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US 6,460,641 B1Granted
Mid-wheel drive wheelchair with front wheel multiple bias suspension and anti-tip assembly
AssigneeInvacare Corporation
InventorStephen L. Kral
Life of this patent
Estimating the term…
Abstract
A wheelchair has a plurality of central wheels which can be either power or manually driven, at least one rear caster wheel, and at least one resiliently biased ground engaging front wheel having a multiple suspension assembly. The wheelchair has improved tracking since the front wheel is maintained on the ground even on undulating, bumpy, or irregular surfaces. The wheelchair also has improved stability since the front ground engaging wheel also acts as a resiliently biased anti-tip wheel.
Claims22
A wheelchair, comprising:
- a frame;
- a seat assembly operatively connected to said frame;
- a plurality of drive wheels operatively connected to said frame;
- at least one rear caster wheel operatively connected to said frame;
- and
- at least one front wheel assembly resiliently and pivotally connected to said frame by a multiple compression range suspension assembly having at least two biasing members, said multiple compression range suspension assembly adapted to biasly urge said front wheel into contact with a surface, wherein each said biasing member of said suspension assembly has a compression range which can be separate from or can overlap the at least one other biasing member, wherein said suspension assembly has an upper housing containing a substantially vertically extending elongated slot therein, and wherein a pin connects said suspension assembly to said wheelchair frame, and wherein said pin extends through and is movable substantially vertically upwardly and downwardly within said slot.
3 more elements
An anti-tip wheelchair, comprising:
- a frame;
- at least a power driven drive wheel operatively connected to said frame and at least a rear caster wheel operatively connected to said frame;
- at least one anti-tip wheel located forward of said drive wheel, said anti-tip wheel pivotally attached to said frame by a caster arm, said anti-tip wheel adapted to be resiliently biased on a riding surface by a multiple compression range suspension assembly, said multiple compression range suspension assembly pivotally connected at substantially one end to said frame and pivotally connected at substantially the remaining end to said caster arm, said multiple compression range suspension assembly having at least two biasing members, wherein each said biasing member has a compression range which can be separate from or can overlap the range of the at least one other biasing member, wherein said suspension assembly has an upper housing containing a substantially vertically extending elongated slot therein, wherein an upper pin connects said suspension assembly to said wheelchair frame, and wherein said upper pin extends through and is movable substantially vertically upwardly and downwardly within said slot.
A wheelchair comprising:
- a frame;
- a seat supported by said frame;
- at least two drive wheels which support said frame;
- and
- at least one caster member pivotally jointed to said frame by a swing arm which is biased toward the ground by a multiple compression range suspension assembly, wherein said multiple compression range suspension assembly contains two biasing members each having compression ranges which can be separate from each other or can overlap, wherein said biasing members are a primary spring and a secondary spring, wherein said suspension assembly comprises a base, a shaft, and an upper bracket, wherein said suspension assembly has an upper housing containing a substantially vertically extending elongated slot therein, and wherein a pin connects said suspension assembly to said wheelchair frame and wherein said pin extends through and is moveable substantially vertically upwardly and downwardly within said slot, wherein said secondary spring has a higher compression range than said primary spring, and wherein said secondary spring is adapted to provide a bias resistance after said primary spring is substantially fully compressed and said pin has traveled to a lower end of said slot.
2 more elements
Dependencies are inferred from the claim text.