. Railroad construction. Theory and practice . aring of the forward truck. On eachside the pressure is so distributed among the drivers that evenii a driver rises or falls with reference to the others, the loadcarried by each driver is unaltered, and that side of the engine §324. ROLLING-STOCK. 355 rises or falls by one ?2th of the rise or fall of the single driver,where n represents the number of wheels. The principle in-volved is shown in an exaggerated form in Fig. 195. In thediagram,MX represents the normal position of the frame A\henthe wheels are on line. The frame is supported by the ha
. Railroad construction. Theory and practice . aring of the forward truck. On eachside the pressure is so distributed among the drivers that evenii a driver rises or falls with reference to the others, the loadcarried by each driver is unaltered, and that side of the engine §324. ROLLING-STOCK. 355 rises or falls by one ?2th of the rise or fall of the single driver,where n represents the number of wheels. The principle in-volved is shown in an exaggerated form in Fig. 195. In thediagram,MX represents the normal position of the frame A\henthe wheels are on line. The frame is supported by the hanger^at a, c, /, and h. ah, de, and gli are horizontal levers vibratingabout the points H, K, and L, which are supported by theaxles. While it is possible with such a system of levers to makeMN assume a position not parallel with its natural position,yet, by an extension of the principle that a beam balance loadedwith equal weights will always be horizontal, the effect of rais-ing or lowering a wheel will be to move il/iV parallel to 771--^::. Fig. 195.—Action of Equalizing-levers. It only remains to determine hoiu much is the motion of MNrelative to the rise or drop of the wheel. The dotted lines represent the positions of the wheels andlevers when one wheel drops into a depression. The wheelcenter drops from p to q, a distance m, L drops to L, adistance m (see Fig. 195, h); M drops to M, an unknown dis-tance x; therefore aa^=x; hh=x, cc =^x\ dd! =^Zx = ee\ f]=x\.\gg = 5x; hh=x, LU = h{gq+ h]i)=h{^x)=m\ .\ x = lm.\, MN drops, parallel to itself, l/n as much as the wheeldrops, where n is the number of wheels. The resultant effectcaused bv the simultaneous motion of two wheels with refer- 356 RAILROAD CONSTRUCTION. § 324, ence to the third is evidently the algebraic sum of the effectsof each wheel taken separately. The practical benefits of this device are therefore as follows: (a) When any driver reaches a rough place in the tracks ahigh place or a low place, t
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