US1858772A - Park cable - Google Patents

Description

May W, E932. Q. A. IFREEHHQKSN PARK CABLE Filed Aug. 7 1929 MM WM Hw/H @3513 l" @Hof/wmf Patented May 17., 1932 UNITED' STATE OTTOABTHUR FREDMICKSON, 0F BEN AWGN. PENNElYDWM, ASSIIGNGR T0 NTNAL ELECTRIC PRODUCTS CDRPOMTIGN, @E NEW YORK, El Y, A' CORPRATION 0F DELAWARE PMK @ABLE Application died .august A E929. Serial lilo. llldtl.

This invention relates to improvements in cables. Heretofore cables have been used which are known as park cables and such. cables as heretofore constructed have been made by starting with a lead sheath cable? applying a roving of jute over the lead and over the jute applying two layers of steel tape and over these steel layers applying other layers of jute and it has been the general practice to treat the jute with pitches, etc., to protect the coverings. The use of such steel tapes is unsatisfactory for 'various reasons, among which may be mentioned the fact that the tapes are subject to corrosion and when they are employed it is difficult to splice the cable because the lea-d is often times punctured when the steel tape is being removed and furthermore, the use of steel tape aects the flexibility of the cable. Also in the event that a spade or fork is abbed into the cable the sharp edges of the steel from the tape frequently puncture the lead.

Heretofore attempts have been made to dispense with the use of steel tapes inpark cables and in lieu thereof cardboard Wrappings have been employed. ln practice it has been found necessary to have such cardboard Wrappings with a width of about 1% of an inch. Such Width of Wrap ings of cardboard material has detracted rom the 'HeXibility of the cable. Narrower Wrappings of cardboard material have not been found practicable because the cardboard is in laminated form andif it is slit to narrower widths say to about 1/8 or kof an inch, such cardboard tape will open up and the laminations Will separate during 'the Wrapping operation. If attempt is made to so construct the cardboard and so stick the laminations together that the laminations will not open up, it has been found that when the paper is slit into such narrower widths it is so brittle that it is practically impossible to wind it around the conductors. Furthermore, when cardboard Wrappings are cmployed such cardboardmaterial is diiicult to remove because the cardboard material is relatively stiif and if a subsequent splice is to be made the cardboard strip breaks off at every convolution or so during the unwinding operation and therefore such park cables with cardboard tapes have heretofore been found dicult to splice.

it is accordingly the object of the present invention to provide an improved form of cable 4which is suitable for the uses where Vpark cable has heretofore been employed and 'which new cable is not subject to the aforevious constructions.

A further object of the present invention resides in theprovision of a cable which is suitable for park cable applications wherein in lieu of steel tapes as used heretofore or cardboard strips, convolutions'of twisted and attened Kraftex paper are employed.

A. further object of the present invention resides in the provision of a park cable with a Wrapping which serves in lieu of steel tapes or cardboard strips as have heretofore been employed and which is strong and durable and which has suthcient strength to enable it to be readily pulled off from the cable without the use of great care in unwinding and Without the attendant breakage of the Wrappings which has heretofore been encountered When cardboard has been employed in lieu of steel tapes.

Further and other objects and advantages Will be hereinafter set forth in connection with the accompanying drawing.

ln the drawingf l0 is the copper conductor which is` preferably tinned-as shown at 11, 12 is the rubber insulation over which is wrapped tape 13. @ver the tape is a lead sheath 14. After the lead sheath is applied the outer surface of the sheath is covered with an impregna/ting compound 15.

rlhe next step in the manufacture of the cable is to Wrap upon the layer of compound a layer of hard flattened twisted kraft paper as lgenerally indicated at 16, thereafter another layer of impregnating compound 17 is applied and over this layer there is placed another serving or Wrapping of hard ilattened twisted kraft paper as shown at 18. rlfhe convolutions of this layer extend in opposite directions to the convolutions of layer 16. @ver layer 18 there is placed more impregnating compound 19 and on top of this v mentioned disadvantages and defects of precompound there is placed a serving or wrapping of saturated (gute 20. After the jute wrapping is applic this wrapping 1s coated with stearin pitch 21 constituting a fire retardent and protective coating and over this stearin pitch coating there is a final coating or layer of wax-like material 22 which provides an anti-stick finish for the exterior of the cable.

In the drawing for clarity of illustration certain of the parts are shown exaggerate in thickness. Obviously the tinning 11- is relatively thin and also the impregnating compound layers 15, 17 and 19 in the actual cable permeate into the inside and outside oi flattened twisted paper servings. Other coatings and compounds are also shown exaggerated as to thickness.

By employing twisted flattened paper servings the previous objectionable characteristics of steel tape Wrappings or of cardboard wrappings are overcome. The twisted fiattened paper provides the desirable shock absorbing characteristics and at the same time provides a construction which has the maximum of flexibility. The material is also partlcularly adapted to protect the underlying lead sheath against damagewithout effecting the flexibility characteristics of the finished cable. The flattened convolutions of twisted paper furthermore facilitate splicing operations since the twisted paper wrappings provide a strong durable cord that has sufcient strength to enable it to be pulled off from the cable without the necessity of the splicer going through the unwinding operation. The splicer merely has to grasp the ends of either convolutions 16 or 18 and draw it off to the desired extent. During such removal the kraft material or twisted flattened paper serving does not break in the manner that the cardboard strips broke with previous constructions.

What I claim is:

1. An electrical cable adapted for underground use and having the usual conductor insulation and lead sheath and including in combination therewith servings of relatively one serving being reversed with respect to' an adjacent serving and each serving being impregnated from the inside and outside.

4. The invention set forth in claim 3 in which a serving of jute is provided outside of the flattened paper servings to protect the same. o

5. The invention set forth in claim 3 in which a serving of jute is provided outsideof the flattened twisted paper servings to protect the same and which the jute is covered with a coating of a fire retardent materia-1 over which another coating of wax-like material is placed to provide an anti-stick slick finish.

6. An electrical cable adapted for underground use and including an insulated cable and a lead sheath encasing the same and compr1sing in lieu of the usual metal protection for the lead sheath a flexible exterior protective layer for said sheath, which layer is hard and relatively rigid and which layer comprises a serving of paper impregnated with a protecting compound to prevent deterioration of the paper when the cable is in the ground, said serving being in twisted and in flattened form with the convolutions of the serving relatively narrow in Width and disposed exteriorly of said lead sheath to form the relatively hard protective layer therefor.

In testimony whereof I hereto aflix my signature.

OTTO ARTHUR FREDERICKSON.

hard twisted and flattened paper disposed exteriorly of the lead sheath and therearound said servings constituting by themselves a hard relatively 'rigid protective layer for the leath sheath.

2.' An electrical cable adapted for underground use and having the usual conductor insulation and lead sheath, and having in combination therewith a plurality of impregnated and reversely wrapped servings therearound formed of twisted flattened paper said reversely wrapped twisted flattened paper servings constituting by themselves the only hard and relatively rigid protective layer for the lead sheath.

3. An electrical cable adapted for under ground use and having the usual conductor

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