FAI.SI.WOKK. 



473 



TABLE XIII. 

 BILL OF TIMBER IN TRAVELER, FIG. 24. 



TABLE XIV. 

 BILL OF BOLTS IN TRAVELER, FIG. 24. 



TABLE XV. 

 BILL OF IRONS IN TRAVELER, FIG. 24. 



run past the completed bridge or structure. Travelers may be made of timber or structural steel. 

 Outline plans for fouc standard timber travelers designed by the American Bridge Company are 

 given in Fig. 23, while the detail plans for traveler No. I are given in Fig. 24. The bill of lumber 

 for traveler No. I is given in Table XIII; the bill of bolts is given in Table XIV, and the bill of 

 irons in Table XV. Traveler No. I may be used for single track railway spans up to 250 ft.; 

 traveler No. 3 for single track spans up to 175 ft.; traveler No. 2 for double track spans up to 

 175 ft.; and traveler No. 4 for double track spans up to 250 ft. 



Derrick Cars. Derrick cars with a capacity up to 75 tons are in common use. The derrick 

 cars are usually self-contained and can move under their own power. The boom can be folded 

 back over the car out of the way when not in use. A sketch of a derrick car is shown in Fig. 20. 



FALSEWORK. Falsework for the erection of bridges is built up of bents made of three or 

 more posts or piles, braced transversely in the same manner as for permanent trestles. Framed 

 bents are carried on mudsills, or on piles where the foundation is inadequate or where the false- 

 work is in flowing water. Where piles can not be driven in running water or where there is danger 



