REED B50HPG, Technical Manual, Page: 26 / 235

OPERATION and MAINTENANCE
Rev 1.2 25 of 80
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•
SOLENOID VALVE CARTRIDGE
There are two (2) of these cartridges used in the circuit. Both, which may be referred
to as a dump valve, are designed into the circuit as SAFETY VALVES. Their
purpose is to automatically relieve pressure from the shift circuit as commanded
by the emergency stop circuit. At start up, the normally open cartridges are open
to tank so the shift circuit cannot build any pressure. When the emergency stop
circuit is reset, an electrical signal is generated which energizes the solenoids,
closing the cartridges and allowing the shift circuit to pressurize. When the
emergency stop function is activated or the key switch turned off, the power is
taken away from solenoids, causing the cartridges to open and dump shift circuit
pressure back to tank.
• SOLENOID DIRECTIONAL VALVE
This valve is a directional control valve that is shifted by
electronically activated solenoids. Its purpose is to direct
the flow of oil stored in the accumulator to one or the other
end of the shift cylinder based on the signal received by the
logic controller that was generated by the proximity sensor.
•
ACCUMULATOR
The accumulator is incorporated into the
shift circuit to provide instant pressure and
volume for the shifting of the s-tube, which
cannot be obtained under normal
circumstances. An accumulator is a
hydraulic reservoir that retains the hydraulic
fluid under high pressure.
The accumulator contains a rubber bladder
on the inside of the reservoir. The bladder
is pre-charged with dry nitrogen. In the
application of the shift circuit, the hydraulic
fluid is pumped into the accumulator at a
higher pressure than that inside the
bladder. This compresses the bladder
building up high pressure within the
accumulator that is retained until released.