WALKWAY WITH SELF-LIFTING ASSEMBLY

Abstract

A walkway comprises a fixed platform and a support structure connected to the fixed platform such that it allows the support structure to rotate relative to the fixed platform between a raised, locked position and a lowered, deployed position. A self-lifting assembly is used to rotate the support structure from the deployed position to the locked position. The self-lifting assembly includes at least one fluid-actuated cylinder connected between the fixed platform and a distant end of the support structure. A lifting actuator is usable by an operator to operate the cylinder so as to rotate the support structure to the locked position.

Description

WALKWAY WITH SELF-LIFTING ASSEMBLY Field of Invention The present invention relates to a lowering restraint device, and more particularly, relates to a walkway or gangway that is operative to move between a raised (engaged) position and a lowered (deployed) position. Background of the Invention Gangways may be used to provide access from a platform to an area, such as the top of a storage container, vehicle, or vessel. For example, a semi-trailer truck or rail car carrying goods may need to be inspected, loaded, or unloaded from the top of the container. A gangway is used to extend the distance between a stationary platform and the top of the container. In this regard, the proximal end of the gangway is pivotally connected to the stationary platform so that it locks into a raised position. Typically, a foot lock is provided to hold the gangway in the raised position. Once the container is in position, the foot lock is released by the operator, allowing the gangway to move forward. Ref. 326923 lowered position. Once fully lowered, the far end of the gangway is adjacent to the top of the container. When access to the top of the container is no longer required (for example, due to the completion of the unloading process), the gangway is manually raised back to the locked position until the foot lock engages. In a common arrangement, heavy-duty chains are attached to each side of the walkway near its distal end. The chains can be locked to the platform columns to prevent further lowering of the walkway when the desired location is reached. The chains are then pulled to raise the walkway to its desired position. Summary of the Invention The present invention recognizes and addresses the foregoing and other considerations of prior art construction and methods. An aspect of the present invention provides a walkway comprising a fixed platform and a support structure connected to the fixed platform in a manner that allows the support structure to rotate relative to the fixed platform between a raised, engaged position and a lowered, deployed position. A lifting assembly is operative to rotate the support structure from the deployed position to the engaged position. The lifting assembly includes at least one fluid-actuated cylinder connected between the fixed platform and a distal end of the support structure. For example, at least one fluid-actuated cylinder could include a cylinder rod having a spacer member coupled to a distal end thereof. A lifting actuator is usable by an operator to cause operation of the cylinder in a manner that rotates the support structure toward the engaged position. According to some embodiments, the cylinder is retracted to rotate the support structure into the engaged position. Preferably, at least the cylinder may include first and second cylinders located on the left and right sides of the support structure, respectively. The lift actuator may comprise a plunger associated with a lift valve, the plunger movable to change the position of the lift valve. In some embodiments, the plunger is moved outward to cause the support structure to be lifted, while in other embodiments, the plunger is moved inward to cause the support structure to be lifted. According to some embodiments, the lifting assembly could include a hydraulic pump driven by a motor, such as a pneumatic motor or an electric motor. In the case of an electric motor, embodiments in which the electric motor is powered by an AC source are contemplated. In some embodiments, the electric motor could be powered at least in part by at least one solar panel. According to some embodiments, the lifting assembly may include at least one accumulator. For example, a first rod accumulator and a second concealed accumulator may be provided connected, respectively, to be in fluid communication with a rod side and a concealed side of each of the cylinder(s). According to some embodiments, the lift actuator may be configured to stop lifting the support structure if released by the operator. According to some embodiments, the lift assembly may further include a lowering actuator usable by an operator to cause the cylinder to operate in a manner that rotates the support structure toward the deployed position. In this regard, the lift assembly may be configured such that the support structure will stop further rotation toward the deployed position if the lowering actuator is released. For example, the lowering actuator may be configured to have a master cylinder with an associated lowering plunger, the lowering plunger being movable inwardly to cause unseating of at least one pilot-operated check valve. Another aspect of the present invention provides a walkway comprising a fixed platform and a support structure connected to the fixed platform in a manner that allows the support structure to rotate relative to the fixed platform between a raised, engaged position and a lowered, deployed position. A lifting assembly is operative to rotate the support structure from the deployed position to the engaged position. The lifting assembly includes at least one fluid-actuated cylinder connected between the fixed platform and a distal end of the support structure, the cylinder operative to move so as to rotate the support structure toward the engaged position. A lifting actuator in this case comprises a lifting plunger associated with a lift valve, the plunger movable to change the position of the lift valve.According to this aspect, an air motor can be connected to a compressed air source by means of the lift valve to operate a hydraulic pump. Yet a further aspect of the present invention provides a walkway comprising a fixed platform and a support structure connected to the fixed platform in a manner that allows the support structure to rotate relative to the fixed platform between a raised, engaged position and a lowered, deployed position. A lifting assembly is operative to rotate the support structure from the deployed position to the engaged position. The lifting assembly includes first and second cylinders located, respectively, on left and right sides of the support structure and are connected between the fixed platform and a distal end of the support structure. The cylinders retract to rotate the support structure toward the engaged position. A lifting actuator is usable by an operator to cause operation of the cylinders in a manner that rotates the support structure toward the engaged position.Additionally, the lift actuator is configured to stop the lifting of the support structure if it were released by the operator. One or more embodiments of the present invention are illustrated in the accompanying figures, which are incorporated into and constitute a part of this description. Brief Description of the Figures The complete description of the present invention, including the best mode thereof and directed to a person of ordinary skill in the art, is set forth in the description, in which reference is made to the attached figures, in which: A side elevation of a platform equipped with a walkway having a self-elevating assembly in accordance with the present invention is shown in Figure 1. Figure 2 shows a simplified elongated elevation showing the aspects of the walkway and its lifting assembly. A schematic hydraulic circuit diagram illustrating a lifting assembly according to one embodiment of the present invention is shown in Figure 3. Left and right enlarged perspective views are shown in Figures 4A and 4B showing a housing for containing the lifting assembly components. A rear perspective view of the housing of Figures 4A and 4B is shown in Figure 5, which is shown in schematic view to reveal certain components located therein. Figures 6A and 6B schematically illustrate modifications to the hydraulic circuit of Figure 3 that use an electric motor to drive the hydraulic pump. A perspective view illustrating a hydraulic cylinder with a rod length adjustment spacer that could be used with embodiments of the present invention is shown in Figure 7. A schematic hydraulic circuit diagram illustrating a lifting assembly according to one embodiment of the present invention is shown in Figure 8. The repeated use of reference numerals in the present description and in the figures is intended to represent the same or analogous features or elements of the invention. Detailed Description of the Invention Reference will now be made in detail to presently preferred embodiments of the invention, one or more examples of which are illustrated in the accompanying figures. Each example is provided by way of explanation of the invention, not limitation of the invention. Indeed, it will be clear to those skilled in the art that modifications and variations could be made to the present invention without departing from the scope or spirit thereof. For example, features illustrated or described as part of one embodiment could be used in another embodiment to produce a still further embodiment. Thus, the present invention is intended to cover such modifications and variations as fall within the scope of the appended claims and their equivalents. Examples of walkways or gangways, their components and associated lowering restraint equipment are pointed out in U.S. Patent Nos. 7,950,095 (entitled Gangway and Method for Manufacturing Same), 8,387,191 (entitled Gangway Bearing Retainer Plate), U.S. Patent No. 10,145,070 (entitled Gangway Having Hydraulic Position Locking Assembly), and U.S. Patent No. 10,253,464 (entitled Gangway Having Position Locking Assembly), all of which are fully incorporated herein by reference for all purposes. A walkway 10 including a self-elevating assembly in accordance with the present invention is illustrated in Figure 1. The proximal end of the walkway 10 is pivotally connected to a fixed platform 12 located at the appropriate height (in this example, 3.64 m (12 ft)). The platform 12 is supported in this case by a support column 14. A cage assembly 16 is pivotally connected to the distal end of the walkway 10. As shown, the cage assembly 16 includes a rail structure 18 that defines the enclosed area within which a worker may stand when the cage assembly 16 is lowered into the working position. Typically, the cage assembly 16 is lowered to position around an access hatch of a storage container (such as a trailer 20).Examples of suitable gangways that could be used with embodiments of the present invention are shown in U.S. Patent No. 7,950,095, which is referenced above. Another exemplary gangway that could be used with embodiments of the present invention is described in U.S. Provisional Application Serial No. 62 / 962,552, entitled Gangway Assembly, filed on January 17, 2020, in the name of Robert W. Honeycutt as the inventor, which is incorporated herein by reference for all purposes. The walkway 10 has a support structure 22 that pivots relative to the platform 12. (As used herein, the term "platform" may refer to the entire platform 12 or to a portion of the walkway 10 that is fixedly engaged with an existing platform.) A ramp (or set of turntable stairs) is carried by the support structure 22. In this embodiment, the walkway 10 further includes a pair of parallel hand rails (e.g., hand rail 24) between which an operator walks to access the top of the container. Respective ends of the hand rails are pivotally connected to proximal and distal columns 26 and 28. The walkway 10 may be housed or nested when not in use by rotating the support structure 22 so that it is oriented in an upward (i.e., generally vertical) position. Ά Now, also with reference to Figure 2, the present embodiment incorporates a self-raising assembly (or more simply, the lifting assembly) that moves the support structure 22 into the nested position when actuated by a user. For example, the lifting assembly may include at least one fluid-actuated cylinder 30 which causes upward movement of the support structure 22 while also providing controlled downward movement of the support structure 22. In this embodiment, a pair of hydraulic cylinders 30a and 30b are provided (Figure 3). In this embodiment, cylinders 30a and 30b are located on the left and right sides of support structure 22. As indicated at 32 and 33, each cylinder may be connected in this embodiment between a fixed structure on platform 12 and a distal end area of ​​support structure 22. (As used herein, the terms proximal end and distal end of the support structure and / or walkway refer to the area near the actual nearer and farther ends of the platform.) Preferably, for example, cylinders 30a and 30b may be positioned in the same location where prior art walkways have left and right springs balanced. For example, the proximal end of cylinder 30 in this case is coupled to a mount 34 which itself couples to the outboard side of column 26.In this regard, a prior art walkway or catwalk could be retrofitted according to the present invention, or a new walkway according to the present invention could be substituted for a prior art one. Indeed, the cylinders could be covered with a lining 35 (Figure 1) similar to those used in the past for balanced springs. Now, also referring to Figure 3, a pair of actuators 36 and 38 could be provided to control the functions of the lifting assembly. For example, actuator 36 could be used to effect lifting of support structure 22 to the engaged position. In this embodiment, actuator 36 includes a valve housing 40 and a reciprocating plunger 42. Plunger 42 is spring-loaded to be normally out of the position (shown), although it can be pulled by the user into the actuated position to actuate the lifting assembly. For example, a pull rope 43 (Figure 2) could be interconnected with the plunger 42 so that the plunger 42 could be pulled by an operator standing on the platform 12. In this embodiment, upward movement of the plunger 42 occurs when the operator pulls the rope 43, as indicated by arrow P, in the region between the upper and lower guides 44a-b.In other embodiments, the end of the rope 43 is only pulled upward in a vertical direction. In any case, as described more fully below, the user must continue pulling the plunger 42 in this embodiment as the support structure 22 is raised. If the user stops holding the plunger 42 in the actuated position, the support structure 22 will stop in its current, partially raised position. In addition, other embodiments are contemplated in which the plunger 42 could be pushed toward the actuated position. In this embodiment, the actuator 38 is operated by the foot lock 45 which is used to lock the walkway in the engaged position. As is well known in the art, this foot locks the clutch of a small post 46 located on the support side 22. When the operator desires to lower the support structure 22, the pedal 47 of the foot lock 45 is depressed, causing the foot lock 45 to swing and thereby disengage from the post 46. However, in accordance with the present invention, a cable 48 is coupled to the foot lock 45 near the pedal 47. In this way, depressing the pedal 47 causes the cable 48 to slide relative to its lining or coating 49 to operate the actuator 38. Embodiments are contemplated in which the pedal 44 must be depressed the entire time that the support structure 22 is lowered or else the descent will stop and the support structure 22 will remain in its current position.This allows the operator to precisely control the descent of the walkway to containers of different heights. In other embodiments, pedal 44 could be pressed momentarily to begin the lowering process, although the lowering process will continue at a later time. Preferably, the lift assembly is configured to have a compact design that allows various other components (described more fully below) to be conveniently housed in an out-of-the-way location. As indicated at numeral 50, for example, these components could be located in a housing 52 depending from the underside of the platform 12. Various hoses, such as hoses 54 and 56, interconnect the cylinders 30, the actuator 36, the actuator 38, and the components 50. A gangway lift assembly 100 in accordance with one embodiment of the present invention is schematically illustrated in Figure 3. As can be seen, each of the cylinders 30a and 30b has a housing 102 containing a piston 104. A rod 106 engages one side of each piston 104 and extends outwardly from the housing 102. The rods 106 are shown fully retracted in this view as they would be when the gangway is in the engaged position. Hydraulic fluid is trapped on the rod side of the piston 104 by pilot-operated check valves 108 and 110. As discussed above, actuator 38 is used to lower the walkway. In this embodiment, actuator 38 comprises a master cylinder 112 having a plunger 114. Master cylinder 112 is actuated by pushing on plunger 114, such as by depressing foot pedal 47 as described above. This movement compresses the fixed volume of fluid between the master cylinder and pilot-operated valves 108, 110, and 116. As a result, check valves 108, 110, and 116 will be moved off their seats to allow fluid flow. In this manner, fluid can flow from the rod end of the cylinders through valves 108, 110, and 115 to valve 116. Valve 115 has an adjustable orifice that restricts fluid flow, thereby controlling the rate at which fluid can leave the rod end of cylinders 30a and 30b. This limits and controls the rate at which the walkway is lowered. With the flow path open as described, gravitational forces acting on the rod pull it outward, circulating fluid from the rod side through valves 108 and 110 to valve 115 and then to valve 116. The fluid continues to flow through valve 116 to the blind end of cylinders 30a and 30b. Because the volumes are different between the rod side and the blind side of each cylinder 30a and 30b, a suction is created due to the vacuum. This vacuum will pull fluid up from tank 122 through valve 120 to the blind side of cylinders 30a and 30b to increase the volume. It is noted that valve 120 incorporates a check valve that allows free flow in this direction. In this embodiment, the removal of physical pressure from the master cylinder 112 (i.e., the release of plunger 114) will cause plunger 114 to move outward (due to the spring associated with master cylinder 112). In this manner, pilot pressure is removed from valves 108, 110, and 116, causing them to seat. Once again, fluid is trapped, which prevents further downward movement of the walkway. To raise the walkway, plunger 42 of actuator 36 is moved to shift the position of a valve 124. In this case, plunger 42 is moved upward by the operator pulling on rope 43 as described above. As a result, air can flow from a compressed air source to a pneumatic motor 126. Typically, most locations where the walkway might be installed will have a compressed air system that can be diverted to various purposes as needed. In the absence of such a system, a small dedicated air compressor could be provided. In this way, the air motor rotates and transmits power to a fluid pump 128 (via shaft 130). Pump 128 pumps fluid from tank 122 to generate pressure at the pump outlet. (Preferably, the maximum pressure is regulated by pressure relief valve 132.) Fluid thus flows through check valve 134, but cannot flow through valve 116. Fluid thus flows through valves 108 and 110 to the rod side of the respective cylinder. The pressure on the rod side retracts the pistons, forcing fluid out of the hidden side of the cylinders. Rods 106 are thus retracted, causing the walkway to move to the engaged position. By way of further explanation, fluid from the hidden side of the cylinders flows out to valve 120 which has an adjustable restricted orifice parallel to the check valve seen above. This orifice in valve 120 regulates flow and controls the rate at which the cylinders can be retracted (i.e., the rate at which the walkway can be raised). Even though the check valve of valve 116 is facing in the flow direction, fluid will not flow through valve 116 of valve 120. This is because the outlet pressure of pump 128 on the opposite side of valve 116 exceeds the pressure of the fluid exiting the hidden side of cylinders 30a and 30b. Thus, fluid exiting the hidden side of cylinders 30a and 30b will flow into tank 122. When plunger 42 is released, it moves (e.g., due to an associated spring) and valve 124 changes its position. In this way, the source of compressed air is cut off from the air supply to motor 126. As a result, pump 128 stops pumping. The fluid trapped on the rod side of cylinders 30a and 30b prevents gravity from pulling the walkway downward. As described in the aforementioned U.S. Patent No. 10,145,070, it is desirable that upward movement of a lowered walkway be prevented unless an operator on the platform acts directly to move the walkway into the engaged position. In a lowered condition, the mass of the walkway 10 is normally balanced and static due to the increased pressure in the fluid trapped in the hidden side of the cylinders. To physically raise the walkway (e.g., to raise its distal end) would require forces significantly greater than those that could be exerted by a person. In the event that large forces are applied to the walkway in an upward direction (e.g., a rail car suspension may generate a lifting force on the walkway as the rail car is unloaded), the present embodiment allows for upward sliding of the walkway. In this situation, a force is applied to the rod side of the cylinders, which lowers or decreases the pressure on the rod side and forces fluid out of the hidden side of the cylinders. The fluid is free to leave the hidden side of the cylinders and flows through the restriction in valve 120 into tank 122. Fluid is also pulled toward the rod side of the cylinders through check valves 108, 110, and 116. If large forces are removed from the walkway, the pressure will rise on the rod side of the cylinder due to gravity.Due to the column of fluid trapped by valves 108 and 110, the walkway will be held in place until: (1) another large force is applied to the end of the walkway; (2) plunger 42 is pulled to raise the walkway; or (3) plunger 112 is pushed to lower the walkway. Front perspective views of the housing 52 are shown in Figures 4A and 4B from the left and right sides, respectively. As can be seen, the liner 49 extends into the interior of the housing 52 on the left side while the cord 43 connects to a swivel joint 58 on the right side of the housing 52. Preferably, the housing 52 may have a hinged cover plate 60 that may be easily opened when access to the interior of the housing is desired. In this embodiment, the housing 52 is coupled to the underside of a fixed base surface by means of existing mounting holes. Certain additional details can be seen in Figure 5. For example, it can be seen that the push cable 48 is connected to the plunger 114 in this embodiment by means of a swivel joint 62. The fittings 64 are located on the exterior of the housing 52 to provide a convenient location for the connection of the cylinder hoses. A corrosion-resistant breathing vent 66 is also provided in this embodiment. While the fluid pump 128 is shown in Figure 3 to be driven by an air motor, one skilled in the art will appreciate that any suitable motor could be used. In this regard, embodiments are shown in Figures 6A and 6B in which the pump 128 is being driven by an electric motor, in this case a 12 V DC motor 626. In the embodiment of Figure 6A, power is supplied by a primary AC source 150, such as a 120 V DC source or a 240 V DC source that are commonly provided in North America. The source 150 supplies power to suitable circuitry which converts the AC power to the required DC level (e.g., 12 VDC). The circuitry 152 also constitutes suitable switching elements (e.g., solid state or electromechanical relays) for operating the motor 626 when elevation of the walkway is desired.Preferably, the switching elements will be controlled by actuator 636, which, from a user perspective, operates in a manner similar to actuator 36 described above. As one skilled in the art will appreciate, it may be necessary or desirable, particularly in the case of 120 VGA power, for circuitry 152 to include one or more internal batteries or other suitable energy storage elements to augment the instantaneous current that the primary supply could supply on its own. In the embodiment of Figure 6B, power is supplied by one or more solar panels 154 (in addition to or instead of primary power). The panels 154 supply or feed power to suitable circuitry 156 which stores the accumulated solar energy (e.g., using one or more internal batteries or other suitable energy storage elements) and provides it when needed at the appropriate DC level (e.g., 12 VDC). The circuitry 156 also includes suitable switching elements (e.g., solid-state or electromechanical relays) for operating the motor 626 when elevation of the walkway is desired. Preferably, the switching elements will be controlled by the actuator 636 as described with reference to the previous embodiment. Next, with reference to Figure 7, one aspect of the cylinder 30 that is useful in some implementations of the present invention will be described. As one of skill in the art will appreciate, the necessary length of the extended cylinder when the walkway is in the deployed, lowered position will generally depend upon the length of the walkway itself. Because walkways come in various lengths, this may require stocking multiple cylinder lengths. However, in accordance with the present invention, it has been found that the length of the rod 106 may be adjusted using spacer members, such as spacer member 706. As can be seen, the spacer member 706 is positioned between the end of the rod 106 and the associated coupling 708 by which the rod 106 is connected to the walkway. For example, the spacer member 706 could have the same connection arrangement by which the coupling 708 would otherwise be directly connected to the rod 106. Spacer members of various lengths could be provided so that the appropriate spacer member can be chosen for the length of walkway being used, thereby eliminating or decreasing the need to stock cylinders of different lengths. A gangway lifting assembly 200 is illustrated in Figure 8 in accordance with an alternative embodiment. This embodiment uses one or more passive energy storage devices to eliminate the need for any external power source to raise and lower the gangway. For example, one or more fluid accumulators could be provided to store and release energy as the gangway moves between the engaged and lowered positions. To this end, rod accumulator 202 is in fluid communication with the rod sides of cylinders 30a and 30b. Similarly, a concealed accumulator 204 is in fluid communication with the concealed sides of cylinders 30a and 30b. Preferably, accumulators 202 and 204 could be diaphragm accumulators having a gas (e.g., nitrogen) on one side of the diaphragm charged to a predetermined resting pressure.The hydraulic fluid is located on the other side of the diaphragm opposite the gas. In this embodiment, many of the components are located in the control block 206, which could be mounted on or in the platform or support structure as described above. Hoses (e.g., hose 208) to and from cylinders 30a and 30b and control block 206 could be connected by means of respective quick-disconnect fittings (indicated collectively at 210). This facilitates installation of the walkway and / or assembly 200. In addition, respective line-rupture protection valves (indicated collectively at 212) could be provided to prevent loss of hydraulic fluid if a hose rupture occurs near cylinders 30a and 30b. Obviously, the above embodiment could also be equipped with various quick-disconnects and line-rupture protection valves for the same reasons. When the walkway is in the lowered position, the rods of cylinders 30a and 30b will be extended as described above. As a result, hydraulic fluid will be collected in the rod accumulator 202. In this way, the diaphragm will be compressed and exert pressure on the hydraulic fluid side of the accumulator. However, the fluid is trapped on the hidden side of cylinders 30a and 30b because valve 214 is in the closed position. As a result, the lowered walkway will remain locked in the lowered position. To raise the walkway, valve 214 is moved to the open position, in this case by depressing a plunger 216. In this manner, rod accumulator 202 forces fluid back into the rod sides of cylinders 30a and 30b, retracting the pistons. Fluid is forced out of the blind sides of cylinders 30a and 30b into concealed accumulator 204. In this embodiment, plunger 216 will move back to the closed position (e.g., due to the associated spring) if plunger 216 is released. An adjustable orifice in valve 218 controls the flow out of the blind side of the cylinders, thereby regulating the rate at which the walkway is raised. Preferably, a conventional foot lock could be provided in this embodiment to further maintain the walkway in the retracted position. MIL / a / zuzi / a zuoa To lower the walkway in this embodiment, the operator simply releases the foot lock and pushes the walkway into the lowered position. After an initial push, gravity and the pressure imposed on the collected fluid in the concealed accumulator 204 cause fluid to flow (through check valve 214 and an additional check valve 220) into the concealed side of cylinders 30a and 30b. Fluid exiting the rod side of cylinders 30a and 30b flows into the rod accumulator 202. An adjustable orifice in valve 222 controls the flow out of the rod side of the cylinders, thereby regulating the rate at which the walkway is lowered. Based on the foregoing, one skilled in the art will be able, without undue experimentation, to adjust the gas precharge in accumulators 202 and 204 to achieve proper operation. Furthermore, a precharge system 224, disconnected during operation, could be provided to facilitate hydraulic fluid adjustment. A slide release valve 226 is provided to allow some fluid to exit the blind sides of cylinders 30a and 30b if large forces are applied to the walkway in an upward direction. Valve 226 bypasses check valve 214 and check valve 220 if a preset pressure is reached. Those skilled in the art will appreciate that the foregoing description provides a walkway having a novel lifting assembly. While one or more preferred embodiments of the invention have been described above, it is to be understood that any and all equivalent embodiments of the present invention are included within the scope and spirit thereof. The depicted embodiments are presented by way of example only and are not intended as limitations of the present invention. Furthermore, it is to be understood by those skilled in the art that the present invention is not limited to these embodiments because modifications may be made. Therefore, it is contemplated that any and all such embodiments are included in the present invention that would fall within the scope and spirit thereof. It is noted that in relation to this date, the best method known to the applicant to put the aforementioned invention into practice is the one that is clear from the present description of the invention.

Claims

1. A walkway comprising: a fixed platform; a support structure connected to the fixed platform in a manner allowing the support structure to rotate relative to the fixed platform between a raised, engaged position and a lowered, deployed position; and a lifting assembly operative to rotate the support structure from the deployed position to the engaged position, the lifting assembly including: at least one fluid-actuated cylinder connected between the fixed platform and a distal end of the support structure; and a lifting actuator usable by an operator to cause the cylinder to operate in a manner to rotate the support structure toward the engaged position.

2. The walkway according to claim 1, characterized in that the cylinder is retracted to rotate the support structure towards the engaged position.

3. The walkway according to claim 2, characterized in that at least the cylinder includes the first and second cylinders located on the left and right sides of the support structure, respectively.

4. The walkway according to claim 3, characterized in that the lifting actuator comprises a plunger associated with a lifting valve, the plunger being movable to change the position of the lifting valve.

5. The walkway according to claim 4, characterized in that the plunger is moved outward to cause the support structure to be raised.

6. The walkway according to claim 4, characterized in that the plunger is moved inward to cause the support structure to be raised.

7. The walkway according to claim 1, characterized in that the lifting assembly includes a hydraulic pump driven by a motor.

8. The walkway according to claim 7, characterized in that the motor is a pneumatic motor.

9. The walkway according to claim 7, characterized in that the motor is an electric motor.

10. The walkway according to claim 9, characterized in that the electric motor is powered by an AC source.

11. The walkway according to claim 9, characterized in that the electric motor is powered at least in part by at least one solar panel.

12. The walkway according to claim 3, characterized in that the lifting assembly includes at least one accumulator.

13. The walkway according to claim 12, characterized in that at least the accumulator comprises a first rod accumulator and a second hidden accumulator connected, respectively, to be in fluid communication with a rod side and a hidden side of each of the first and second cylinders.

14. The walkway according to claim 1, characterized in that the lifting actuator is configured to stop the lifting of the support structure if it were released by the operator.

15. The walkway according to claim 1, characterized in that the lifting assembly further includes a lowering actuator usable by an operator to cause the cylinder to operate in a mode that rotates the support structure toward the deployed position.

16. The walkway according to claim 15, characterized in that the lifting assembly is configured such that the support structure will stop further rotation toward the deployed position if the lowering actuator is released.

17. The walkway according to claim 15, characterized in that the lowering actuator is configured to have a master cylinder with an associated lowering plunger, the lowering plunger being movable inwardly to cause unseating of at least one pilot-operated check valve.

18. The walkway according to claim 1, characterized in that at least the fluid-actuated cylinder includes a cylinder rod having a spacer member coupled with a distal end thereof.

19. A walkway comprising: a fixed platform; a support structure connected to the fixed platform in a manner allowing the support structure to rotate relative to the fixed platform between a raised, engaged position and a lowered, deployed position; and a lifting assembly operative to rotate the support structure from the deployed position to the engaged position, the lifting assembly including: at least one fluid-actuated cylinder connected between the fixed platform and a distal end of the support structure; the cylinder being operative to move so as to rotate the support structure toward the engaged position; a lifting actuator comprising a plunger associated with a lift valve, the plunger movable to change the position of the lift valve; a pneumatic motor connectable to a source of compressed air via the lift valve;And a hydraulic pump operated by the pneumatic motor.; 20. The walkway according to claim 19, characterized in that the cylinder retracts to rotate the support structure towards the engaged position.

21. The walkway according to claim 19, characterized in that at least the cylinder includes the first and second cylinders located on the left and right sides of the support structure, respectively.

22. The walkway according to claim 19, characterized in that the plunger is moved outward to cause the support structure to be raised.

23. The walkway according to claim 22, characterized in that the lifting actuator is configured to stop the lifting of the support structure if it were released by the operator.

24. The walkway according to claim 19, characterized in that the lifting assembly further includes a lowering actuator usable by an operator to cause the cylinder to operate in a mode that rotates the support structure toward the deployed position.

25. The walkway according to claim 19, characterized in that the lowering actuator is configured as a master cylinder having an associated lowering plunger, the lowering plunger being movable inwardly to cause unseating of at least one pilot-operated check valve.

26. A walkway comprising: a fixed platform; a support structure connected to the fixed platform in a manner allowing the support structure to rotate relative to the fixed platform between a raised, engaged position and a lowered, deployed position; and a lifting assembly operative to rotate the support structure from the deployed position to the engaged position, the lifting assembly including: first and second cylinders respectively located on left and right sides of the support structure and connected between the fixed platform and a distal end of the support structure, the cylinders retracting to rotate the support structure toward the engaged position; a lifting actuator usable by an operator to cause operation of the cylinders in a manner to rotate the support structure toward the engaged position;and where the lifting actuator is configured to stop lifting the support structure if it were released by the operator.; 27. The walkway according to claim 26, characterized in that the lifting assembly includes at least one accumulator.

28. The walkway according to claim 27, characterized in that at least the accumulator comprises a first rod accumulator and a second hidden accumulator connected, respectively, to be in fluid communication with a rod side and a hidden side of each of the first and second cylinders.

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