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MULTIBESTOS HANDBOOK FOR BRAKE SERVICE Vacuum Power Brakes (Continued J Pig. 1 show* th# three unit* of a standard B-K hooater system and the relation. hip each unit bear* to th# other. This system I* the one tt*ad oa tha majority of truck installation* and on heavy passenger car* up to 19}}. Similar installations without the valve control on tb dash are equally as common as the three unit system shown. The power unit should be lubricated twice a year through port* in end of cy.inder with two ounce* of Bendix vacuum cylinder oil. Dut cover* hould be removed and the curled hair in the air cleaner washed and thoroughly cleaned in high test gasoline. It is important that the rubber piaton rod guard be in good condition and properly fitted in its recesses at each end. The vacuum suspended, internal valve type of booster ayetem commonly found on passenger cars is shown in Big. 2. The arrangement shown is that used on 1913 Studebaker with Power Brakes. The important point to observe is the method of connecting the power unit to the brake linkage ao aa to provide "feel" at th* brake pedal. Tbi* gives a slight play or sloppinet*-to the system not found In conventional linkage. 48 MULTIBESTOS HANDBOOK FOR BRAKE SERVICE MECHANICAL LEVERAGE SYSTEMS AND EQUALIZERS ThERE *rt such 8 vast variety and combination of mechanical leverage hookups on car* that without going into detail for each car. only generalities will bo diacuaaed. To isture maximum braking efficiency all brake levers should be o adjusted that the greateet mechanical advantage i* obtained (see Fig. 1) which mean* that all lever* with brake pull applied wil! be on dead center, Fig. 1 al*o show* that a reserve travel to compenaate for wear of lining thoyld be m*ide in any setup. Figs. 2 and 3 how the wrong position of levers to give greatest efficiency. In the c*e of Pig. 2 the lever is pulled beyond the center, thus decreasing efficiency at the time when it Is needed most, that it, at the greatest pedal pressure, or when making an emergency stop. Pig. 3 ahows the leverage too far forward. A /ever act in tM* position would require unusually severe pressure even to start the brake mechanism moving. e C* *OlA Correct position of Vvrr* tu nur nunumim brok ing efficiency. To lain some rr*wyv* travel t compensate for Wf,r *>f lining, lever* aSould be #t In position ' A) with brakes fully applied. CORRECT . Fig. 1 &-:-:= = :: = = = = * 0`*tC'O OF Wrong position of lever* -- lever pulling beyond center. WRONG Fig. 2 WRONG Fig. 3 A twisted, bent or weak cross shaft wil! not deliver full pedsl power to thr brake which results in hard pedal and unequal brakes. Worn drvis pins should bs replaced as they cause lost motion. Cotter pins should be in good condition end ooot missfag. Th* following diagrams illustrate some of the most common types of leverage hookups. Oftentimes a combination of two or even three of the types is found oa s sing!* car. The same general principles, however, apply to combinations of type* ss wpuld apply if only a single type were used. 49