Patent ID: 8418626

Claim:
A truck, comprising: a first non-linear spring system that couples a first powered axle carrier to a truck frame element; a second spring system that couples a second unpowered axle carrier to the truck frame element, wherein the first spring system has an effective spring rate curve that is different from an effective spring rate curve of the second spring system, and wherein the first spring system includes a first outer spring coiled around a second inner spring, and a spring seat bar that pre-compresses the second spring such that the second spring is engaged at a greater displacement of the first axle carrier towards the truck frame element than the first spring; a third non-linear spring system coupling a third powered axle carrier to the truck frame element; a first actuator coupled to the first powered axle, the first actuator configured to selectively push down on the first powered axle carrier, away from the truck frame element, against a bias, to at least partially relieve a load on the second unpowered axle carrier; and a second actuator configured to selectively push down on the third axle carrier, away from the truck frame element, against a bias, to at least partially relieve a load on the second unpowered axle carrier; wherein the third spring system has a non-linear effective spring rate curve that is different from the effective spring rate curve of the first non-linear spring system.