Easy folding cross brace design

1. An apparatus comprising:

first and second U-shaped cross-members, each of said cross-members including a front portion, a rear portion, and a cross bar perpendicularly connecting the front portion to the rear portion, wherein the respective front portions of the first and second cross-members are pivotally connected with each other at central portions thereof and the respective rear portions of said cross-members are pivotally connected with each other at central portions thereof,

wherein the cross-members are mutually movable from a generally X-shaped set-up condition in which the cross bars of the first and second cross-members are transversely spaced apart, to a generally flat collapsed condition in which the cross bars of the first and second cross-members are generally adjacent one another; and

right and left frame side assemblies are pivotally connected to each of the first and second cross-members, wherein at least one of the right and left frame side assemblies is pivotally connected to one of the first and second cross-members by a lost motion linkage;

wherein said lost motion linkage comprises a longitudinal link having a first end pivotally connected to one of the first and second cross-members via a first pivot pin and a second end pivotally connected to the at least one of the right and left frame side assemblies via a second pivot pin, said longitudinal link further comprising a slot extending partially along a length of the link proximate at least one of the first end and the second end and in which the first pivot pin or the second pivot pin is received for sliding movement within said slot with movement of the cross-members between the set-up condition and the collapsed condition.

2. The apparatus according to claim 1 , wherein each of the right and left side frame assemblies is connected to a respective one of the first and second cross-members by a lost motion linkage.

3. The apparatus according to claim 1 , wherein when the cross-members are moved to their collapsed condition the right and left frame side assemblies are transversely moved to positions adjacent to one another.

4. The apparatus according to claim 1 , further comprising at least one snubber attached at one of the right and left frame side assemblies for frictionally locking at least one of the cross-member into its setup condition.

5. The apparatus according to claim 4 , wherein the snubber prevents the at least one cross-member from travelling over-center when moving said at least one cross-member to its set-up condition.

6. The apparatus according to claim 4 , wherein the snubber is positioned on the rear leg portion of one of the right and left frame assemblies for interaction with a rearward corner of the at least one cross-member with which it interacts.

7. The apparatus according to claim 6 , wherein the snubber projects inwardly from the frame side assembly to which it is attached towards the other frame side assembly.

8. The apparatus according to claim 1 , wherein the at least one lost motion linkage is attached to the rear portion of one of the first and second cross-members and a rear portion of the frame side assembly adjacent to the one of the first and second cross-members when said cross members are in the set-up condition.

9. The apparatus according to claim 8 , wherein the at least one lost motion linkage is attached to the forward surface of the rear portion of one of the first and second cross-members and a rear surface of the rear portion of the corresponding frame side assembly to which the lost motion linkage is attached.

10. The apparatus according to claim 1 , further comprising a seat panel attached at the cross bars of the first and second cross-members, which is taut across the cross bars in the set-up condition of the cross-members, and is flaccid in the collapsed condition of the cross-members.