New Holland T8010 Manual page 747

Valve spools are controlled by levers, pedals, pilot oil, electric
solenoids, etc., which are called actuating controls. These
actuating controls are shown by symbols placed on the ends
of the envelopes.
Section 35 - Hydraulic Systems, 3PT - Chapter 1
35-1-10
SOLENOID CONTROL WITH
INTERNAL PILOT PRESSURE
SPRING
THREE POSITION, SPRING CENTERED
To show that a valve is spring centered, a spring symbol is
placed at each end of the envelope. The above schematic
shows that an electrical solenoid and pilot pressure assist are
required to overcome spring force to move the valve spool.
Flow Control Symbols
Restrictors
NON ADJUSTABLE RESTRICTOR
716L8A
The basic flow control symbol is a representation of a
restrictor. If the restrictor is adjustable, a slanted arrow is
drawn across the symbol. The restrictor could be a special
fitting with a small hole in it or a small drilled passageway
within a valve. If it is an adjustable restriction, it could be
thought of as a water faucet that can be controlled by turning
the handle to regulate the flow. Restrictors can be applied to
meter out, meter in and bleed off circuits.
ADJUSTABLE RESTRICTOR
PRESSURE COMPENSATED
716L8C
T h e r e a r e a d j u s t a bl e r e s t r i c t o r s t h a t a r e p r e s s u r e
compensated. That means that the size of the opening in the
restrictor will change with increases and decreases in
pressure. A per pendicular arrow indicates press ure
compensation. If the restrictor has both pressure and
temperature compensation, the symbol for a thermometer will
also be shown.
SPRING
713L8C
ADJUSTABLE RESTRICTOR
716L8B
ADJUSTABLE RESTRICTOR
PRESSURE AND
TEMPERATURE COMPENSATED
716L8D