CH. Ill 



MAIL AXLE 



31 



arms were tapered, and projected beyond the face of 

 the hub of the wheel, and through a hole near the 

 end a linchpin of iron or hard wood passed, to keep 

 the wheel on. Until the end of the last century, 

 the linchpin was universally used, but it was then 

 superseded by a nut screwed on the end of the 

 axle. On private carriages the linchpin was used 

 to a much later date than on coaches ; until 1830 

 or 1840. (Beaufort, p. 307.) 



A simple axle-arm is used in light carriages and 

 in business wagons ; it is tapered, and the nut, which 

 screws against a shoulder so that it cannot be set 

 up too tight, is cut with a right hand thread on the 

 off side axle and a left hand thread on the near 

 side axle, so that the turning of the wheel tends to 

 keep the nut on and not to screw it off. 



All coaches have either mail axles or Collinore 

 axles. The mail axle (Fig. 13), so called because it 

 was originally 



used on the 

 mail - coaches, 

 is not tapered, 

 but the arm 

 is cylindrical. 

 It is not lono- 



Fig. 



!3- 



enough to extend through the hub of the wheel, 

 and it has at the back end a wide collar against 

 which the back of the hub bears. The box in the 

 hub is turned to fit the cylindrical axle-arm, and 

 the two are ground together, or ground by gauges, 



