Cab suspension

1. A vehicle comprising:

a chassis frame having a length running longitudinally between a front and a rear and a width running laterally between a right side and a left side;

a cab supported on the chassis frame and having a front and a rear;

a suspension system which is disposed between the chassis frame and the cab rear and comprises: a cross rail which is fastened to the chassis frame sides; a gas spring having a base mounted laterally centrally of the chassis frame sides on the cross rail, a deformable gas chamber which confines a pressurized gas and is disposed on the base, and a top plate disposed on the gas chamber opposite the base; a damping mechanism which damps vertical displacements of the cab on the chassis frame; and a multi-limb bar assembly interfacing the cab, the chassis frame, and the gas spring, the bar assembly comprising a hub fastened to the top plate of the gas spring, a left front limb extending from the hub frontward to a left front constraint disposed laterally outboard of the hub and attached to the cab rear, a left rear limb extending from the hub rearward to a left rear constraint disposed laterally outboard of the hub and attached to the chassis frame, a right front limb extending from the hub frontward to a right front constraint disposed laterally outboard of the hub and attached to the cab rear, a right rear limb extending from the hub rearward to a right rear constraint disposed laterally outboard of the hub and attached to the chassis frame, and at least one gusset bar spaced from the hub and joining one of the limbs to another of the limbs.

2. A vehicle as set forth in claim 1 in which a left side gusset bar joins the left front limb and the left rear limb at respective locations spaced from the hub, a right side gusset bar joins the right front limb and the right rear limb at respective locations spaced from the hub, and a rear gusset bar joins the left rear limb and the right rear limb at respective locations spaced from the hub.

3. A vehicle as set forth in claim 2 in which the left front limb has a greater extent laterally of the hub than frontward of the hub, the left rear limb has a greater extent rearward of the hub than laterally of the hub, the right front limb has a greater extent laterally of the hub than frontward of the hub, and the right rear limb has a greater extent rearward of the hub than laterally of the hub.

4. A vehicle as set forth in claim 3 in which the left side gusset bar joins the left front limb at a location which is laterally outboard of a location at which the left side gusset bar joins the left rear limb, and the right side gusset bar joins the right front limb at a location which is laterally outboard of a location at which the right side gusset bar joins the right rear limb.

5. A vehicle as set forth in claim 4 in which the left side gusset bar has a concave curvature which faces laterally outboard along its length, and the right side gusset bar has a concave curvature which faces laterally outboard along its length.

6. A vehicle as set forth in claim 2 further comprising a front gusset bar which joins the left front limb and the right front limb at respective locations spaced from the hub.

7. A vehicle as set forth in claim 2 in which the damping mechanism comprises a left damper operatively disposed between the chassis frame and the left front limb adjacent its attachment to the cab rear, and a right damper operatively disposed between the chassis frame and the right front limb adjacent its attachment to the cab rear.

8. A vehicle as set forth in claim 1 in which the left front constraint is disposed laterally outboard of the left rear constraint, and the right front constraint is disposed laterally outboard of the right rear constraint.

9. A vehicle as set forth in claim 8 in which the chassis frame comprises a left side rail and a right side rail each having a bottom flange which is directed laterally inward, and each rear constraint comprises a bracket mounted on the bottom flange of the respective side rail and a motion constraint mechanism which is movable on the bracket and to which the respective rear limb is attached.

10. A vehicle as set forth in claim 9 in which each front constraint comprises a bracket via which the respective front limb is attached to the cab rear and a motion constraint mechanism having a movable part and to which an end of the respective front limb is attached.

11. A vehicle as set forth in claim 10 in which the motion constraint mechanism of each rear constraint has a movable part which is movable on the respective bracket, and to which an end of the respective rear limb is attached, and the movable part of each rear constraint and of each front constraint comprises a rocker pivotally mounted on the respective bracket for coactions with the bracket to limit rotary motion of the rocker about a respective axis which extends widthwise of the chassis frame.

12. A vehicle as set forth in claim 11 in which the bracket of each front constraint is fastened to the cab rear to dispose the respective front constraint laterally outboard of the respective side rail.

13. A vehicle as set forth in claim 8 in which the chassis frame comprises a left side rail and a right side rail each having a top flange which is directed laterally inwardly, and each rear constraint comprises a bracket mounted on the respective side rail and extending vertically higher than the top flange of the respective side rail.

14. A vehicle as set forth in claim 13 in which each front constraint comprises a bracket via which the respective front limb is attached to the cab rear and a motion constraint mechanism that has a movable part which is movable on the bracket and to which an end of the respective front limb is attached.

15. A vehicle as set forth in claim 14 in which each rear constraint comprises a motion constraint mechanism having a movable part which is movable on the respective bracket, and the movable part of each rear constraint and of each front constraint comprises a rocker pivotally mounted on the respective bracket for limited rotary motion about an axis which extends widthwise of the chassis frame.

16. A vehicle as set forth in claim 15 in which the bracket of each front constraint is fastened to the respective side rail to dispose the respective front constraint laterally outboard of the respective side rail.

17. A vehicle as set forth in claim 1 in which each front constraint comprises a front bracket which is attached to the cab rear and a motion constraint mechanism having a movable part which is constrained on the front bracket for pivotal movement about an axis which extends widthwise of the chassis frame and to which an end of the respective front limb is attached, and each rear constraint comprises a rear bracket which is attached to the chassis frame and a motion constraint mechanism having a movable part which is constrained on the rear bracket for pivotal movement about an axis which extends widthwise of the chassis frame and to which an end of the respective rear limb is attached.

18. A vehicle as set forth in claim 17 in which the motion constraint mechanism of each rear constraint and of each front constraint comprises an elastomeric bushing through which the respective movable part of the motion constraint mechanism is torsionally elastomerically coupled with the respective bracket for turning on the respective bracket about the respective axis.

19. A vehicle as set forth in claim 18 in which the movable part of each motion constraint mechanism of each constraint comprises a rocker with which the respective bracket coacts to limit turning of the rocker about the respective axis.