GB372571A - Improvements relating to electric insulators - Google Patents

Abstract

372,571. Insulators. TRIGGS, W. W., 57, Lincoln's Inn Fields, London.-(Ohio Brass Co. ; Mansfield, Ohio, U.S.A.) May 27, 1931, No. 15495. [Class 36.] In order that an insulator may be given a high mechanical strength without increasing its liability to damage by changing temperature conditions, a reinforcing or stress exerting band is applied, subsequently to assembly of a metal and a dielectric part of the insulator, to one of the parts. In the construction of Fig. 1, a metal cap 12 is cemented to the head 11 of a dielectric shell 10. The cap 12 has bearing shoulders 16 and may have a thin sheet metal lining 17 corrugated to permit expansion. A reinforcing band 19 is applied over the tapered edges of the cap 12. The band 19 may be applied by hydraulic pressure, or the ring may be applied hot to the cold cap. The reinforcing band may be of composite structure, and the cap edge may be slit and reinforced with helically wound spring wire. Compensating members, consisting of segments surrounding the pin in the pin cavity may also be provided, and the pin may have a tapered thread. A reinforcing band may be similarly applied to a bushing insulator. The insulator pin may be of the form shown in Figs. 11, 15. A steel pin 66 has a portion 67 with slots 68, the portion 67 being threaded to receive a thimble 69. In a modified pin construction, the pin is made hollow and is provided with tangentially directed slots, or a metal sleeve may be threaded about a central spindle. The sleeve may consist of separate collars each bearing a resilient flange. Fig. 18 shows a reinforcing band for the insulator cap. The band 88 is of drawn metal and has a radial flange 89. A band 90 may reinforce the band 88 as shown. Fig. 19 shows a pin having a reinforcing spider 92 within the outer shell 93, which may be slotted. In order to secure accurate compression, the reinforcing band may be corrugated or formed with spaced contacts bearing on the cap, or a corrugated sheet of metal may be inserted between the band and the cap. Fig. 20 shows an apparatus for applying reinforcing bands to insular caps. A frame 96 fits over the cap 97 and bears on the reinforcing band 98. A threaded pull-bar 99, with a head 100 which fits a socket 101 in the cap, carries a screw head 102. Rotation of a hand-wheel 104 will press down the frame 96 to exert tension on the bar 99 and force the band 98 on to the cap 97. For relieving pressure on the band, the device shown in Figs. 21 and 22 may be used. A spider 105 has pivoted grappling hooks 106. A head 108 bears on the cap 97 and is adapted to press on the cap 97 by a screw 109 which is rotated by a hand-wheel 110 in the yoke 105. Springs 111 hold the grappling hooks 106 in the upper position. A band 112 encloses the hooks 106 and is adapted to force the hooks into position beneath a reinforcing band 98. The yoke 105, hooks 106 and band 98 are lifted to relieve pressure on the cap 97 by rotation of the hand-wheel 110.