engine is illustrated in fig3 in which the pistons 24 and 25 are shown as they apply forces against a stiffener 26 mounted to the shaft 11 while a second set of pistons 43 and 44 are mounted to the other side of the spider assemblies 34 and 45 and would reach their maximum compression at the opposite end of the cycle as shown in fig3 ignition of the charge between the pistons 24 and 25 will of course take place near or adjacent top dead center or where the pistons are at their closest point for maximum compression in the case of a diesel engine ignition also occurs near top dead center of the pistons such as shown in pistons 24 and 25 in the diagrammatic view of fig3 fig2 more clearly shows the stiffener member 26 having the wobbler slugs 27 and 28 mounted thereon adjacent the surfaces 30 and 31 the wobbler slugs 27 and 28 of course are mounted to have an elongated axis perpendicular to the angles 30 and 31 and are held to the stiffener with the threaded fasteners 32 and 33 and ride over the shaft 11 thus the greater portion of the forces applied to the wobbler slugs 27 and 28 is applied against the ends of the stiffener 26 to reduce the bend and other forces applied directly to the shaft 11 each wobbler slug 27 and 28 consists of two identical halves securely held to the end stiffener.