Dacia SuperNova (engine E7J). Service manual — part 76
MECHANICAL ELEMENTS CONTROL
37
BRAKE PUMP
BRAKE PUMP WITH PRESSURE DROP INDICATOR ( ICP ) INCLUDED
COMPONENTS
1. Assembled primary piston with gaskets
2. Assembled secondary piston with gaskets
3. Primary piston pin.
4. Secondary piston pin.
5. Primary piston return spring
6. Secondary piston return spring.
7. Purging screw
8. ICP transducer
A –A ICP assembly section
OPERATION
A. BRAKING
THE FRONT BRAKE CIRCUIT
The primary piston
is controlled by the pushing rod. A part of the brake fluid under
pressure
will
operate together with the spring on the secondary piston, and
the other part of the brake
fluid
shall
penetrate through the ducts to the upper floor
towards
both exits leading to the front brake
calipers.
THE REAR BRAKE CIRCUIT
The secondary piston is continuing its movement, conducting the brake fluid under pressure,
through
the ducts, to the upper floor, towards the exit
to
the pressure-reducing valve. During
all
this time,
the linings-pistons
assembly will be balanced
due to the two side springs.
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MECHANICAL ELEMENTS CONTROL
37
B. DE-BRAKING
After effort ending, the two pistons resume their initial position under the effect of the retainer
springs, while the fluid is coming back and the pressure is decreasing in both circuits.
PRIMARY CIRCUIT – PRESSURE LOOSING
Lack of pressure in the primary circuit leads to the following situation:
The primary piston is advancing up to the pin, so is controlling mechanically the secondary
piston. The secondary piston reaches a fluid pressure that shall operate on the piston – linings
assembly moving it to the right, opening also the second exit of the rear circuit ( the by-pass
circuit) increasing the pressure for this circuit.
In this moment, by means of the transducer, the warning light on the instrument panel is on.
SECONDARY CIRCUIT – PRESSURE LOOSING
Both pump pistons go on. The caliper cylinders of the front brake shall normally operate.
The secondary piston reaches its respective pin, but the pressure will decrease (due to the
failure).
BRAKE PUMP
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MECHANICAL ELEMENTS CONTROL
37
BRAKE PUMP
Close the connection pipe between the brake fluid reservoir and clutch transmitter cylinder
by means of the MOT 453 device.
Disconnect the battery.
Drain the brake fluid reservoir.
Disconnect the connection pipe between the brake fluid reservoir and clutch transmitter
cylinder.
Dismount the brake fluid reservoir off the brake pump (avoiding fluid leakage).
Dismount :
- the rigid pipe screws from the brake pump and mark their position;
- the two attachment nuts of the brake pump on the servobrake .
DISMOUNTING
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TIGHTENING MOMENTS (daNm)
Rigid pipe connection
1,5
Nut attachment P.C. with servobrake
1,3
I.C.P. (pressure drop indicator)
2
MECHANICAL ELEMENTS CONTROL
37
BRAKE PUMP
REMOUNTING
Perform the dismounting operations in reverse order.
Check the length of the pushing rod , value X = 9 mm and correct if necessary.
Before remounting, check the servobrake pushing rod stroke ( min.30 mm ).
After assembling the brake with the fluid reservoir and filling with brake fluid, no leakage must
occur in the surface of separation between the two elements.
IMPORTANT
The I.C.P. transducer is mounted after the braking system purging.
ICP sub-assembly is not reparable ( ICP – pressure-decreasing indicator)
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