It may happen that the distance between the pit and the manufactory is such that it will be advantageous to replace horse by steam traction.
This occurs, for example, when a manufactory, in order to make use of an economical means of transport such as a river or canal, is installed on its banks, while the clay-pit is at some distance and a large daily output is required.
In this case a railway is laid down the gauge of which will depend upon the importance of the factory and its distance from the pit. Usually the 60 centimetre gauge will be sufficient, and wooden waggons will be employed of the type used for large earthworks, containing about a cubic metre and emptying by side-tip.
The framework is of oak and the body of poplar. A waggon of this kind costs 190 francs.
If the amount of clay to be carried daily is very great, waggons measuring two cubic metres and of the type represented in Fig. 14 can be used. The sides arc wood, the base sheet iron resting on T-shaped iron bars. The price of a waggon of this type is 600 francs.
Fig. 14. Waggon of the Couvreux System Tipped.
The side door is automatic and shuts itself when the waggon is raised by pulling down the other side.
The installation of locomotive traction is always expensive on account of the rails, which must weigh at least 9.5 kils. per metre.
To give some idea of the expense, we add an approximate estimate of the plant necessary for such a system.
A small locomotive tike that represented in Fig. I 5 weighs 3000 kilos (three tons nearly), and can haul a weight of 40 to 50 tons on the level at a speed of 10 to 12 kilometres an hour.
Fig. 15. Three-ton Locomotive for .60 metre gauge.
20 waggons (Fig. 14) of 2 cubic metres at 600 fr. each .
20 waggons (Fig.14) of 2 cubic meters at 600 fr. each.
Fixed outlay varying from
16.450 fr. to 20.850 fr.
There must be added for each kilometre :
For the permanent way at 7.15 fr. a metre
Sundries - 5 per cent., about .
7. 500 fr.
Which makes for 1 kit. of line, with rolling-stock, from
23.950 ft. to 28.350 ft.
,, for 2 kil. of line, with rolling-stock, from
31.450 fr to 35.850 fr.
„ for 3 kil. of line, with rolling-stock, from
38.950 fr to 43.350 fr.
„ for 4 kil. of line, with rolling-stock, from
46.450 fr. to 50.850fr.
These figures are sufficient to show under what circumstances a system of traction of such a kind becomes economical. In fact the annual expense for each distance will be -
10 per cent.
Oil and maintenance .
Fixing, according to the distance, the maximum cost of amortisation for each cubic metre carried at 0.075 fr. 0.15 fr., and 0.225 fr. Respectively, it will be seen that the minimum annual bulk carried should be respectively -
55.400 cm. 35.200 cm. 29.100 cm. 25.600 cm.