A dumb iron is a "curved side piece of a chassis, to which the front springs are attached."Article title
/ref> This is an older term, applicable mainly to vehicles built before 1950, and which had their front axle suspended on

leaf spring A leaf spring is a simple form of spring commonly used for the suspension in wheeled vehicles. Originally called a ''laminated'' or ''carriage spring'', and sometimes referred to as a semi-elliptical spring, elliptical spring, or cart spring, it ...

s. At the front of the car, dumb irons project forward, providing a location to attach the front of the leaf springs. The modern alternative is suspension mount.

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