Patient Transport Apparatus For Traversing Stairs

1 . A patient transport apparatus operable by a user for transporting a patient, the patient transport apparatus comprising:

a support structure having a front strut and a rear upright;

a seat section and a back section each coupled to the support structure for supporting the patient;

a front wheel operatively attached to the front strut; and

a carrier assembly arranged for movement relative to the support structure between a chair configuration for traversing floor surfaces and a stair configuration for traversing stairs, the carrier assembly comprising:

a shaft defining a wheel axis,

a rear wheel supported for rotation about the wheel axis,

a track assembly having a belt, and

a hub supporting the shaft and the track assembly for concurrent pivoting movement about a hub axis defined by the rear upright;

wherein at least a portion of the back section is disposed longitudinally between the wheel axis and the front strut when the carrier assembly is arranged in the chair configuration; and

wherein movement of the carrier assembly from the chair configuration to the stair configuration simultaneously deploys the track assembly for engaging stairs and moves the rear wheel toward the front wheel such that the wheel axis is disposed longitudinally between the back section and the front strut when the carrier assembly is arranged in the stair configuration.

2 . The patient transport apparatus of claim 1 , wherein the seat section defines a front edge;

wherein the wheel axis is spaced from the front edge at a first longitudinal distance when the carrier assembly is arranged in the chair configuration; and

wherein the wheel axis is spaced from the front edge at a second longitudinal distance when the carrier assembly is arranged in the stair configuration, the second longitudinal distance being smaller than the first longitudinal distance.

3 . The patient transport apparatus of claim 2 , wherein the hub axis is spaced from the front edge at a first reference longitudinal distance when the carrier assembly is arranged in the chair configuration; and

wherein the hub axis is spaced from the front edge at a second reference longitudinal distance when the carrier assembly is arranged in the chair configuration, the second reference longitudinal distance being substantially equal to the first reference longitudinal distance.

4 . The patient transport apparatus of claim 3 , wherein the first reference longitudinal distance is larger than the second longitudinal distance; and

wherein the first reference longitudinal distance is smaller than the first longitudinal distance.

5 . The patient transport apparatus of claim 3 , wherein the second reference longitudinal distance is larger than the second longitudinal distance; and

wherein the second reference longitudinal distance is smaller than the first longitudinal distance.

6 . The patient transport apparatus of claim 2 , wherein the rear wheel defines a rear wheel radius;

wherein an axle traversal distance is defined by subtracting the second longitudinal distance from the first longitudinal distance; and

wherein the axle traversal distance is larger than or equal to the rear wheel radius.

7 . The patient transport apparatus of claim 1 , wherein the seat section is pivotably coupled to the front strut about a front seat axis and pivotably coupled to the rear upright about a rear seat axis.

8 . The patient transport apparatus of claim 7 , wherein the support structure further comprises an intermediate arm pivotably coupled to the front strut about a front arm axis and pivotably coupled to the rear upright about a rear arm axis.

9 . The patient transport apparatus of claim 8 , wherein the front arm axis is substantially parallel to the rear arm axis.

10 . The patient transport apparatus of claim 7 , wherein the rear seat axis is substantially parallel to the hub axis.

11 . The patient transport apparatus of claim 1 , wherein the seat section is pivotably coupled to the front strut about a front seat axis.

12 . The patient transport apparatus of claim 11 , wherein the support structure further comprises an intermediate arm pivotably coupled to the front strut about a front arm axis and pivotably coupled to the rear upright about a rear arm axis.

13 . The patient transport apparatus of claim 12 , wherein the front arm axis is substantially parallel to the rear arm axis.

14 . The patient transport apparatus of claim 12 , wherein the rear arm axis is substantially parallel to the hub axis.

15 . The patient transport apparatus of claim 1 , comprising a drive system including a motor operatively attached to the belt of the track assembly for driving the belt along stairs.

16 . The patient transport apparatus of claim 1 , wherein the front wheel defines a front wheel radius;

wherein the rear wheel defines a rear wheel radius; and

wherein the front wheel radius is larger than or equal to half of the rear wheel radius.

17 . The patient transport apparatus of claim 1 , wherein the rear upright comprises a lower upright end arranged adjacent to the hub axis; and

wherein the hub defines a pocket region shaped to accommodate the lower upright end therein as the carrier assembly moves between the chair configuration and the stair configuration.

18 . The patient transport apparatus of claim 17 , wherein the rear upright defines a front surface facing towards the front strut;

wherein the pocket region of the hub defines a first stop face arranged adjacent to the front surface when the carrier assembly is arranged in in chair configuration; and

wherein the pocket region of the hub defines a second stop face arranged adjacent to the front surface when the carrier assembly is arranged in the stair configuration.

19 . The patient transport apparatus of claim 17 , wherein the hub axis extends through the pocket region of the hub.