Patent Description:
Gangways may be used to provide access from a platform to an area such as the top of a storage container, vehicle, or ship. For example, a semi-trailer truck or a railroad carriage transporting dry goods may need to be inspected, loaded, or unloaded from the container's top. A gangway is used to span 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 as to be stowed in a raised position. Typically, a foot lock is provided to maintain 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 into its lowered position. Once fully lowered, the distal end of the gangway will be adjacent the top of the container. When access to the top of the container is no longer needed (e.g., due to completion of the unloading process), the gangway is manually raised back to the stowed position until the foot lock is engaged.

In a common arrangement, heavy-duty chains are attached on each side of the gangway near its distal end. The chains can be locked with respect to platform uprights to prevent further lowering of the gangway when the desired location is reached. In addition, the chains are pulled to raise the gangway to its raised position.

<CIT> describes a gangway according to the preamble of claim <NUM> and a conveyor crossover having a pivotable ramp which is moved from a horizontal bridging position across a conveyor to an upright position in which it is out of the way of material being moved by the conveyor.

The present invention recognizes and addresses the foregoing considerations, and others, of prior art construction and methods.

The present invention provides a gangway according to claim <NUM>, comprising a fixed platform and a support structure connected to the fixed platform in a manner that allows the support structure to rotate with respect to the fixed platform between a raised stowed position and a lowered deployed position. A raising assembly is operative to rotate the support structure from the deployed position to the stowed position. The raising assembly includes at least one fluid actuated cylinder connected between the fixed platform and a distal end of the support structure. For example, the at least one fluid actuated cylinder may include a cylinder rod having a spacer member attached to a distal end thereof. A raising actuator is usable by an operator to cause operation of the cylinder in a manner that rotates the support structure toward the stowed position.

The cylinder retracts to rotate the support structure toward the stowed position. The at least one cylinder includes first and second cylinders situated on left and right sides of the support structure, respectively. The raising actuator comprises a plunger associated with a raising valve, the plunger being movable to change a position of the raising valve. In some embodiments, the plunger is moved outward to cause raising of the support structure whereas, in other embodiments, the plunger is moved inward to cause raising of the support structure.

According to some embodiments, the raising assembly may 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 are contemplated in which the electric motor is powered by an AC source. In some embodiments, the electric motor may be powered at least in part by at least one solar panel.

According to some embodiments, the raising assembly may include at least one accumulator. For example, a first rod accumulator and a second blind accumulator may be provided, respectively connected to be in fluid communication with a rod side and a blind side of each of the cylinder(s).

According to some embodiments, the raising actuator may be configured to cease raising of the support structure if released by the operator. According to some embodiments, the raising assembly may further include a lowering actuator usable by an operator to cause operation of the cylinder in a manner that rotates the support structure toward the deployed position. In this regard, the raising assembly may be configured such that the support structure will cease further rotation toward the deployed position if the lowering actuator is released. For example, the lowering actuator may be configured having a master cylinder with an associated lowering plunger, the lowering plunger movable inward to cause unseating of at least one pilot operated check valve.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more embodiments of the present invention.

A full and enabling disclosure of the present invention, including the best mode thereof directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended drawings, in which:.

Repeat use of reference characters in the present specification and drawings is intended to represent same or analogous features or elements 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 drawings. In fact, it will be apparent to those skilled in the art that modifications and variations can be made in the present invention without departing from the scope thereof, as defined by the claims.

For instance, features illustrated or described as part of one embodiment may be used on another embodiment to yield a still further embodiment.

Examples of gangways, their components, and associated fall restraint equipment are set forth in <CIT> (entitled "Gangway and Method for Manufacturing Same"), <CIT> (entitled "Gangway Bearing Retainer Plate"), <CIT> (entitled "Gangway Having Hydraulic Position Locking Assembly"), and <CIT> (entitled "Gangway Having Position Locking Assembly").

<FIG> illustrates a gangway <NUM> including a self-raising assembly in accordance with the present invention. The proximal end of gangway <NUM> is pivotally connected to a fixed platform <NUM> located at the appropriate height (twelve feet in this example). Platform <NUM> is supported in this case by a support column <NUM>. A cage assembly <NUM> is pivotally connected to the distal end of gangway <NUM>. As shown, cage assembly <NUM> includes a rail structure <NUM> defining an enclosed area within which a worker can stand when cage assembly <NUM> is lowered into the working position. Typically, cage assembly <NUM> is lowered so as to be located around an access hatch of a storage container (such as trailer <NUM>). Examples of suitable gangways that may be used with embodiments of the present invention are shown in previously-mentioned <CIT>. Another exemplary gangway that may be used with embodiments of the present invention is disclosed in <CIT>as inventor.

Gangway <NUM> has a support structure <NUM> that pivots with respect to platform <NUM>. (As used herein, the term "platform" may refer to the entire platform <NUM> or to a portion of gangway <NUM> which is fixedly attached to an existing platform. ) A ramp (or a set of pivotal stairs) is carried by the support structure <NUM>. In this embodiment, gangway <NUM> further includes a pair of parallel hand rails (e.g., hand rail <NUM>) between which the operator walks to access the top of the container. Respective ends of the handrails are pivotally connected to proximal and distal uprights <NUM> and <NUM>.

Gangway <NUM> may be stowed when not use by rotating support structure <NUM> such that it is oriented in an upward (i.e., generally vertical) position. Referring now also to <FIG>, the present embodiment incorporates a self-raising assembly (or more simply "raising assembly") that moves support structure <NUM> to the stowed position when actuated by a user. For example, the raising assembly may include at least one fluid-actuated cylinder <NUM> which causes the upward movement of support structure <NUM> while also providing controlled downward movement of support structure <NUM>. In this embodiment, a pair of hydraulic cylinders 30a and 30b (<FIG>) are provided.

Cylinders 30a and 30b are located in this embodiment on left and rights sides of support structure <NUM>. As indicated at <NUM> and <NUM>, each such cylinder may be connected in this embodiment between a fixed structure at platform <NUM> and the area of the distal end of support structure <NUM>. (As used herein, the terms "proximal end" and "distal end" of the support structure and/or gangway refer to the area near the actual ends nearer to and farther from the platform. ) Preferably, for example, cylinders 30a and 30b may be positioned at the same location where gangways of the prior art have left and right counterbalanced springs. For example, the proximal end of cylinder <NUM> is in this case attached to a mount <NUM> which is itself attached to the outboard side of upright <NUM>. In this regard, a prior art gangway may be retrofit according to the present invention, or a new gangway according to the present invention may be substituted for one of the prior art. In fact, the cylinders may be covered which a sheath <NUM> (<FIG>) similar to those used in the past for the counterbalanced springs.

Referring now also to <FIG>, a pair of actuators <NUM> and <NUM> may be provided to control functions of the raising assembly. For example, actuator <NUM> can be used to effect raising of the support structure <NUM> into the stowed position. In this embodiment, actuator <NUM> includes a valve housing <NUM> and a reciprocating plunger <NUM>. Plunger <NUM> is springloaded to be normally in an off position (shown), but can be pulled by a user into an actuation position to actuate the raising assembly. For example, a pull rope <NUM> (<FIG>) may be interconnected to plunger <NUM> so that plunger <NUM> can be pulled by an operator standing on the platform <NUM>. In this embodiment, the upward movement of plunger <NUM> occurs when the operator pulls rope <NUM>, as indicated by arrow P, in the region between upper and lower guides 44a-b. In other embodiments, the end of rope <NUM> is simply pulled vertically upward. In any event, as described more fully below, the user must continue pulling plunger <NUM> in this embodiment as support structure <NUM> is raised. If the user ceases to maintain plunger <NUM> in the actuation position, support structure <NUM> will stop at its current, partially-raised position. Other embodiments are contemplated in which plunger <NUM> may be pushed into an actuation position.

Actuator <NUM> is operated in this embodiment by the foot lock <NUM> which is used to lock the gangway in the stowed position. As is well-known in the art, such foot locks engage a small post <NUM> located on the side of support structure <NUM>. When the operator wishes to lower support structure <NUM>, the pedal <NUM> of foot lock <NUM> is depressed, causing foot lock <NUM> to see-saw and thereby disengage from the post <NUM>. In accordance with the present invention, however, a cable <NUM> is attached to foot lock <NUM> near pedal <NUM>. Depressing pedal <NUM> thus causes cable <NUM> to slide with respect to its sheath <NUM> so as to operate actuator <NUM>. Embodiments are contemplated in which pedal <NUM> must be depressed the whole time that support structure <NUM> is lowered or else the lowering will stop and the support structure <NUM> will remain at its current position. This allows the operator to precisely control lowering of the gangway to containers of different heights. In other embodiments, pedal <NUM> may be momentarily depressed to begin the lowering process but the lowering process will thereafter continue.

The raising assembly is preferably configured to have a compact design that allows various other of its components (described more fully below) to be conveniently housed in an out-of-the-way location. As indicated at <NUM>, for example, these components may be located in a housing <NUM> that depends from the underside of platform <NUM>. Various hoses, such as hose <NUM> and <NUM>, interconnect cylinder(s) <NUM>, actuator <NUM>, actuator <NUM>, and the components <NUM>.

<FIG> schematically illustrates a gangway raising assembly <NUM> in accordance with an embodiment of the present invention. As can be seen, cylinders 30a and 30b each have a housing <NUM> containing a piston <NUM>. A rod <NUM> is attached to one side of each piston <NUM> and extends outside of the housing <NUM>. Rods <NUM> are shown fully retracted in this view as they would be when the gangway is in the stowed position. Hydraulic fluid is trapped on the rod side of piston <NUM> by pilot operated check vales <NUM> and <NUM>.

As discussed above, actuator <NUM> is utilized to lower the gangway. In this embodiment, actuator <NUM> comprises a master cylinder <NUM> having a plunger <NUM>. Master cylinder <NUM> is actuated by pushing in plunger <NUM>, such as by depressing foot pedal <NUM> as described above. This action compresses a fixed volume of fluid between the master cylinder and pilot operated checks <NUM>, <NUM>, and <NUM>. As a result, check valves <NUM>, <NUM>, and <NUM> will be unseated to allow fluid flow. Fluid is thus able to circulate from the rod end of the cylinders across valves <NUM>, <NUM>, and <NUM> to valve <NUM>. Valve <NUM> has an adjustable orifice that restricts fluid flow, thereby controlling the rate that fluid can leave the rod side of cylinders 30a and 30b. This limits and controls the rate at which the gangway drops.

With the flow path open as described, gravitational forces acting on the rod pull it outward circulating fluid from the rod side across valves <NUM> and <NUM> to valve <NUM> then valve <NUM>. Fluid continues to flow though valve 116to the blind end of the cylinders 30a and 30b. Because the volumes are different between the rod side and blind side of each cylinder 30a and 30b, a suction due to vacuum is created. This vacuum will pull fluid up from the tank <NUM> through valve <NUM> to the blind side of the cylinders 30a and 30b to make up the volume. Note that valve <NUM> incorporates a check valve which freely allows flow in this direction.

In this embodiment, removal of physical pressure from master cylinder <NUM> (i.e., release of plunger <NUM>) will cause plunger <NUM> to move outward (due to a spring associated with master cylinder <NUM>). Pilot pressure is thus removed on valves <NUM>, <NUM>, and <NUM>, causing them to become seated. Fluid is once again trapped, which stops further downward movement of the gangway.

To raise the gangway, plunger <NUM> of actuator <NUM> is moved to shift the position of a valve <NUM>. Plunger <NUM> is moved upward in this case due to the operator pulling on rope <NUM> as described above. As a result, air can flow from a compressed air source to an air motor <NUM>. Typically, most locations at which the gangway might be installed will have a compressed air system that can be tapped into for various purposes as needed. In the absence of such a system, a small dedicated air compressor could be provided.

Air motor <NUM> thus rotates and transmits power to a fluid pump <NUM> (via shaft <NUM>). Pump <NUM> pumps fluid from tank <NUM> to generate pressure at the pump's outlet. (Maximum pressure is preferably regulated by pressure relief valve <NUM>. ) Fluid thus flows across check valve <NUM>, but cannot flow across valve <NUM>. The fluid thus flows through valves <NUM> and <NUM> to the rod side of the respective cylinder. The pressure in the rod side retracts the pistons, forcing fluid out of the blind side of the cylinders. The rods <NUM> thus retract, causing the gangway to move toward the stowed position.

By way of further explanation, fluid from the blind side of the cylinders flows out to valve <NUM> which has an adjustable restricted orifice in parallel to the check valve noted above. This orifice in valve <NUM> regulates flow and controls the speed that the cylinders can retract (i.e., the speed at which the gangway can be raised). Even though the check valve of valve <NUM> is in the flow direction, fluid will not flow through valve <NUM> from valve <NUM>. This is because the outlet pressure from pump <NUM> on the opposite side of valve <NUM> exceeds the pressure of the fluid exiting the blind side of cylinders 30a and 30b. The fluid exiting the blind side of cylinders 30a and 30b will thus flow into tank <NUM>.

When plunger <NUM> is released, it moves (e.g., due to an associated spring) and valve <NUM> switches its position. The compressed air source is thus blocked from supplying air to motor <NUM>. As a result, pump <NUM> stops pumping. The fluid trapped in the rod side of cylinders 30a and 30b prevents gravity from pulling the gangway down.

As described in previously-mentioned <CIT>, it is desirable to inhibit upward movement of a lowered gangway unless an operator on the platform affirmatively acts to move the gangway into the stowed position. In a lowered condition, the mass of gangway <NUM> is normally balanced and static due to an increase in pressure in fluid trapped in the blind side of the cylinders. To raise the gangway physically (e.g., to lift its distal end) would require forces significantly greater than a person could exert.

In the event that high forces are applied to the gangway in an upward direction (e.g., a rail car's suspension can generate a lifting force on the gangway as the rail car is unloaded), the present embodiment allows upward slippage of the gangway. In this situation, force is applied to the rod side of the cylinders lowering the pressure in the rod side and pushing fluid out of the blind side of the cylinders. Fluid is free to leave the blind side of the cylinders and flow across the restriction in valve <NUM> to tank <NUM>. Fluid is also pulled into the rod side of the cylinders across the check valves <NUM>, <NUM>, and <NUM>. If the high forces are removed from the gangway, pressure will rise in the rod side of the cylinder because of gravity. Because of the column of fluid trapped by valves <NUM> and <NUM>, the gangway will hold in place until: (<NUM>) another high force is applied to the end of the gangway; (<NUM>) plunger <NUM> is pulled to raise the gangway; or (<NUM>) plunger <NUM> is pushed to lower the gangway.

<FIG> are perspective front views of housing <NUM> from left and right sides, respectively. As can be seen, sheath <NUM> extends into the interior of housing <NUM> from the left side whereas rope <NUM> connects to a pivotal linkage <NUM> on the right side of housing <NUM>. Housing <NUM> may preferably have a hinged cover plate <NUM> that may be easily opened when access to the housing interior is desired. In this embodiment, housing <NUM> is attached to the bottom of a stationary base tread via existing mounting holes.

Certain additional details can be seen in <FIG>. For example, it can be seen that push cable <NUM> connects with plunger <NUM> in this embodiment via a pivotal linkage <NUM>. Fittings <NUM> are located on the exterior of housing <NUM> to provide a convenient location for connecting the cylinder hoses. A corrosion-resistant breather vent <NUM> is also provided in this embodiment.

While fluid pump <NUM> is shown in <FIG> being driven by a pneumatic motor, one skilled in the art will appreciate that any suitable driver could be utilized. In this regard, <FIG> show embodiments in which pump <NUM> is being driven by an electric motor, in this case a <NUM>-volt DC motor <NUM>. In the embodiment of <FIG>, power is supplied by an AC mains source <NUM>, such as a <NUM> VAC source or a <NUM> VAC source as are commonly provided in North America. Source <NUM> supplies the power to appropriate circuitry which converts the AC power to the required DC level (e.g., <NUM> VDC). Circuitry <NUM> also includes appropriate switching elements (e.g., solid state or electromechanical relays) to operate motor <NUM> when raising of the gangway is desired. Preferably, the switching elements will be controlled by actuator <NUM>, which, from the standpoint of the user, operates similarly to actuator <NUM> described above. As one skilled in the art will appreciate, it may be necessary or desired, especially in the case of <NUM> VAC power, for circuitry <NUM> to include one or more internal batteries or other suitable energy storage elements to augment the instantaneous current that the mains source could supply by itself.

In the embodiment of <FIG>, power is supplied by one or more solar panels <NUM> (in addition to or in lieu of mains power). Panel(s) <NUM> supply the power to appropriate circuitry <NUM> which stores accumulated solar energy (e.g., using one or more internal batteries or other suitable energy storage elements) and provides it when necessary at the appropriate DC level (e.g., <NUM> VDC). Circuitry <NUM> also includes appropriate switching elements (e.g., solid state or electromechanical relays) to operate motor <NUM> when raising of the gangway is desired. Preferably, the switching elements will be controlled by actuator <NUM> as described in reference to the previous embodiment.

Referring now to <FIG>, an aspect of cylinder <NUM> will be described that is useful in some implementations of the present invention. As one skilled in the art will appreciate, the necessary length of the extended cylinder when the gangway is in the lowered deployed position will generally depend on the length of the gangway itself. Because gangways come in various lengths, this might require stocking multiple cylinder lengths. In accordance with the present invention, however, it has been found that the length of rod <NUM> can be adjusted using spacer members, such as spacer member <NUM>. As can be seen, spacer member <NUM> is positioned between the end of rod <NUM> and the associated coupling <NUM> by which rod <NUM> is connected to the gangway. For example, spacer member <NUM> may have the same connection arrangement by which coupling <NUM> would otherwise directly connect to rod <NUM>. Spacer members of various lengths may be provided so that the appropriate spacer member can be chosen for the gangway length being used, thereby eliminating or lessening the need to stock cylinders of different lengths.

<FIG> illustrates a gangway raising assembly <NUM> in accordance with an alternative embodiment. This embodiment utilizes one or more passive energy storage devices to eliminate the need for any source of external energy to raise and lower the gangway. For example, one or more fluid accumulators may be provided to store and release energy as the gangway moves between stowed and lowered positions. Toward this end, a rod accumulator <NUM> is in fluid communication with the rod sides of cylinders 30a and 30b. A blind accumulator <NUM> is similarly in fluid communication with the blind sides of cylinders 30a and 30b. Preferably, accumulators <NUM> and <NUM> may be diaphragm accumulators having a gas (e.g., nitrogen) on one side of the diaphragm charged to a predetermined at-rest pressure. The hydraulic fluid is on the other side of the diaphragm opposite the gas.

In this embodiment, many of the components are located on a control block <NUM> which may be mounted on or in the platform or support structure as described above. Hoses (e.g., hose <NUM>) to and from cylinders 30a and 30b and control block <NUM> may be connected via respective quick disconnect fittings (collectively indicated at <NUM>). This facilitates installation of the gangway and/or assembly <NUM>. In addition, respective line break protection valves (collectively indicated at <NUM>) may be provided to prevent loss of hydraulic fluid if there is a hose break near the cylinders 30a and 30b. Of course, the previous embodiment may also be equipped with various quick disconnects and line break protection valves for the same reasons.

When the gangway is 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 rod accumulator <NUM>. The diaphragm will thus be compressed and exerting pressure on the hydraulic fluid side of the accumulator. However, fluid is trapped in the blind side of the cylinders 30a and 30b because valve <NUM> in is the closed position. As a result, the lowered gangway will remain locked in the lowered position.

To raise the gangway, valve <NUM> is moved to the open position, in this case by depressing a plunger <NUM>. Rod accumulator <NUM> thus forces fluid back into the rod sides of cylinders 30a and 30b, retracting the pistons. Fluid is pushed out of the blind sides of cylinders 30a and 30b into blind accumulator <NUM>. In this embodiment, plunger <NUM> will move back to the closed position (e.g., due to an associated spring) if plunger <NUM> is released. An adjustable orifice in valve <NUM> controls the flow out of the blind side of the cylinders, thus regulating the speed at which the gangway raises. Preferably, a conventional foot lock may be provided in this embodiment to further maintain the gangway in the stowed position.

To lower the gangway in this embodiment, the operator simply releases the foot lock and pushes the gangway toward the lowered position. After an initial push, gravity and pressure imposed on the collected fluid in blind accumulator <NUM> causes fluid to flow (through the check valve of valve <NUM> and an additional check valve <NUM>) into the blind side of cylinders 30a and 30b. Fluid exiting the rod side of cylinders 30a and 30b flows into rod accumulator <NUM>. An adjustable orifice in valve <NUM> controls the flow out of the rod side of the cylinders, thus regulating the speed at which the gangway lowers.

Upon reading the foregoing, one skilled in the art will be able without undue experimentation to set the precharge of the gas in accumulators <NUM> and <NUM> to obtain appropriate operation. In addition, a preload system <NUM>, disconnected during operation, may be provided to facilitate set up of the hydraulic fluid.

Claim 1:
A gangway (<NUM>) comprising:
a fixed platform (<NUM>);
a support structure (<NUM>) connected to the fixed platform in a manner that allows the support structure (<NUM>) to rotate with respect to the fixed platform between a raised stowed position and a lowered deployed position; and
a raising assembly (<NUM>) operative to rotate the support structure (<NUM>) from the deployed position to the stowed position, said raising assembly (<NUM>) including
at least one fluid actuated cylinder (<NUM>) connected between the fixed platform (<NUM>) and a distal end of the support structure (<NUM>); and
a raising actuator (<NUM>) usable by an operator to cause operation of the cylinder (<NUM>) in a manner that rotates the support structure (<NUM>) toward the stowed
wherein the cylinder (<NUM>) retracts to rotate the support structure (<NUM>) toward the stowed position;
wherein the at least one cylinder (<NUM>) includes first and second cylinders (30a, 30b) situated on left and right sides of the support structure (<NUM>), respectively,
characterized in that
the raising actuator (<NUM>) comprises a plunger (<NUM>) associated with a raising valve of the gangway (<NUM>), said plunger (<NUM>) being movable to change a position of the raising valve (<NUM>).