DREDGE BUCKETS.

Stratford Evening Post, Volume XXXI, Issue 81, 18 November 1911, Page 5

DREDGE BUCKETS.

THE IMPORTED AND LOCAL ARTICLE. AN INTERESTING REPORT. In accordance with a resolution passed at last meeting, Mr F. Henderson (superintendent of works) submitted the following report in connection with the Paritutu dredge buckets at yesterday’s meeting ot the Harbour board:—The dredge Paritutu had only been at work for a few weeks when the plates of the buckets began to onlge inwards at the side and later on the side flanges at the bottom castings began to break. Every means were adopted to preserve the buckets, the working sped was reduced, and while dredging among boulders systematic blasting was begun to loson the ground, and the larger boulders were pulled up by the wharf crane with the asistance of the diver, i lie buckets were carefuly watched and each one that showed signs of cracking was taken off and fitted with a fin. steel plate rivotted inside across the bottom and about oin. up the side. Phis work was done in Dunedin, proving most successful. The whole of the buckets have been similarly treated and though some have been working over twelve months not one has yet given way. On point of strength the cracket buckets, after being fitted with plates, arc not as strong .is sound ones, but the plate flanges will allow a certain amount of spring, while the cast flanges, being absolutely rigid, will break under a severe pressure. Ten new buckets have been received from Homo, and I recommend that tficy be fitted with olates before being used to avoid all iisk of them being damaged permanently. The bruslies, lips, and pins of the imported buckets are of' the highest grade manganese steel. I have not seen steel of equal quality used in the Dominion. In designing, a backet to be made entirely of wrought steel, and to work on tlie' ladder in conjunction with the existing ones. I was met at the outset by aclitiiculty. The buckets of the Paritutu have four links incorporated in the bottom casting, and each basket is connected to the other by two forged links, whereas wrought steel buckets, as made in the Dominion, have only two links on the bucket and are connected to each other by four forged links. I had, therefore, to introduce an extra plate with two flanges at the bottom of the bucket to carry the extra pair of links. This alone nearly doubled tfio labour in manufacturing and added largely to the cost. Two of these buckets were supplied by Messrs A. and T. Burt, of Dunedin, and placed on the ladder on Ist July. After live weeks one had to be taken off, the lip having cracked right across the centre. The other has worked five months but the lip has cracked, and it will not work much longer. These lips are made of spring steel, nine inches wide by one inch thick, and flught to stand any amount 'of hard wear. Ihe steel, however, seems to lie ot an unusually brittle nature, although at the same time it wears much faster than the cast manganese lips. I have written tb Messrs Burt on the matter, ’and they suggested trying spring', steel lips IJin. thick, which they have lately supplied to the Otago Hatboiir Board’s; dredge No. 222. This' was open to the objection of unduly increasing the weight, but as there are only two of them it may be as well to have them re-liped with the heavier steel. The lips were the only apparent weakness. The other materials are firstclass, and the workmanship creditable. I would not,! ; recommend any more being made unless a full set was required, as they could then be fitted with only two links, and the price would then be about equal the imported bucket. The cast steel bottoms of the imported bucket had three advantages. First, they give a wide, and even hearing on the tumblers and rolers. Secondly,-they are not liable to twist ; and, thirdly, less than half the number of rivets are required. The two points of weakness are the flanges and the piece of unprotected 600 tons), also 33 large bounders. The plate on each side of the mouth. If die flanges are made fin. to -Jin. thicker at the roots and the lips are extended 12in. on each side $0 as to overlap the flanges, they would be much stronger. In ordering additional buckets from the makers these alterations should be specified. The works committee reported that it had been decided to adopt the superintendent’s recommendation to forward the ten new buckets to Dunedin to be strengthened as suggested.— Adapted.