Volume Ten - Pre-Victorian to the present day - even more aspects - The Patent for the Penarth Slipway - 1881 . . .

Mr. T. Summers cont'd :

The first slip-way on which their system of wire-rope haulage had been used, was on their longest slip, which was set to work January 1879, and had been constantly in use ever since. The ground-ways were on an incline of 1 in 24, and were 622 feet in length, the cradle being 221 feet long, and 82 tons in weight. The engines which worked the hauling gear had two cylinders, each 10 inches in diameter and 12 inches length of stroke, fitted with link motion for reversing them. 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 the large barrel, which thus made one revolution whilst the engine made three hundred and fifty-five.

A smaller barrel, keyed on to the first-motion shaft, was found very useful for hauling up the empty cradle, or for small vessels, and, as it ran six and a third times as fast as the large barrel, it saved much time. The importance of such a means of hauling up the empty cradle quickly had been alluded to in the Paper, but of course, with hydraulic gear such an apparatus would be an additional complication and expense, whereas on the system referred to, that supplementary barrel was only a small portion of the winch.

The large barrel was 5 feet in diameter, and 7 feet 3 inches long, and wound on itself a steel-wire rope 9 inches in circumference, and manufactured by Messrs. Bullivant, who guaranteed its ultimate strength to be not less than 180 tons, although they believed it would not break under a strain of less than 200 tons. They had hauled up vessels on this slip, some weighing 1,000 tons, which added to that of the cradle was equal to 1,080 tons, giving 45 tons theoretical pull on the hawser. Their experiments showed that the friction was about 50 per cent., which gave 67½ tons pull on the hawser, or a factor of about one in three. The wire rope after four years usage was as good as when first set to work.

The next slipway on their system was that at Ayr, designed by Mr. J. Strain, M. Inst. C.E., to haul up vessels weighing 1,200 tons, with a cradle weighing 150 tons, and worked by a 12-inch wire rope, also supplied by Messrs. Bullivant, and guaranteed to have a breaking strength of 360 tons.