Questa è la mia smontata e rimessa a nuovo 3 anni fa:

A questo link trovi un po' di foto ed una breve descrizione di come ho risolto io (su gentile suggerimento di Roby65)
http://www.africaland.it/forum/viewtopic.php?f=33&t=13799&hilit=valvolaSe la tua valvola è come la mia dovrebbe essere la PDWA/PCR in figura la "A"
Valvola combinata PDWA-PCR 1.jpg
Land Rover 110 models have a Pressure Differential
Warning Actuator Valve (P.D.W.A. Valve) or in some
cases a combined P.D.W.A. Valve and a Pressure
Conscious Reducing Valve (P.C.R. Valve) situated
between the master cylinder and the front and rear
brakes.
The valves are bolted to the bulkhead within the engine
compartment. The type of valve fitted is dependent
upon the nature of the vehicle and the braking
classification regulations prevailing in the territory
where the ehicle is to operate. Both types of valve
incorporate an electrical switch wired to a warning bulb
on the vehicle control panel. The bulb will illuminate
momentarily when the starter motor is actuated
indicating that the brake warning circuit is functioning
correctly. A fault in either the primary or secondary
circuits is evident if the warning bulb illuminates upon
application of the foot brake while the engine is
running. Should a pressure failure occur in the front
brake circuit (secondary) the piston in the P.D.W.A.
valve will move in the diretion of the failed circuit
causing the switch to operate and the warning bulb to
illuminate. At the same time full fluid prcssure in the
primary circuit to the rear brakes will continue. The
P.D.W.A. will function in a similar manner should a
failure occur in the primary, rear brake circuit. A
Girling type 80 vacuum servo is fitted when a
combination valve is used.
The P.C.R. valve allows fluid to the rear brakes until a
predetermined pressure is reached when the valve
closes. the valve, from this point on, will only permit a
proportion of any increase in fluid pressure to reach the
rear brakes to prevent premature locking of the rear
wheels. Should a failure occur in the front brake
secondary circuit the design of the valve will ensure that
the fluid to the rear brakes will by-pass the valve and
allow full circuit pressure to the rear wheel cylinder.
To satisfy the demand of other regulations certain
vehicles are equipped with a deceleration actuated
anti-lock valve fitted in the rear brake (primary) line
instead of a P.C.R. valve. Then this valve is used a
Girling type 80 vacuum servo is fitted. The valve is
situated on the inner face of the chassis right-hand side
member at an angle of 20" to the horizontal so that the
angle of inclination is towards the front of the vehicle.
Under normal braking conditions the valve remains
passive. When fierce or emergency braking is necessary
the valve operates at a pre-determined deceleration
figure and reduces the rate of increase in the hydraulic
pressure to the wheel cylinders.
La valvola combinata verifica
1) che la pompa dei freni funzioni correttamente monitorando la pressione tra il circuito anteriore e quello posteriore in ingresso alla valvola (deve essere sempre uguale) attraverso il "sensore" che altro non è che un semplice interrruttore a pulsante comandato dal pistoncino estratto nella mia foto che fa accendere o meno la spia anomalia dei freni sul cruscotto
2) regola la frenata al posteriore attraverso un secondo pistoncino (posto più in basso del primo) che limita, per mezzo di una molla, il passaggio dell'olio al condotto posteriore evitando il bloccaggio delle ruote posteriori
Non hai i permessi necessari per visualizzare i file allegati in questo messaggio.