A spool valve for variable cam timing phaser comprising a spool, a plurality
of
check valves and passages from the advance chamber and the retard chamber to a
port in the spool valve. The spool having at least two lands separated by a central
spindle, slidably mounted within a bore. When the spool is in the first position,
fluid from the advance chamber flows through the passage and the port to the bore
surrounding the central spindle of the spool valve and through a check valve and
port to the passage to the retard chamber. When the spool is in the second position,
fluid from the retard chamber flows through the passage and the port to the bore
surrounding the central spindle of the spool valve and through a check valve and
port to the passage to the advance chamber.