Note: Descriptions are shown in the official language in which they were submitted.
1134
This invention relates to a stair-climbing device
adapted to transport heavy loads up and down a stairway.
More particularly, the invention is related to a load-carrying
stair-climbing device which incorporates an endless belt
mechanism by means of which the device can be used to trans- ; -~
verse a stairway with only a single operator to guide it.
Heavy loads such as hot water tanks and appliances
are usually transported up and down stairways on hand trucks. -
A great deal of effort is required to accomplish the task and
in cases where the load is excessive, two or more men may be
required to operate the truck. In an attempt to ease the ;
task, various self-propelled stair-climbing devices have been
proposed. Many such devices incorporate endless traction
mechanisms for engaging successive steps in a flight of steps
lS for lifting and lowering the device on the steps. The
advantage of such devices is that only a minimum effort is -
required on the operator's part.
Where a stair-climbing device is used to transport
very heavy loads up and down a stairway, it is important
that the operator have the device under complete control at
every moment during the time of ascent or descent. Should
the operator lose control at any time, the device may get
away from him and cause great damage to the load being
carried or to the stairway. Many of the proposed stair-
climbing devices do not afford the means for such control.
For example, where such devices are used to transport a
load down a flight of steps, they must be correctly positioned
manually at the forward edge of each step before their
traction mechanism can be used to lower them to the next step.
The operator of any of the devices, who stands behind it, can -
usually not see precisely the position of the device on the
step since his vision is impaired by the load. If the
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operator pushes the device too far forward, it will topple
over the step with resulting damage to the load and to the
next lower step.
The operator of any of the stair-climbing devices
described above may also lose control of it when it is used
to transport a load up a flight of stairs. After the device
has been deposited on each higher step by the traction
mechanism, the device is free to roll on the step. Unless
-the operator has a firm hold on the device, it may roll
forward and fall off the step. Since the operator's attention
during this time is directed to operating the traction
mechanism, it may be difficult for him at the same time to
prevent the device from rolling on the steps. -;~
It is an object of this invention to provide a
stair-climbing device having means which, when the device is
used to carry a load down a flight of steps, automatically
retards the forward advance of the device when the device is
in the required position for operation of the lowering
mechanism. The device resists being pushed off the forward
edge of the step even though the operator mistakenly attempts
to do so.
Another object of the invention is to provide a ;
device having means which, when the device is used to carry
a load up a flight of steps, automatically maintains the device
stationary on a step after the elevating mechanism has
deposited the device on that step and thereby prevents the
device from rolling forward and off the step. ~
A still further object of the invention is to provide ~ -
a stair-climbing device which is provided with retractable
wheels and which is useful for transporting heavy loads over
soft ground, gravel driveways and over curbs, doorsteps and
the like.
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The stair-climbing device of the invention may be
broadly described as comprising: a frame; wheel means
rotatably mounted to support said frame; a prime mover; means
operatively connected to the prime mover for engaging
successive steps in a flight of steps to produce displacement
of the device along the flight of steps; sensing means for ~:
detecting when said wheel means is within a predetermined
distance from the forward edge of a tread of a step; and
braking means activated by said sensing means to retard
movement of said wheel means, said braking means being
activated by said sensing means when the latter detects ~:
that said wheel means is within said predetermined distance.
The invention is described in détail below with :
; reference to the accompanying drawings in which:
Figure 1 is a perspective view of the stair-climbing
device of the invention;
Figure 2 is a side elevational view of the device;
Figure 3 is a fragmentary enlarged perspective
view of a side rail and handle of the,~j
` 20 device;
. Figure 4 is a fragmentary perspectiue view of the
lower portion of the device;
Figures 5, 6 and 6a are fragmentary side elevations
of the lower portion of the device
showing two embodiments of the
mechanism for retarding advance of
the device;
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Figures 7, ~ and 9 are fragmentary side elevations
of the lower portion of the device
showing the operation of the elevating
and lowering mechanism; and
Figure lO is a fragmentary side elevation of another
embodiment of the lower portion of
-the device.
Like reference characters refer to like parts
throughout the description of the drawings.
With reference to Figure 1, the stair-climbing
device of the invention is indicated generally 10 and comprises ;~
a pair of elongated spaced apart parallel side rails or
members 12,14, a foot plate 16 and a reinforcing cross
member 1~. A handle 20 extends between the side rails
adjacent their upper ends while an intermediate handle 21
extends outwardly from each side rail. Non-driven wheels 22,24
~ are mounted in bearings at the ends of short axles (not visiblej
f which are secured to and extend outwardly from the side rails
adjacent their lower ends. ;~
Affixed to the forward side of the sides rails 12,14
is a generally U-shaped shield 2~ having a lower portion 2ga
which protects the mechanism which raises and lowers the
J, stair-climbing device (described below) from the load as the
, load is being placed on foot plate 16 or is being removed
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~ therefrom. ~ pair of bars 30,32 extend upwardly from
`~i opposite sides of the foot plate and are connected at their
upper ends to the upper portion of shield 2~. Straps 34
' attached to bars 30,32 are provided for affixing the load to -~
;~`f the device. ~'
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With reference to Figures 1 and 2, a pair of :
wheels 36,3~ are provided at opposite sides of rails 12,14
to facilitate movement of the loaded device over level or '
inclined surfaces. ~ach wheel is provided with a pneumatic ;
tire and is mounted for free rotation in bearings provided
in wheel support brackets 40. The brackets are in turn
mounted for rotation in bearings at opposite ends of a -
shaft 42.
The position of wheel 36 is locked in the inopera-
tive position shown in Figure 1 and in the operative position
shown in Figure 2 by means of a plunger 44
slideably accommodated within aperture 46 provided in
bracket 40. A similar plunger is provided in the bracket
to which wheel 3~ is attached. Plunger 44 is biased inwardly
by resilient means, such as a tension spring (not
illustrated) and when wheel 36 is in the inoperative position
shown in Figure 1, the resilient means forces the inner end
of the plunger into an aperture ~ in the adjacent side rail
which registers with aperture 46. In such position, the ,
plunger maintains the bracket in the illustrated position. ~ ''
To move the wheels 36,3~ to the operative position,
plunger 44 and the like plunger on the opposite side of the
device are pulled outwardly to remove their inner ends from ',
the apertures in the side rails. The brackets are then
rotated to the position illustrated in Figure 2 to bring the ,
inner ends of the plungers into line with a second aperture
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'~ formed in each side rail (the aperture in rail 12 being
marked ~ ). The plungers are then released whereupon their ,
free ends pass into the latter apertures thereby locking the
brackets in position.
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When the w~éels 36,3~ are in their operative
position, the stair-climbing device may be used to transport
loads over soft ground, gravel driveways and over curbs, -
doorsteps and the like. The wheels may be moved to their
inoperative positions when the device is used to transport
a load up or down a flight of steps.
~ ith reference to Figures 1 and 3, the mechanism
for raising and lowering the stair-climbing device on a
flight of steps is indicated generally 52 and includes a
prime mover 54 which imparts rotation to an output axle 56
via a gear reducer 5~. The axle is mounted for rotation in
bearings provided in a side bracket 60. The gear reducer
is mounted on the lower surface of cross member 1~ and the
bracket is fastened to side rail 14. The prime mover is
fastened to side rai1 12 and is preferably in the form of a
reversible D-C motor selectively powered by battery 64 ;
fastened to a lower support plate (not illustrated)by strap 66 ;~
or by an external A-C source. Suitable switch means (not
illustrated) is provided for selectively connecting the prime
mover to one or the other of the two power sources.
The A.G. source is reduced to a suitable voltage
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by transformer 6~ and is converted to direct current by a
! rectifier (not illustrated). Preferably the battery 64 is
also connected to the rectifier so that the battery charges ,~
~ 25 when the raising and lowering mechanism is activated by an
A.C. sourceO
The control for the prime mover is illustrated in
Figure 3 and comprises a knurled sleeve 70 rotatable about
upper handle 20 and a conventional three position switch 72 -
having forward and reverse positions and spring loaded to
return to an intermediate off position (such as Superwinch
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model PM-2000)~ Switch 72 is connected in series with the
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04~ 34
prime mover and the power supplies. An endless cord 74 is
trained about the sleeve and the switch and the cord is
maintained under tension by coil springs 76. ~ clip 7~
maintains the cord adjacent the side rail 12. ~ -
Manual rotation of sleeve 70 as indicated by the
double-headed arrow results in a change in position of the
switch 72. Depending upon the position of the switch, the
prime mover is caused to rotate clockwise, counterclockwise
or to shut off.
With reference to Figure 1, keyed to output
axle 56 is a sprocket wheel ~2 which has trained over it a
sprocket chain ~4 which is also trained about and imparts
rotation to a driven sprocket wheel ~6. The latter sprocket
wheel is keyed to an upper driven shaft ~ which is disposed
horizontally and is journalled in bearings secured to side ~-
rails 12, 14. Two pairs of upper sprocket wheels 90a,b
and 92a(and a second hidden by shield 2~) are keyed to
shaft ~, the pairs being disposed on opposite sides of
sprocket wheel ~6. Trained around each of upper sprocket
wheels 90 and 92 are belts or sprocket chains 94a,b and
~ 96a,b respectively and as illustrated in Figure 4, the latter
j chains are trained about lower sprocket wheels 9~a,b, 100
3~ (and a wheel hidden by side rail 14 in Figure 4) respectively.
The lower sprocket wheels are all rotatably mounted to a
lower shaft 102 and are vertically aligned with the upper
~! sprocket wheels about which the same sprocket chains are trained.
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With reference to Figure 4, a triangular-shaped
bracket 104 is secured to links at the same elevation of
each of the four sprocket chains 94,96. hdjacent the outer ~;
edge of each bracket 104 an aperture 106 is formed for receipt
of a pin 107 which projects outwardly from each side of a
triangular-shaped, load-bearing shoe 10~. As illustrated,
one shoe is disposed between each pair of adjacent brackets
104. Preferably each sprocket chain 94,96 is provided with
at least two brackets 104 spaced 1~0 apart on the chain.
The chains are thus provided with two sets of load-bearing
shoes 10~
The aperture 106 formed in each bracket is larger
in cross-section than the pin 107 accommodated therein so
that the shoe may rotate freely in the bracket. The pins ;~
of each shoe are located adjacent an apex of the pin to
ensure that the flat lower side lO~a of the shoe opposite
the apex lies horizontally by force of gravity when the shoe
is travelling in the vertical reaches of the sprocket chains
and when it is travelling around the lower sprockets wheels
20 9~,100. It is unnecessary that the flat side lO~a be ;
similarly oriented when the shoes are passing around upper
sprocket wheels 90,92 and hence the brackets 10l~ to which
the shoes are attached need not be constructed to allow the
shoes to rotate freely when the shoes are so located.
A sheave 110 is rotatably mounted to upper shaft
adjacent side rail 14 and a like sheave (hidden by shield 2~)
is also rotatably mounted to shaft ~ adjacent side rail 12.
Vertically aligned with these sheaves is a pair of like
sheaves rotatably mounted to lower shaft 102. A belt 112,
i composed of rubber or similar relatively soft material, is
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trained about each pair of vertically aligned sheaves. The
sheaves are of sufficiently large diameter that the belts
project beyond the side edges and loweredges of side rails
12,14 and thereby serve as guards against damage to stairs
being traversed by the stair-climbing device.
The stair-climbing device is equipped with sensing
means in the form of arms 114,116 which are rotatably mounted
to the axles upon which wheels 24,22 respectively revolve.
The arms are of like construction and hence the structure and
operation of only one arm (114) will be described. Arm 114
tapers forward of wheel 24 and terminates at a rounded forward
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end portion 114a to which a sensing head/is attached. As -
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shown, the sensing head is in the form of a roller journalled
in bearings in the arm end portion 114a.
Arm 114 is provided with a flat lower surface 120 to
which is affixed braking means in the form of a friction plàte
122. The lower surface 122a of the friction plate has a
relatively high coefficient of friction and is preferably
disposed on arm 114 such that as the arm rotates, the lower
friction surface 122a revolves in the same vertical plane as
an imaginary line (marked 124-124) which revolves about the :
lowermost point on the circumference of wheel 24.
While the sensing head 11~ is in contact with tread
126 upon which the wheel 24 is rolling, the head maintains
the lower friction surface 122a above and out of contact with
the tread. When the sensing head is beyond the forward
edge 126a of the tread, as depicted in Figure 6, the arm 114
- rotates downward about the wheel axle until the friction
surface contacts the stair tread. Where the lower friction
surface is disposed according to the preferred embodiment
described above, its entire area will contact the tread.
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Resilient means in the form of a coil tensionend
spring 130 is attached at one/to a lug 132 on the upper side
of the arm and the upper end of the spring is fastened to a
pin 13~ attached to the side rail. The spring urges the arm
to pivot clockwise and hence serves to bias the sensing
head 114 downwardly and, as illustrated in Figure 6, to cause
the friction surface 122a to move into contact with the tread
when the sensing head is beyond the forward edge of the tread.
With reference to Figure 6a~ a bifurcated braking
member 136 is pivotally connected at 13~ to arm 140 between
sensing head 142 and wheel 24a. The braking member comprises
a lower limb 136a having an intermediate head 146 adapted to
contact stair tread 147 and an upper limb 136b having braking
means in the form of a braking shoe 150 conforming in shape
15 to the periphery of wheel 24a and disposed in appositlon ~-
thereto.
Braking member 136 may be provided in lieu of the
friction pad 122 illustrated in Figures 5 and 6 or it may be ~ ~;
provided on the arm in addition to the friction pad.
The operation of the stair-climbing device is
explained with reference to Figures 5 to 9. With reference
first to Figures 5 and 6, the arm and sensing head therein
illustrated are us-efully employed when the device is used to ;
carry a load down a flight of steps. In such a case, the
operator will be standing behind the stair-climbing device on
a higher step than the one on which the device rests and he
will be gripping upper handle 20 or intermediate handles 21.
The operator's vision of the wheels 22,24 will,
in most cases, be blocked by the load carried by the device
30 and he will be unable to see how close the wheels are to the -
front edge of the stair tread. By means of the arm and ~ ~;
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sensing head, however, he will be able to detect when the
wheels are adjacent the front edge. The reason is that
when he pushes the device from the rear, it will roll on the
wheels toward the forward edge 126a of the tread until the
sensing head 11~ (and the like head at the opposite side of
the device) is beyond the edge. The heads will thereupon
drop and the friction surfaces 122a will descend into contact
with the tread. Once contact is made, the friction surfaces
impede or halt further forward movement of the device and the
operator will know that the lowering mechanism must be
activated.
When the stair-climbing device is equipped with
the braking assembly illustrated in Figure 6a, a positive
braking force is applied to wheel 24a when the sensing head
142 is beyond the forward edge of the stair tread. This is
because when the head is beyond the forward edge, it causes -~
the arm 140 to rotate clockwise downwardly. As the arm
rotates, the intermediate head 146 is caused to move upward
relative to the arm and the braking shoe 150 pivots into
positive contact with the periphery of the wheel.
When further forward movement of the stair-climbing
.~r
assembly is halted by the friction surface 1~2a and/or by the
braking member 136 of Figure 6a, the lowering mechanism
described above is activated. The mechanism is activated by
rotating the sleeve 70 on the upper handle to cause the prime
mover to rotate the sprocket chains clockwise in the direction
of the arrow in Figure 7.
As sprocket chain 94a in Figure 7 rotates, the
load-bearing shoe 10~ descends from the right of lower
sprocket wheel 9~a and when its lower surface is below the
lowermost edge of the wheel 24, the shoe elevates the
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stair-climbing device above the stair tread. As the shoe
continues to rotate about the lower sprocket wheel, the
stair-climbing device is elevated and is moved horizontally ~ ~ -
forward, as shown in Figure ~. When the shoe is in the
upwardly moving reach of the sprocket chain as shown in
Figure 9, wheel 24 has cleared the forward edge of the stair
tread and the stair-climbing device descends as the shoe
continues in its upward path toward the upper sprocket wheel.
As the shoe moves upwardly, arm 114 hangs freely, ~;
balanced at approximately 45 from a horizontal position.
When the sensing head 11~ touches the tread of the next
lower step, it raises the arm and the arm remains elevated ~;
until the sensing head again falls over the forward edge of
the next step. ~;
When the wheels 22,24 contact the next lower step ;
in succession, the weight of the loaded stair-climbing device
transfers to the wheels from the shoes. The sprocket~
chains should be rotated further clockwise to lift the shoes
off the stair tread so that the shoes will not prevent the
device from being moved forward. The device is then manually
rolled forward on the stair tread until the sensing head
drops downward in the manner described before and the lowering
mechanism is again activated.
Should the stair-climbing device be used to carry
a load up a flight of steps, the device is rolled backward~ ;
toward the lowermost step until the belts 112 at the rear side
of the device contact the forward edge of the next higher step
in succession. The prime mover is then activated to cause
the sprocket chains 94,~96 to rotate counterclockwise and -
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thereby cause the two adjacent load-carrying shoes above and
closest to the next higher step to descend into contact with
the tread of that step. The shoes being pivotally connected
to the sprocket chain will rock upon contact with the tread
until their entire lower surfaces are in contact with the
tread. Further counterclockwise rotation of the sprocket
chains will result in elevation of the device by the shoes.
When the device ascends to the step on which the
lifting shoes are resting, as shown in Figure ~, the shoes
will be adjacent the lower sprocket wheels 9~,100. As the
shoes rotate about the sprocket wheels, the stair-climbing
device will be drawn horizontally rearwardly to the position
shown in Figure 7. Subsequently, as the shoes begin to
ascend on the upwardly travelling reaches of the sprocket
chains, the wheels 22,24 of the device will be deposited on
the tread.
When the device is in the position shown in
Figure 7, the friction pad 122 and/or the braking shoe 150
will prevent the device from rolling toward the forward
edge of the stair tread. By manually rolling the device - -
backward toward the next higher step, the sensing head will
roll up and over the forward edge of the step thus lifting
the friction pad and/or causing the brake shoe to separate
from the wheel 24. Thus the loaded assembly will be under
control during the entire ascent of a flight of stairs.
The horizontal movement of the stair-climbing
device brought about by the shoes as they rotate about the
lower sprocket wheels must be sufficient to displace the
device from a position in which its wheels are squarely on
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a tread (as depicted in Figure 7) to a position in which
the device clears the tread (as depicted in Figure 9). The
extent of horizontal displacement of the device will depend
upon the diameter of the lower sprocket wheels and the offset
of the load-bearing shoes 10~ from the sprocket chains 9~,96.
By correct choice of sprocket wheel diameter and dimension
of brackets 104, the stair-climbing device will be displaced
the required distance as the shoe rotates about the lower
sprocket wheels.
With reference to Figure 10, a frusto-spherical ~;
pad 154 is provided beneath and midway between the side
edges of foot plate 16. The pad is composed of strong, ;
tough material having a relatively low coefficient of
friction. The pad is provided to facilitate rotation of
the loaded stair-climbing device about a generally vertical ;~
axis. The pad is particularly useful where the direction ~
of movement of the device must be changed in a confined ;
space such as on a landing or in a tight corner. To make
use of the pad, the side rails 12,1~ of the device are
tilted upward until they are substantially vertical. The
device will then be resting wholly on the pad and may be
easily rotated about a vertical axis until it is correctly
positioned for further movement.
It will be understood, of course, that modifications
2S can be made in the preferred embodiments of the invention
described and illustrated herein without departing from the
scope and purview of the invention as defined in the
appended claims.
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