Specifications
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(P305):pHseriesSPECS.fm
13
Operation Manual - SP 305
Functional Description of the
Main Control Block
When the spool of the NG06 solenoid valve is in the
neutral position (no electrical signal to the solenoids of
the NG06), the S-port of the load sensing pump is
vented to tank so that the pump is in “stand-by” mode.
When the NG06 solenoid valve is switched to an
activated position (forward or reverse), the S-port of
the load sensing pump is closed, the pump will create a
pressure, and at 3.5 bar the S1 spool starts to open the
internal connections to the S2 spools. At 5 bar the S1
spool is totally switched over into the activated
position, so the pump kit starts to work. (The 5 bar
pressure is always necessary to hold the S1 spool in the
activated position, just like the NG 20 control block).
The signal of the shifting cylinder pilots the S2 spool
and the signal of the switching valve pilots the S3
spool.
The needle valve cartridge DVE 16 of the manifold at
the pump regulates the flow of the pump, and the direct
acting SUN pressure relief cartridge limits the max.
pressure if the regulator of the pump fails. (The SUN
pressure relief cartridge is good for a flow of 200 l/
min.)
The small accumulator damps the pressure spikes.
To stop pumping, the NG06 solenoid valve has to be
deactivated; the spring centers the NG06 spool in the
neutral position. The S1 pilot system, the S-port of the
load sensing pump, and the accumulator are vented to
tank, the S1 spool switches into the neutral position,
and the pump kit stops working. The nozzle in the P-
line restricts the flow so that the accumulator is vented
softly. During “stand-by” mode, the pump creates the
stand-by pressure, so there is a flow through the nozzle
back to tank. If the stand-by pressure of the pump is
adjusted to 15 bar (218 PSI), there would be a flow
through the 1.5mm orifice of 4.3 l/min. In this
operating status we would create a lost energy of 0.1
KW.
Even a bigger orifice (quicker reaction) should not
cause a heat problem.
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