Stair lift

A stair lift incorporates a pair of power jacks linked to a stair or step and associated with a vehicle such as a trailer adjacent the vehicle doorway, with the jacks operating in tandem to raise or lower the stair or step with a person standing thereon.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The invention relates to means for automatically raising or lowering a 
stair or step with a person standing thereon relative to a vehicle for 
facilitating entry into or egress from the vehicle of the person should he 
be elderly or infirm. 
2. Description of the Prior Art 
A wide variety of devices is available for raising or lowering a vehicle 
stair or step while carrying a load. However, for the most part, they are 
complicated in their structure, unreliable in their use, or expensive in 
their manufacture. 
SUMMARY OF THE INVENTION 
The invention incorporates a pair of power jacks linked to a stair or step 
and associated with a vehicle such as a trailer adjacent the vehicle 
doorway, with the jacks operating in tandem to raise or lower the stair or 
step, with a person standing thereon, the structure being uncomplicated, 
reliable and inexpensive.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
With reference to FIG. 1, a stair lift 10 embodying one form of the 
invention is associated with the side wall of a wheeled recreational 
vehicle RV, such as a trailer or the like, adjacent a doorway D of the 
vehicle, the doorway being situated at a relatively high level above the 
ground or road G, making it difficult for the elderly or infirm to enter 
or exit the vehicle. 
Stair lift 10 includes a pair of identical, spaced, parallel, 
vertically-disposed jack assemblies 12, one disposed at each side of 
doorway D and supporting a stair or step 14 extending horizontally between 
their lower ends below the doorway. 
Each jack assembly 12 is supported in spaced relation to a side of the RV 
by upper and lower L-shaped brackets 16 and 18 respectively. 
Each upper bracket 16 includes a vertically-disposed brace 20 fixed to the 
RV side wall and a horizontally-disposed brace 22 fixed to and extending 
outwardly from the upper end thereof. 
Each lower bracket 18 includes a pair of spaced, parallel 
vertically-disposed upper and lower braces 24 and 26 respectively, a lower 
horizontal brace 28 which connects between the lower end of brace 24 and 
the upper end of brace 26, and an upper horizontal brace 30 which extends 
outwardly from the upper end of upper vertical brace 24. 
Lower vertical brace 26 of each lower bracket 18 is fixed to a vehicle 
support frame member F which extends the length of the RV and is disposed 
inwardly of the RV side wall below door D. 
Gussets 32 extend between each of the braces 24 and 30, 24 and 28, and 26 
and 28 of each lower bracket 18 to strengthen the structure. 
An outer cylindrical sleeve 34 of each jack assembly 12 passes vertically 
through and is rigidly held by the horizontal braces 22 and 30 of upper 
and lower brackets 16 and 18 respectively. 
Outer cylindrical sleeve 34 of each jack assembly 12 is fixed at its upper 
end to the bottom wall of a housing 36 which contains a 12-volt motor 38, 
a light 40, a light switch 42 and a three-way power switch 44, with 
electric leads 46 connecting these components to each other and to the RV 
battery, not shown. 
Motors 38 each incorporate an override clutch, not shown, to prevent the 
jacks from overextension, overretraction, or overload. 
Each three-way switch 44 includes an off mode, or central position, an 
extension mode, or down position, and a retraction mode, or up position. 
A vertically-disposed externally threaded ram 48 of each jack assembly 12 
is linked at its upper end to motor 38 and is rotated by the motor. 
Ram 48 of each jack assembly 12 is sleeved by an inner internally threaded 
cylindrical sleeve 50 telescopically sleeved by outer cylindrical sleeve 
34. 
The lower end of inner sleeve 50 of each jack assembly 12 is disposed in 
the open mouth of a cylindrical foot pad 52 fixed to and extending 
upwardly from the upper surface of stair or step 14 adjacent the opposite 
ends of the latter. 
A locking pin 54 extends through provided openings, not shown, in each foot 
pad 52 and sleeve 50 to insure against separation of the two components. 
Jack assemblies 12 operate in tandem upon activation of one of the power 
switches 44. 
Activation of motors 38 by switch 44 effects rotation of each ram 48 
relative to its inner sleeve 50 to raise or lower stair or step 14 as 
desired through a distance of approximately sixteen and one-half inches in 
approximately sixty-five seconds. 
Each jack assembly 12 has a lifting capacity of 2500 pounds. 
Thus, stair lift 10 can easily and safely support a person standing on 
stair or step 14 when the stair is raised or lowered relative to the 
ground or road G, to facilitate entry into or exit of the person from 
trailer doorway D. 
While a one-part stair or step 14 is acceptable when the RV is to be 
permanently parked, it is not desirable when the vehicle is to be moved 
since it protrudes outwardly an unwanted distance from the side of the 
vehicle making it difficult to maneuver the vehicle in narrow or confined 
spaces. 
Accordingly, a modified two-part folding stair or step 114 is provided and 
is illustrated in FIGS. 4-8. 
In this embodiment, when the vehicle is parked the stair is placed in an 
unfolded or use position as shown in FIGS. 4, 5 and 6. 
When traveling, the stair is placed in a folded or non-use position as 
shown in FIGS. 7 and 8. 
Stair 114 includes a fixed rear portion 116 and movable front portion 118. 
Rear portion 116 has a pair of cylindrical foot pads 152 fixed thereto 
adjacent its rearward edge and extending upwardly therefrom at each end 
thereof, with the lower ends of the inner cylindrical sleeves 50 of each 
jack assembly 12 being secured therein as with the one-part stair 14 of 
FIGS. 1-3. 
A flange 120 extends vertically upwardly from each end of rear portion 116. 
Movable front portion 118 is pivotally mounted to rear portion 116 by a 
pair of pivot bolts 122 for movement between a horizontal or use position 
wherein it is aligned with rear portion 116 and a vertical or non-use 
position wherein it is disposed normal or perpendicular to rear portion 
116. 
Pivot bolts 122 pass freely through aligned openings in flanges 120 of rear 
portion 116 and pair of upright transversely-extending flanges 124 of a 
pair of angle irons 126 fixed to front portion 118 at each end thereof. 
Upright flanges 124 of angle irons 126 are spaced outwardly from flanges 
120 of rear portion 116. An integral web 128 of each angle iron is fixed 
to the lower surface of front portion 118 and extends rearwardly from said 
front portion and underlies and supports rear portion 116 when the front 
portion is in a horizontal or use position. 
Nuts 130 are threaded on the ends of pivot bolts 122 to retain the bolts in 
position. 
Reflectors 132 are provided on the outer faces of upright flanges 124 so 
that stair or step 114 is readily visible at all times. 
Of course, similar reflectors, not shown, may be provided on stair or step 
14. 
When it is desired to move front portion 118 of stair or step 114 to a 
non-use position, its front edge is moved upwardly causing the front 
portion to pivot relative to pivot bolts 122 and fixed rear portion 116 to 
an upright position as shown in FIGS. 7 and 8. 
Locking pins 134 may be inserted in aligned openings 136 and 138 provided 
in flanges 120 and 124 respectively at each end of stair or step 114 to 
secure front portion 118 in either a raised or lowered position. 
A longitudinally-extending brace, not shown, may be provided below the 
opening between the front edge of rear portion 116 and the rear edge of 
front portion 118 to further strengthen the stair structure.