Fig. 11 - Checking the operating pressure of
auxiliary spool valves.
A - Quick coupler
B - Implement oil line
C - Tee
Fig. 12 - A conversion screw allowing conversion
from double to single acting operation; B conver-
sion screw lock washer.
Fig. 13 - Longitudinal section through 4/6-way
spool valve.
Checking the pressure relief valve setting
The setting of the pressure relief valve must always be 190 bar,
and can be checked by fitting gauge p/n 5.9030.513.0 to either of
the valve work ports and operating the relative lever. If the gauge
reading is not correct, adjust the pressure relief valve (see pages
383 - 384 - 385).
NOTE: Remember that the purpose of the relief valve is to
maintain pressure in the hydraulic lift circuit within a given safety
limit, in this instance 190 bar.
Checking the operating pressure (see fig 11)
To verify the operating pressure of an implement connnected to
the work ports of the auxiliary spool valves, proceed as follows:
— Connect a Tee between quick coupler A and the implement
pressure line B.
— Connect pressure gauge p/n 5.9030.513.0 to the Tee.
— Start the engine, apply the parking brake in the interests of
safety, and operate the spool valve connected to the imple-
ment.
— The gauge will show the operating pressure currently register-
ing in the circuit.
The operating pressure depends on the weight of the hitched
implement, and should not normally exceed 150 bar.
Conversion of auxiliary spool valves from double
acting to single acting operation (see fig 12)
Where particular requirements dictate, a double acting spool valve
can be converted to operate in single acting mode.
To effect the conversion from double to single acting, hold the
fitting secure and loosen the screw A by between 4 and 5 turns.
NOTE: Once slack, the screw is best rotated by hand to avoid
applying excessive force and unseating the lock washer B; if this
were to happen, the washer would find its way into the hydraulic
circuit and disallow normal operation of the lift system.
The conversion from single to double acting operation is effected
by tightening the screw A fully.
Checking the surface of the valve spools
Check that the machined surface of the spool is free of scoring or
any other kind of wear.
pressure relief valve
88
8
systems
auxiliary systems
388
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