GB2423760A

GB2423760A - Mobile scissor lift

Info

Publication number: GB2423760A
Application number: GB0501622A
Authority: GB
Inventors: Haroutune Kesterlian; Misak Kesterlian
Original assignee: AFTEC Ltd
Current assignee: AFTEC Ltd
Priority date: 2005-01-26
Filing date: 2005-01-26
Publication date: 2006-09-06
Also published as: GB0501622D0

Abstract

A load distribution device has a chassis 1 with wheels 4, 5 or similar means to allow it to be moved, a platform 6 for supporting a load and a lazy tong or scissor lift 5 to raise and lower the platform. The device may be used with palletised loads which may be air freight unit load devices. The raised height of the platform H2 may be 1500mm and the lowered height may be 500mm. The scissor mechanism may be within the frame of the chassis when the platform is lowered. The platform may have rollers, wheels or bearings to allow the load to be moved on the platform. They may be arranged to allow the load to be moved in two different directions and may be passive, driven or a mixture of both.

Description

LOAD DISTRIBUTION DEVICE

The invention relates to a device for distributing a load about a storage space, especially a palletised load, and for example an air freight load, in a warehousing and/or distribution system.

Air freight handling is a particularly standardised logistical field, with regulations developed by the likes of the International Air Transport Association (IATA) in conjunction with carriers and container manufacturers tending to produce a relatively standardised set of system and logistical requirements. The present invention relates in particular to such systems.

Air freight loads are typically carried in standard containers, known as unit load devices (ULDs). For handling at a distribution centre, these are typically palletised. The palletised loads are handled within the distribution centre typically by means of roller track paths fixed to the floor. Truck dock areas for onward transportation are typically provided both landside and airside. The floor tracking allows distribution of ULDs or other load items between the truck docking areas and/or to load manipulation and storage positions within a distribution centre. The invention relates in particular to devices for the manipulation of such pallets, especially as part of an air freight cargo handling system.

For safety reasons, floor tracking is typically at a relatively low height, around 500 mm being typical, and 508 mm being one industry standard. It follows that pallets for use in such a system are of a similar height to this standard or (as is the case with certain systems discussed in more detail below) at a lower height. At the truck docking stations it is necessary to raise the pallets to a truck loading height, which is typically at least 1500 mm. To this end, lift means are provided at the truck dock areas to raise a load from the floor track level to a truck loading level.

Stability requirements, at the loading levels often involved, generally mandate stable platform lifts in the truck dock area. Platform lifts are typically provided which are fixed to the floor, for example being corner post lifts or scissor lifts.

The lifts are large scale structures, and often need to be accommodated within recesses in the floor so that the platform can be deployed down to the distribution track level in a lowered configuration. The fixed nature of these lifts inevitably limit the flexibility of a distribution system, and can for example obstruct doorways in the truck dock area.

Recent developments in pallet technology, driven in particular by safety considerations, have seen the introduction of an alternative standard pallet at a height significantly less than the standard distribution track height. Pallets have been provided with a vertical height as low as 225 mm. Such pallets are generally considered to be safer in use, but present problems of compatibility with standard floor distribution tracking. This has led to the development of smaller lifting devices, based on fork lift principles, which are provided with paired tines designed to engage in suitable recesses in the 225 mm pallet and raise them to a 508 mm height so that they can function as a virtual 508 mm pallet and be compatible with existing systems. Such smaller lifts can be made mobile, offering a degree of additional flexibility within the distribution part of the warehouse, but lack the stability to be practical for use hoisting the load to truck loading heights.

It is an object of the invention to provide a more flexible solution to the problem of raising a load item, and in particular an air freight ULD, from a distribution floor to a truck loading level within a cargo distribution system.

It is a particular object of the invention to provide a solution which is less obstructive of access routes and/or doorways, in particular in a truck dock area.

Thus, according to the invention in a first broadest aspect there is provided a load distribution device comprising a chassis base adapted to engage with a floor, for example in a warehouse, with means to enable its translation therearound; a platform to receive a load item, especially a palletised load for example comprising an air freight ULD as above described, deployable between a lower position suitable to facilitate the distribution of the load within a load handling centre and a higher position suitable for transferring the load onto a truck or the like for onward distribution; and a scissor lift means carried on the chassis acting between the chassis and the platform to effect deployment of the platform.

As a result, the whole lift comprises a lift which is movable about the warehouse or other logistics area and which can be deployed at any location therewithin. The lifting arrangement is based on broad principles which are generally established, comprising a scissor lift in which at least one scissor elevator, for example one pair of scissoring arms, and more conveniently at least two elevators such as two pairs of scissoring arms, for example disposed generally along two opposing sides of the platform, are deployed under the action of a suitable lift drive means, such as a hydraulic drive, to effect translation of the platform from a lower to a higher position. However, the arrangement is made portable.

There is a long standing prejudice within the air freight logistics sector that it is likely to be impractical to make lifts based on scissor mechanisms mobile in this way. To be effective for the envisaged purpose, the lift needs to cope with a design load of up to 7 tons or more, in some cases up to 10 tons or more. It needs to close to a platform height below the distribution track height, for example below 500 mm, but be deployable to a truck loading height which will typically be in excess of 1500 mm.

The prevailing view has been that mobile platform lifts based on a scissor mechanism could not simultaneously meet all these requirements. In particular, the need for the presence of a mechanically robust mechanism below the platform makes a low profile undeployed height difficult.

Consequently although scissor lifts have been quite widely used as truck dock area hoists, they have generally been floor mounted for stability, and frequently incorporated in recesses to comply with the height requirements.

Where mobile truck load height hoists have been suggested, they have been suggested based on a full four post platform lift loader arrangement.

However, in accordance with the present invention it has been surprisingly found that with suitable careful modifications to the way that the scissor lift is disposed, an effective, safe and stable movable platform lift device using a scissor mechanism can be produced. The resultant structure is much smaller and more practical than a movable four post platform hoist would be and much more practical as a flexible mobile unit.

In particular, the scissor mechanism is so designed as to ensure that it is able to deploy from an open configuration at which the platform is raised to at least 1500 mm for example for truck loading and a closed configuration at which the platform is lowered to a height of less than 500 mm above the ground surface on which the chassis is engaged.

In a preferred embodiment, this is achieved in that the chassis comprises a frame structure, with the scissor mechanism deploying between an open and a closed configuration from within the area defined by the frame, such that in a closed configuration it is at least partly within the height profile above ground defined by the frame. In other words, the scissor mechanism is mounted in mechanical engagement with the chassis frame so that the chassis frame carries the load and serves as a base for the lift, but is nevertheless mounted within the area which the frame of the chassis surrounds, rather than mounted directly atop the frame.

Subject to this design requirement, various arrangements of scissor mechanism might suggest themselves. However, in a preferred embodiment, the chassis frame comprises a generally square or rectangular frame, with the scissor mechanism comprising at least one scissor mechanism in mechanical association with each of a pair of opposing sides of the said frame, in particular being the longer sides of a rectangular frame.

Scissor mechanisms may be envisaged wherein a plurality of separately articulated arms are provided to form a concertina structure. However, in a preferred embodiment of the invention, the scissor mechanism comprises pairs of single elongate arms. An upper end of each scissor means is in direct or indirect mechanical engagement with the platform, and a lower end of each means is in direct or indirect mechanical engagement with the chassis, to effect deployment in familiar manner via a scissoring action.

For compactness in the closed configuration, it is particularly convenient if there is provided on each such side a single pair of scissor arms pivotally articulated together to effect a scissor action, for example within the general vicinity of a mutual midpoint of the length thereof.

A first end of each arm engages with and supports the load platform, either directly or via suitable support means. A second end of each scissor arm engages with and carries load to the chassis and hence to the ground. Any suitable mechanical engagements may be envisaged, which are not pertinent to the invention, and may for example include sliding and pivoting engagements in familiar manner.

In a convenient way of achieving this, the scissor mechanism comprises a pair of C-frame structures, each such C-frame structure thereby defining a transverse support and two longitudinal arms to serve as scissor arms when pivotally engaged with a corresponding arm of the other frame. A distal end of the arm is engaged with the chassis, for example to be sideable relative thereto as it deploys. The arrangement folds down effectively to be retained within the area defined by the chassis frame and at least partly within the height defined by the chassis frame such that the folded scissor structure need protrude at most only partly above the chassis frame. This gives the low undeployed height which is so necessary for the present application.

The chassis comprises means to niake a translating engagement with the ground on which it engages, for example by making a rolling engagement therewith. For example, the chassis includes rollers, balls, wheels or the like mounted for rotation on the chassis and protruding therebelow to effect ground engagement.

In the preferred embodiment, the chassis is a frame, for example square or rectangular, with such means towards some or all of the edges and/or corners.

The chassis may be adapted to be driven, including drive means to drive at least one of the translation means, and for example having at least one driven wheel. Control means may be provided under direct and/or remote user control. The translational means associated with the chassis preferably include S a mechanism to allow the chassis to be steered, for example in that they include directionally steerable wheels, a system to skid steer, or other suitable system.

Conveniently, the drive means, control means, steering means and the like are located within a common drive unit. In a preferred embodiment, where the chassis is generally rectangular, this may be located at one end.

The load platform is a rigid planar structure, and is again preferably square or rectangular. The platform preferably incorporates means to enable a load thereon to be translationally moved, for example comprising rolling supports to effect rolling engagement with a load, such as rollers, captured bearings, or wheels within the platform structure.

These preferably facilitate movement in at least two orthogonal directions, corresponding for example to longitudinal and transverse directions in the preferred embodiment of a square or rectangular platform. Most simply, this can be achieved in that the translational means are multi-directional, for example comprising captured spherical bearings.

The sliding means may be entirely passive and operated purely by application of an external force to push the load, for example comprising freely rotating rollers or captive bearings. Alternatively, at least some of the sliding means may be driven directly by drive means incorporated into the load distribution device, for example comprising powered rollers or wheels.

In a particularly preferred embodiment, the platform comprises an array of passive rollers or captive bearings, together with at least one set of driven wheels, the wheels being deployable from a lowered configuration in which they sit below the upper surface of the platform and do not engage a load thereon to a raised configuration in which they protrude through the platform to engage a load thereon.

A suitable drive means drives the powered wheels, for example under the control of a control unit mounted upon the chassis or remotely. A suitable deploying drive, which is preferably separate from the rotational drive, deploys the wheels as above described. Conveniently, the rotational drive comprises a rotary electric motor mechanically coupled via suitable gearing and transmission to each of the wheels to be driven, so as to drive the wheels simultaneously or selectively. Conveniently, the deploying drive comprises a secondary rotary electric motor linked by suitable gearing and transmission to each powered wheel location, to effect deployment of the powered wheels simultaneously or selectively.

In a particularly preferred embodiment, for the reasons above described, an active drive arrangement is provided to allow for driving of a load in either of two generally orthogonal directions, preferably corresponding to a longitudinal and a transverse direction on the platform. Passive sliding means are additionally provided which comprise multi-directional means such as captured bearings. The active drive arrangement conveniently comprises two sets of driven wheels which are selectively deployable, a first to drive in a transverse direction and a second to drive in a longitudinal direction.

Conveniently, the two sets of driven wheels are mechanically linked via the same deployment system which is so configured to ensure that only one set of wheels, for driving a load in one direction, can be deployed at any one time, and that when that set of wheels is fully deployed the other set of wheels is fully undeployed.

The deployment mechanism is preferably electromechanical, and in particular comprises mechanically linked arrangements of eccentric cam, each cam rotating from a first to a second position in mechanical engagement with the wheel so as to deploy the wheel when in the second position. To accommodate the loads involved, the eccentric cam arrangement is spring damped in that the cam is configured to be urged back down through the platform by a heavy load, with a suitable spring biasing means tending to bias it back to the deployed position. The mechanism is driven by suitable drive means, such as the rotary electric motor above described.

The platform option includes deployable side/back plates to prevent the load slipping off in use.

A device configured in this way combines the virtues of the prior art floor level pallet mover above described with the full height capacity of a truck loader. The driven top allows a degree of accommodation of truck position. In use, a truck need only align roughly with the load, and the driven platform can be used to fine tune the position. The device offers great flexibility is an air freight distribution environment.

The invention will now be described by way of example only with reference to figures 1 to 5 of the accompanying drawings wherein: Figure 1 is an isometric view of an embodiment of device in accordance with the invention; Figure 2 is a plan view of the device of figure 1; p Figure 3 is a side view of the device of figure 1, shown deployed in figure 3a and undeployed in figure 3b; Figures 4 and 5 provide a detailed illustration of the mechanism for deploying and powering the pallet drive wheels in the device of figure 1.

Referring first to figure 1, a device for the distribution of air freight pallets in accordance with the invention is shown in a deployed position with the load bearing platform raised. The same pallet distributor is illustrated in figure 2 in plan view, and in figure 3 in side view, both deployed with the platform raised (figure 3a) and retracted with the platform lowered (figure 3b). Where applicable, like numerals are used to refer to like components in all of these figures.

The basic structure of the pallet distributor comprises a chassis (1), a scissor assembly (5) and a powered load deck (6).

The chassis (I) comprises a generally rectangular frame structure which supports the lift/hoist arrangement, and makes contact with the ground, when the distributor is being operated in mobile mode, via the wheels (4, 5). An optional additional safety feature, illustrated in the figures, may be applied when the platform is extended to stabilise the distributor in position. For this mode of operation, stabiliser jacks (13) are provided in the vicinity of the small wheels (4), deployable by means of the hydraulic actuator (14) to make contact with the floor and stabilise the distributor for stationary operation as a hoist.

In the embodiment, the wheel (5) is a powered driven wheel situated generally on a mid line of the chassis footprint, and freely rolling wheels (4) are provided distally therefrom on each of the long sides of the rectangular frame of the chassis (1). However, the precise arrangement is not particular to the invention, and other arrangements of wheel/roller/track or other translational means might be suitable for particular applications. Depending on the application, the wheels of the embodiment could be single wheels or multiple wheels on a single axle and may be of solid construction or tyred with solid or pneumatic tyres, as the application demands.

The scissor lift comprises two pairs of scissor arms, one in a mechanical association with each longitudinal element of the rectangular chassis frame (1). Each arm in a scissoring pair (5a, 5b) is a rigid elongate arm, the pair being pivoted generally about the mid point of their length, and being driven by the hydraulic ram (7) to effect a scissoring action whereby the whole scissor mechanism can be extended or retracted in familiar manner. A cross support links each scissor arm (5a or 5b) with its counterpart on the other side, and bears the load of the powered deck (6).

The scissor mechanism is mounted in mechanical association with and so that the load is carried by the chassis frame (1), but as can be seen in particular from figure 1 is mounted so as sit within the area defined by the frame. This assists in limiting the retracted height. In consequence, a retracted height Hi of 478 mm can be achieved, with an extended height 1-12 of 1512 mm. The compactness of the structure makes practical a genuinely mobile hoist based oii a scissor mechanism, which has previously being considered only suitable for fixed hoists in aircraft in air cargo handling facilities. The unit is powered byabattery(16).

A control unit (15) is provided at one end of the chassis, which houses a driven wheel (5), drive means for the driven wheel (not shown) and a control unit to control operation of the scissor lift and powered deck. In the embodiment, control is by a manual control (17) designed for a pedestrian user, but remote control of some or all of the functions can also be readily envisaged. In particular, even in such cases where the pallet distributor is adapted for pedestrian control when being moved about the air cargo facility, some or all of the raising, lowering or powered deck functions associated with truck loading may still be carried out under remote control.

A particularly preferred feature illustrated in this embodiment of the invention is the powered deck (6). The deck comprises a rectangular load bearing structure, measuring 2490 by 3225 mm, which is raised and lowered by means of the scissor lift (5). The deck includes freely rotated captured bearings (9) over which a carried load can slide freely in any direction. However, the deck is additionally provided with powered means to effect translation of the load, in the form of driven wheels (1 Oa and 1 Ob) respectively directed in transverse and longitudinal directions. These wheels are deployable for use through apertures (12) in the deck (6) , between a lowered configuration where they do not engage a load on the deck, and a raised configuration where they do engage the load.

Deployable side and back stops (11) provide an additional safety feature, to ensure that the load does not slide off the platform.

The wheels (l0a and lOb) are co-operably actuated so that if a first set (i.e. transverse or longitudinal) is deployed, then the other set is fully undeployed, so that the load moves only in the desired direction. In an intermediate state, neither set of wheels is fully deployed, and neither engages the load. In figure I, the wheels designed to move the load in a longitudinal direction (lOb) are deployed, and the transverse wheels (lOa) are undeployed.

Deployment is effected by an electromechanical system connecting all wheels, and under control of a single central actuation, which is described in more detail in figure 5. A separate drive is provided to power the rotation of the wheels and is described in figure 4.

The mechanisms need to sit compactly underneath the powered deck above the scissor hoist mechanism and need to maintain a low profile to ensure that the compact retracted configuration necessary for the invention is achieved.

This requirement presents particular difficulties in creating a powered deck for application in a device in accordance with the invention, which require careful design to overcome, for example by means of the drive in figures 4 and 5. The provision of such a low profile powered system for a deck represents a significant development in the field of air cargo handling.

The drive has two essential functions and can consequently be divided into two essential sub-systems: a mechanism to drive the rotating wheels, and a mechanism to deploy the wheels through the apertures in the deck. To improve clarity, these are shown separately, respectively in figures 4 and 5. Of course, in practice, the two drive sub-systems will be located together below the deck in a compact and low profile arrangement.

Each of figures 4 and 5 shows the applicable drive sub-system in plan view (figure 4a, 5a) and in side view (figure 4b, 5b). A more detailed inset of the deployment mechanism is shown at figure 5c.

The figures illustrate both longitudinal (lOa) and lateral or transverse (lOa) drive means, each comprising paired wheels journalled for rotation via a common axis. Four pairs of wheels make up each drive means. The rotation drive system is illustrated in figure 4, and comprises a motor (21) and brake (22) via a primary gear box (23) and a system of driven shafts (25) and chain roller arrangements (27). Wheel sets are additionally controlled via a secondary gearbox (28) held in place by the gear box mounting (29).

The wheels are deployed by means of the electromechanical arrangement illustrated in figure 5. The two wheel sets (lOa, lOb) are co-operably linked so that when a first set is fully deployed, that is, project through its recesses in the deck to engage the load, the second wheel set is fully undeployed. The mechanism of figure 5 shows an example of how this can be achieved.

A motor drive (31), suitably geared and braked, is provided to power the deploying mechanism. The drive is conveniently a rotary electric motor, as is the main drive powering the wheels, but is provided in a separate mechanical system. The system again comprises a suitable arrangement of drive shafts (33) and chain and roller drives (35) and sprockets (36). A secondary gear box (38) is associated with the wheel set.

The inset in figure 5c shows the mechanism in more detail. A wheel set (10) is mounted on an axle (41) to be rotationally driven in the manner described for figure 4. A cam (43) is mounted about a second axle (42). Rotation of this cam under the action of the drive means described with reference to figures 5a and 5b acts via the mechanical arrangement shown to deploy the wheel (10) between a lowered position where it sits below the deck (6) and a raised position where it protrudes therethrough. In the raised position it is capable of engaging and applying a drive to a load on the deck.

To accommodate the high loads involved, a damping unit (45) which in this example is a spring but could for example also be a hydraulic biasing means introduces some flexibility into the system, allowing the wheel even in the deployed state to be depressed under the weight of a load, but tending to urge it back into a fully deployed state as the load is taken off.

At the final assembly the drive components are timed in such a way that the four longitudinal drives are all the way extended when the four lateral or transverse drives are all the way retracted. In this way, a single electromechanical drive based on a single rotary electric motor can be used to power the deployment mechanism, which can be incorporated compactly alongside the power drive mechanism in a low profile arrangement allowing for a low profile driven deck structure compatible with the low overall profile needed for the purposes of the present invention.

All drive means may be under the control of a pedestrian user operating a control panel associated with the vehicle and/or under some form of remote control.

Claims

1. A load distribution device comprising a chassis having a base adapted to engage with a floor with means to enable its translation therearound; a platform to receive a load item, deployable between a lower position suitable to facilitate the distribution of the load within a load handling centre and a higher position suitable for transferring the load onto a truck or the like for onward distribution; and a scissor lift means carried on the chassis acting between the chassis and the platform to effect deployment of the platform. *1.

2. A device in accordance with claim 1 wherein the load item is a pallatised load. *

I

3. A device in accordance with claim 2 wherein the load items is an air SS* freight ULD.

4. A device in accordance with any preceding claim wherein the scissor lift means comprises at least one scissor elevator

5. A device in accordance with claim 4 where in the lift means comprises at least two scissor elevators disposed as two pairs of scissoring arms generally along two opposing sides of the platform.

6. A device in accordance with any preceding claim wherein the scissor mechanism is so designed as to ensure that it is able to deploy from an open configuration at which the platform is raised to at least 1500 mm and a closed configuration at which the platform is lowered to a height of less than 500 mm above the ground surface on which the chassis is adapted to engage.

7. A device in accordance with any preceding claim wherein the chassis comprises a frame structure, with the scissor mechanism deploying between an open and a closed configuration from within the area defined by the frame, such that in a closed configuration it is at least partly within the height profile above ground defined by the frame.

8. A device in accordance with claim 7 wherein the chassis frame comprises a generally square or rectangular frame, with the lift means comprising at least one scissor mechanism in mechanical association with each of a pair of opposing sides of the said frame. 9.

9. A device in accordance with any preceding claim wherein the scissor lift means comproses a scissor mechanism comprising pairs of single elongate arms, an upper end of each scissor means being in direct or indirect mechanical engagement with the platform, and a lower end of each scissor means being in direct or indirect mechanical engagement with the chassis, to effect deployment via a scissoring action.

10. A device in accordance with claim 9 wherein there is provided on each such side a single pair of scissor arms pivotally articulated together to effect a scissor action, within the general vicinity of a mutual midpoint of the length thereof.

11. A device in accordance with claim 9 or 10, wherein the scissor mechanism comprises a pair of C-frame structures, each such C-frame structure thereby defining a transverse support and two longitudinal arms to serve as scissor arms when pivotally engaged with a corresponding arm of the other frame.

12. A device in accordance with any preceding claim wherein the load platform is a rigid planar structure, and incorporates means to enable a load thereon to be translationally moved, comprising rolling supports to effect rolling engagement with a load, such as rollers, captured bearings, or wheels within the platform structure.

13. A device in accordance with claim 12 wherein the translation means are disposed to facilitate movement in two orthogonal directions. S **. : 4.

14. A device in accordance with claim 12 or 13 wherein at least some of the translational means are driven by drive means incorporated into the load.. . distribution device. 41*

S *SP I S...

15. A device in accordance with claim 14 wherein the platform comprises an array of passive rollers or captive bearings, together with at least one set of driven wheels, the wheels being deployable from a lowered configuration in which they sit below the upper surface of the platform and do not engage a load thereon to a raised configuration in which they protrude through the platform to engage a load thereon.

16. A device in accordance with claim 15 wherein an active drive arrangement is provided to allow for driving of a load in either of two generally orthogonal directions, corresponding to a longitudinal and a transverse direction on the platform, and passive sliding means are additionally provided which comprise multi-directional means such as captured bearings.

17. A device in accordance with claim 16 wherein the active drive arrangement conveniently comprises two sets of driven wheels which are selectively deployable, a first to drive in a transverse direction and a second to drive in a longitudinal direction.

18 A device in accordance with claim 17 wherein the two sets of driven wheels are mechanically linked via a common deployment system which is so configured as to ensure that only one set of wheels, for driving a load in one direction, can be deployed at any one time, and that when that set of wheels is fully deployed the other set of wheels is fully undeployed.

19. A device in accordance with claim 18 wherein the deployment mechanism comprises mechanically linked arrangements of eccentric cam, each cam rotating from a first to a second position in mechanical engagement with the wheel so as to deploy the wheel when in the second position.