower comprising a transverse crossarm, carrying attachment points for conductor supports thereon located in a plane of attachment, two compression members under said crossarm one on each side of the center, hinges on said crossarm to permit motion of the crossarm across the line, while resisting overturning of said crossarm, said hinges being located below said plane of attachment and means for restraining displacement of said crossarm longitudinally, said means being attached to said crossarm in said plane of attachment, together with crossed ties restraining transverse displacement of said crossarm connected near the opposite ends of said compression members.

11. A transmission line tower comprising a transverse overhanging crossarm, a single