A Treatise On The Principles And Practice Of Dock Engineering

STEAM PILING MACHINES. 57 Piling machine is constructed, with two long vertical guides or runners, up ^nd down the face of which the monkey slides, being kept in position by a ug or projection fitting into the groove between the guides. The simplest kind of pile driver is the ringing machine, in which the Work is performed entirely by hand. The monkey rarely weighs more than one-third of a ton, and it is lifted by a rope which, after passing over the Pulley at the head of the frame, is connected with a number of short lengths, so as to afford a hold to a corresponding number of men, in the proportion of about 40 Ibs. weight per man. The lift does not exceed 4 feet. At a given signal the monkey is allowed to fall, the men taking advantage of each rebound to raise the monkey. Driving is usually carried on in spells of three or four minutes’ duration, with intervals of rest, and in this way ^en are said to be capable of delivering from 4,000 to 6,000 blows per The explosion of a cartridge has been utilised to augment the effect of the ow upon the pile and to increase the recoil of the ram. The cartridges are Insel ted in a small hollow in the pile-head, and, after percussion, are replaced y fresh ones during the ascent of the ram.* The cartridges are either of gunpowder or of dynamite; in the latter case the head of the pile is protected y an iron plate. Explosive drivers can readily make from 30 to 40 blows °f from 5 to 10 feet per minute. In another pile driver, called a crab engine, the rope, instead of being 'irectly held by hand, passes round the drum of a crab or windlass, by means of which the monkey can be given a fall of 10 or 12 feet. Such merely manual methods, however, are primitive; they are really '"dy suitable for driving small piles in insignificant numbers, and are 1utiiely superseded in works of importance by steam piling machines. Steam Piling Machines are of various design. In the earlier examples steam power simply replaced manual effort in lifting the weight. A hook Nigger at the end of the lifting chain engaged in a staple in the head of e pile, and was released by pulling a counter-weighted lever. The chain ad to be lowered after each blow. The intermittent action involved in this arrangement has been obviated y the device of an endless lifting chain, characteristic of the machines of essrs. Sissons & White (fig. 23). The chain passes up the groove between .6 Inders and down over a spur wheel in the gearing, by means of which is kept running continuously. The ram, which weighs from 15 to - cwts., is raised by a tongue passing through its centre and capable of engaging in the moving chain, through the medium of a rack and pinion ■novement actuated by a lever. The man in charge of this apparatus pulls e cord attached to the end of the lever, causing the tongue to shoot out at d e back of the monkey into the nearest open link. The tongue is with- lawn at any desired level by the other end of the lever coming in contact 11 a staple fixed to the face of one of the guides. The holes for these Sir F. Bramwell, Presidential Address, 1885, Min. Proc. Inst., C.E., vol. Ixxx.