8 JACK PINE AND HEMLOCK FOR MECHANICAL PULP. 



EQUIPMENT USED IN THE EXPERIMENTS. 

 ELECTRICAL EQUIPMENT. 



To study accurately the fundamental variables of grinding it was 

 necessary to install an elaborate electrical drive and apparatus for 

 control and manipulation. There has also been provided a system 

 of recording instruments for the determination of speed, pressure, 

 and load fluctuation. The electrical apparatus consists of a motor- 

 generator set and a direct-current variable-speed motor. The 

 variable-speed motor, direct connected to the pulp grinder, is rated 

 at 225 horsepower at 100 revolutions per minute and 500 horsepower 

 at 300 revolutions per minute, with a 50 per cent overload capacity 

 at all speeds. However, it is possible to obtain about 25 per cent 

 more capacity than the rating. Variation in speed is obtained by 

 variation of voltage applied to the motor armature, and by means 

 of a rheostat in the field circuit of the generator it is possible to 

 maintain this voltage at any point desired, thus giving a very con- 

 stant speed. 



The efficiency of the grinder motor has been determined for all 

 values of speed and load throughout the range of usage. Conse- 

 quently, the power applied to the grinder at any value of peripheral 

 speed or at any pressure on the cylinders can be calculated. 



Individual motor drives have also been installed for the various 

 other pieces of pulp-making machinery and their auxiliary apparatus. 

 The machines for wood preparation and the wet-machine vacuum 

 pump are the only ones which are not direct connected to indi- 

 vidual motors. In several cases variable-speed motors have been 

 installed to permit adjustment of speed to the most effective value. 



PULP MACHINERY AND AUXILIARY EQUIPMENT. 



The pulp-making machinery, machines for wood preparation, and 

 the auxiliary pieces of apparatus are all of standard commercial 

 types and were loaned by the following manufacturers or others 

 interested in the work of the laboratory: 



Grinder Friction Pulley and Machine Works. 



Wet machine Improved Paper Machinery Co. 



Flat screen Harmon Machine Co. 



Ruth centrifugal screen H. L. Orrman & Co. 



5 by 8 inch triplex pump Goulds Manufacturing Co. 



4 by 6 inch triplex pump Do. 



5-inch centrifugal pump Do . 



4-inch centrifugal pump Do. 



Storage tank Valley Iron W T orks. 



Barker Green Bay Foundry and Machine Works. 



