Wheelchair automatic anti-rollback assembly

A wheelchair comprising:

• a frame structure;
• a rear drive wheel assembly and a front wheel assembly supporting said frame structure, said rear drive wheel assembly comprising first and second drive wheels that have respective rotational axes and are each rotatable relative to said frame structure along a forward rotational direction which causes said wheelchair to move forward and a rearward rotational direction which causes said wheelchair to move rearward;
• a seat member supported by said frame structure and constructed and oriented to accommodate an occupant;
• at least one first one-way brake assembly comprising a first brake member having a first end portion movable from an activated state in which said first end portion engages said first drive wheel at a point of contact on said first drive wheel to a non-activated state in which said end portion is spaced from the point of contact of said first drive wheel so as not to interfere with rotation of said first drive wheel in the forward and rearward rotational directions;
• a second one-way brake assembly comprising a second brake member having a second end portion movable from the activated state in which said second end portion engages said second drive wheel at a point of contact on said second drive wheel to the non-activated state in which said end portion is spaced from the point of contact of said second drive wheel so as not to interfere with rotation of said second drive wheel in the forward and rearward rotational directions;
• at least one biasing member operatively associated with said one-way brake assemblies to exert a biasing force on said brake members, the biasing force urging said first and second end portions into respective engagement with said first and second drive wheels at the points of contact with sufficient force to maintain engagement between said end portions and the respective points of contact and prevent rearward rotation of said first and second drive wheels when said first and second end portions are in the activated state, yet the biasing force exerted by said biasing member on said brake members being insufficient to cause said first and second end portions to prevent forward rotation of said first and second drive wheels when in the activated state;
• and
• at least one automatic brake releasing assembly operatively associated with said first and second one-way brake assemblies and said seat member to automatically move said end portions away from the points of contact and out of the activated state to the non-activated state in response to occupation of said seat member.

An anti-rollback assembly for a wheelchair comprising a frame structure, a seat member constructed and oriented to accommodate an occupant, and a rear drive wheel assembly and a front wheel assembly carrying the frame structure and comprising first and second drive wheels and first and second front wheels, respectively, said anti-rollback assembly comprising:

• first and second mounting brackets mountable on the frame structure;
• first and second pivotal collars pivotally supported by said mounting brackets;
• an automatic brake releasing subassembly;
• a connecting subassembly operatively connecting said first and second collars to each other and to said automatic brake releasing subassembly so that movement of said automatic brake releasing subassembly relative to said mounting brackets pivots said first and second pivotal collars in unison;
• a first brake arm having a first distal end portion and a second brake arm having a second distal end portion, said first and second brake arms being connected to said first and second pivotal collars, respectively, so that pivotal movement of said first and second pivotal collars relative to said mounting brackets guides said first and second distal end portions along respective arcuate paths;
• and
• at least one biasing member exerting a biasing force on said first and second pivotal collars,
• wherein said first and second mounting brackets are mountable on the frame structure to position said automatic brake releasing subassembly under the seat member and said first and second distal end portions in contact with the first and second drive wheels, respectively, causing said biasing member to urge said first and second distal portions into contact with the first and second drive wheels with sufficient force to prevent rearward rotation of the drive wheels, yet permitting said automatic brake releasing assembly to automatically move said distal end portions along arcuate paths out of contact with the drive wheels in response to occupation of the seat member.