Patent Description:
Ram air turbines (RATs) are small turbines installed on aircrafts to provide emergency power. Generally, the RAT can be stowed inside of the fuselage or wing of an aircraft and manually or electronically deployed into an airstream outside of the aircraft during a power outage. The RAT rotates in the airstream to generate hydraulic and/or electric power for the aircraft. Once the aircraft has landed, the RAT can be restowed, depending on the deployment actuator configuration, by either manually operating a hydraulic actuator pump for retracting the RAT into a stowed position or operating an electrical switch that controls an electrically activated hydraulic solenoid valve that retracts the RAT into the stowed position. <CIT> describes a remote power source pump system, the pump being activated on ground by an electric drill or a suitable wrench to activate a spool valve which is spring loaded, for stowing a ram air turbine. <CIT> describes an actuator assembly for stowing a RAM air turbine. <CIT> describes an actuator for rat deployment. <CIT> describes an actuator device. <CIT> describes an aircraft hydraulic system.

A ram air turbine (RAT) restow system and a RAT are defined in claim <NUM>, whereby the system includes an actuator assembly with a piston interposed between an upper fluid compartment and a lower fluid compartment. The actuator assembly is configured to selectively move the piston between a deployed position and a stowed position. A hydraulic restow circuit is interposed between the actuator assembly and a hydraulic fluid system that is configured to output fluid. The hydraulic restow circuit includes a manually actuated restow valve configured to operate in a first position that establishes a first fluid path to deliver the fluid to the upper fluid compartment and a second position that establishes a second fluid path to deliver the fluid to the lower fluid compartment.

A hydraulic restow system with its circuit is defined in claim <NUM> and configured to restow a ram air turbine (RAT) coupled to an actuator assembly. The hydraulic restow circuit includes a first pair of actuator fluid lines in fluid communication with the actuator assembly, and a second pair of aircraft fluid lines in fluid communication with a fluid source. The hydraulic restow circuit further includes a manually actuated restow valve configured interposed between the first pair of actuator fluid lines and the second pair of aircraft fluid lines. The manually actuated restow valve is configured to operate in a normal position to deliver fluid from the fluid source to an upper fluid compartment of the actuator assembly and a restow position to deliver the fluid to a lower fluid compartment of the assembly actuator.

A method is provided to restow a ram air turbine (RAT) coupled to an actuator assembly and is defined in claim <NUM>. The method comprises displacing a piston included in an actuator assembly from a stowed position into a displaced position so as to deploy a RAT coupled to the piston, and delivering fluid from a hydraulic fluid system to a hydraulic restow circuit interposed between the actuator assembly and the hydraulic fluid system. The method further comprises manually transitioning a manually actuated restow valve from a normal position to a restow position to deliver the fluid to a lower fluid compartment of the actuator assembly, and increasing the pressure in the lower fluid compartment so as to force the piston into the stowed position so as to restow the RAT.

As previously discussed, the RAT, depending on the deployment actuator configuration, can be restowed by either manually operating a hydraulic actuator pump for retracting the RAT into a stowed position or operating an electrical switch that controls an electrically activated hydraulic solenoid valve that adjusts the RAT to and from the stowed position. The conventional manual operation process requires a human maintenance operator to manually operate a hydraulic pump. The hydraulic pump supplies high pressure fluid to the actuator, which in turn forces the actuator to retract such that the RAT is transitioned into a stow position and within the aircraft. However, the conventional manual restow process involves strenuous activities that are inconvenient to the maintenance operator. For instance, the manual pump operation requires the maintenance operator to transition and hold a momentary valve within the restow pump to allow fluid from the restow pump to enter the actuator. Simultaneously, the maintenance operator must manually actuate the restow pump handle over several pump cycles to pressurize fluid contained within the restow pump body.

The electrical switch (which can be implemented by a stow panel or controller) and electrically activated hydraulic solenoid valve aim to reduce the physical work and effort required by the maintenance operator. However, additional components such as the stow panel/controller, hydraulic solenoid valve, aircraft fluid ports, a secondary pilot valve, and additional pressure sensors are necessary to facilitate the electrical restow operation. As a result, the conventional electrical restow approach adds complexity, monetary costs, and weight to the RAT system.

Various non-limiting embodiments described herein provides a manually activated hydraulic circuit that omits the costly additional components employed in the conventional electronic restow approach, while still allowing a maintenance operator to conveniently facilitate RAT restow. The manually activated hydraulic circuit includes a manually actuated hydraulic valve that supplies high pressure fluid from the aircraft hydraulic system to the actuator, which in turn forces retraction of actuator and transitions the RAT into the stow position.

In one or more non-limiting embodiments, the manually actuated hydraulic valve is installed between the supply and return ports of the RAT actuator and the hydraulic supply and return ports of the aircraft hydraulic system. To restow the RAT, a maintenance operator manually rotates the hydraulic valve from a first position (e.g., normal position) to a second position (e.g., restow position). The restow position allows high pressure fluid to be ported into the actuator cylinder so as to increase the pressure applied to the lower end of the actuator piston. In turn, the piston is displaced so as to retract the actuator and RAT back into the stowed position. In this configuration, fluid on the opposite side of the piston is also allowed to exit the actuator, returning to the aircraft. Once the RAT is restowed, the hydraulic valve is returned to the normal position to properly configure the hydraulic connections for future deployment.

With reference now to <FIG>, a RAT restow system <NUM> including a RAT assembly <NUM> in fluid communication with a manually actuated hydraulic restow circuit <NUM> is illustrated according to a non-limiting embodiment. The RAT assembly <NUM> is mounted to an airframe <NUM> and is deployable between a stowed position for storage when not in use and a deployed position to provide electric power and/or hydraulic pressure. <FIG> illustrates the RAT assembly <NUM> in a deployed position. The RAT assembly <NUM> includes a turbine <NUM>, a gearbox <NUM>, a generator <NUM>, a hydraulic pump <NUM>, a strut <NUM>, a pivot post (or swivel post) <NUM>, an actuator assembly <NUM>, a low pressure fluid supply location <NUM>, a high pressure fluid delivery location <NUM>, an electricity delivery location <NUM>, a generator housing <NUM> (also simply called a "housing"), and a door linkage <NUM>. It should be noted that the RAT assembly <NUM> illustrated in <FIG> is shown merely by way of example and not limitation. Those of ordinary skill in the art will recognize that other RAT assembly configurations are possible. For instance, in further embodiments, either the generator <NUM> or the hydraulic pump <NUM> could be omitted entirely. Other components not specifically identified can also be included with the RAT assembly <NUM>.

The turbine <NUM> is supported at or near the end of strut <NUM>, which in turn is attached to the generator housing <NUM>. The generator housing <NUM> is mounted to the airframe <NUM> with the swivel post <NUM>, which allows pivotal movement of the turbine <NUM>, strut <NUM>, generator housing <NUM>, etc. relative to the airframe <NUM> and can further provide fluid paths between the hydraulic pump <NUM> and both the low pressure fluid supply location <NUM> and the high pressure fluid delivery location <NUM>. The generator <NUM> is disposed within the generator housing <NUM>, and the hydraulic pump is supported on the generator housing <NUM>. The generator <NUM> can generate electric power that can be supplied to the electricity delivery location <NUM>. The hydraulic pump <NUM> can pump the fluid to various systems that utilize pressurized fluid for operation.

During flight, the turbine <NUM> can rotate responsive to airflow along the outside of the airframe <NUM>. Rotational power from the turbine <NUM> can be transmitted through the gearbox <NUM> to either or both the generator <NUM> and the hydraulic pump <NUM> for operation. The hydraulic pump <NUM> can be coupled to the generator <NUM> such that the hydraulic pump <NUM> rotates at the same speed as the generator <NUM>. In alternative embodiments, the hydraulic pump <NUM> and the generator can be rotated at different speeds.

The actuator assembly <NUM> can be configured as a combination spring- and fluidically-actuated mechanism for selectively deploying and stowing the RAT assembly <NUM>. A spring mechanism (not visible in <FIG>) can provide a biasing force to the RAT <NUM> in order to deploy the RAT assembly <NUM> when a locking mechanism such as, for example, a locking pawl or uplock (not shown) is released. A fluid (e.g., conventional hydraulic fluid) can be selectively introduced to a fluidic cylinder of the actuator assembly <NUM> to selectively provide force to stow the RAT assembly <NUM>, and can act as a part of a snubbing mechanism to help control movement of the RAT assembly <NUM> during deployment, and/or provide other functions. Further details of the actuator assembly are described below.

The actuator assembly <NUM> further actuates at least one door <NUM> that can cover a RAT storage compartment in the airframe <NUM> in which the RAT assembly <NUM> can be stowed. The door linkage <NUM> can mechanically connect the door <NUM> to the strut <NUM> or another suitable structure (e.g., the generator housing <NUM>) of the RAT assembly <NUM>. In this way, movement of the strut <NUM> accomplished using the actuator assembly <NUM> can be transmitted to the door <NUM> through the door linkage <NUM>, such that the door <NUM> is concurrently and simultaneously moved by the actuator assembly <NUM>, relative to the airframe <NUM>.

Still referring to <FIG>, the manually activated hydraulic circuit includes a manually actuated hydraulic valve <NUM>. The manually actuated hydraulic valve <NUM> selectively supplies high pressure fluid (e.g., hydraulic fluid) to the actuator assembly <NUM>, which in turn forces the actuator assembly <NUM> in a retracted position. Accordingly, the RAT assembly can be transitioned into the stow position and restowed in the RAT storage compartment in the airframe <NUM>.

Turning to <FIG>, a cross-sectional view of the actuator assembly <NUM> included in a RAT restow system <NUM> is illustrated according to a non-limiting embodiment. The view of the actuator assembly <NUM> is taken along line <NUM>-<NUM> of <FIG> is illustrated according to a non-limiting embodiment and depicts the actuator assembly <NUM> in a stowed position. The actuator assembly <NUM> includes a housing <NUM>, a piston <NUM>, a piston subassembly <NUM>, one or more springs <NUM> and <NUM>, a spring guide <NUM>, a stop <NUM>, a lower fluid compartment <NUM>, an upper fluid compartment <NUM>, an actuator supply fluid port <NUM>-<NUM>, and an actuator return fluid port <NUM>-<NUM>. The actuator assembly <NUM> can further include a conventional locking mechanism (not shown), such as a locking pawl, uplock, etc., to help maintain the RAT assembly <NUM> in a stowed position prior to selective release of the locking mechanism.

The housing <NUM> can be configured as a two-part cylinder. A connection point <NUM>-<NUM> can be provided at one end of the housing <NUM>, to allow mechanical connection of the housing <NUM> to a desired mounting location (e.g., to a portion of the RAT assembly <NUM> or to the airframe <NUM>). The housing <NUM> can be made of a metallic material.

The piston <NUM> can be configured as a single unitary and monolithic piece that includes a piston head <NUM>-<NUM> (sometimes referred to as a downlock portion) <NUM>-<NUM> and a rod portion <NUM>-<NUM>. The piston head <NUM>-<NUM> can be positioned inside the housing <NUM>, and the rod portion <NUM>-<NUM> can extend through the housing <NUM>. A diameter of the piston head <NUM>-<NUM> can be relatively small relative to prior art actuator piston heads to help make room for a first (e.g., inner) spring <NUM>. An end of the rod portion <NUM>-<NUM> of the piston <NUM> can be connected to an eyelet structure <NUM>, in which a monoball or spherical bearing can be positioned. The eyelet structure <NUM> can provide a connection point <NUM>-<NUM>, allowing the eyelet structure <NUM> and the piston <NUM> to be mechanically connected to a desired mounting location (e.g., to a portion of the RAT assembly <NUM> or to the airframe <NUM>). Actuation of the actuator assembly <NUM> can produce displacement between the connection point <NUM>-<NUM> (associated with the housing <NUM>) and the connection point <NUM>-<NUM> (associated with the piston <NUM>). Movement of the piston <NUM>, and therefore available displacement between the connection points <NUM>-<NUM> and <NUM>-<NUM>, defines an overall actuation (or deployment) stroke that places the actuator assembly in the deployed position.

The fluid compartment <NUM> can provide a working area for a suitable fluid (e.g., hydraulic fluid) used to selectively control operation of the actuator assembly <NUM>. The piston <NUM> can be positioned along the fluid compartment <NUM>, such that the fluid compartment <NUM> provides a volume for the fluid to be introduced to control the relative positions of the housing <NUM> and the piston <NUM>. The fluid can pass into and out of the fluid compartment <NUM> through the housing <NUM> by way of an actuator supply fluid port <NUM>-<NUM> and an actuator return fluid port <NUM>-<NUM>. The fluid in and out of the actuator assembly <NUM> is controlled using the manually actuated hydraulic restow circuit <NUM>, which is discussed in greater detail below.

The piston subassembly <NUM> can be of any desired configuration, including known designs. When the actuator assembly <NUM> is in a fully deployed position (as shown in <FIG>), the piston subassembly <NUM> can selectively lock the piston <NUM> relative to the housing <NUM>, thereby helping to lock the actuator assembly <NUM> in the fully deployed position for operation. Further, it should be understood that the piston subassembly <NUM> is provided merely by way of example and not limitation. Persons of ordinary skill in the art will appreciate that other downlock mechanisms can be utilized in further embodiments, or can be omitted entirely.

The springs <NUM> and <NUM> can be helical coil springs that cooperate to provide actuation force capable of deploying the actuator assembly <NUM>, along with any connected deployable components such as the RAT assembly <NUM> and the door <NUM>. Although two springs <NUM> and <NUM> are described herein, it should be appreciated more or less springs can be employed without departing from the scope of the invention.

The springs <NUM> and <NUM> can be held in compression when the RAT assembly <NUM> is in the stowed position, and the potential energy of the springs <NUM> and <NUM> released to provide deployment force when the locking mechanism (e.g., locking pawl) is released (as already noted, the locking mechanism is not specifically shown). The first and second springs <NUM> and <NUM> can each have relatively high spring load capacities. In one embodiment, round spring wires are used for one or both of the springs <NUM> and <NUM>. Alternatively, square cross-section spring wires can be used for one or both of the springs <NUM> and <NUM> to provide even higher load capacity within the same envelope as a round wire spring. Titanium, and alloys thereof, can be used to make one or both of the springs <NUM> and <NUM>, which offers a larger load capacity in the same envelope than stainless steel springs. In still further embodiments, other materials such as stainless steel can be used for the springs <NUM> and <NUM>, typically with corresponding adjustments to the diameter of the housing <NUM> to accommodate the necessary spring size for given material combinations.

In the illustrated embodiment, the springs <NUM> and <NUM> are coaxially and concentrically position with the first spring <NUM> positioned radially inward from (i.e., at least partially within and encircled by) the second spring <NUM>. In one embodiment, the first and second springs <NUM> and <NUM> can be helical springs having coil shapes wound in opposite directions, which can help reduce a risk of interference as the springs <NUM> and <NUM> compress and/or expand.

First ends of each of the first and second springs <NUM> and <NUM> can each be operatively engaged with the piston <NUM>, and the first end of the first spring <NUM> can be in physical contact with the piston head <NUM>-<NUM> of the piston <NUM>. A second end of the first spring <NUM> located opposite the first end can be operatively engaged with the spring guide <NUM>. A second end of the second spring <NUM> located opposite the first end can be operatively engaged with the housing <NUM>, and can further be in physical contact with an interior surface of the housing <NUM>. Persons of ordinary skill in the art will appreciate that relative relationships of the first and second springs <NUM> and <NUM> relative to the spring guide <NUM> can readily be reversed in alternative embodiments.

The spring guide <NUM> can be a sliding member that allows the first (e.g., inner) spring <NUM> to deploy as long as necessary, and then allows the first spring <NUM> to travel-unloaded to its minimum working height-with the piston <NUM> during a remainder of a deployment stroke. Use of the spring guide <NUM> helps prevent the first spring <NUM> from becoming misaligned during any portion of the deployment stroke.

The spring guide <NUM> of the illustrated embodiment is configured as a generally sleeve-like member having a stop <NUM>-<NUM> and a flange <NUM>-<NUM>. The stop <NUM>-<NUM> can be arranged at an inner diameter portion of the spring guide <NUM>. The flange <NUM>-<NUM> can extend generally radially outward, and can be arranged at or near an opposite end of the spring guide <NUM> from the stop <NUM>-<NUM>. The flange <NUM>-<NUM> can provide opposing contact surfaces for the first spring <NUM> and the housing <NUM>, respectively, and can selectively transmit actuation biasing force from the first spring <NUM> to the housing <NUM> when in contact with the housing <NUM>. The stop <NUM>-<NUM> can be arranged for sliding engagement with a portion of the piston subassembly <NUM>, and can interact with the stop <NUM> to restrict axial movement of the spring guide <NUM> (relative to the piston subassembly <NUM>) during the deployment process. In that way the spring guide <NUM> can be operatively engaged with the piston <NUM> in an indirect manner, via the sliding engagement with at least a portion of the piston subassembly <NUM> that moves with the piston <NUM>.

In alternative embodiments, the spring guide <NUM> can be engaged with either spring <NUM> or <NUM>, and can be engaged with any desired portion of the piston <NUM>, the piston subassembly <NUM> or any other suitable component of the actuator assembly <NUM> that can travel with the piston <NUM>. Accordingly, the spring guide <NUM> can still provide a suitable stroke limit on the engaged spring <NUM> or <NUM>.

During operation, the springs <NUM> and <NUM> can work together to overcome an opposing load (i.e., loading on the actuator assembly <NUM> from the RAT assembly <NUM>, the door <NUM>, etc.). More particularly, the springs <NUM> and <NUM> coil springs can both provide actuation force over a first portion of the overall actuation stroke. In general, to help optimize performance, the first spring <NUM> (e.g., the inner spring) can provide the most load capacity if only applying load for the minimum portion of the actuation stroke needed (compared to the total deployment stroke for the actuator assembly <NUM>), with the second spring <NUM> (e.g., the outer spring) providing the remaining load capacity to finish the deployment stroke, or vice-versa.

Still referring to <FIG>, the manually actuated hydraulic restow circuit <NUM> includes a manually actuated hydraulic valve <NUM> interposed between a pair of actuator fluid lines 104a, 104b and a pair of aircraft fluid lines 106a, 106b. The hydraulic valve <NUM> is illustrated as a rotary valve; however, other types of valves can be employed. For example, the hydraulic valve <NUM> can be packaged into a normally closed, momentarily actuated, linear hydraulic valve.

The actuator fluid lines include an actuator supply line 104a in fluid communication with the actuator supply fluid port <NUM>-<NUM> and an actuator return line 104b in fluid communication with the actuator return fluid port <NUM>-<NUM>. The aircraft fluid lines include an aircraft supply line 106a and an aircraft return line 106b. The aircraft supply line 106a and aircraft return line 106b are in fluid communication with a hydraulic system <NUM> integrated with the aircraft (i.e., installed directly on the aircraft) to deliver and receive hydraulic fluid.

The manually actuated hydraulic restow valve <NUM> includes a grip <NUM> (e.g., a handle) configured to transition the valve from a first position, e.g., a normal operating position (see <FIG>) to a second position, e.g., a restow operating position (see <FIG>). In one or more embodiments, the valve <NUM> can employ a restrictive orifice (not shown) that limits the hydraulic fluid flow rate to control the speed to retraction, and a pressure relief valve (not shown) to limit pressure within the actuator assembly <NUM>.

In the normal operating position, the actuator supply line 104a is placed in fluid communication with the actuator return line 104b while closing the fluid path to the aircraft supply line 106a (see <FIG>). Accordingly, fluid can be ejected from the lower fluid compartment <NUM> of the actuator assembly <NUM> and recycled back into the upper fluid compartment <NUM> as discussed in greater detail below. In addition, the need for a localized fluid reservoir is eliminated. When placed in the restow operating position, however, the actuator supply line 104a is placed in fluid communication with the aircraft supply line 106a (see <FIG>). In this manner, fluid can be delivered from the aircraft supply line 104a to the actuator supply line 106a and into the lower fluid compartment <NUM> of the actuator assembly <NUM>.

The valve <NUM> includes a valve spring <NUM> that is biased according to the normal operating position. When the valve <NUM> is placed into the restow operating position, the valve spring <NUM> is loaded so that the valve <NUM> can be automatically returned to the normal operating position when a human operator (e.g., ground maintenance crew member) releases the grip <NUM>. The automatic retraction of the valve <NUM> into the normal operating condition ensures that the correct pressure differential is applied to the actuator assembly <NUM> so that the actuator assembly <NUM> can properly transition into the deployed position when the uplock is released.

With reference now to <FIG>, operation of the RAT actuator assembly <NUM> and manually actuated hydraulic restow circuit <NUM> will be described according to non-limiting embodiments of the invention. At <FIG>, the RAT actuator assembly <NUM> is illustrated in an initial stowed position. In the initial stowed position, the piston <NUM> is locked in its upper-most position via the locking mechanism. Further, the manually actuated hydraulic valve <NUM> exists in the normal operating position such that the actuator supply line 104a is placed in fluid communication with the actuator return line 104b while blocking the fluid path to the aircraft supply line 106a.

Referring to <FIG>, the RAT actuator assembly <NUM> is illustrated in the deployed position with arrows showing fluid communication during deployment. The deployed position is effected by releasing the locking mechanism and forcing fluid (indicated as dark arrows) into the aircraft return line 106b. The fluid from the lower fluid compartment <NUM> is recirculated through the valve <NUM> and into the upper fluid compartment <NUM> rather than flowing into the aircraft supply line 106a. Accordingly, the valve <NUM> allows fluid communication between the actuator return line 104b and the aircraft return line 106b, while blocking the high pressure aircraft supply line 106a to force the piston <NUM> downward into its lower-most position to deploy a RAT (not shown if <FIG>) coupled to connection point <NUM>-<NUM>.

Turning now to <FIG>, the RAT actuator assembly <NUM> and manually actuated hydraulic restow circuit <NUM> is illustrated when placing the manually actuated restow valve <NUM> in the restow position to restow a RAT. The restow position is invoked by manually transitioning (e.g., rotating) the hydraulic valve <NUM> from the normal operating position to the restow operating position as further shown in <FIG>. As mentioned above, the valve <NUM> can include a valve spring <NUM> that is biased according to the normal operating position. When the valve <NUM> is placed into the restow operating position as shown in <FIG>, the valve spring <NUM> is loaded so that the valve <NUM> can be automatically returned to the normal operating position when a human operator (e.g., ground maintenance crew member) releases the grip <NUM>.

In response to effecting the restow position, the actuator supply line 104a is placed in fluid communication with the aircraft supply line 106a. In this manner, fluid can be delivered from the aircraft supply line 106a to the actuator supply line 104a and into the lower fluid compartment <NUM> of the actuator assembly <NUM>. The fluid input to the lower fluid compartment <NUM> increases the pressure therein, which in turn forces the piston <NUM> upward until it is locked via the locking mechanism in its upper-most position. As the piston <NUM> moves upward, fluid is ejected from the upper fluid compartment <NUM> via the actuator return line 104b and can be delivered back into the aircraft hydraulic system via the aircraft return line 106b.

Turning to <FIG>, the RAT actuator assembly <NUM> and manually actuated hydraulic restow circuit <NUM> when returning the manually actuated restow valve <NUM> in the normal position. Accordingly, the actuator supply line 104a is again placed in fluid communication with the actuator return line 104b while blocking the fluid path to the aircraft supply line 106a. In embodiments where the valve <NUM> includes the valve spring, the valve <NUM> is automatically returned to the normal operating position when a human operator (e.g., ground maintenance crew member) releases the grip <NUM> as shown in <FIG>. Accordingly, the automatic retraction of the valve <NUM> into the normal operating condition ensures that the actuator assembly <NUM> can properly transition back into the deployed position when the locking mechanism is released to deploy the RAT for future use.

As described herein, various non-limiting embodiments provide a hydraulic restow circuit that includes a manually actuated hydraulic restow valve that supplies high pressure fluid to an actuator assembly. The high pressure fluid forces a piston in the actuator to retract, thereby restowing a RAT coupled to the piston into a stow position. The hydraulic restow circuit includes a restow valve installed between the actuator ports of the in fluid communication with the actuator assembly and hydraulic ports in fluid communication with the aircraft. Transitioning the valve from a normal position to a restow position allows high pressure fluid to be ported into a lower fluid compartment of the actuator assembly, thereby transitioning the actuator assembly in the stowed state to restow the RAT.

Claim 1:
A ram air turbine (RAT) restow system (<NUM>) and a ram air turbine, "RAT", said RAT restow system being configured to restow said RAT, said system comprising:
an actuator assembly (<NUM>) including a piston (<NUM>) interposed between an upper fluid compartment (<NUM>) and a lower fluid compartment (<NUM>), the actuator assembly (<NUM>) configured to selectively move the piston (<NUM>) between a deployed position and a stowed position; and
a hydraulic restow circuit (<NUM>) interposed between the actuator assembly (<NUM>) and a hydraulic fluid system configured to output fluid, the hydraulic restow circuit including a manually actuated restow valve configured to rotate between a first position and a second position wherein the first position establishes a first fluid path to deliver the fluid to the upper fluid compartment (<NUM>) and the second position establishes a second fluid path to deliver the fluid to the lower fluid compartment (<NUM>),
and wherein the manually actuated restow valve includes a valve spring that is elastically biased according to the first position,
wherein the valve spring is elastically loaded in response to transitioning the manually actuated restow valve from the first position to the second position, and the valve spring automatically returns the manually actuated restow valve to the first operating position in response to releasing the manually actuated restow valve from the second position.