SOME COMMON MACHINES 



525 



is formed. The common classes are ROTARY-HOOK, OSCIL- 

 LATING-HOOK or osciLLATiNG-SHUTTLE machines, and VIBRAT- 

 ING-SHUTTLE machines. 



BOBBIN CASE 

 ROTATING HOOI\ 



1. Hook entering the loop of the needle 

 thread. 



2. Loop of needle thread enclos- 

 ing bobbin case. 

 FIG. 326. How a rotary hook makes the knot. 



While the majority of all lock-stitch machines in use today 

 are of the vibrating-shuttle type (Fig. 325), certain rotary- 

 hook machines have been among the most successful from the 



