Equalized suspension system for a tandem axle vehicle

Claim 1

In a suspension system for a vehicle having front and rear tandem axles, first and second elongated semi-elliptic compound leaf springs mounted in tandem one behind the other on each side of the vehicle and independent of one another, means coupling the medial portion of each of said springs to the axles so that the springs at each side of the vehicle have inner ends disposed adjacent to one another and outer ends spaced remotely from one another; means supporting the outer ends of the respective springs on the frame of the vehicle to react against the frame of the vehicle in the event a corresponding spring is flexed upwardly by an upwardly applied force encountered by the corresponding axle; a first equalizer bracket secured to the frame of the vehicle adjacent the inner end of said first spring, a first equalizer crank pivotally mounted on said first equalizer bracket; a first shackle assembly pivotally mounted on said first equalizer crank and engaged in sliding contact with the inner end of said first spring so as to rock said first equalizer crank upon a vertical force being impressed on the corresponding axle, a second equalizer bracket secured to the frame of the vehicle adjacent the inner end of said second spring; a second equalizer crank pivotally mounted on said second equalizer bracket; a second shackle assembly pivotally mounted on said second equalizer crank and engaged in sliding contact with the inner end of said second spring so as to rock said second equalizer crank upon a vertical force being exerted on the corresponding axle and spring; a link interconnecting said first and second equalizer cranks, said first and second eQualizer cranks being pivotally mounted within said first and second equalizer brackets intermediate the inner ends of said springs, and said equalizer cranks each having an arm portion depending below the respective coupling points with said first and second shackle assemblies, and each of said cranks having a point of direct pivotal connection to said link, so that an encountered force exerted on one axle deflecting the associate spring and causing one of the equalizer cranks to turn in one direction is transmitted directly through the link to the other equalizer crank causing the other equalizer crank to turn in the opposite direction, which imposes part of the encountered force on the inner end of the other spring associated therewith.