210 u00b0 past top dead center as the openings 88 and 91 align in an incipient overlap position thus as shown in fig4 c when nutating opening 91 moves into the overlap position with static opening 88 flow is permitted complete opening occurs as shown in fig4 d with overlap of static opening 88 and nutating opening 91 in a manner similar to that discussed with reference to fig3 a through 3h nutating opening 91 moves towards the closed position as shown in fig4 e until closing is completed as shown in fig4 f at 15 u00b0 before top dead center i e the selected design point it is to be understood that the width w of nutating opening 91 is determined by positioning the left edge thereof tangent to upper circle of nutation 94 in the manner shown accordingly the widths w of openings 88 and 91 which are by definition equal differ for a fixed circle of nutation from that of symmetrically timed device shown in fig3 a through 3h in the event a long duration valving device is desired a similar construction may be accomplished as shown in fig5 a through 5f with reference to 5a it will be noted that point a 39 i e the closing point with reference to a clockwise rotating device is constructed on upper circle of nutation 94 while point b the closing point is.