US1648462A - Cross arm - Google Patents

Description

Nov. 8, 1927.

J. H. NEVILLE CROSS ARM Filed Dec. 5, 1925 Snow tow John Ne 3 j %JZ W- filmm v Patented Nov. 8, 1927.

UNITED STATES JOHN H. NEVILLE, OF WALVILLE, WASHINGTON. I

cnoss ABM.

Application filed. December 5, 1925. Serial No. 73,456.

My invention relates to'cross arms, such asare used on pole lines to carry electric conductors. Itconsists of a new and useful improvement in cross arms, whereby is produced an arm having excellent qualities, including greater strength, superior mechanical properties, longer life, less susceptibility to climatic and atmospheric deterioration, reduced weight, less bulk, cheapness of manufacture and ability to more fully use all the timber in a log which is of suitable quality.

The points of novelty and of advantage possessed by an arm of my new construction will be "hereinafter set forth and the novelty particularly defined in the claims.

I The accompanying drawings illustrate a cross arm'made in accordance with my invention, the same being of the type which is now most approved by me.

Figure 1 is a top or edge view of the complete cross arm;

Figure 2 is a side face view of a cross arm mounted upon a pole;

' Figures 3, 4 and 5 are cross sections of the i arm, taken respectively on the planes indicated by the lines 3-3, 44 and 5-5 of Figure 1;

Figure 6 shows in face View a type of key [which may be used if desired to strengthen the bond between the two halves of the arm. A number of facts and conditions exist which afiect the manufactureand use of single-piece or solid-wooden cross arms,

which increase their cost and decrease their life, which objectionable conditions may be either avoided or minimized by making the arm of two or more pieces. 1

' In the first place, it is generally recognized that it costs more per board foot to get out 40 timbers of relatively large size or thickness, than it does to get out thinner stock. One reason for this is that an imperfection which would cause rejection of a stick or large timber would not prevent half or more of the same stick bein graded as clear or No. 1 stock, thus raising the percentage of the higher grade.

It is also a well-known fact that proper drying of a large stick takes a much longer 5 time and is much more difiicult than drying a thinner stock. This difficulty increases at a much greater ratio than the ratio of their thickness. In fact, it is more nearly according to the square of their thickness. This eatly increases the cost of drying.

If the drying is pushed, case hardening and other troubles are rather sure to arise. A stick so afflicted is liable to crack, thus opening up avenues for decay, decreasing the strength and shortening the life.

To overcome these difliculties, as well as to secure advantages not above mentioned, I have devised a composite or built-up cross arm, of which that illustrated in the drawings is atypical example.

This cross arm is composed of two planks '1, 1, which are secured together along a central vertical plane, either in face contact or separated by spacers. While two layers would be'sufficient for most uses, more might be used if desired. This provides a laminated type of construction.

The contacting faces of these'laminations are provided with ventilating channels 2,

proof glue on the contacting faces of theparts, and, in addition, by nails, rivets, bolts or'screws 4, located close alongside the pinreceiving holes 3, giving maximum holding where most needed. The glue is desirable more as a sealing agent for the joints to prevent entrance of moisture, than as a positive holding agent. As an additional means for securing the two bars 1 against relative movement, I may employ keys or dowels 5, such as are shown in Figures 5 and 6. These are inserted in saw kerfs which extend transversely across the bars, preferably stopping short'of the side edges of the bars, as is shown in Figure 5. In the assembled cross arm these kerfs do not extend to the outer surface, are sealed by the Waterproof glue, and moisture cannot enter. In Flgure 1, I have shown one such key used at each end of the cross arm.

The top surface of the assembled cross arms is preferably rounded, as best shown in the sections given. Provision is made for bracesas 7, and for a bolt as 9, by which the cross armmay be braced and securely held to the pole 8. a

By reason of the smaller dimension ofthe bars used, due to the built-up construction employed, a larger percentage of the log may be used than would be possible if the arm were made of one solid piece. By reason of the manner of securing the halves together, particularly because the screws 4 are close to the pin-receiving holes where disruptive strains would be applied, these holes may be nearer the end face, thereby saving two inches of length at each end.

The half thickness of the stock employed 7 makes possible thorough drying in a short time without checking, case hardening or otherwise injuring the material. This source of decay and deterioration is therefore elimi nated.

The ventilating channels 2 secure quick drying after wetting and thus prevent decay. The pinsv placed in the holes 3 each serve as a dowelor key connectingv the two halves to prevent sliding movement. The manner of forming the pin-receiving holes 3 insures smooth, clean cut holes with nosplintering, as is-likely to occur at the side where an auger emerges. All of these holes as wellas the channels 2, being formed at one passage'of the stick through the machine, the labor cost is very slight.

Tests made upon cross arms of this construction have shown 'them to be as strong against strain, in either transversedirection, as the best solid arm having the same outside dimensions. As it is evident that they are"consid'erably lighter, freight charges are less. For reasons stated they permit use ,of" a higher percentage of the log, as Well as saving four inches in length, which decreases the lumber cost. By reason of more I perfect drying of the stock and in asmall part of the time required for the solid arms, their cost of manufacture is decreased. Also, because of better andsounder drying in manufacture, and also because of the smaller section of the parts and the ventilation provided, they better resist atmospheric deterioration and are longer lived. They 'also'pl'acea slightly less load on the poles.

I 'do'n'ot wish to be understood as relying verystrongly upon the glue to hold the bars together; the chief holding agent is understood to be the-nails, screws, rivets or equivalent holding means employed. The glue is of great benefit as a sealing agent, preventing entrance of moisture between the conta'ctln'g sur'it'a'ces.

What I claim as my invention is:

1. A cross arm composed of two bars secured together in face contact along a central vertical plane, and having sectlons of said contacting faces cut away to form free air-circulating channels between the two bars.

2. Across arm composed oftwo bars secured together in face contact along a central vertical plane, and having pin-receiving sockets with their axes located upon said plane of contact, andsecuring members; joining said bar-sclose alongside of. the pin-receiving sockets, the contacting faces of said bars being transversely cut away between said sockets to form ventilating channels.

3. A cross arm composed of two bars secured in face contact and having pin-receiving sockets located on the plane of contact:

and partly in each bar, the contacting faces of said bars being cut away between the pinreceiving sockets toform ventilating channels, securing members located adjacent to said-sockets, and keys seated in the contact-.1

the bars and seated in each, said keys and their seats terminatingshort of the side margins of. the contacting faces. 7 v

6. A cross arm composed of a plurality of bars secured together by face contacts between its parts, said parts beingshapedto.

provide transversely extending ventilating channels between the bars. y

Signed at Seattle, King County, Washing ton, this 14th "day of N0vember, l925.

JOHN NEVILLE.

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