TRANSACTIONS OF SECTION G. 753 



gravitation, and haul the rope after them. The cost of the conveyance of coal 

 underground is a very considerable item in South Wales, probably amounting to 

 600,000/. to 700,000/. per annum, and consequently has caused great attention to 

 be given to the subject. It has been found that the endless-rope system, where it 

 can be conveniently applied, is the cheapest. This system, however, necessitates 

 the laying and maintaining of either a double Hue of rails, or frequent passing 

 points or loops, and as the nature of the strata does not always admit of the roads 

 being made and maintained wide enough for this to be done, the main-and-tail 

 system, which requires a single line of rails only, has in that event to be adopted. 

 The distance to which some of these haulage systems extend is very great (in some 

 cases exceeding three miles); and, having regard to the large quantities which have 

 to be conveyed by mechanical haulage in single collieries, in many instances 1,000 

 to 1,500 tons of coal in ten hours, very good and powerful machinery is required, 

 and it is not unusual to have engines of 600 indicated horse-power placed under- 

 ground for this purpose. In other cases where the coal is brought from several 

 districts to the bottom of the shafts, smaller engines are used. For endless-rope 

 haulage, the speed at which the trams or tubs travel is from two to six miles per 

 hour, as against from ten to twenty miles per hour by the main-and-tail system ; 

 thus there is much greater wear and tear in the latter than in the former. The 

 type of engine usually adopted for this work varies considerably according to cir- 

 cumstances, and the ideas of the engineer by whom the work is planned. They 

 are, however, invariably horizontal, and fitted with a second motion shaft, on which 

 the hauling drums are arranged. There is still a large number of horses employed 

 underground, at very great cost, principally to collect the trams from the colliers 

 and convey them to the station, from which poiut the engine hauls them, and it is 

 to this class of haulage that I would particularly direct the attention of mechanical 

 engineers. What is required is an absolutely safe and simple means of light haul- 

 age, made as portable as possible, so that it can be readily moved from one position 

 to another, as circumstances may require, and arranged so as to replace the horses. 



Thus the coal is brought to the bottom of the shaft, and thence up the shaft by 

 means of the winding engine. This class of engine has of late years been very 

 materially improved ; instead of the low-pressure vertical-beam condensing engine, 

 which was so commonly in use many years ago, and some of which are still iu 

 existence, we have now the high-pressure compound condensing engine, working 

 with a boiler pressure varying from 80 to 150 lbs. per square inch. Some of our 

 winding engines are very powerful and run at very high velocities. This will be 

 the more readily understood from the fact that, at some pits, the carriages on which 

 the coal is raised in the shaft attain a speed equal to from forty to forty-five miles 

 per hour, and the dead load lifted is as great as twenty tons each lift. A few of the 

 leading sizes of a large pair of winding engines now in use at one of the collieries 

 in this district may be mentioned. The engines are vertical, with inverted 

 cylinders of 54 inches in diameter, and admit of a 7-feet stroke ; the cylinders are 

 Steam-jacketed, and the valves double-beat, placed in pairs in nozzle-boxes, fixed 

 to the port-branches at the top and bottom of each cylinder. The valves are 

 worked by the ordinary rocking lifters, to which is added, for the steam valves, 

 the simple triple expansion gear first introduced by Mr. Barclay, of Kilmarnock. 

 The cylinders are supported by double A frames of cast iron, fixed to heavy cast- 

 iron bedplates, to which also is attached the main shaft plummer-blocks. The 

 winding-drum is of the conical type, graduating from 16 feet to 32 feet, and is 

 made of steel plates and ribs and cast-iron centres. The total weight of the 

 drum, drum-shaft, and the engine-cranks, and one rope, exceeds 100 tons. The 

 engine is fitted with a powerful steam brake, and also a self-acting reversing gear, 

 which reversing gear also applies the steam brake, in case of any neglect on the 

 part of the engine-man. There is also being built, for a colliery in this coalfield, 

 a pair of large compound condensing winding engines, by Messrs. Fowler, of Leeds. ' 

 which will embrace all the latest improvements. They will consist of a pair i f 

 horizontal compound winding engines fitted with condensers ; the high-pressure 

 cylinder, being 32 inches in diameter by 5-feet stroke, will actuate one crank, 

 whilst the low-pressure cylinder, 48 inches in diameter by 5-ftet stroke, will actuate 



1891. 3 c 



