in compression this is also the position shown schematically to the left in fig3 when the connecting rod is put in tension the eccentric pin 16 will not be subjected to any torque but the eccentric pin 18 will be turned clockwise to move into its top dead centre position shown to the right in fig3 the eccentric pin 18 will act directly on the link 22 which in turn will push through the elastomeric material 24 onto to the link 20 and act to rotate the eccentric pin 16 out of its bottom centre position the return to the position shown to the right in fig3 will likewise occur automatically when the connecting rod is subjected to compression during this movement any slight tendency for the eccentric pins to move towards or away from one another is accommodated by contraction or expansion of the elastomeric material 24 as is clear from fig3 the effect of the rotation of the two eccentrics 16 18 is to move links 20 22 and thereby vary the effective length of the connecting rod assembly by an amount x as the forces on the connecting rod assembly alternate between tension and compression in operation at the end of the compression stroke of the engine the connecting rod 10 is held at one end by the crank pin while the inertial force on the piston acts to place the connecting rod assembly in tension there is.