WO2007046793A1

WO2007046793A1 - Drive mechanism for an access system

Info

Publication number: WO2007046793A1
Application number: PCT/US2005/037378
Authority: WO
Inventors: David D. Merrick
Original assignee: The Braun Corporation
Priority date: 2005-10-18
Filing date: 2005-10-18
Publication date: 2007-04-26

Abstract

An access system (100) selectively driven by a drive mechanism (500) is presented. The access system (100) includes a transfer member (200) that is selectively stowed and deployed to provide a path from one surface to another by the drive mechanism (500). The transfer member (200) and the drive mechanism (500) may be mounted onto or within a surface by a frame (300). The drive mechanism (500) includes a travel assembly (600) that enables the transfer member (200) to be moved within the frame (300), and an automatic power assembly (700) that selectively engages a motor (740) with the travel assembly (600) to automatically stow or deploy the transfer member (200) and disengages the motor (740) from the travel assembly (600) to enable manual stowing or deployment of the transfer member (200). The automatic power assembly (700) includes an engagement with a bias member (769) that moves the motor (740) into engagement and a disconnect mechanism (760) that moves the motor (740) out of engagement with the travel assembly (600), or alternatively includes linkages.

Description

DRIVE MECHANISM FOR AN ACCESS SYSTEM

BACKGROUND [0001] Access systems, such as motorized lifts, have been used to transport people and cargo. These access systems include platforms, ramps, moving seats, movable steps, and the like, which may be attached to stationary structures, such as buildings and loading docks, or mobile structures such as vehicles. Access systems have been used to provide disabled individuals access to structures that traditionally were accessible only via steps or stairs, or required an individual to step over or across an obstacle. For example, motorized lifts have been used to allow disabled individuals to enter and exit vehicles. In another example, motorized lifts have been used to load and/or unload stretchers from vehicles, such as ambulances. Motorized lifts have also been used on loading docks and trucks to allow cargo to be loaded, unloaded or otherwise moved.

SUMMARY

[0002] An access system and a drive mechanism for selectively driving the access system are presented. The access system may be deployed to provide a path, such as a ramp or bridge, from one surface to another, and stowed for storage. For example, the access system may be installed in a vehicle and, when deployed, provide a path through a door in the vehicle and between the floor of the vehicle and the ground. Thus, the access system provides a gradual transition between the floor and the ground for individuals experiencing mobility impairment. When the access system is stowed, it may be stored within the floor of the vehicle, thus allowing the doors of the vehicle to close. In another example, the access system may be deployed to form a bridge between the back of a truck and a loading dock, which facilitates the loading of heavy and/or bulky items into the truck.

[0003] The access system generally includes a frame, transfer member and a drive mechanism The frame supports, protects and allows the access system to be mounted to a surface, such as the floor of a vehicle. The transfer member is connected with the frame and provides the path between surfaces, such as the floor of a vehicle and the ground. The drive mechanism allows the transfer member to be deployed and stowed. The drive mechanism includes a travel assembly that allows the transfer member to be deployed and stowed automatically or manually. In addition, the drive mechanism includes an automatic power assembly connected with the frame. The automatic power assembly engages a motor with the travel assembly to stow or deploy the transfer member automatically, and disengages the motor from the travel assembly to allow the travel assembly to be moved manually.

[0004] The transfer member includes a ramp or bridge and a carriage. The carriage is connected with the frame and the ramp or bridge so that as the carriage is moved from one end of the frame to another by the travel assembly, the ramp is deployed or stowed. For example, the carriage may be slide along a rail included in the frame. In addition to the motor, the automatic power assembly generally includes a motor mounting, which connects the motor to the frame, and an engagement assembly. The engagement assembly may also include a bias member that moves the motor into engagement with the travel assembly and a disconnect mechanism that moves the motor out of engagement with the travel assembly. Alternately, the engagement assembly may include linkages that move the motor into and out of engagement with the travel assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] The invention can be better understood with reference to the following drawings and description. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, in the figures, like referenced numerals designate corresponding parts throughout the different views.

[0006] Figure 1 is an isometric view of an access system in a vehicle and in a deployed position. [0007] Figure 2 is an isometric view of the access system of Figure 1 in a stowed position.

[0008] Figure 3 is an isometric view of a frame, with top and bottom covers removed, and a transfer assembly in a deployed position.

[0009] Figure 4 is an isometric view of the frame and the transfer assembly of Figure 3 in a stowed position. [0010] Figure 5 is a top plan view of the frame of Figure 3.

[0011] Figure 6 is a top plan view of the frame of Figure 5 with the top cover removed.

[0012] Figure 7 is a right-front isometric view of the frame of Figure 5. [0013] Figure 8 is a left-front isometric view of the frame of Figure 5.

[0014] Figure 9 is a right-rear isometric view of the bottom cover and a drive mechanism cover of the frame of Figure 5.

[0015] Figure 10 is an isometric view of the bottom cover, drive mechanism cover, and rear bracket of the frame of Figure 5. [0016] Figure 11 is a top plan view of a travel assembly and the carriage in the frame of Figure 5 with the covers removed.

[0017] Figure 12 is an isometric view of a right portion of the travel assembly of Figure 1 1.

[0018] Figure 13 is a bottom isometric view of the carriage of Figure 1 1 and a guide assembly.

[0019] Figure 14 is a top isometric view of a left portion of the travel assembly of Figure 1 1.

[0020] Figure 15 is a top isometric view of an automatic power assembly mounted on a frame with the covers removed and engaged with a travel assembly. [0021] Figure 16A is a rear view of the automatic power assembly of Figure 15 with the covers removed and engaged with a travel assembly.

[0022] Figure 16B is a rear view of the automatic power assembly of Figure 15 with the covers removed and disengaged with a travel assembly.

[0023] Figure 17 is a front isometric view of the automatic power assembly of Figure 15 with the covers removed and disengaged from the travel assembly.

DETAILED DESCRIPTION

[0024] Access systems are presented that may be deployed to provide a path or bridge from one surface to another and stowed to store the path. For example, the access systems may provide a path or bridge from the floor of a vehicle, such as an automobile, bus, van, train, airplane and other motorized and unmotorized modes of transportation, to the ground. In this example, the path provided by the access system may be inclined to provide a gradual transition for individuals, such as those who use a wheelchair, walker, or scooter, or who are experiencing permanent or temporary mobility impairment, thus allowing these individuals to avoid the abrupt transition between the ground and the floor of the vehicle. Alternately or additionally, the access system may provide a horizontal path from one surface to another. For example, the access system may provide a path or bridge between the back of a truck and a loading dock. In this example, the path enables heavy and/or bulky items to be loaded onto or unloaded from the truck or loading dock.

[0025] In general, the access system includes a frame, a transfer member and a drive mechanism. The frame (shown and discussed in connection with Figures 1-1 1) supports and protects the access system and allows the access system to be mounted to a surface, such as the floor of a vehicle. The transfer member (shown and discussed in connection with Figures 1-4) is connected to the frame and provides the path or bridge, such as a ramp, between surfaces, such as the floor of a vehicle and the ground. The drive mechanism (shown and discussed in connection with Figures 11-17) allows the transfer member to be deployed and stowed. The drive mechanism includes a travel assembly (shown and discussed in connection with Figures 11-14) that allows the transfer member to be deployed and stowed automatically or manually. In addition, the drive mechanism includes an automatic power assembly (shown and discussed in connection with Figures 1 1 and 15-17). The automatic power assembly engages a motor with the travel assembly to stow or deploy the transfer member automatically, and disengages the motor from the travel assembly to allow the travel assembly to be moved manually.

[0026] In the description that follows, access systems that provide an inclined path between the floor of a vehicle and the ground are provided as examples. In addition, the access systems are described as having certain features located on the right side and others on located on the left side of the system. However, these systems may be implemented in a wide variety of circumstances for a wide variety of uses, and the features described in connection with the right side or the left side may alternately be included on the opposing side.

[0027] An example of an access system 100 is shown in Figures 1 and 2. In this example, the access system 100 is installed in a vehicle 40 to provide an access path between the vehicle 40 and the ground 50. The access system 100 generally includes a ramp 210 and a frame 300. The frame 300 supports the access system 100 within the vehicle 40, and provides the structure that allows the ramp 210 to be deployed and stowed. As shown in Figures 1 and 2, the frame 300 is located within the vehicle 40. In contrast, the ramp 310 may be located outside or inside the vehicle in a deployed or stowed position, respectively. To reach the deployed position (Figure 1), the ramp 210 exits the vehicle 40 through the doorway 46 so that the proximate end 212 of the ramp 210 extends from a distal end 320 of the frame 300, and the distal end 214 of the ramp 210 makes contact with and rests upon the ground 50. In the stowed position (Figure 2) the ramp 210 is stored within the frame 300, with the distal end 214 of the ramp 210 approximately flush with the distal end 320 of the frame 300, so that the doors 44 of the vehicle 40 may be closed and the vehicle 40 operated safely.

[0028] As shown in Figure 1 , the ramp 210 may include a mat 220 with a frictional surface. This frictional surface provides traction so that people and/or objects may ascend and/or descend the ramp 210 more safely. The ramp 210 may include other safety features. For example, the mat 220 may include a pressure sensitive pad (not shown) and be connected with a controller (not shown). The pressure sensitive pad measures the weight on the ramp 210 and communicates the weight to the controller so that when the ramp 210 is deploying or stowing, the controller prevents the ramp 210 from operating until the weight is removed. In addition, the ramp 210 may include a handle or aperture 218 of any suitable shape or design by which the ramp 210 may be gripped so that the ramp 210 may be stowed and/or deployed manually. Further, the ramp 210 may also include a wedge-shaped element 216 extending from the ramp's distal end 214 to provide a gradual transition between the ramp 210 and the ground 50. The aperture 218 and/or the wedge-shaped element 216 may be located in proximity to the distal end 214 of the ramp 210.

[0029] The ramp 210 is connected to the vehicle 40 via the frame 300. In the example of Figures 1 and 2, the frame 300 is installed in the floor 42 of the vehicle 40 with the distal end 320 of the frame 300 and the distal end 214 of the ramp 210 in approximate alignment with the doorway 46. The frame 300 may include a top cover 330, and may be installed in the vehicle 40 so that the top cover 330 is located below the floor 42. Alternately, the frame 300 may be installed so that the top cover 330 is approximately flush with or above the top surface of the floor 42 with the remainder of the frame 300 located approximately below the plane of the top surface of the floor 42. If the frame 300 is installed so that the top cover 330 is approximately flush with or above the top surface of the floor 42, the top cover 330 may replace the floor 42 in the location in which the frame 300 is installed. In this case, the top cover 330 may include a material of sufficient strength to support loads that may be placed on the floor 42. For example, composite materials such as, plastic and aluminum honeycomb composites. [0030] To provide a smooth transition between the ramp 210 and the top cover 300, or the ramp 210 and the floor 42 of the vehicle 40, the frame 300 may include a transition member 260. The transition member 260 may be connected with the top cover 300 via a hinge 270 or other rotatable connection, so that when the ramp 220 is deployed or stowed, the transition member 260 moves relative to the top cover 330 to allow the ramp to rotate downward or upward, respectively.

[0031] To install the frame 300 within the vehicle 40, a portion of the floor 42 having a footprint approximately equal to that of the frame 300 is removed. In addition, the depth of the floor removed should be sufficient to accommodate the height of the frame 300, with or without the top cover 330. To secure the frame 300 to the floor 42, the frame 300 may include one or more tabs 410 (Figures 7, 8 and 10). As shown in greater detail in Figure 8, each tab 410 may include an aperture 420. The tabs 410 may rest on the floor 42 to which they may be permanently or removably secured by one or more fasteners including, bolts, screws, and nails inserted through the apertures and into the floor 42, or by welding.

[0032] The manner in which the ramp 210 is connected with the frame 300 is shown generally in Figures 3 and 4. In these figures, the top cover 330 of the frame 300 has been removed to reveal that the frame 300 has several brackets including a right front bracket 360, left front bracket 370, and rear bracket 390. The ramp 210 may be connected with the frame 300 via a carriage 230. The carriage 230 and the ramp 210 may be connected together via a hinge 220 or other rotatable connection attached to the top surfaces of carriage 230 and the ramp 210. The ramp 220 and carriage 230 may also or alternatively be connected together via a hinge attached to the lower surfaces of the carriage 230 and the ramp 210 (not shown). The ramp 210 and the carriage 230 (collectively the "transfer member 200") move within the right 360 and left 370 brackets to deploy and stow the ramp 210. When the ramp 210 is in the deployed position (Figure 3), the carriage 230 is located towards the distal end 320 of the frame 300. When the ramp 210 is in the stowed position (Figure 4), the carriage 230 is located towards the proximal end 310 of the frame 300. [0033] The frame 300 is shown in greater detail in Figures 5-10. In Figure 5, the frame 300 is shown as viewed from above. In Figure 6, the frame is also shown as viewed from above, but with the top cover 330 removed. In addition to the right side bracket 360, left side bracket 370, the rear bracket 390, and the top cover 330, the frame may include a guide member 430, front bracket 380 and bottom cover 340. The bottom cover 340 provides protection to the access system 100 (shown in Figures 1 and 2) from below and may include a plurality of protrusions 342 for connecting the bottom cover 340 with the front bracket 380. An example of the way in which the bottom cover 340 may be connected with the front bracket 380 is shown in Figure 8. The front bracket 380 may include a plurality of slots 382 into which the protrusions 342 of the bottom cover 340 may be inserted. Referring again to Figure 6, the bottom cover 340 may also include a cutout portion 344. The cutout portion 344 allows a drive mechanism 500 used to deploy and/or stow the ramp 210 (shown and discussed in connection with Figures 1 1 and 15-17), to be included within the frame 300.

[0034] The top cover 330 may be permanently or removably connected to the frame 300 using one or more fasteners including, bolts, screws, and nails, or by welding. To accommodate such connection, the top cover 330 may include one or more apertures 336 located proximate to its right, left and rear edges, as shown in Figure 5. In addition, the right 360, left 370, and rear 390 brackets may include one or more slots or other orifices 420, as shown in Figure 6, which approximately align with the apertures 336 in the top cover 330 so that one or more fasteners may be inserted into the right 360, left 370, and rear 390 brackets and into the top cover 330. The right 360, left 370, and rear 390 brackets may also include the tabs 410 shown in Figures 1 and 2

[0035] The guide member 430, shown in Figure 6, is generally parallel with the right side bracket 360. The guide member 430 is used to attach the carriage 230 (shown in Figures 1 and 2) to the frame 300 so that the carriage 230 may travel within the frame 300 to deploy and stow the ramp 210 (shown in Figures 1 and 2). To further enable the stowing and deployment of the ramp 210, the top cover 330 may include an open portion 332 at the distal end 320 of the frame 300 through which the ramp 220 (shown in Figures 1 and 2) may travel.

[0036] The front bracket 380, guide member 430, bottom cover 340, top cover 330, and right side bracket 360 are shown relative to each other and in greater detail in Figure 7. The front bracket 380 and the guide member 430 are connected with the bottom cover 340. The front bracket 380 is generally L-shaped and rests on the front end of the bottom cover 340. The bottom cover 340 includes a right side lip 346 that extends along a portion of the right side of the bottom cover 340. The guide member 430 includes a base portion 432 and a rail portion 434, and is connected with the bottom cover 340 inside the right side lip 346, so that the base portion 432 faces and is substantially parallel with the right side lip 346. The right side bracket 360 is also substantially parallel with the right side lip 346. The right side bracket 360 is generally S-shaped and connects with the base portion 432 of the guide member 430. The right side bracket 360 may also be connected with the right side lip 346 of the bottom cover 340 with the tabs 410 extend outwardly. The right side of the top cover 330 is in approximate alignment with and rests upon the right side bracket 360 so that the right side of the top cover 330 may be connected with the right bracket 360.

[0037] The front bracket 380, bottom cover 340, top cover 330, and left side bracket 370 are shown relative to each other and in greater detail in Figure 8. In a manner similar to that shown in Figure 7, the front bracket 380 connects with the front end of the bottom cover 340, the bottom cover 340 includes a left side lip 348 that extends along a portion of the right side of the bottom cover 340, the left side of the top cover 330 is approximately aligned and connected with the left side bracket 370 so that the left side of the top cover 330 rests upon bracket 370. The left side bracket 370 is generally L-shaped and oriented so that the tabs 410 face outwardly. As shown in Figure 8, the open portion 332 of the top cover 330 may include a shelf 334 to which the transition member 260 may be connected via the hinge 270 (shown in Figures 1 and 2).

[0038] As previously discussed in connection with Figure 6, the bottom cover 340 may include a cutout portion 344 that allows the automatic power assembly 700 (shown in Figures 1 1 and 15-17) to be included within the frame 300. Because the depth of the drive mechanism 500 may exceed that of the frame 300, the cutout 344 allows the frame 300 to accommodate the drive mechanism 500. In addition, the cutout 344 may accommodate a cover 440 for the drive mechanism 500, an example of which is shown in Figures 9 and 10. Referring to Figure 9, the drive mechanism cover 440 generally includes a cup portion 450 and a ledge portion 470. The cup portion 450 is deeper than the ledge portion 470 to accommodate the drive mechanism 500. The cup portion 450 generally includes a rear wall 454, right wall 452 and a left wall 456 that may include an aperture 458. The ledge portion 470 may include a right lip 472 that is in approximate alignment with the right wall 452 of the cup portion 450. The drive mechanism cover 440 may be connected with the bottom cover 340 by overlapping the ledge portion 470 with a portion of the bottom cover 340 proximate the edge of the cutout portion 344 and permanently or removably securing the drive mechanism cover 440 to the bottom cover 340 using one or more fasteners including, bolts, screws, and nails, or by welding. [0039] The bottom cover 340 may include a rear lip 350. When the drive mechanism cover 450 is connected with the bottom cover 340, the rear wall 454 is in approximate alignment with the rear lip 350. This alignment allows the rear bracket 390 to be placed over the rear lip 350 and the rear wall 454, as shown in Figure 10. The rear bracket 390 is similar to the right and left brackets 360, 370, in that it may be generally S-shaped and is oriented within the frame 300 so that the tabs 410 face outwardly. As shown in Figure 9, the right wall 452 and right lip 472 of the drive mechanism cover 440 are in approximate alignment with the right side lip 346 of the bottom cover 340 so that the right bracket 360 (shown in Figure 7) may be placed over the right wall 452, right lip 472, and right side lip 346 when the drive mechanism cover 450 is connected with the bottom cover 340. [0040] As stated above, the transfer member 200, including the ramp 210 and the carriage 230 (shown in Figures 1-4), may be deployed and stowed by a drive mechanism 500. An example of a drive mechanism 500 connected with portions of the frame 300 and the carriage 230 is shown in Figure 11. The drive mechanism 500 includes a driving sprocket 680, idler sprocket 660 and a drive chain 570 (collectively referred to as the "travel assembly" 600), and an automatic power assembly 700. In general, the travel assembly 600 is connected to the carriage 230 and enables the carriage 230 to be moved along the guide member 430 manually or automatically. If the automatic power assembly 700 is engaged with the travel assembly 600, the travel assembly 600 moves the carriage 230 automatically. In contrast, if the automatic power assembly 700 is disengaged from the travel assembly 600, the travel assembly 600 enables the carriage 230 to be moved manually.

[0041] In Figure 12, the travel assembly 600, including the driving sprocket 680, idler sprocket 660 and a drive chain 670, is shown mounted within the frame 300. The drive sprocket 660 is mounted near the proximal end 310 and the idler sprocket 660 is mounted near the distal end 320 of the frame 300. The drive chain 670 generally forms a loop around the drive sprocket 660 and the idler sprocket 660. The travel assembly 600 also includes a sprocket gear 684, fixed shaft 686 and a free spinning shaft 682. The sprocket gear 684 and the free spinning shaft 682 are fixedly connected with the drive sprocket 680, all of which are coaxial with the fixed shaft 686. The drive sprocket 680, sprocket gear 684, free spinning shaft 682, and fixed shaft 686 are mounted to the frame 300, within the cutout 344 of the bottom cover 340 via a sprocket housing 690. The sprocket housing 690 includes a side mounting plate 692 that connects with the right bracket 360 and the cup portion 450 of the drive mechanism cover 440 (not shown). The sprocket housing 690 also includes a top mounting plate 694 and a bottom mounting plate 696 connected with the side mounting plate 692. The fixed shaft 686 is fixedly connected between the top mounting plate 694 and the bottom mounting plate 696, and the drive sprocket 680, sprocket gear 684 and free spinning shaft 682 may rotate about the fixed shaft 686 to drive the chain 670 and the idler sprocket 660.

[0042] The carriage 230 may be connected with the travel assembly 600 as shown in Figure 13. In Figure 13, the carriage 230 and the travel assembly 600 are viewed from underneath and looking forward to the distal end 320 of the frame 300. To moveably connect the carriage 230 with the rail portion 434 of the guide member 430, the carriage 230 may include one or more coupling members 240. Although three coupling members 240 are shown in Figure 13, the carriage may include 230 any number of coupling members 240, depending on the size of the carriage 230, among other factors. The coupling members 240 include a concave portion 242 that mates with and rides upon the rail portion 434. The coupling members 240 may also include one or more apertures 276 through which connectors such as, screws, bolts or nails may be inserted to connect the coupling members 240 with the underside of the carriage 230. To connect the drive chain 670 to the carriage 230, the carriage 230 may include a first chain connector 232 and a second chain connector 236. As shown in Figure 13, the first chain connector 232 may be connected with the carriage 230 at approximately the center of the carriage 230. The second chain connector 236 may connect with the end of the carriage 230 that faces the proximal end 310 of the frame 300. However, the first and second chain connectors 232, 236, respectively, may be located in a variety of locations on the under and top surfaces of the carriage 230. The first and second chain connectors 232, 236 may include first and second protrusions 234, 238, respectively, to which the drive chain 670 is connected. To connect the chain 670 to the first and second protrusions 234, 238, the chain 670 may include first and second master links 276, 274, respectively, each of which include two interlocking pieces. The interlocking pieces of the first and second master links 276, 274, may be separated from each other, inserted into apertures (not shown) in the protrusions 234, 238, respectively, and reconnected.

[0043] In addition, the carriage may include an adjustment mechanism 245 for adjusting the tension in the chain 670. For example, the adjustment mechanism 245 may include a nut 233 and a bolt 241. The bolt 241 is connected between the first chain connector

232 and the first protrusion 234 and inserted through an aperture (not shown) in the first chain connector 232. The nut 233 is connected to a portion of the bolt 241 that exits from the aperture (not shown) in the first chain connector 232. To increase the tension in the chain 670, the nut 233 is tightened causing the bolt 241 to exit further from the aperture (not shown) in the first chain connector 232. As a result, the first protrusion 234 is drawn closer to the first chain connector 232. Similarly, to reduce the tension on the chain 670, the nut

233 is loosened causing the bolt 241 to retreat back into the aperture in the first chain connector 232 and thus, the first protrusion 234 to move away from the first chain connector 232. [0044] As shown in Figure 14, the travel assembly 600 may also include a wheel 610 that facilitates movement of the carriage 230 along the left bracket 370. The wheel 610 may be connected to the carriage 230 via an axel 612, and rolls along the left bracket 370 when the carriage is moved by the drive chain 670 (shown in Figures 12 and 13). The travel assembly 600 may also include a first wheel stop 620 and a second wheel stop 640, which prevent the wheel 610, and thus the carriage 230, from moving beyond a first predetermined point located towards the distal end 320 of the frame 300, and a second predetermined point located towards proximal end 310 (not shown) of the frame 300, respectively. As an added safety feature, the travel assembly 600 may include a first switch 630 and a second switch 650 mounted to the carriage 230. The switches 630, 650 may be coupled with a power source (not shown) that enables the travel assembly 600 to operate automatically by providing power to the automatic power assembly 700 (shown in Figures 15-17). The first and second switches 630, 650 may also include first and second levers 632, 652, respectively, which interrupt the flow of power when depressed. Thus, when the carriage 230 reaches the first predetermined point, the first lever 632 will be depressed as it comes in contact with first wheel stop 620, thus activating the first switch 630, which interrupts the flow of power to the automatic power assembly 700 (shown in Figures 15-17). Similarly, when the carriage 230 reaches the second predetermined point, the second lever 652 will be depressed as it comes in contact with the second wheel stop 640, thus activating the second switch 650, which interrupts the flow of power to the automatic power assembly 700. The first and second wheel stops 620, 640 may include first and second slanted edges 622, 642, respectively, to provide a less abrupt activation of the first and second switches 630, 650. [0045] As shown in Figure 11 , the drive mechanism 500 includes an automatic power assembly 700. When engaged, the automatic power assembly 700 drives the travel assembly 600 to move the carriage 230 between a location near the distal end 320 and a location near the proximal end 310 of the frame 300. An example of an automatic power assembly 700 shown in engagement with the sprocket gear 684 of the travel assembly 600 is shown in Figure 15. In general, the automatic power assembly 700 includes a motor 740, motor mounting 710 and an engagement assembly 900. The motor 740 drives a motor gear 742 that, when engaged with the sprocket gear 684, drives the driving sprocket 680. In general, the motor 740 is mounted to the frame 300 via the motor mounting 710. The motor mounting 710 includes a mounting plate 720, which is connected with the rear wall 454 of the drive mechanism cover 440 (shown in Figures 9 and 10). In addition, the mounting plate 720 may be mounted within indentations 392 in the rear bracket 390. To allow for mounting plate 720 to be connected with rear wall 454, the mounting plate 720 may include one or more slots 730, 732. The motor mounting 710 may also include a first rod mount 726, second rod mount 728, first support rod 718, second support rod 736, first motor flange 714, and a second motor flange 716. The mounting plate 720 supports the first and second rod mounts 726, 728, which support the first and second support rods 718, 736, respectively. The first and second support rods 718, 736 may also be supported by the side mounting plate 692 of the sprocket housing 690 (shown in Figure 12). The motor 740 is slideably connected with the first support rod 719 via first motor flange 714, and the second support rod 736 via a second motor flange 716.

[0046] The motor 740 may be engaged with and disengaged from the sprocket gear 684 by the engagement assembly 900, an example of which is shown in Figures 15-17. In this example, the engagement assembly 900 includes a bias member 769, and engagement stop 780, and a disconnect mechanism 760. The bias member 769 biases the motor gear 742 into engagement with the sprocket gear 684 so that the motor 742 drives the travel assembly 600 automatically. The bias member 769 may include a first spring 770 and second spring 771, which are wrapped around the first and second support rods 718, 736, respectively. The engagement stop 780 limits the extent to which the motor gear 742 engages the sprocket gear 684, and may be connected to the second rod mount 728 or the second motor flange 716. As the motor assembly 700 engages with the sprocket gear 684, the second motor flange 716 will come into contact with the engagement stop 780, thus limiting the pressure exerted by the motor gear 742 on the sprocket gear 684. The length of the engagement stop 780 may be altered to adjust this pressure. The engagement stop 780 may include a screw or other adjustable projection.

[0047] To disengage the motor 740 from the sprocket gear 684, the engagement assembly 900 may also include a disconnect mechanism 760, an example of which is shown in Figure 16A. In this example, the disconnect mechanism 760 may include a cam 800 and a cable 764. The cam 800 is connected to the mounting plate 720 (shown in Figure 15) by a pivot connector 886 and includes a pivot portion 882 and a protrusion 884. The cable 764 is inserted through the first rail mount 726, the protrusion 884 of cam 800, and terminates in an enlarged end 752. The cable 764 may also be inserted through the first motor flange 714. The disconnect mechanism 750 is activated by pulling on the cable 764 away from the automatic power assembly 700 (shown in Figure 15). When the disconnect mechanism 750 is activated, the enlarged end 762 contacts the protrusion 884 of the cam 800 and causes the protrusion 884 to rotate clockwise so that the pivot portion 882 contacts the first motor flange 714. As the protrusion 884 continues to rotate, the protrusion 884 moves the first motor flange 714, and thus the motor 740 and the motor gear 742, away from the sprocket gear 684. As a result, the motor 740 is disengaged from the travel assembly, as shown in Figures 16B and 17. To enable a person or mechanism to activate the disconnect mechanism 760, the cable 764 may include a connector 766 for connecting the cable 764 with a handle (not shown), such as a T-handle. [0048] If the motor 740 is disengaged from the sprocket gear 684, as shown in Figure

16B, the engagement assembly 900 may be used to engage the motor 740 with the sprocket gear 684. By pushing the cable 764 towards the automatic power assembly 700 (shown in Figure 15), the protrusion 884 of cam 800 rotates counterclockwise, thus allowing the first and second springs 770, 771 to push the motor 740 and motor gear 742 into engagement with the sprocket gear 684. Alternately, the engagement assembly 900 may include linkages that when activated by the cable 764 engage and disengage the motor gear 742 from the sprocket gear 684. Thus, if the engagement assembly 900 includes linkages, the first and second springs 770, 771 and the cam 800 may not be needed.

[0049] Referring to Figures 15 and 17, the engagement assembly 900 may also include a switch 790 that, when activated, communicates a signal to a controller (not shown) that the motor 740 has been disengaged. As a result, the controller will deactivate the motor 740, so that when the motor 740 has been disengaged from the travel assembly 600, the motor 740 will cease to operate. The switch 790 may be connected between a power supply (not shown) and the motor 740, and include an arm 792 that, when depressed, interrupts the power supplied to the motor 740. To connect the switch 790 with the first rod mount 726, the frame may include a switch mount 724. When the motor 740 is disengaged from the travel assembly 600, the first motor flange 714 will depress the arm 792 of the switch 790, to discontinue the power to the motor 740, thus causing the motor 740 to stop operating.

[0050] While various embodiments of the invention have been described, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible within the scope of the invention. Accordingly, the invention is not to be restricted except in light of the attached claims and their equivalents.

Claims

CLAIMSWhat is claimed is:

1. An access system comprising: a frame; a transfer member movably connected with the frame; and a drive mechanism including: a travel assembly connected with the transfer member and the frame; an automatic power assembly connected with the frame and configured to selectively drive the travel assembly.

2. The access system of claim 1, wherein the transfer member is slideably connected with the frame.

3. The access system of claim 1, wherein the drive mechanism is configured to enable manual movement of the transfer member.

4. The access system of claim 1, wherein the drive mechanism is configured to enable automatic movement of the transfer member.

5. The access system of claim 1, wherein the drive mechanism is configured to move the travel assembly between a deployed and a stowed position.

6. The access system of claim 1, wherein the automatic power assembly is further configured to engage the travel assembly to enable automatic movement of the transfer member.

7. The access system of claim 1, wherein the automatic power assembly is further configured to disengage from the travel assembly to enable manual movement of the transfer member.

8. The access system of claim 1 , wherein the automatic power assembly comprises a motor.

9. The access system of claim 8, wherein the automatic power assembly further comprises an engagement assembly configured to selectively engage the motor with the travel assembly.

10. The access system of claim 9, wherein the engagement assembly includes a bias member configured to bias the motor into engagement with the travel assembly.

11. The access system of claim 10, wherein the engagement assembly includes a disconnect mechanism configured to disengage the motor from the travel assembly.

12. The access system of claim 1, wherein the travel assembly comprises a chain connected with the transfer member.

13. The access system of claim 12, wherein the travel assembly further comprises a pair of sprockets around which the chain forms a loop.

14. The access system of claim 13, wherein the loop is a discontinuous loop.

15. A drive mechanism for an access system that includes a frame and a transfer member slideably connected with the frame, the drive mechanism comprising: a travel assembly configured to connect with the transfer member and the frame; a drive mechanism connected with the frame and configured to selectively drive the travel assembly.

16. An access system comprising: a frame configured to attach to the vehicle; a transfer member slideably connected with the frame; and a drive mechanism including: a travel assembly connected with the transfer member and the frame; and an automatic power assembly connected with the frame and configured to selectively drive the travel assembly.

17. A method for providing access compπsing: providing a frame; providing a transfer member slideably connected with the frame; and providing a drive mechanism that includes: a travel assembly connected with the transfer member and the frame; and an automatic power assembly connected with the frame and configured to selectively drive the travel assembly.