THE AXLE. 385 



THE AXLE. 



Since the general introduction of the iron axle, the 

 wooden axle has gone out of use, except for the heaviest 

 description of wagons for the farm, or other heavy work. 



Axles may be either straight, arched, or cranked ; the 

 arched form, which is essential for all very light axles, 

 being stronger than straight ones, though a very slight 

 arch answers the purpose. Cranked axles are adopted for 

 the purpose of allowing the body to hang low. Particu- 

 lar care should be given to setting the axles exactly at 

 a right angle to the line of travel. Any deviation from 

 this rule causes undue friction to the arm of the axle and 

 the hub, and places the wheel in a position to receive more 

 injury from concussions, and to be more easily wrenched 

 out of its proper shape than when properly directed.* 



The Patent Axle, or as it is sometimes called the Mail 

 Axle is represented in Figure 70, 

 a is the arm of the axle, around which 

 the hub revolves ; 6 is a shoulder 

 which serves to keep the hub in 

 place ; c is a circular iron plate, 

 having through its centre a hole to 

 fit the arm of the axle, behind the 

 shoulder, where it revolves ; it is B' " ^ 



secured to the inside end of the Imb 

 by the long bolts, e e, which run 

 through the entire hub and the plate 

 d. There is a washer, which should 

 be of hard sole-leather, nicely a']- Fw. to. -The Patent Axie. 



*Thes'i remarks do not refer lo the slight "gather" which is IVequently 

 given to wheels, to cause them to crowd slightly toward the carriage, 

 rather than to run against the nuts at the end of the axle. 



17 



