New Holland T8010 Manual page 751

Valve A
This valve is a three position valve. The spool is lever
operated and spring centered. It is an open center valve.
Visually place the envelopes into the center position and you
will see that the valve will direct oil into one end or the other
of cylinder A. When the spool in valve A is moved out of the
centered position, the valves downstream will receive no oil.
Valve B
Valve B is similar to valve A but it is a four position valve. The
fourth position is a float position and is held into that position
with a detent. With this valve the cylinder B can be extend,
retracted, or placed in the float position. Visualizes the
envelope for the float position in the inlet passageway.
You will see that oil can continue to flow to the next valve
downstream and that the rod in cylinder B could be pushed
back and for th. The oil could move from one end of the
cylinder to the other via the valve. Both ends of the cylinder
are also connected to the return line to the reservoir.
Section 35 - Hydraulic Systems, 3PT - Chapter 1
35-1-14
Valve C
This valve is also similar to valve A but is designed to control
a single acting cylinder. When you visualize placing the upper
envelope in the center position you will see that oil can drain
back to the reservoir from cylinder C.
At the same time, oil from the pump can flow through valve C
to the next valve.
Valve D
Valve D is a lever operated, spring centered valve and is
designed to control a hydraulic motor. If a hydraulic motor
was turning a flywheel and the oil supply and return were
shut off abruptly, this would cause damage to the hydraulic
lines, the motor, or whatever it was powering. Therefore when
the valve supplying the motor is shut off, the motor should be
able to slow down gradually. The center (neutral) position of
valve D will allow that to happen by letting oil from the outlet
of the motor return to the inlet side.
As you have seen, this brief information is all you need to
read hydraulic schematics. The more you use it, the more you
will be comfor table using hydraulic schematics as a
troubleshooting guide.