TYRONE POWER SENSOR
The power sensor is a unit consisting of two gear
hydraulic system IS low. oil from the front pump
flows around the control spool in the sensor valve,
pumps and a valve which controls pump flow. The
t h r o u g h several holes. past the check valve (6)
pumps are piggyback* with a common suction. The
and out the discharge port (5). Oil from the rear
valve is mounted on the pumps so that it receives
t h e flow from both pumps. At lower pressures.
pump flows into the center of the control spool at
approximately 100 PSI to 1500 PSI. both sections
(4). and join with the flow from the front pump at
of the pump supply the main hydraulic system. From
(5).
approximately 1500 PSI to system relief pressure,
(See position 2)
the sensor valve unloads one of the pumps by by-
passing its flow back to the suction side of the
When pressure in the system increase, it is felt
pump housing. The other pump continues to de-
by the pilot poppet (8), through a hole in the pop-
liver the necessary flow to supply the system.
pet seat (7) and a hole (3) in the last land on the
right of the control spool. When pressure is high
This unit provides a balance between the power
enough to move the pilot poppet from its seat, a
delivered to the hydraulic circuit and the power de-
pressure drop is created in the cavity where the
livered to the power train. It supplies a high vol-
spring (10) is located The control spool moves to
ume of oil to the hydraulic circuit for high speed
right, allowing the flow from the front pump to re-
o p e r a t i o n when the working pressure is low as
turn to the suction side of the pumps. The check
when a loaded bucket IS raised from ground level
valve (6) seats, preventing loss of flow from the
to maximum height It supplies a low volume of oil
rear pump through the holes in the spool and back
to the hydraulic circuit when the working pressure
to the front pump.
is high as when braking a load of material from a
pile. By reducing the flow at high working pressure,
W h e n pressure in the system drops, the pilot
l e s s horsepower IS used by the hydraulic circuit,
moves back on its seat. The pressure in the cav-
more horsepower is available to the power train.
ity where spring (10) is located increases and the
control spool moves to the left. The check valve
Operation of power sensor (See page 193)
(6) opens and both pumps supply flow to the dis-
charge port.
The pumps are driven direct from the engine
(refer to position 1). When pressure in the main
[40]
