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P l lO. P 1 8OO Control plunger is also deCreased and tfe p(ungg, i5 moved Jurther to the ,igft. Tfg va_ve a,m i, tfe, furned so that the vacuum valve open,. Tfe Cavitig, on both sides ot the uacuum plu,ger tfg,eby fave a free passage between e8ch offer. ffe p,e,,u,e equalizes and fhe plunger i, moved to tfe ,ight by spring pressure. The pressure oJ ffe plunge, ,od on the hydraulic plunger d8crease, and tfj, p_unge, i5 pfessed back to the right so tfat ffe outgoing brake pressure decreases. IJ the pedg_ i, ,e_ea,ed Completely. all fhe parts ot the se,vo b,ake Cy_i,de, _ _i_o_p_. _ _ _,,. will return to the rest position and the b,akes wj__ Prg__uro '''''_ ,_cui._ di,engage. _ brake _ brake _ b___g fluid. flu_d, low iiuid, __g_ _t re_t pre__uro Dre__urg _ Fig_ 9_ Rest position. 1_ From air tilter 3. FroM _a_*e, Cy_inde, Z_ f,Om vacuum fank 4. _o w_ee_ b,ake unif _ The outgoing hydraulic pressure and tfg p,e,,urg on the lett_hand side ot the control plunger in- C,ea5e5 a5 more air enter,. Il the p,e,,u,e on tfe brake pedal. and therefore the hydrauliC p,e,,ure on the large. righf-hand side ot tfe Control p_unge, Femains unalt8red, this is finally ove,Come and tfe Plunger is pressed to th.e righl. see Fig. 1 1 . wfen this happens the valve arm is inJlue,Ced ,o ffgt tfe air valve also closes. Tfe pressure to tfe ,igft oJ the vacuum plunger remains Consfgnf and i, unab(e Fi9_ 1 1_ COn,Iant braking_ tO Overcome the hydraulic ,e,i,tanCe in tfe p,e,,u,e cylinder_The moving parts oJ ffe se,vo b,ake Cy_in_ der tfereJore remain in this position and Con,tan+ __e__ va_ve brakėng is obfained as long a, ffe ,ame p,e,,u,e i, f. _ ma__nta_ined on *fe peda_. 7 e CheCk Valve
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