MORE PLANT

Evening Post, Volume CVI, Issue 139, 10 December 1923, Page 8

MORE PLANT

A,TRENCH CUTTER.

The American road trenching machine now on order to the City Council is. according to.notes on its working, photographs, and diagrams received , by the engineer in charge of waterworks and drainage, as : efficient as it is weird-look-ing. The fore-carriage resembles that of a farm tractor, .with perhaps rather more gear about it, but in place of rear wheels caterpillars are fitted, the business end of th« machine, the cutting wheel—or, rather, cutting rim, since it has no axle, but runs on four double pulley guides—being carried behind the caterpillars again on a heavy steel boom and raised or lowered for transport or varying,depths of cut by a short derrick, hoist. Looks, however, do not jount if the machine, digs in Wellington as similar trenchers have dug ■ els»where, as, for instance, 450 miles of trenches in and around about Log Angeles in • two years, in addition to travels from one point to another, totalling 400 miles/ 180 miles of trenching for a Californian sas company in a year and ten months,.averaging 2000 to 300j feet.of trench Hl.inches wide and three feet deep per day through sandy soil and 1500 feet per. day in hard and heavy ground, and.2ooo feet of .trench 21 inches wide and four feet deep through macadam so hard that a pick would not penetrate it. to any depth, lhe. digger goes straight at the surface, requiring no preliminary breaking up of the hard, packed surface crust. - A different type .of trencher, on which the cutters are carried very much on the lines;of dredge buckets, can dig down to ten or ■ twelve feet, but the wheel type is limited to six or seven feet. ' ■■" . '

The trencher's first work will probably be in connection with the laying of *■«? new pipe line from the Wainui side of the Orongorongo tunnel to the Karori reservoir. ' .••■•.