CA1294589C - Service ladder - Google Patents
Service ladderInfo
- Publication number
- CA1294589C CA1294589C CA000555374A CA555374A CA1294589C CA 1294589 C CA1294589 C CA 1294589C CA 000555374 A CA000555374 A CA 000555374A CA 555374 A CA555374 A CA 555374A CA 1294589 C CA1294589 C CA 1294589C
- Authority
- CA
- Canada
- Prior art keywords
- platform
- stair assembly
- assembly
- stair
- box
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 230000007246 mechanism Effects 0.000 description 4
- 230000000712 assembly Effects 0.000 description 3
- 238000000429 assembly Methods 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000002787 reinforcement Effects 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- 230000009194 climbing Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
Classifications
-
- E—FIXED CONSTRUCTIONS
- E06—DOORS, WINDOWS, SHUTTERS, OR ROLLER BLINDS IN GENERAL; LADDERS
- E06C—LADDERS
- E06C5/00—Ladders characterised by being mounted on undercarriages or vehicles Securing ladders on vehicles
- E06C5/02—Ladders characterised by being mounted on undercarriages or vehicles Securing ladders on vehicles with rigid longitudinal members
- E06C5/04—Ladders characterised by being mounted on undercarriages or vehicles Securing ladders on vehicles with rigid longitudinal members capable of being elevated or extended ; Fastening means during transport, e.g. mechanical, hydraulic
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Vehicle Step Arrangements And Article Storage (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A foldable ramp structure is disclosed arranged to be mounted on a pick-up truck and to be used for servicing aircraft or the like purposes wherein the ramp is to provide a stairway to an elevated point. The invention provides a first stair assembly and an intermediate platform. Both are fixedly secured to the box of the truck. A second stair assembly extends forward and horizontally away from the platform, at a level just above the top of the cab of the pick-up truck. In an extended state, it is only the second stair section which is raised by pivoting same about a transverse axis located near the rear end of the cab. m e free end of the second stair assembly is provided with a horizontal, second platform. Two separate rails are provided, one for the second platform and the other for the second stair assembly itself. The railing is foldable such that, in a folded state, it clears the intermediate platform and also does not extend beyond the forwardmost end of the second platform. The device is of a very simple structure and thus inexpensive to produce. It is especially adapted for convenient securement to an existing pick-up truck or the like, to avoid the high cost of a specialized vehicle for the purpose.
A foldable ramp structure is disclosed arranged to be mounted on a pick-up truck and to be used for servicing aircraft or the like purposes wherein the ramp is to provide a stairway to an elevated point. The invention provides a first stair assembly and an intermediate platform. Both are fixedly secured to the box of the truck. A second stair assembly extends forward and horizontally away from the platform, at a level just above the top of the cab of the pick-up truck. In an extended state, it is only the second stair section which is raised by pivoting same about a transverse axis located near the rear end of the cab. m e free end of the second stair assembly is provided with a horizontal, second platform. Two separate rails are provided, one for the second platform and the other for the second stair assembly itself. The railing is foldable such that, in a folded state, it clears the intermediate platform and also does not extend beyond the forwardmost end of the second platform. The device is of a very simple structure and thus inexpensive to produce. It is especially adapted for convenient securement to an existing pick-up truck or the like, to avoid the high cost of a specialized vehicle for the purpose.
Description
' ' 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 lZ94589 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 1:294589 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 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 1294589 ) 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.
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 lZ94589 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 1:294589 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 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 1294589 ) 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.
Claims (4)
1. A foldable ramp structure for servicing aircraft or the like, adapted to be mounted on a pick-up truck which has a given size of the box and a given height of the cab relative to the bottom of the box, said structure comprising, in combination:
(a) a normally normally generally horizontal first platform having a front end and a rear end and adapted to be fixedly secured to the box of the truck at a normally generally vertical distance from the the bottom of the box, said distance being greater than the height of the cab;
(b) a first stair assembly adapted to become fixedly secured to the box such that its upper end coincides with the rear end of the first platform and its lower end is disposed near and is fixed to 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 assembly being of a fixed length;
(d) a second platform pivotably secured 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 is generally horizontal and extends forwardly of the first platform, 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.
(a) a normally normally generally horizontal first platform having a front end and a rear end and adapted to be fixedly secured to the box of the truck at a normally generally vertical distance from the the bottom of the box, said distance being greater than the height of the cab;
(b) a first stair assembly adapted to become fixedly secured to the box such that its upper end coincides with the rear end of the first platform and its lower end is disposed near and is fixed to 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 assembly being of a fixed length;
(d) a second platform pivotably secured 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 is generally horizontal and extends forwardly of the first platform, 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.
2. A foldable ramp structure as claimed in claim 1, wherein the pivotable securement of the second stair assembly to the first platform is provided for by way of pivot means having a pair of transverse, generally horizontal axes located at a closed spacing above the top of the cab and above the forward end of the box, whereby, in the folded state, the second stair assembly extends forwardly over the top of the cab at a closed spacing therefrom and is normally generally horizontal.
3. A foldable ramp structure as recited in claim 2, wherein the second stair assembly is operatively associated with a first foldable handrail assembly of the type of a parallelogram-shaped arrangement comprising struts, one end of each strut being pivotably secured 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 stair assembly, and second link means connected to the first handrail assembly and to the second stair assembly, said second link means being to arranged and disposed that on lowering of the second stair assembly the rail moves toward the second stair assembly and away from the rear end of the first platform, and is generally flush with the second stair assembly when the latter assumes its folded position, whereby the space above the first platform is generally clear of the handrail assembly.
4. A foldable ramp structure as recited in claim 2 or in claim 3, wherein the second platform is operatively associated with a second foldable handrail assembly of the type of a folding parallelogram arrangement comprising struts, 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, the second foldable handrail assembly further comprising 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 second platform and toward the first platform and is generally flush with the second platform when the latter assumes its folded position, whereby the second rail does not protrude forwardly beyond the folded ramp.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000555374A CA1294589C (en) | 1987-12-24 | 1987-12-24 | Service ladder |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000555374A CA1294589C (en) | 1987-12-24 | 1987-12-24 | Service ladder |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1294589C true CA1294589C (en) | 1992-01-21 |
Family
ID=4137150
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000555374A Expired - Lifetime CA1294589C (en) | 1987-12-24 | 1987-12-24 | Service ladder |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1294589C (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2010097512A1 (en) | 2009-02-26 | 2010-09-02 | Bronto Skylift Oy Ab | Ladder, personnel hoist, and method for using ladder |
| CN104648622A (en) * | 2015-02-15 | 2015-05-27 | 苏州大方特种车股份有限公司 | Marine passenger ladder car |
| CN114873530A (en) * | 2022-05-11 | 2022-08-09 | 国网安徽省电力有限公司定远县供电公司 | Anti-falling climbing device for equipment maintenance of power system and working method thereof |
-
1987
- 1987-12-24 CA CA000555374A patent/CA1294589C/en not_active Expired - Lifetime
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2010097512A1 (en) | 2009-02-26 | 2010-09-02 | Bronto Skylift Oy Ab | Ladder, personnel hoist, and method for using ladder |
| EP2401223A1 (en) * | 2009-02-26 | 2012-01-04 | Bronto Skylift OY AB | Ladder, personnel hoist, and method for using ladder |
| EP2401223A4 (en) * | 2009-02-26 | 2013-11-06 | Bronto Skylift Oy Ab | Ladder, personnel hoist, and method for using ladder |
| CN104648622A (en) * | 2015-02-15 | 2015-05-27 | 苏州大方特种车股份有限公司 | Marine passenger ladder car |
| CN114873530A (en) * | 2022-05-11 | 2022-08-09 | 国网安徽省电力有限公司定远县供电公司 | Anti-falling climbing device for equipment maintenance of power system and working method thereof |
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| Date | Code | Title | Description |
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| MKLA | Lapsed |