SLIP IV AYS. 327 



small size of the ram, it is forced out much more rapidly than 

 are the hauling-up rams, the respective areas being approxi- 

 mately I to 19. During the short time the links are stationary, 

 that is, at the reversal top and bottom, water under pressure is 

 accumulated, to be given out so soon as the rams are permitted 

 to travel in one direction or the other. 



Several modifications of this hauling machinery can be made, 

 all involving the upward and downward movement of the links 

 as described, and in some cases the rams might be worked direct 

 from a set of force-pumps. The accumulation is, however, 

 convenient not only as a means of economizing time, but as 

 a safety-valve to prevent shocks, and a regulator for adjusting 

 the speed of the engine or the working of the pumps according to 

 the demand for water. 



Hydraulic hauling-gear, constructed by Messrs. Hayward, 

 Tyler & Co., consisted of a double set of cylinders and rams. 

 These were so arranged that while one set of cylinders was 

 in upward motion the other was returning. By attaching the 

 hauling-links first to one set of rams and then to the other, the 

 cradle was drawn up by an almost continuous motion. 1 



Wire-rope Haulage. 2 Messrs. Summers and Day have 

 successfully employed hauling machinery in which an engine 

 working, through gearing, on to a large drum, rolls up a 9-inch 

 wire rope attached to the cradle. 



The advantages claimed for this system of haulage for slip- 

 ways are, that it is more rapid in its action, inasmuch as the delay 

 due to the reciprocatory action of the hydraulic ram, by which 

 half the time is lost, and also the loss of time due to fluting the 

 links, is altogether avoided. It is less costly to lay down, and 

 less expensive to work, and can be employed for any size of vessel. 



The following description of a set of gearing for working 

 a slipway by wire-rope haulage is given by Mr. T. Summers : 3 

 "The engines which worked the hauling-gear had two cylinders 

 each 10 inches in diameter and 12 inches stroke, fitted with link- 

 motion for reversing. A worm on the engine crank-shaft geared 

 into a worm-wheel having fifty-six teeth, and that drove a shaft 

 carrying a pinion with fifteen teeth and 4-inch pitch, which 

 geared into a spur-wheel with ninety-five teeth, to which was 

 bolted a large band, which made one revolution whilst the 

 engine made three hundred and fifty-five. 



1 M.P.LC.K,\ol. Ixxii. p. Hi. * Hid. Ibid., p. 161 



