Note: Descriptions are shown in the official language in which they were submitted.
' ' lZ9~589
~ield of the Invention
-
The present invention relate~ to a foldable ramp
structure ~uch as folding scaffolds or access assemblies
used for servicing aircraft or other devices dispo~ed at
an elevated levei. m e ramp is of the type adapted to ~e
~ounted on a ~tandard size pick-up truck having a given
8 ize of the box and a given height of the cab.
Background of the Invention
It has long been known to provide 6caffolds or
ramps in which a 8tair assembly, usually provided with a
parallelogram mechanism maintaining the stair steps in a
horizontal position, is ~ounted on a mobile base such as a
pick-up truck or on a special frame for the scaffold
itself.
Reference may be had in this context, for
instance, to U.S. Patent 2,362,170 issued to R.H.
Swaisgood on November 7, 1944 and showing a mo~ile base
which has a stair assembly provided at its free end with a
platform which i8 generally horizontal. From the
standpoint of the present invention, the device is
disadvantageous in that even when it assu~e6 a fully
folded position, its railings still protrude well above
the level of the folded stair a~embly requiring extra
overhead ~pace for storage.
U.S. Patent 3,529,694, issued to G.L. Atschey on
September 22, 1970, di6closes a foldable assembly or
collapsible scaffold wherein two arms arranged in parallel
to each other are provided with a generally permanently
horizontal platform disposed between the two arms~ The
arms are secured to the box of a pick-up truck such as to
pivot about a point which i6 close to the rear end of the
pick-up box. The device does not provide convenient
access from the ground to the horizontal platform at the
free end of the arms. me 6tructure is very complex and
thus expensive to manufacture and to maintain. The
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folding of the scaffold itself i8 cumbersome. There is no
access by stair~ or by a ladder to the platform of the
~caffold.
U.S. Patent 2,164,327, issued to P.E. Ha~kins on
July 4, 1939 ~hows another arrangement of an extensible
ladder pivotably ~ecured to the box of a truck. The
securement to the truck requires ~pecial arrangements on
the truck as the ladder is arranged on a pivotable basi~
which is itself a complex structure. Besides, the railing
of the ladder is not foldable which result6 in that the
overall structure plu8 the supporting mobile base i8 too
high which Day give rise with problems in naneuvering the
vehicle and parking same in a garage of a limited height.
Another complex structure of the type i5
disclosed in Canadian Patent 937,711 issued December 4,
1973 to J.F. Sauer et al., the patent corresponding to
U.S. Patents Nb~. 3,625,306 and 3,664,456. Evaluated from
the standpoint of the present invention, the Sauer et al.
arrangement comprises two 6tair sections which are
slideable relative to each other. This arrangement is
space con6uming and relatively comple~ to operate. Also,
the railing and other elements of the platform at the end
of the ramp provided on extension is bulky and space
consuming. The overall structure i8 very complex and in
actual application would probably require a fiubstantial
modification of the supporting vehicle. It could not be
successfully used on a regular, standard size pick-up
truck.
Summarv of the Invention
It iR an object of the present invention to
provide a ramp or folding scaffold of the above type,
wherein the structure is substantially simplified and
allows attachment to an existing standard pick-up truck
without expensive modifications of the vehicle. Another
object of the present invention is to provide a device of
129~5~9
the aforesaid type which would require a minimum space
above the confines of the maximum height of the pick-up
truck. The confines are usually determined by the height
of the top of the cab of the vehicle.
In accordance with the present invention, a
foldable ramp structure i8 provided for servicing aircraft
or the like devices at an elevation above the ground. The
foldable ramp is adapted to be mounted on a pick-up truck
having a given size of the box and a given height of the
cab relative to the bottom of the box, said ~tructure
comprising, in combination: (a) a normally qenerally
hori~ontal fir~t platform having a front end and a rear
end and adapted to be fixedly ~ecure to the box of the
truck at a normally generally vertical aistance from the
bottom of the box, said distance being greater than the
height of the cab (b3 a fir6t stair assembly adapted to
become fi~edly secured to the ~ox ~uch that its upper end
coincides with the rear end of the first platform and its
lower end i8 disposed near the rear portion of the box;
(c) a second stair assembly having a rear end and a front
end, the rear end being pivotably secured to the front end
of the first platform, said second stair ~ssembly being of
a fixed length; (d) a second platform pivotably eecured to
the front end of the second stair assembly; (e) motor
means for selectively raising the second stair assembly
from a folded position, wherein the second stair assembly
i8 generally horizontal and extends forwardly of the first
platform, at a close spacing above the cab, to an extended
position, wherein the second stair assembly extends
upwardly and forwardly of the first platform; (f) first
link means operatively associated with the second platform
and with the second stair assembly to maintain the second
platform in a generally horizontal position regardless of
the instant inclination of the second stair assembly.
In a particularly preferred embodiment, the
pivotal ~ecurement of the second stair assembly to the
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first platform is provided by way of pivot means having a
tran6verse, generally horizontal axis which i~ located at
a close spacing above the top of the cab and above the
forward end of the box, whereby, in a folded state, the
second stair as~embly, when brought to a folded state,
extends forwardly over the top of the cab at a clo6e
spacing therefrom and i6 normally generally horizontal.
According to another preferred feature of the
present invention, the ~econd stair assembly is
operatively associated with a first foldable handrail
as6embly of the type of a parallelogram-shaped arrangement
~omprising a number of struts, one end of each strut being
pivotably 6ecured to the second stair assembly for
pivoting about a transverse axis, the other end being
pivotably secured to a rail generally parallel with the
second ~tair assembly, and ~econd link means connected to
the first handrail assembly and to the second stair
assembly, said second link means being 80 arranged and
dispo6ed that on lowering of the second stair assembly,
the rail moves toward the second stair assembly and away
from the first platform and is generally flush with the
~econd stair a~sembly when the latter assumes its folded
position, whereby only a ~mall space above the first
platform is taken by the handrail assembly.
It is also of advantage if the platform is
operatively associated with a second foldable handrail
assembly of the type of a folding parallelogram
arrangement comprising strut6, one end of each strut being
pivotably secured to the second platform, for pivoting
about a transverse axis, the other end being pivotably
secured to a second rail generally parallel with the
second platform, and third link means connected to the
second handrail assembly, said third link means being so
arranged and disposed that, on lowering of the second
stair assembly, the second handrail moves toward the
129~58~
secQnd platform and toward the first platform and iB
generally flush with the second platform when the latter
assumes it folded position, whereby the second rail does
not protrude forwardly beyond the folding ramp.
Brief Description of the Drawings
The present invention will now be described in
greater detail with reference to the accompanying
simplified drawings wherein:
FIGURE 1 i8 a simplified diagrammatic ~ide view
representing a pick-up truck with the ramp of the present
invention mounted thereon, the ramp being shown in a
folded state;
FIGURE 2 i8 a view similar to that of FIGURE 1
but showing the ramp in an extended state;
FIGURE 3 is an enlarged detail III of FIÇURE l;
FIGURE 4 is an enlarged detail IV of FIGURE l; and
FIGURE 5 i6 a simplified, diagrammatic rear view
taken from the left hand side of FIGURE 1.
Detailed Description
Reference numeral 10 designates a pick-up truck
of a atandard type, comprising a cab 11, a box 12 a pair
of front wheels 13 and a pair of rear wheel~ 14. The cab
11 has a predetermined ~tandard height relative to the
bottom 15 of the box 12.
Fixedly secured by bolting and/or by welding to
the bottom 15 of the box 12 (and through it to the frame
of the pick-up truck 10) is a normally generally
horizontal first platform 16. The platform is mounted at
its front end on a pair of upright supports 17. The rear
end of the first platform 16 is fixedly secured to the
upper end of a first stair assembly 18. m e lower end of
the first stair assembly 18 rests on and is fixedly
secured to the bottom 15 of the box 12 as best seen in
FIGURE 5.
m e securement of the first stair assembly 18 and
of the supports 17 i~ carried out in the usual way. There
lZ~4589
may be reinforcement members between the first stair
assembly 18 and the supports 17 to further enforce the
rigidity of the overall arrangement of elements 16, 17, 18.
It is apparent on review of FIGURE 5 in the
context of FIGURES 1, 2, 3 and 4, that many of the
elements of the ~tructure to be described are provided in
pairs, one at each side. One of such pair~ of elements is
represented by a generally triangular bracket 19
(FIGURE 4) which i8 fi~edly eecured by welding to the
upper end of each of the 6upports 17. m e bracket 19 thu6
forms an integral part of the supports 17 and of the first
platform 16. Ihe bracket 19 6erves the purpo6e of
securing to the front end of the first platfor~ 16 two
pairs ~f longitudinal members of what iæ generally
referred to as a second stair assembly. The uppermost
part of the bracket 19 defines a pivot point 20 about
which one end of a pair of upper longitudinal ~embers 21
of the ~econd stair assembly can pivot counter-clockwise
from a folded position shown in FIGURE 1, and clockwise
from the extended position shown in FIGURE 2. There is
another pivot point at 22 pivotably securing one end of a
pair of lower longitudinal ~ember6 23 to the bracket 19
(and thus to the platform 16). The 6en6e of pivotiny of
the member6 23 is the same as that of the upper
longitudinal member 21. In the embodiment shown, the
upper longitudinal members 21 are gteel rods of circular
cross-section while the lower longitudinal members 23 are
channel shaped.
The pivoting movement of the second stair
assembly is indicated by arrow A in FIGURE 2. The arrow A
shows the pivoting of the second stair assembly from an
extended position to a folded poæition.
At the downwardly facing side of the lower
longitudinal members 23 is disposed a pair of brackets 24
' ` 12~45891
(FIGURE 2) pivotably securing one end of an arm 25 to the
lower longitudinal member 23. The other end of the arm
25, in turn, pivots about a lower arm 26 on actuation of a
hydraulic cylinder 27. The casing of the hy~raulic
cylinder 27 is secured to a pair of brackets 28 mounted at
the corner formed by a horizontal reinforcement Dember 29
nnd a vertical support 30 whose lower end i8 suitably
fi~edly ~ecured to the bumper 31 of the truck 10 or to
another auitable element connecting the vertical support
30 with the frame of the pick-up truck 10. There is a
second upwardly oriented strut 32 to further reinforce the
frame supporting the mechanism of the hydraulic cyl~nder
27. The arrangement of the mechanism of the arms 25, 27
and of its a6sociated parts i8 well known in the art and
therefore does not have to be described in greater
detail. It can be substituted by many other known
~echanisms for selectively raising or lowering the second
stair ~ssembly.
The pick-up truck itself i8 further provided with
four hydraulic cylinders of which the front cylinders 33
are also suitably secured to the front bumper of the truck
while the rear cylinder~ 34 are fixed to the rear bumper
of the trucX. It should be mentioned at this point that
the rear bumper 35 of the truck can be provided with a
step 36 to facilitate the climbing into the box from the
rear end of the pick-up truck 10.
Turning now back to the second stair assembly,
the front or free end of the upper longitudinal member 21
is pivotably secured to an upper or second platform 37 at
38. Similarly , the lower longitudinal member 23 is
pivotably secured to the same platform at 39. The mutual
arrangement of pivots 38, 39 is such that the two points
38, 39, the aforesaid pivots 20, 22 and the longitudinal
members 21, 23 define a parallelogram, as is well known in
the art. A~s best seen from PIGURE 3, the pivot 39 is
1~9'~589
disposed at a lower end of a bracket 40 which is integral
with the platform 37. Thus, the pivot points 38, 39
coincide with two levels which are spaced one above the
other to allow the assuming of a full horizontal po6ition
of each of the longitudinal member~ 21, 23, in which the
aembers are disposed one above the other. The position of
the second platform 37 remain~ the 6ame, i.e. generally
horizontal, regardless of the degree of inclination of the
longitudinal ~embers 21, 23 and thus of the ~econd stair
assembly caused by pivotal movement along the path of the
arrow A of FIGU~E 2. The bracket6 40 and pivot6 38, 39
therefore constitu~e ~first link ~eans" for ~aintaining
the second platform 37 generally horizontal at all times.
The second stair assembly further utilizes the
parallelogram arrangement of the longitudinal elements 21,
23 for ~aintaining a plurality of steps 41 in a generally
horizontal position at any inclination of members 21, 23.
Thi6 is effected by mounting each of the steps pivotably
about a pivot point 42 a~ the upper longitudinal member
21. m us, as shown in FIGURE 3, in the folded position,
the steps 41, being generally horizontal, are flush with
the upper longitudinal members 21 which are now al80
generally horizontal. m e end of each step 41 remote from
its pivot 42 is provided, at each side, with a right
angled bracXet having a generally vertical arm depending
downwardly to a pivot point 43 at the lower longitudinal
member 23. Thus, the steps form a parallelogram
arrangement which retains a horizontal position generally
in the same sense as the second platform 37 at the free
end of the second stair assembly.
The second stair assembly is further provided
with a pair of handrail assemblies 44, one on each side of
the second stair assembly, as indicated in FIGURE 5. Each
handrail assembly 44 is arranged to fold, on folding of
the second stair assembly, in a way which will now be
129~589
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described in greater detail. The representations of
FIGURES 1, 2, 3 and 4 show only one of the handrail
asQemblies 44 as the other a~sembly iB not visible in
those side views.
Turning now to FIGURES 1 - 4, the handrail
assembly 44 (al60 referred to as "a first foldable
handrail assembly") is comprised of four atruts 45, 46, 47
and 48. Each strut is pivotably secured, near its one
end, to the upper longitudinal member 21. In FIGURE 3,
the pivotal securement of strut 48 is indicated by way of
a pivot point 49. A short length of the ~trut 48
protrudes downwardly of the pivot point 49 and i~ normally
guided during the pivotal motion of the strut 48 ~y a
generally triangular guide plate 50 which is integral with
the upper longitudinal member 21. The opposite end of
each of the struts 45 - 48 i8 secured to a rail member 51
by way of a pivotal ~ecurement. Thus, the strut 45 is
pivotally ~ecured to the rail 51 a~ 52, the 6trut 46 at
53, the strut 47 at 54 and the strut 48 at 55. As best
seen from FIGURE 4 and FIGURE 2, the strut 45 is further
connected, by way of second link means 56, with the lower
longitudinal member 23. The link 56 is pivotally ~ecured
at its one end, to the strut 45 by a pivot 57 and, at the
other end, to a pivot 58 which is provided in a bracket
integral with the longitudinal member 23 as best seem in
FIGURE 4. It i6 to be mentioned at this point that the
strut 45 pivotably secured to the upper longitudinal
member 21 at a pivot 59. The arrangement is identical to
that of the strut 48 and does not have to be described in
greater detail. It will thus be appreciated that when the
second stair assembly, which ia generally comprised of the
two pairs of longitudinal members 21, 23 and of the
associated stairs 41, moves clockwise in FIGURE 2 to a
folded state, the distance between pivot points 59 and 58
gradually increases. With the length of the link 56 and
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of the associated part of the strut 45 remaining the same,
the movement results in gradual pivoting of the strut 45
and, due to the connection with the rail 51, ~1BO of the
remaining struts 46, 47 and 48, clockwise relative to the
5 stair assembly, to as6ume a folded state, shown in
FIÇURE 1, in which the second 6tair 2ssembly iE~ generally
hori~;ontal. It will be ~een that in this folded ~tate the
railing 51 i6 only very slightly above the rest of the
~nem~ers of the assembly and can thus be termed as being
10 ngenerally flush" with the 6econd stair assembly.
mere i8 a second handrail assembly 60
operatively associated with the ~econd platform 37. The
second l-andrail assembly comprises, at each gide of the
second platform 37, two çtruts 61, 62 connected, at their
15 free end, with a rail 63 at pivots 64, 65 (FIGURE 3),
respectively. me lower ends of struts 61, 62 are
pivotably secured to the platform 47 at pivots 66, 67
respectively. A link 68 (al80 referred to as ~third link
means") is pivotably secured to the strut 62 at pivot 69.
20 The opposite end of link 68 is pivoted to the lower
longitudinal member 23 at 70. It can be laeen on
comparison of the arrangement of FIGURE 2 and FIGVRE 3
that when the second rail assembly of FIGliRE 2 is moved to
the folded position (clockwise-arrow A) then this not only
25 results in the aforesaid pivoting of struts 45 - 48
clockwise relative to the second stair assembly (arrow B
in FIGURE 2) but also in an anti-clockwise pivoting (C in
FIGURE 2) of the struts 61, 62.
Thus, the folding of the two handrail assemblies
30 is such that, on folding, the railing does not protrude
over the forwardmost part of the second stair assembly,
nor does it protrude beyond the rear end of the second
stair assembly leaving the intermediate or first platform
16 clear.
The embodiment shown in the drawings is intended
for use in servicing aircraft and is provided with a
lZ5~4S~9
resilient concave ~hield 71 6u6pended from the lower
longitudinal member 23. The 6hield i6 simply intended to
reduce the specific weight at which the free end of the
extended rail a6sembly rests on the wing of an aircraft.
The arrangement of the 6hield 71 does not form a part of
the present invention and could be replaced by ~ny other
~uitable accessory depending on the intended use of the
present invention.
It will be appreciated upon review FIGURE 1, that
the vehicle provided with the present invention iB
relatively compact in the folded state ~nd can be easily
maneuvered around aircraft or the like.
In operation, the vehicle i8 driven to the
proximity of the site to be serviced, for in~tance the
wing of an aircraft. When the vehicle is near the
aircraft, the second rail assembly i6 raised from the
position of FIGURE 1 to the position of FIGURE 2 and the
vehicle is slowly driven towards the front edge of the
wing. Due to the location of the second stair assembly,
the ghield 71 can be conveniently observed by the operator
of the pickup. Once engaged with the aircraf~ wing, the
vehicle 10 i~ stabilized by engaging the stabilizing pads,
associated with hydraulic cylinders 33 and 34, with the
ground as shown in FIGURES 1, 2 and 5. The device is now
ready for the maintenance crew to climb onto the aircraft
wing or the like.
The present invention provides a light-weight,
relatively simple arrangement which can be produced such
as to fit the standard size of pick-up trucks. Due to the
low weight and relatively compact arrangement in the
folded state, it is particularly suitable for applications
in environment which does not have the provision of smooth
ground and where, therefore, speciali~ed scaffolds would
be relatively difficult to move around the rough terrain.
The structural simplicity of the device results in a
relatively low production cost.
~` lZ94589
mose skilled in the art will readily appreciate
that many elements of the present invention can be
substituted by an number of mechanical equivalents. For
instance, the arrangement to retain the steps 41 in a
horizontal position can be made by many other different
parallelogram mechanisms one of them being shown in U.S.
Patent 2,362,170 referred to above. The folding of the
railings can also be carried out in many different ways.
Accordingly, the present invention i6 not be be
viewed as being limited to the ~hown exemplary embodiment
but includes all such embodiments as properly fall within
the scope of ~y contribution to the art.
