Originally Posted by JohnDThompson

That looks like a "New Winner" freewheel. Unlike other SunTour freewheels, which used a left-hand threaded cone that could be removed with a pin spanner, and a variety of thin spacers to provide adjustment, the New Winner has a cone and lockring and a special tool to open and adjust the freewheel:



I've found it to be rather a PITA, though. Unless there's some egregious problem, I'd just flush it out with solvent and re-lubricate. If there is an egregious problem, I'd consider sending it to pastorbob for rehabilitation.