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Begin OCR Text:
A warning valve is located befween the master rest position the brake Iinings are always at a,
cylinder and the brake Iines for both the circuits certain distance from the brake disc regardIess of.
The valve is connected to the same warning lamp wear, so that the wheel brakes are self-adjusting.
which indicates when the parking brake is applied Should leakage occur _n one of the circuits fuII. ,
The Iamp wiIl light during brahe application if there braking effect is still obtained on both the front
is too large a pressure difference (about 1 O kp/cm2 wheels and one rear wheel if pedal pressure is in -
142 p s i ) between the two brake circuits creased Fig f 13 shows how this operates when= . . . . . . -
yWhen the preSSure In fhe master c _jnder r_ses aS Ieakage oCCUfS In the SeCOndafy ClrCuIt When.
a result of brake appIication the pistons are dis there is a pressure difference in the brake circuits, -
placed and press the lining pads against the rotat of about 1 O kp/cm2 (142 p s i ) the warning valve- _ _ _ _
ing friction surface of the brake disc see Fig 5 12 piston is pressed ouer to the side with less pres, . - . -
The pressure applied, and thus the brake effect. sure and the wari_ing lamp lighfs. The warning lamp
varies in proportion to the foot efforf applied to the will remain Iighted until the leakage in the circuit
pedal. When the pistons are displaced. the sealing concerned is repaired.
rings are tensioned laterally. They remain in this
state as long as the footbrake is applied. When the
brake pedal is reIeased, the pistons are relieved of
hydraulic pressure. Since there is no residual hyd- A.S.B, DEVICE (REAR BRAKE CALlPERS, EAffLY
raulic pressure in the system line. the tension in PROD_)
the sealing rings _s sufficient to moue the pistons When the brake jg re_eaged gee F_g 5 _4 th _gi ere, _ - _
baCk tO a certain e_tent see Fig 5 1 1 The return a cIearançe A betwee the brak ad d th d_- n e p an e isc_ _ _
mOVement fofms the clearance between the brake and a_go a ç_earance _ betwee the gh ndn wa er a
Ilnings and the bfake disC This means that in the the gpring With brake app_ çatio gee the F_ rei n igu_ _ _ _ _
SeGondary Gircult, Pr_may circuit. - _
_ preSSUre 8boUE _ preS8Ure abDVE _ _ _ _ _g4V4__
_ _pjcm_ i_ii p s 1 ) i9 _pjcm_ i_ii p.s 1.)
_ _ d _ _ p _ _ __ SeConday SeConday PrImayeGo_ ay G__Gu_ , _imay G__Gui , . _ . _ .
reduced pressure reduced pressure C'rfUl _ C'fdCUl _ C'fC''t_
presGure above re uced press rel_ssu c
29 kpJCm2 preGSUre
(412 p s i )
ra pFlg fl2 B _e ap Ilcallo_ FIg 5 l_ Br8ke applicatIon leakage in p_lmary cIrCUlt_ _ _ - _ _ f.9
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