SCIENCE OF THRESHING. 



TRACTION ENGINES. 



133 



The accompanying figure shows the most common 

 type of combined engine and boiler. The parts are 

 indicated by the reference letters. A, boiler; B, drive 

 wheels or traction wheels ; C y front truck wheels ; D, 

 bull gear; E, bull pinion; F, main pinion; G, 

 steering chain drum; H, steering drum bracket; J, 

 steering chain; L, front axle or king bolt bracket; 

 M, smoke stack; TV, extension front or smoke box; 



O, damper; P f damper regulator; Q, smoke box 

 door; R, high pressure cylinder; S, low pressure 

 cylinder; T, steam supply pipe; u, governor; a, 

 cylinder lubricator; b, governor belt; c y crank disc; 

 d f connecting rod; e, girder frame; f t crosshead; g, 

 piston rod; h, stuffing box; i t crank pin; W t fly- 

 wheel; ;, friction shoe; /, whistle; m, safety valve; 

 n, reverse lever ; p } throttle valve lever ; q t quadrant ; 

 r, steering wheel; ss, injectors; tt, check valves; w, 

 water tank; x, draw bar; y t draw bar spring. 



