Terrain King KB21 - Valve Section Components

KB21 Service Manual Pub 09-14
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Cylinder Control Systems
40-B. Bucheer L.8S - Electric Control/Cable
Segment compensating spool, pressurized oil must pass by the segment pressure compensating spool
before it is used by the cylinders. The compensating spool uses load sense and spring pressure to
maintain constant pressure drop across the main spool, both when the load changes and when a segment
with a higher load pressure is activated.
Anti-cavitation check / work port relief valves, work port relief valves are installed in the swing, lift and
dipper circuits to limit the max pressure in those particular circuits to a lower pressure than the main
system relief. The anti-cavitation check valve allows oil to be taken from the return (tank “t” port) galley of
the valve when needed to prevent cavitation of cylinder. The tilt and door valve sections do not contain
these valves.
of oil to the cylinders. The spool is actuated by pilot oil pressure, which is controlled by the proportional
control system. It can also be mechanically operated with the use of an external lever or wrench. Spools
cannot be interchanged in the valve section due to the special individual designs of spools. Maximum
stroke adjusters are pre-set at the factory and will not need adjusting.