Arresting cable retraction system

An arresting cable retraction mechanism for use across an aircraft runway. The retraction mechanism functions to extend a cable across a runway (for capture by a tailhook of an aircraft) without causing the cable to recede below the runway surface during an aircraft rollover/deflection event. The arresting cable retraction mechanism is also designed to help prevent damage to a retraction motion actuator due to high speed aircraft rollover. The disclosed system separates components related to retraction vs. deflection due to rollover, such that rollover events do not affect or load the motion actuator used for retraction.

FIELD OF THE INVENTION

The field of this disclosure relates to an arresting cable retraction mechanism for use across an aircraft runway. The retraction mechanism functions to raise a cable above a runway (for capture by a tailhook of an aircraft) without causing the cable to recede below the runway surface during an aircraft rollover/deflection event. The arresting cable retraction mechanism is also designed to help prevent damage to a motion actuator due to high speed aircraft rollover. The disclosed system separates components related to retraction vs. deflection due to rollover, such that rollover events do not affect or load the motion actuator used for retraction and the mass of the system being deflected is minimized.

BACKGROUND

One type of aircraft arresting system that is used to decelerate an aircraft functions by raising a cable across the runway. These systems are often installed on runways (commercial or military) where aircraft equipped with a tailhook may need to land. In use, the tailhook of the aircraft can engage the cable in order to bring the aircraft to a safe stop.

One component of an aircraft arresting system10is an arresting cable retraction mechanism. As shown byFIG. 1, these mechanisms are used to retract a cross-runway cable12into a trough that spans the runway below the runway surface in order to provide an obstruction-free runway when the cross-runway cable12is not in use. During flight operations, an arresting cable retraction mechanism14raises the cable12to the battery (i.e., engagement ready) position. This position holds the cross-runway cable at the correct height above the runway to allow the tailhook of an aircraft to engage the cable connected to the aircraft arresting system, bringing the aircraft to a controlled and safe stop.FIG. 1illustrates an aircraft arresting system10with a cable12extending across the runway.FIG. 2illustrates the system ofFIG. 1, along with runway edge sheaves150and brake systems/energy absorbers152. These components are positioned alongside the runway for managing payout tape154that is secured to the cable12for a safe aircraft stop.FIG. 3illustrates a schematic view of an aircraft with a tailhook engaging a cross-runway pendant cable12.

Referring back toFIGS. 1 and 2, there are multiple individual retraction mechanisms14mounted below the runway surface. Operation of the retraction mechanisms14takes place from a control tower system16or a control system located off the runway near the arresting system, depending upon fight operations and requirements.

Because these systems are installed on runways over which aircraft travel at high speeds, the mechanisms14often experience impact loading from aircraft wheels during a rollover event. This means that the systems are consequently subject to frequent periodic maintenance. Current arresting cable retraction mechanisms available on the market are not designed to withstand the forces of a high-speed aircraft rollover. These mechanisms are typically only rated for rollovers of up to 25 knots. However, current military operating procedures dictate that an arresting cable retraction mechanism must be able to withstand rollover speeds in excess of 25 knots. Improvements to arresting cable retraction mechanisms are thus desirable.

SUMMARY

Accordingly, the present inventors have designed an arresting retraction system that decouples the motion actuator used to lower the cable below the runway surface from components associated with deflection due to rollover. Decoupling these components helps isolate the motion actuator and related components from the dynamic loading associated with a rollover event. This allows the presently disclosed system to withstand high speed and high frequency rollover events, extending the life and operational envelope of the motion actuator and the system as a whole.

According to certain embodiments of this disclosure, there may be provided an arresting cable retraction system for securing a cross-runway cable across an aircraft runway, comprising: a cable support block assembly configured to receive a cross-runway cable; a first axis of rotation about which the support arm assembly rotates during an aircraft rollover event, wherein the cable is maintained above the runway; and a second axis of rotation about which the cable support block assembly rotates during a retraction event, wherein the cable is retracted into a runway trough. The system may also include a support arm assembly, with the cable support block assembly comprising a lock mechanism that secures the support block assembly to the support arm assembly. In some examples, when the lock mechanism is locked, the support arm assembly rotates about the first axis of rotation upon aircraft will pressure to the cable support block assembly. The system may also include a retraction arm assembly, wherein the retraction arm assembly functions to release the lock mechanism to decouple the support block assembly from the support arm assembly. In some examples, when the lock mechanism is unlocked, the support block assembly rotates about the second axis of rotation to retract the cable into the runway trough. The support arm assembly can have a main shaft that functions as the first axis of rotation, and the retraction arm may have a support block shaft that functions as the second axis of rotation.14. The arresting cable retraction system may be positioned in a support box that comprises a top cover with a cable relief indentation.

For locking the cable support assembly to the support arm assembly, the support arm may have one or more lock blocks that receive a lock pin in order to secure the support block assembly to the support arm assembly. There may also be provided a retraction arm and a motion actuator, wherein the motion actuator is operably coupled to the retraction arm assembly.

In other examples, the motion actuator may be coupled to a latch lock via a cable. In a further example, a movable trolley may be provided, wherein when the movable trolley is in a first position, the cable support block is permitted to rotate with respect to the movable trolley, wherein when the movable trolley is in a second position, the cable support block is prevented from rotation with respect to the movable trolley.

There may also be provided a modular cable support clock for an arresting cable retraction system for securing a cross-runway cable across an aircraft runway, comprising: a modular support block defining an opening for receiving a cross-runway cable; a housing configured to receive the modular support block, wherein the modular support block is removeably secured with respect to the housing; and a lock mechanism that secures the modular support block with respect to the housing. In some examples, the removable securement is achieved via insert grooves positioned along one of the modular support block or the housing that cooperate with tracks positioned on the other of the modular support block or the housing.

DETAILED DESCRIPTION

Arresting cable retraction mechanisms are generally designed to raise and lower a cross-runway cable above and below an aircraft runway. The mechanisms should also be capable of withstanding rollover by aircraft tires. The present disclosure provides an arresting cable retraction mechanism that decouples the retraction components from the components that experience the force from an aircraft rollover. This provides a more robust system that can withstand higher aircraft speeds while requiring reduced maintenance.

During military operations, arresting cable retraction mechanism systems are often left in the battery position (i.e., a raised and engagement ready position), which exposes the system to frequent impacts due to aircraft rollovers. The frequency of impacts due to rollovers can result in damage to the actual retraction components, can prevent the retraction mechanism from operating reliably, or can require additional servicing or repairs of the system.

Based on some of the above-described problems with current arresting cable retraction mechanisms, the present inventors realized that it is desirable to provide a system that more effectively absorbs and distributes the forces of frequent high-speed aircraft rollovers. A stronger and more robust mechanism has been developed. The increased robustness of the disclosed system can help decrease maintenance costs and keep maintenance personnel off of active runways and out of danger during flight operations due to fewer required maintenance actions. The system is also more effective at absorbing and distributing the forces of frequent high-speed aircraft rollovers, increasing operability and reliability while decreasing time spent on maintenance.

As background, the most common current arresting cable retraction mechanism14in use is referred to as a BAK-14M, one example of which is shown inFIGS. 4-6. This mechanism14consists of a single assembly, called a support arm18, which is mounted to a cover plate20and that rests within a support box22. The support box22is mounted below the runway surface, and the cover plate20is flush with the runway surface. The support arm18includes components required for the retraction process, including a linkage assembly24and a motion actuator26. The support arm18also includes a cable support block30, which extends above the support box22and is used to secure a cross-runway cable above the runway.FIG. 4illustrates the cable support block30in a cable raised position. Actuation of the motion actuator26causes retraction movement of the linkage assembly24(which is generally formed as two toggle links as shown), which moves the cable support block about a pivot point32, retracting the cable support block30as illustrated byFIG. 5. This action will occur when the cable support block should be retracted into the runway trough.

When an aircraft rolls over the cable support block30, the entire support arm18deflects to the rollover position shown inFIG. 6. In this example, the support arm18is forced downwardly. A torsion spring34is provided along a support arm shaft that adds deflection capability of the support arm18. The support arm, which carries the motion actuator26, moves down to impact the down stop bumper28. The torsion spring34may also help absorb impact energy. A compression spring36helps return the linkage assembly24and the motion actuator26to their battery position. Once the aircraft wheels have rolled over the support arm18/cable block support30, potential energy of the torsion spring34returns the support arm18/cable block support30back up to the raised position ofFIG. 4.

Incorporating the components required for the retraction process in association with the support arm18, which is also the component that deflects during a rollover event, can increase the mass of the support arm18, which in turn can increase the force experienced by the retraction components (F=ma). Additionally, the motion actuator26and other retraction components experience the shock of every aircraft rollover event, further contributing to system damage.

Military procedures often require that the cross-runway cable be up and ready any time that an aircraft equipped with a tailhook is landing. Accordingly, the arresting cable retraction mechanism(s) potentially experience the force of aircraft wheels due to rollover during every landing. Also, during an aircraft rollover event, the inventors have identified that cross-runway cable should not move below the runway surface as it would during a retraction command. The cross-runway cable should remain above the runway surface during an aircraft rollover, in the event that a tailhook engagement is required. Failure of the cross-runway cable to maintain its position above the runway surface can create the possibility of a hook skip or failure of the aircraft tailhook to engage the arresting system entirely.

The described embodiments thus provide an arresting cable retraction system40that separates the retraction assembly arm from the rollover/deflection components. The retraction assembly arm supports the components that raise the system's cable support block in order to position the pendant cable in its battery position above the runway and which lower the system cable support block and cable to its retracted position in order to position them the either flush or below the with runway or in a retracted position within a trough of the runway. The deflection components support the components that allow the cable support block to lower during a rollover event but spring back up to its ready position as soon the aircraft wheels have passed. Separating the system components from one another provides a more robust and reliable system.

Referring now toFIG. 7, the system40may be contained within a support box22that is mounted below a runway surface. It is possible for the disclosed system40to be used with a currently-installed (and/or prior art) support box22, such that the system40is retrofittable. This allows the system40to be installed into an existing retraction mechanism installation without the need for additional runway civil work or extensive excavation efforts. Existing electrical power, motion control, and/or sensing capabilities of an existing system may be used without modification.FIG. 7shows a support box22mounted with respect to an aircraft runway surface48. The runway48is designed with a trough50that extends the length of the runway surface48. When the system40is not in use, retraction mechanism system components (described in detail below) may be used to lower the cable12into the trough50. When in a raised position, the cable12extends through a cable support block44. When in a lowered position, the cable support block44is retracted/rotated forward such that the cable12can be received into the trough50.

The system40operates in three primary positions.FIG. 8illustrates the system40in the battery position, which is the system in a raised position. The cross-runway cable will be mounted within the support block44above the runway surface and is ready for an aircraft tailhook engagement if needed.FIG. 9illustrates the support arm assembly52of the system40.FIG. 10Aillustrates a close up view of the support arm52in a locked configuration.FIGS. 10B and 11illustrate the system support arm52in the rollover position, which is the system in the deflected position. This position is achieved when an aircraft tire impacts the support block44, causing the assembly to deflect and rotate under load in order to absorb the impact energy. In this position, the cross-runway cable remains above the runway surface. Not allowing the cross-runway cable12to recede below the runway surface, even in this deflected position, helps prevent a hook skip. (A hook skip is the failure of the aircraft to engage the cable when needed.)

FIG. 12illustrates the retraction assembly68of the system40.FIG. 13illustrates a midway step in the retraction of the system40, andFIG. 14illustrates the system in a fully retracted configuration. In this position, the cross runway cable12lies beneath the cover plate20(which is flush with the aircraft runway surface48) and can be positioned within the trough, creating an obstruction-free runway. This position may be used when the runway is not in use by tailhook equipped aircraft and the cable is not required to be accessible. Reference will now be made to these figures and the components that coordinate the rollover event as distinct from the retraction event.

The movement of the cable support block44is controlled via a support arm assembly52, illustrated byFIGS. 9 and 10, and a retraction assembly68, illustrated byFIG. 12. These components work together in order to cause the described types of movement of the cable support block44, and consequent movement of the cross-runway cable12.

FIGS. 9 and 10illustrate the support arm assembly52, which is also shown in combination with other system components byFIGS. 11 and 13-14. The support arm assembly52contains multiple axes of rotation. A first axis of rotation54provides for rotation of the support arm assembly52during rollover (illustrated byFIGS. 10B-11). This first axis54allows the support arm52, including the cable support block44, to absorb the energy applied during rollover impact. A second axis of rotation56provides for rotation of the cable support block44and its related components (which may be referred to collectively as a support block assembly80as illustrated byFIG. 15) during retraction (illustrated byFIGS. 13-14). This second axis56allows the support block assembly80to rotate below the surface of the runway. Providing these two different axes of rotation prevents the retraction components from receiving excessive force during high-speed rollovers. The functioning of these different axes of rotation will be described in more detail below.

Referring more specifically toFIG. 9, the support arm assembly52may be secured to a cable support block assembly80. The cable support block assembly80includes a cable support block44with a cable receiving opening58. This opening58receives and supports a cross-runway cable12in use, as shown byFIG. 7. The cable support block assembly80also includes a housing82which supports a lock mechanism66and a retention plate88. (FIG. 15illustrates one embodiment in which these components of a cable support block assembly80are modular and is described in more detail below. It should be understood however, that modularity is not required.) As illustrated byFIG. 10A, the lock mechanism66may be defined by side lock blocks160on the support arm assembly52and a lock pin162of the housing of the support block assembly80. As illustrated byFIGS. 10A and 10B, lock blocks160are provided with a curved rear face164that is configured to receive the lock pin162. When the lock pin162is engaged in the side lock blocks160as shown, the support block assembly80is rigidly secured to and moves with the support arm assembly52. This collective movement is illustrated by the rollover event shown inFIGS. 10A and 11.

Referring back toFIG. 9, the support arm assembly52also has a main shaft60which defines the first axis of rotation54. Associated with the main shaft are one or more rollover torsion springs62. The main shaft60and the one or more rollover torsion springs62to provide the support arm assembly52with the ability to be deflected into the support box22, as shown byFIGS. 10B and 11during a rollover event. The one or more rollover torsion springs are wound around the main shaft60. The spring(s)62may have rear supports63that extend generally parallel to a support box cover plate20. The rear supports63help provide a counter lever support against the cover plate20during rotation of the support arm assembly52about the main shaft60. This is illustrated byFIG. 11. In this figure, the lock pin162is engaged, such that the support block assembly80and the support arm52are secured to one another and move as a single unit.

When rollover pressure is applied to the cable support block44(e.g., in the form of force from aircraft wheels), it causes the support arm assembly52to rotate down and pivot with respect to the main shaft60, moving from the position illustrated byFIGS. 9 and 10Ato the position illustrated byFIGS. 10B and 11. The cable support block44is depressed downwardly with respect to the cover plate20, such that it lowers partially into the support box22. The main shaft60is positioned in the rear of the support arm assembly52. The torsion springs62absorb some of the energy of the aircraft wheel pressure. Pivoting about the first axis54continues until the abutment members166of the support arm assembly52contact the downstop bumper78located on the retraction assembly68(FIG. 12illustrates the retraction assembly68on its own, and will be described in more detail below). It is important to note that during a rollover event, the cable12does not retract into the trough50. Instead, it remains above the runway surface, as illustrated by the rollover position ofFIG. 11. In prior art systems, there has been the possibility that the cable could catch in the trough and not be in battery position during a tailhook event. However, in this disclosed system, the cable12does not rotate into the trough because the support block44and its related components (assembly (80) is restrained from rotating with respect to any other components of the support arm assembly52by the locking mechanism66. The geometry is such that as the support arm52rotates on axis54during a rollover, and the support block is prevented from pivoting on axis56due to the lock between the support block assembly80and the support arm assembly52. The cable12can come down flush on the top cover20and there is insufficient arc for the cable to get pushed into the trough. The stop defined by the support arm52abutment members166and the downstop bumpers78can also help prevent the cable12from retracting further.

In one example, it is possible to provide a scalloped shape along the cable12where it impacts the cover plate20of the support box22. In another example, it is possible to provide a scalloped shape168along the cover plate20, in order to provide an area for the cable12to rest. One example is illustrated byFIG. 16. This cable relief indentation may alleviate damage caused by a scissoring motion between the cable12and the cover plate20during an aircraft rollover.

The described deflected configuration is only maintained upon pressure from the aircraft wheels during the rollover. The torsion spring(s)62absorb a portion of the rollover force. Once pressure from the rollover wheel force is released from the cable support block44, potential energy of the torsion spring62causes the support arm assembly52(with the locked cable support block assembly80) to spring back up to the battery position ofFIGS. 9 and 10A. This ensures that the cable support block44supporting the cable12is back up in time to present the cable12to an aircraft tailhook if necessary. This spring release can be analogized to the metal spikes positioned along one way entry barrier. Once the wheels of a vehicle have rolled over the spikes, they are allowed to spring back up into their ready position.

Reference will now be made toFIGS. 12-14in order to describe retraction of the cable support block40. Retraction occurs along the second axis of rotation56of the support arm assembly52. During retraction, the cable support block assembly80is unlocked or otherwise released from the support arm assembly52via release of the lock mechanism66. Retraction moves the cable support block assembly80but not the support arm assembly52. The support arm assembly52remains stationary and does not pivot or rotate about the first axis54within the support box22during retraction. The second axis of rotation56allows movement of the support block assembly80with respect to the support arm assembly52. A comparison between the rollover configuration ofFIG. 11and the retraction configuration ofFIG. 14helps illustrate which axis of rotation is active.

The second axis of rotation56of the support arm assembly52is used for retraction. This is the process of retracting the cable support block44entirely below the runway surface48and into the trough50for storage or non-use. This is distinct from the rollover deflection described above. As shown byFIG. 9, the second axis of rotation56is defined by a support block shaft70. The support block shaft70is associated with one or more a support block torsion springs72. The support block shaft70is the pivot shaft for the support block assembly80during retraction. When retraction is to occur, the lock mechanism66between the support block assembly80and the support arm assembly52is released, as described in more detail further below.

Referring now toFIG. 12, the retraction arm assembly68is provided with a motion actuator74and a retraction arm76. The retraction arm assembly68is also provided with one or more downstop bumpers78, which are as described above. The motion actuator74may be a pneumatic actuator, a mechanical actuator, or any other type of motion actuator that may be used to raise and lower the system40. The retraction arm assembly68does not move during rollover deflection but does provide some dampening to abutment members166through the downstop bumpers78. The retraction arm assembly68is activated only during retraction of the support block assembly80, which functions to move the cable12into the trough50.

When a retraction command is issued (e.g., which may be from the control tower16), the retraction arm76disengages the lock mechanism66of the support arm assembly52. As illustrated byFIGS. 12-13, actuation of the motion actuator74moves the retraction arm76from its released/disengaged position (ofFIGS. 11 and 12) to its engaged position ofFIGS. 13 and 14. The retraction arm76applies pressure to the lock pin162in order to force the lock pin162out of the curved face164of the lock blocks60. Release of lock pin162decouples the cable support block assembly80from the support arm assembly52. Independent rotation of the cable support block assembly80about the second axis56allows its retraction. After the lock mechanism66is disengaged, the retraction arm76works against upward pressure from the torsion springs72to pull/pivot the cable support block assembly80about the support block shaft70/second axis56into the retracted position, as illustrated byFIG. 14. The lock mechanism66thus enables the system40to have multiple axis of rotation, while only using the one required for a particular operation. When in a locked configuration, the cable support block assembly80and the support arm assembly52are locked to one another such that the support arm assembly absorbs the energy of a rollover. When the lock mechanism66is in an unlocked configuration, the cable support block assembly80is permitted to pivot with respect to the support arm assembly such that the motion actuator74and the retraction arm78of the retraction assembly retracts the support block assembly80(and the cable contained within it) into the support box22in order to clear the runway surface.

For example, when the lock mechanism66is engaged in a locked configuration (and the retraction arm76is disengaged), the support arm assembly52is able to rotate on the main shaft60/first axis54for rollover deflection. The locked configuration does not transmit any force to the motion actuator74or the retraction arm76of the retraction arm assembly68, preventing them from experiencing impact loading imparted by high-speed rollover forces. When the lock mechanism66is disengaged by the retraction arm76, the cable support block assembly80is allowed to rotate with respect to the support block shaft70/second axis56by the continued motion of the retraction arm76, in order to move the cable support block assembly80into a lowered position.

These multiple points of rotation allow the system40to absorb the aircraft rollover energy and retract the system using two unique motion paths. This is necessary in order to ensure that the cable12does not recede into the runway trough50during an aircraft rollover. This is also necessary in order to ensure that a rollover event does not damage the motion actuator74and retraction arm76. Accordingly, the motion actuator74and retraction arm76remain stationary (along with the retraction arm assembly68) during a deflection rollover event.

FIG. 15illustrates a modular option for a modular cable support block system80, and shows the below described components in an exploded view. It should be understood, however, that these components may be formed as a single component if desired. The modular version allows for quick and easy replacement of the support block85itself without requiring replacement of the support block housing82or any other system components. This can be useful because the cable support block is the system component that has the potential to receive the most damage due to aircraft wheel rollover. In order to exchange the cable support block85without removing the remainder of the components, the modular system ofFIG. 15may be provided. For example, the modular support block85may be secured with respect to housing82via insert grooves84that are positioned along the base of the modular support block85that cooperate with corresponding tracks86of the housing. These components could be reversed so that the cooperation is vice versa. It is possible to dovetail/slide the components85,82with respect to one another for securement of the modular support block80with respect to the housing82. The general concept is that the module support block85may be removably secured to the housing82. It may be removed and replaced if needed without removing the entire system from the support box.

FIG. 15also illustrates the lock mechanism, shown as a lock plate88, that secures the modular support block85to the housing82. The lock plate88is secured with respect to the cable support block housing82. For removal of the modular support block85, the lock plate88may be removed, and the support block may slide out from the housing82.

In the described invention, the lock mechanism66is shown and described as a rod restrained within a slot on the support arm assembly52that maintains its position in the locked position via springs that force it into a curved face164of the lock block160. However, the locking functionality can be achieved using designs that include pins, keys, actuating components, slides, etc. and should not be limited to specific lock mechanism described. The general concept is to maintain the support block assembly80in a secured position with respect to the support arm assembly52in order to prevent aircraft wheel rollover forces applied to the cable support block assembly85from extending to the motion actuator components contained in the retraction assembly68.

When the tower or site wishes to raise the system back up to the battery position, the motion actuator74extends, releasing the retraction arm76from the lock mechanism66. The support block torsion spring(s)72located on the support block shaft70provide the force to return the cable support block assembly85to the battery position. This also re-engages the spring loaded lock mechanism66so that the system is in position for an aircraft rollover event. Both lock mechanism disengagement and support block retraction is accomplished using the motion of the retraction actuator74and retraction arm76, of the retraction arm assembly68.

FIGS. 17A-Cand18illustrate an alternate embodiment of a retraction/rollover mechanism90. As with the above discussed system, the system of these figures also provides two axes of rotation for the support block44. A first axis of rotation96is for a latch lock92. The latch lock92pivots about this axis96until it comes in contact with a latch plate104, which stops it from rotating further. At that point, the support block44rotates about a second axis180. This rotation causes the support block44to retract into the trough, as illustrated byFIGS. 17A-C. Referring now toFIG. 18, a third axis of rotation98allows the support block44to experience rollover without impacting the motion actuator74, which may be a pneumatic cylinder or any other appropriate type of actuator.

FIG. 17Aillustrates the retraction/rollover mechanism90in its raised and locked position, holding a pendant cable12in a battery position. In this example, the support block44has a latch lock92. As illustrated by the transition betweenFIGS. 17A and 17B, the latch lock92is translatable between an upright locked position (FIG. 17A) and a translated unlocked position (FIG. 17B). Movement between the locked and unlocked position is managed via a cable94(which may also be a cord, a wire, a link, or other type of retractable mechanism that can couple the latch lock92to a motion actuator74). One end of the cable94is secured to the latch lock92and a second end of the cable94is secured to the motion actuator74. When the motion actuator74is activated, the cable94is pulled, which consequently pulls the latch lock92in order to cause its translation. Release of the locking latch92then allows further retraction of the cable94via the motion actuator, which pulls/rotates the cable support block44down into the cable trough50. This retracted position is shown byFIG. 17C. This rotation takes place around the second axis108, as illustrated byFIG. 17C. The support arm102remains in the same position during the entire retraction process.

FIG. 18illustrates the mechanism90during a rollover event. In this example, the movement of the cable support block44occurs with respect to the third axis98. Third axis98is defined by a main shaft100about which there is positioned a torsion spring101. When the mechanism90is set for a rollover event, the latch lock92remains locked with respect to the cable support block44, such that the second axis108of rotation is locked and not available. The only available axis for rotation is the third axis98(rotation about the main shaft100). Accordingly, during a rollover event, pressure against the cable support block44causes the main shaft100to pivot and the support arm102to rotate downwardly, as shown byFIG. 18. Because the cable94is somewhat flexible, it does not transfer this downward load to the motion actuator74. This separates the retraction mechanism components from the rollover mechanism components, such that the retraction mechanism components do not experience force or load transmitted during rollover. In short, the retraction motion and the rollover motion are in different, separate paths.

FIGS. 19A-19B and 20illustrate an alternate embodiment of a retraction/rollover mechanism110. This mechanism also uses a motion actuator74and a cable94for retraction of the cable support block44. One end of the cable94is secured to the motion actuator74, and one end of the cable is secured to a hook arm of the lock mechanism112. In this embodiment, activation of the motion actuator74causes a pull force applied to the cable94, which releases a lock mechanism112that secures a support arm114to a roller arm116. Release of lock mechanism112disengages the roller arm116from the support arm, as illustrated byFIG. 19B. Continued retraction of the cable94causes a roller118of the roller arm to roll against the lower surface of the cover plate20until it reaches ramp120. Ramp120is formed as a declined ramp on the lower surface of the cover plate. When the roller118reaches the ramp120and rolls down the declined ramp face122, continued retraction motion from the motion actuator74pulls the roller arm116to cause it to recess or decline into the trough50. As illustrated, pulley action can help the described movement. The roller arm116pivots with respect to the support arm114at first axis124.

FIG. 20illustrates the mechanism110during a rollover event. In this example, the support arm114remains locked to the roller arm116via the lock mechanism112. (This is because the cable94is not pulled by the motion actuator74so it does not cause release of the lock mechanism112from pin113.) During a rollover event, the support arm pivots at the second axis126. This pivoting does not translate any force to the motion actuator74. Instead, in this version, only the support arm114rotates with respect to the second axis126. The first axis124remains locked and is unavailable for rotation thereabout.

A further alternate embodiment is illustrated byFIGS. 21, 22A-22B, and 23. These figures illustrate a retraction/rollover mechanism130that uses a rolling or sliding trolley132.FIGS. 21 and 22Ashow the mechanism in battery position. The retraction position is shown inFIG. 22B.FIG. 23is the rollover position. In this embodiment, a trolley132may be provided with one or more wheels134that allow the trolley132to roll with respect to the support frame22. This embodiment provides a cable94with one end that is secured to the cable support block44and another end that is secured to the trolley132. During a retraction event, movement of the trolley132is caused by a motion actuator74. As the trolley132is retracted, pressure on the cable94rotates/pulls the cable support block44around a first axis138with respect to a support block engagement roller136. This moves the cable support block44into the retracted position, as illustrated byFIG. 22B.

FIG. 23illustrates the mechanism130during a rollover event. In this example, the trolley132is not moved via the motion actuator74, such that it remain stationary. This allows the trolley132to primarily function as a lock, preventing the cable support block from rotating with respect to the first axis138support block engagement roller136. Instead, pressure on the cable support block44causes downward deflection movement of an arm140that may be pivotally secured to the motion actuator74at a second axis142. The cable support block is not permitted to rotate with respect to the first axis138due to the location of the trolley132. Instead, downward movement of the arm140allows downward movement of the cable support block44.

Although certain embodiments have been shown and described in this disclosure, it should be understood that the concepts disclosed may be implemented using other mechanical systems. The general goal is that the arresting cable retraction mechanism provides one axis of rotation for the rollover event, and a second, separate axis of rotation for the retraction event. This prevents the motion actuator from absorbing the force from the rollover. Instead, the motion actuator and its related components is mechanically isolated from force during a rollover event. The motion actuator is operably coupled to the cable support block during a retraction event only.