The invention relates to pistons, piston shoes and associated safety means in fluid handling devices including hydraulic or pneumatic pumps, motors and transmissions, wherein recesses for the reception of portions of the piston shoes are provided in a fluid handling body and the walls which are adjacent to the recesses serve to prevent the escape of piston shoes from the recesses, wherein convex and concave semispherical engagement surfaces are provided on the pistons and piston shoes and wherein piston stroke enlargement means and friction preventing means may be associated with the piston shoes and/or pistons or the fluid handling body.