210 GEOLOGY OF OHIO 



casting of good strength and thickness to allow for frequent boring out. 

 The walls are worn by the escape of clay under pressure, the wear being 

 usually greatest about one-third of the way down the cylinder where the 

 clay first begins to feel the effect of the pressure. 



The cylinders can be bored out by hand without moving from the 

 piston by use of appropriate devices, but the usual plan is to send the 

 cylinder and piston to the shop for refitting. 



The area of the steam and clay cylinders is usually in the ratio of 

 four to one. The tendency in the newer shops however is towards the 

 use of a larger ratio. Clay cylinders of twenty inches are now frequently 

 equipped with steam cylinders of forty-four inches, and eighteen by 

 forty is another common combination. Smaller sizes are made down to 

 twenty- four by eleven. 



In response to the growing demand for large pipe, larger presses 

 have been constructed; one in use is forty-eight inch steam, by twenty- 

 four inch clay, by five feet stroke. This press will make thirty inch pipe 

 in one stroke without refilling the clay cylinder. 



Another press not yet in operation but in process of construction is 

 sixty-four inch steam cylinder by thirty-six inch clay cylinder by five 

 feet, eight inch, stroke. 



This will be the largest press ever made for this purpose; the utility 

 of these large presses will be in the ease with which they can get out. a 

 large run of large pipe. They will make twenty-four and thirty inch 

 pipe with the same ease and speed that a forty by twenty press will make 

 fifteen and eighteen inch pipe. The sewer pipe business is conducted on 

 very close margins and consequently any possible source of economy in 

 production is eagerly taken up, and the tendency now is towards using 

 presses capable of making large pipe with a speed and economy com- 

 mensurate with the production of the smaller sizes. 



The steam which is used in the work of the sewer pipe press is regu- 

 lated by a rotary steam valve, controlled by a lever from the level of the 

 working platform; the piston is moved up by the steam as well as down, 

 and is kept at the top of its stroke while the clay cylinder is being filled 

 by the expansive force of the steam used to lift it up; when the clay cyl- 

 inder is filled, the steam is liberated from under the piston which by its 

 weight compacts the clay beneath it and expels most of the air. The 

 steam pressure is now used above the piston and is cut off when the 

 stroke is nearly completed, leaving only a short portion of the stroke to 

 be accomplished by expansion. The use of steam in the sewer pipe 

 press is excessively wasteful and if its lost efficiency were not largely re- 

 covered by use in drying the pipe and heating the building, the loss 

 would be still more grievous, The loss of economy in the steam is 

 greatest when cutting rings or making small sizes of pipe by which the 

 steam cylinder is successively filled and emptied of steam a number of 

 times in each cylinder full of clay. 



