. Electric railway journal . —DESIGN FOR CITY SERVICE PERMITTING FREE TRANS-VERSE MOVEMENT OF BOLSTER vides only for bolster equalization, transverse with thetrack. If we accept noise, reduced flexibility, light loads,low speeds, and abnormal box play, under tolerable trackconditions, this non-equalized type of truck, either mo-tor or trailer, may be said to perform the functions ofcity service. As to the costs, we must offset the lowerfirst cost by the greater distress to the track, truck andbody, due to the rigid hammer blows of the truck on thetrack, this being the effect of non-equalized s
. Electric railway journal . —DESIGN FOR CITY SERVICE PERMITTING FREE TRANS-VERSE MOVEMENT OF BOLSTER vides only for bolster equalization, transverse with thetrack. If we accept noise, reduced flexibility, light loads,low speeds, and abnormal box play, under tolerable trackconditions, this non-equalized type of truck, either mo-tor or trailer, may be said to perform the functions ofcity service. As to the costs, we must offset the lowerfirst cost by the greater distress to the track, truck andbody, due to the rigid hammer blows of the truck on thetrack, this being the effect of non-equalized side-frameconstruction. In Fig. 1 is illustrated an arch-bar truckwithout swing links. An equalizer may be of rigid or flexible case it is rigid, additional springs must be intro-duced ; in case it is flexible it possesses the double func-tion of equalization and resilience. In the first instance,we have the equalization of high-speed interurbantrucks; in the second, the equalization of low-speed FIG. 4—TYPICAL EQUALIZER-BAR CONSTRUCTION FOR HIGH-SPEEDINTERURBAN SERVICE April 21, 1917] If it is essential to produce easier riding with its ac-companying increase in weight, the so-called spring-equalized truck comes next in order. This truck is builtwith semi-elliptic plate springs parallel to the sideframes, having spring and link suspension as shown inFig. 2. This gives greater freedom of transverse move-ment for the bolster than the truck illustrated in Fig. should be noted that the longitudinal plate springacts as a side-frame equalizer because its ends areresiliently connected to the side frame by links andsprings. Some truck designers are endeavoring to eliminate theneed for equalizer bars, which are used in side-frameequalization, by introducing coil springs over thejournal boxes. There are two objections to this design;first, it is not properly equalized; and second, it re-quires undue space over the journal box for its applica-tion. Fi
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