Bul. 300, U. S. Dept. of Agriculture. PLATE III. 
D-613 
FIG. 1.—RACK AND DOLLEY WHEELS. 
D-3197 
Fic. 2.—MECHANISM FOR OPERATING PINION AND SWINGING 
DEVICE FOR RACK-AND-PINION 1 YPE OF DRAG-LINE EXCAVATOR. 
