10 - 6
Operation (cont’d)
Pilot Relief Valve
Pilot pressure is controlled by the pilot relief valve setting.
Pressure can be varied using adjuster 56-6 which holds
poppet 56-2 against seat 56-3 by means of spring 56-5. If
the pressure exceeds the set value, the poppet lifts to vent
excess Pp pressure to tank.
Solenoid Proportional Pressure Control (SPPC) Valve
The function of the SPPC valve is to provide a means of
varying the horsepower settings of the two pumps according
to the operating mode selected. Each mode selection
causes an electrical signal F to be applied to the valve
solenoid. The signal current level is dependent on the mode
selected. The solenoid converts the electrical signal into a
thrust from plunger E.
When solenoid 58 is energised, the thrust of plunger E
moves spool 103 to the left to connect input port B (at pilot
pump Pp pressure) to output port C. The output pressure at
port C is routed to chamber A where it acts as a back
pressure to oppose the thrust of plunger E. High back
pressure causes spool 103 to move so that output port C
connects to drain port D lowering the output pressure and
hence the back pressure. The result is a level output
(horsepower signal) pressure which is proportional to
solenoid plunger thrust and determined by the proportion of
input pressure (at port B) connected to port C via spool 103.
Section E Hydraulics
9803/6410
Section E
10 - 6
Issue 1
Hydraulic Pump/Regulator
To Next Page
Loading...
Need help?
General
