20,424. Fairfax, H. W. Gabbett-. Sept. 7. Movable-abutment type; packing abutments; cooling parts. - In rotary engines having rotary abutments cooperating with skew teeth secured to a piston having a periphery of concave cross - section, additional loose abutment-disks &c. are provided, adapted to be moved by the piston teeth and to seal the gaps in the abutment proper. These packing- devices for the rotary abutment a may take the form of disks f, Fig. 1, free to rotate on stationary rings g, the gaps d in the abutment being formed in inset metal plates e, Fig. 2. Water for cooling or a lubricating medium may be introduced into the spaces between the disks f. In a modification, Fig. 3, the gaps d are formed in members l capable of following the curvature of the piston tooth to an extent limited by pins m on the abutment. The members l are pressed outwards by springs o or weights p. In another modification, a number of thin disks are mounted so as to have a certain amount of free play around the abutment axis, and exchangeable rocking plates may be provided in pockets round the abutment gaps.