156 GEOLOGY OF OHIO. 



pistons are connected together by a pair of connecting frames of heavy 

 design, and the rear side of each piston carries a chilled roller. On the 

 main shaft a large cam is keyed fast and in its revolution it forces the 

 piston frame backward and forward, the motion being received from the 

 cam and conveyed to the frame by the rollers alluded to before. Proper 

 dies bolt into the ends of the press boxes. The press boxes are filled 

 with clay from above by a vertical pug mill which surmounts the entire 

 frame of the plunger machine. This pug mill receives its clay on top 

 and works it down and into the press boxes wherever the vent is open. 



This machine has been used largely in the past in making common 

 brick ; it has been used to some extent in making paving brick. It is a 

 good machine for working a plastic clay and making building brick, 

 For making paving brick from gritty non-plastic clays, and made at a 

 very stiff temper, the machine has proved itself too complicated and too 

 expensive in .repairs, and the simpler method of getting the pressure by 

 steam direct is much preferable. 



The use of Auger Brick Machinery is growing in importance in the 

 manufacture of paving material and all other kinds of brick as well. 



There are several reasons for this increase : 1st, it produces a continu- 

 ous stream of clay which allows of the utmost economy in handling the 

 output and getting the utmost duty from the employees in charge. 2nd, 

 it is always driven by power from shafting and hence the use of steam 

 in the engine can be made economical, while in plunger machinery actu- 

 ated by steam, the use of the steam power is divided and the require- 

 ments do not admit of very high efficiency being attained. 3rd, the ma- 

 chines are capable of doing more work in a specified time than any other 

 of equal cost. 



The main underlying principle of the auger machine is the use of a 

 continuously revolving screw to carry the clay forward and force it out of 

 the die. The mechanism as usually arranged, consists of a cylindrical or 

 conical, horizontal iron case with an opening at the rear end on top for 

 the admission of cla}-, and a movable front which carries the die and 

 former. 



Inside this c^ cjdinder is fixed a horizontal shaft carrying the fittings 

 which give it its character as a screw. Sometimes these fittings are noth- 

 ing less than a cast iron screw cut in sections which slip over the shaft 

 one alter the other. Sometimes the fittings are merely blades forming a 

 slightly interrupted screw and sometimes they are a set of steel forged 

 knives set at variable lead at different points on the shaft. However 

 the effect is obtained, in all cases the essential elements of the screw are 

 there, and its action on the clay is just the reverse of the action which 

 takes place when a carpenter bores a hole with an auger. The chips 

 from an auger are carried back from the point of production the clay is 

 carried forward toward the outlet. 



