Yale hydraulic couplers are selfsealing which means
that the coupler halves only have to be closed hand tight. Both female and male parts have inner balls which seal the coupler halves in un-coupled condition, so that no hydraulic fluid will leak.
      Please note that all Yale hydraulic cylinders are equipped with the standard female coupler half CFY-1 and dust cap CDF-9.

! Hydraulic couplers must always be completely closed, since otherwise the circulation cannot be released.