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54
HYDRO-PNEUMATIC SYSTEM - BRAKES
CHECKS
Device
Functional check of vacuum brake system
With the engine stopped, press the brake pedal a few times in order to annul the vacuum in the servo brake. Press the pedal once
again and keep it pressed, in the brake position, by putting a certain pressure on it. Start the engine and check the pedal stroke:
- if the stroke of the pedal increases, this implies that the servo brake and pipes are satisfactory;
- if the pedal remains still, this implies that the outside has penetrated into the vacuum plant that is not perfectly sealed, or the
servo brake is faulty.
Base - March 2006
Designation
Pressure Reducer
Vacuum servo brake
Brake liquid compensation tank
Load proportioning valve
Disk brake caliper
Pipes and fittings
Checks
Connect a vacuum meter to the intake line.
At full operation the pressure reduction must reach the value
of 0.80 ÷ 0.85 bar. If this value is not obtained, check if there
are any leaks in the pressure piping and servo brake
components.
Check that the distance between the top of the rotor and
cover (with unit fitted) is comprised in the range 0.07 ÷
0.14mm.
Check the functionality and that there are no leaks. With the
vacuum meter fitted on the piping between the pressure
reducer and servo brake with engine at full speed, check that
the pressure reduction values are in the range 0.80 ÷ 0.85 bar
with the pedal both released and pressed fully down for a
period of 1 minute of rotation of the engine.
Check the level of the brake liquid and eventually top up with
Tutela DOT SPECIAL to the specified level. Change the brake
liquid once per year.
Check that the values measured with special manometers, via
the test points, correspond to those indicated on the
self-adhesive plate applied to the inside of the vehicle.
Check the condition of the brake linings; check for scratches
on the discs and the efficiency of the pistons.
Ensure that metal pipes are in perfect condition, with no dents
or cracks. Also make sure that they are not near sharp edges
of the body work or chassis that could damage them.
Check that the rubber and cloth flexible hoses are not in
contact with oil or mineral grease, or rubber solvents. Press
hard on the brake pedal and check that the pipes are not
blown, and check that there are no leaks.
Check that all brackets fastening the pipes are securely fixed
- loose fastenings cause vibrations that could give rise to
breakage.
Check that there are no leaks from fittings, otherwise tighten
them fully, taking care when tightening not to cause irregular
pipe torsion.
In all the above cases the parts are to be replaced if there is a
minimum of doubt as to their efficiency.
Apart from their condition, it is recommended to replace hoses
after considerable mileage, or after a period of long vehicle use.
This will avoid sudden breakage due to age and fatigue.
D
E
4
AILY
URO
Print 603.93.651
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