Double Selector Valve
A manually-operated, two-position double selector
A solenoid operated double check valve is located
valve is located in the carrier frame center section.
on the turntable left side plate. The solenoid,
The valve is connected by a control cable to the
controlled by the TELE/CLAMSHELL selector switch
steering mode selector handle located at the rear of
positions the valve to direct hydraulic pilot pressure
the hydraulic reservoir.
The selector valve
so that the telescope/clamshell control pedal
determines if the front steer cylinders are to be
operates the boom telescope cylinder or the
operated from the carrier cab or from the
clamshell/grapple cylinder. With the selector switch
superstructure cab. The hydraulic circuit which is to
in the TELE position, ports T and C4, and ports P
be operated should be selected before pressure is
and C1 are connected together directing pilot
applied. The valve spool is of the open crossover-
pressure to the telescope directional control valve
type. As the spool is moved and one set of outlet
which in turn directs hydraulic flow to operate the
ports start to close, the other set of outlet ports start
telescope cylinder. With the selector switch in the
to open. With the spool pulled out of the housing
CLAMSHELL position, ports T and C3, and ports P
(viewed from the handle end), ports A and D are
and C2 are connected together directing pilot
connected to each other, and ports B and C are
pressure to the clamshell directional control valve to
connected to each other. With the spool pushed into
operate the clamshell/grapple cylinder.
the housing (viewed from the handle end), ports A
and E are connected to each other, and ports B and
F are connected to each other.
Tag and disconnect the six hydraulic hoses
Position the selector valve onto the mounting
from the ports on the selector valve, refer to Figure
Disconnect the handle linkage or electrical
Connect the handle linkage or electrical
connector as applicable.
connector onto the valve as applicable.
Connect the six hydraulic hoses to the selector
the selector valve to the mounting bracket. Move the
valve as tagged prior to removal.
valve to a clean work area.
With the engine running at governed rpm, activate
the replaced selector valve several times. Check for
proper operation and check the valve for any