as viewed in fig2 referring not to fig1 and 2 it will be noted that in fig1 cylinders 50 and 51 are shown in section whereas in fig2 portions of the exterior walls of cylinders 50 52 58 and 60 are shown as probably best shown in fig2 each of the cylinders is inclined at an angle of approximately 30 u00b0 with respect to the horizontal axis of the apparatus furthermore each cylinder is inclined with respect to a transverse plane passed through this horizontal axis at an angle of approximately 60 u00b0 as best shown in fig1 each cylinder slopes inwardly towards the axle moving from the outside to the inside furthermore referring to fig1 each cylinder is inclined with respect to a transverse plane through the longitudinal axis is a direction such that the cylinder is inclined towards the direction of rotation of the cylinder block as will be apparent from the subsequent description the direction of rotation of the cylinder block is indicated by arrows adjacent fig4 and 5 located within the cylinders are a plurality of piston assemblies 62 these piston assemblies are all alike the details of the piston assembly 62 are shown in fig3 it will be noted that there is a piston head 63 with suitable piston rings secured to a piston shaft 64 the piston head 63 is provided with a cylindrical.