THE VALVE-GEAR QI ' 



If the valve be allowed to run dry, the valve-gear is sub- 

 jected to an immense amount of unnecessary work, which 

 soon wears it, so that the valve does not move as it should, 

 and the engine becomes wasteful in its use of steam. The 

 valve should be well lubricated at all times, the wearing 

 parts of the valve-gear should be oiled frequently and every 

 precaution taken to keep the valve-gear in first class con- 

 dition. The wear should be taken up as fast as it appears 

 so that the parts are not allowed to pound. 



The Woolf Valve-Gear. The Woolf valve-gear pos- 

 sesses advantages over the other devices used for reversing 

 traction engines, which entitle it to rank as the most popu- 

 lar and satisfactory means for this purpose known at the 

 present time. It is very simple, consisting of a single 

 eccentric, the "strap" of which is extended to form an arm; 

 to the end of this arm is pivoted a block, which slides in 

 a guide connected to the hand lever and pivoted in such a 

 way that the angle of the block's path depends upon the 

 position of the hand lever ; the eccentric rod transmits the 

 motion from the eccentric arm (to which it is connected), 

 to the valve stem through a rocker arm or guided "slide." 

 It will be seen that the angle of the "block guide" de- 

 termines the amount of travel of the valve. By placing the 

 reverse lever at or near the center of the quadrant, the 

 reverse gear acts as an efficient brake in controlling the en- 

 gine when descending hills, or at any time when it is desir- 

 able to suddenly check the speed of the engine. This reverse 



