COLLINGE'S PATENT AXLE. 379 



the two bearings are at the two ends of the axle, 

 which has an internal shoulder, against which the 

 inner end of the wheel-box takes its bearings. Be- 

 hind this shoulder is a deep groove for a washer to 

 preserve the oil and prevent noise in its use ; also a 

 hollow box on the outer end of the axle-tree arm. The 

 middle portion of the axle-arm is greatly reduced, so 

 that between it and the inner portion of the box there 

 should exist a space containing oil for lubrication. The 

 extreme end of the arm is double screwed, to receive 

 two nuts for securing the wheel ; the one screw turns 

 the way of the wheel, the other the reverse, and is 

 meant as an additional security.* 



The box is made of a very hard metal, nicely 

 polished, and fitted to the arms, having a circular 

 recess all round, at the end nearest the carriage, for 

 containing a supply of oil. The box is longer than 

 the part which bears on the axle, and the projecting 

 part beyond the bearing at each end is bored out 

 larger than the axle-arms. t In fact, the arm of the axle, 

 which revolves in the box, has several shoulders and 

 indentations. There are three spaces for oil : one cut 

 in the box, and two in the arm. At the outer end of 

 the arm are two nuts, and over all is screwed the cap, 

 which is generally of brass. 



Speaking of a wheel in a mechanical sense, it is, in 



* One thing should always be remembered — that proper care and 

 attention should be given to the box of the wheel, and to all those 

 parts bearing on the axle-arm. Every foreign substance that increases 

 friction should be carefully removed with a sponge, after which all the 

 working parts should be thoroughly lubricated with the best oil, by 

 which means draught will be lessened to an extraordinary degree. 



t It is considered by coach-builders of the present day inadvisable 

 to groove the box as a receptacle for oil, it is considered best to 

 make a recess on the top of the axle-arm as a well to contain the 

 lubricating oil, as the axle-arm does not rotate but is stationary ; 

 whereas the box, being fixed in the nave, revolves with the wheel. 



