u00b1 1 25 u00b0 these two values give a magnification factor of 2 08 which from fig7 is a c c c of 0 25 in fig7 magnification ratios are plotted as ordinates and frequency ratios as abscissae the spring element 10 has a number of special features it is machined from a solid forged bar of steel to look like a rectangular section coil spring the outside diameter is ground and the inside diameter is machined by boring the slot is machined with a certain helix to represent the lead or number of turns coils of the spring slotting the spring in the manner as illustrated leaves both ends solid for attaching purposes the material used for the actual part as tested is vasco max 300 maraging steel it was selected for its high strength high endurance limit ease of machining low distortion during heat treating and low modulus of elasticity standard type steels can be used the reason a silicon fluid is preferred for use in this damper is due to its small change in viscosity at increased temperatures since the parts are assembled in the engine proper the maximum temperature in the coupling from engine operation is approximately 250.