760 HYDKAULICS AND ITS APPLICATIONS 



in the illustration, which have a range of 15 feet, and as the shoots 

 themselves are pivoted and may be radiated in either direction 5 feet 

 from the centre of the tip, this gives an extreme range of 25 feet 

 without changing any water connections. 



The capacity of each tip is about 500 tons per hour. Fig. 374 

 shows one of a series of more recent tips erected by the same makers 1 at 

 Newport, Mon. These are designed for wagons of 30 tons gross weight, 

 the total lift being 50 feet. Hoisting is performed by wire ropes, two 

 hoisting cylinders being provided. The walking pipes for supplying the 

 cylinders are shown on the left hand of the sketch. 



The main hoisting cylinder has a ram of 18 inches diameter, with a 

 25 -foot stroke. The auxiliary ram is 9 inches in diameter, and has also 

 a 25-foot stroke, while the tipping ram is 9 inches in diameter, with a 

 stroke of 18 feet. Two cranes, one of 3 tons, and one of 5 tons capacity, 

 are provided for handling anti-coal-breaking gear, having each a lift of 

 500 feet. They are provided with lOJ-inch and 12|-inch rams respec- 

 tively, both of 25-foot stroke. The slewing-gear of each crane is driven 

 by a ram 6J-inch in diameter and 2-foot stroke. The hoist may be 

 worked anywhere within a range of 200 feet, the traverser gear for 

 working the trucks extending over this distance. The cylinders for 

 operating the traverser gear are fixed in pits beneath the track. 2 



ART. 201. HYDRAULIC CRANE VALVES. 



The supply and discharge of water to and from the cylinder of a crane 

 may be adjusted by means of a simple or compound slide or piston valve, 

 as shown in Fig. 375, or by poppet valves directly manipulated by 

 hand. Where pressures are very high and the volume of water large 

 the effort required to actuate such valves becomes excessive and some 

 other arrangement becomes desirable. Such an arrangement 3 is shown 

 in Fig. 376. Here A marks the pressure water inlet, D the connection 

 to hydraulic cylinder, and E the exhaust. 



The valves are operated by handle F, connected to rock-shaft G. 

 Throwing F in one direction opens the inlet valve at A ; throwing it in 

 the other allows the water to escape from D through outlet at E. 



1 Messrs. Fielding & Platt, Ltd., Gloucester, by whose courtesy the foregoing sketches are 

 available. 



2 These hoists were illustrated and described in a paper read before the Institution of 

 Mechanical Engineers at their summer meeting held at Cardiff in 1906, and for further 

 details of working and for drawings, &c., reference may be made to the proceedings of this 

 Institution. 



8 Messrs. Dewhursts' Engineering Co., Ltd., Sheffield, 



