. Supplement to Spons dictionary of engineering, civil, mechanical, military, and naval. e circle on their upperedges, which bear against friction rollers revolving on the same pin which carries the sheaves Q,and that tends to preserve the angle-irons in their proper shape. The sliding collar W has a sheavewithin it, round which tlie main lifting chain B is rove. When working in soft soil, the chain Bis attached directly to the collar W, and when in hard soil, power is gained by passing thechain through the sheave, and fastening the end of it to the spear, as in Fig. 1019. This main 472 DEEDGI
. Supplement to Spons dictionary of engineering, civil, mechanical, military, and naval. e circle on their upperedges, which bear against friction rollers revolving on the same pin which carries the sheaves Q,and that tends to preserve the angle-irons in their proper shape. The sliding collar W has a sheavewithin it, round which tlie main lifting chain B is rove. When working in soft soil, the chain Bis attached directly to the collar W, and when in hard soil, power is gained by passing thechain through the sheave, and fastening the end of it to the spear, as in Fig. 1019. This main 472 DEEDGING. chain is worked over the head of the crane, Fig. 1020, stops E and S being provided to preventthe scoops overrunning tliemselves, and thus getting jammed. T is a float catch hinged to thetop of one of the scoops, and wlien they are open, it hooks on to a lug on the top of the other thus ties the two scoops together at the top and prevents them from closing, as the catch remainsin its position. The hooks H, which are attached to the jib head, are so counterbalanced by the. weight K that they fall forward into the position, Fig. 1020, when the rope attached to them is slack*These hooks have sloping faces at their lower extremities, so that when tlie clutch collar X rises upto them, the projecting arms of the collar push back the hooks and rise past them; when the armsare above the hooks the latter fall forward and support the arms so as to prevent the collar fromreturning. In this position the main lifting chain may be lowered and the whole apparatus hangsby the hooks H on the jib head; tl)e entire weight is thus thrown on the collar X, and the scoops aredrawn openinto the position, Fig. 1017. The lever E is centred on the jib head, and has attacliedto it a cam which bears on a shallow rack fixed to C; on pulling the rope attaclied to thelever, this cam jams the spear in the guide so that it cannot rise. V V iire leatlier valves which allowwater to escape if the buck
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectenginee, bookyear1879
