WO2025162565A1

WO2025162565A1 - Linear actuator with damper

Info

Publication number: WO2025162565A1
Application number: PCT/EP2024/052290
Authority: WO
Inventors: Randy Lee; Zoran PASIC; Dominic D'angelo; Graham Bennett; Laurent DUJOL
Original assignee: Safran Landing Systems SAS
Current assignee: Safran Landing Systems SAS
Priority date: 2024-01-31
Filing date: 2024-01-31
Publication date: 2025-08-07
Anticipated expiration: 2026-07-31
Also published as: WO2025162954A1

Abstract

A linear actuator (200) includes a cylinder (210) having a central cavity (212). A gland (260) is mounted to the cylinder and has an aperture (264) extending through the middle of the gland (260). The actuator further includes a piston (240) with a body (242) slidably disposed within the central cavity (212). A first seal (248) is mounted to an outer surface of the body (242) and sealingly engages the cylinder, and a first damping member (252) is mounted to the outer surface of the body (242) and engages the cylinder. The first seal (248) is made from a different material than the first damping member (252).

Description

LINEAR ACTUATOR WITH DAMPER

BACKGROUND

[0001] Linear actuators convert energy into linear movement that performs mechanical work. Typical forms of energy include hydraulic, pneumatic, and electrical energy. The actuators extend and retract selectively to drive movement of kinematic systems. On aircraft, for example, linear actuators are utilized to extend, retract, and/or lock landing gear. Linear actuators are also employed to drive the operation of flight control surfaces, doors, ram air turbine systems, and the like.

[0002] FIGURES 1 and 2 show a non-limiting example of a known linear actuator 100 (“hereafter “actuator”) that selectively extends and retracts to open and close, respectively, a landing gear door installation 10. The actuator 100 includes a rod 130 partially disposed within a cylinder 110. The rod 130 slidingly extends from and retracts into the cylinder 110 along a centerline 102 of the actuator 100 so that the overall length of the actuator is selectively variable. Landing gear door installations of this type are disclosed in U.S. Patent Publication No. 2023/0294821, “Landing Gear Door Installation,” filed March 15, 2022, and assigned to Safran Landing Systems Canada Inc.

[0003] The landing gear door installation 10 includes a door assembly 14 rotatably mounted about an axis 20 to an aircraft 12. The door assembly 14 includes a door panel 16 with a hinge fitting 18 that rotatably mounds the door panel 16 to the aircraft 12 about an axis 20. A fitting 22 is mounted to the door panel 16 and is pivotably coupled to a first end of the linear actuator 100 about pivot point 24. In some embodiments, the fitting is rotatably coupled to the rod 130 of the actuator 100 about an axis.

[0004] A second end of the actuator 100 is pivotally coupled about a pivot point 28 to a fitting 26 that is mounted to a portion of the aircraft 12. When the door assembly 14 is in the closed position of FIGURE 1, the actuator 100 is in the retracted position and helps prevent the door assembly 14 from moving toward the open position of FIGURE 2.

[0005] To move the door assembly 14 to the open position of FIGURE 2, the rod 130 moves to extend further from the cylinder 110 so that the length of the actuator 100 increases. This increase in actuator length drives rotation of the door panel 16 about axis 20 until the door assembly 14 reaches the open position of FIGURE 2. The actuator 100 maintains the door assembly 14 in the open position by maintaining a constant length, i.e., the rod 130 maintains a fixed position relative to the cylinder 110. [0006] To move the door assembly 14 back to the closed position, the rod 130 retracts back into the cylinder 110, which decreases the length of the actuator 10. The decrease in actuator length drives rotation of the door assembly 14 about axis 20 until the door assembly reaches the closed position.

[0007] Linear actuators are generally designed to generate and retract actuating loads along the central axis. To limit transverse, i.e., non-axial, loads, the ends of the actuators are typically connected to the associated structure by pivotal joints that utilize spherical bearings. However, in operation, the actuators are still subjected to transverse loads resulting from misalignment, friction in the bearing joints, vibration, etc.

[0008] Vibration, in particular, causes fatigue damage that greatly reduces the service life of an actuator. Known actuator designs provide limited damping to mitigate the fatigue damage that results from vibration. As a consequence, such actuators require greater structural fatigue capabilities and/or more frequent inspection, resulting in increased manufacturing and operating costs.

SUMMARY

[0009] Embodiments of a linear actuator with a damper are set forth below according to technologies and methodologies of the present disclosure. Linear actuators often include dynamic seals between moving parts. Disclosed embodiments of linear actuators also include damping members between moving elements. Damping members between fixed elements are also utilized. The damping members dissipate vibration energy throughout the full range of actuator motion.

[0010] An embodiment of a linear actuator includes a cylinder having a central cavity. A gland is mounted to the cylinder and has an aperture extending through the middle of the gland. The actuator further includes a piston with a body slidably disposed within the central cavity. A first seal is mounted to an outer surface of the body and sealingly engages the cylinder, and a first damping member is mounted to the outer surface of the body and engages the cylinder. The first seal is made from a different material than the first damping member.

[0011] In any embodiment, the first damping member has the form of a sleeve that surrounds the piston.

[0012] In any embodiment, the first damping member comprises a fiberglass isolation pad or nitrile rubber. [0013] In any embodiment, the linear actuator further comprises a rod mounted to the piston and slidingly extending through the aperture of the gland. A second seal is mounted to an inner surface of the aperture and sealingly engages the rod. A second damping member is mounted to the inner surface of the aperture of the gland and engages the rod. The second seal comprises a different material than the second damping member.

[0014] In any embodiment, the second damping member has the form of a sleeve that surrounds the rod.

[0015] In any embodiment, the first damping member and the second damping member comprise a fiberglass isolation pad or nitrile rubber.

[0016] In any embodiment, each of the first seal and the second seal comprises an elastomeric material.

[0017] In any embodiment, each of the first seal and the second seal is an O-ring.

[0018] In any embodiment, the gland includes a recess extending axially toward the piston, the linear actuator further comprising a third damping member mounted within the recess of the gland and slidingly engaging the rod.

[0019] In any embodiment, the linear actuator further comprises a nut in threaded engagement with a threaded portion of the gland. A fourth damping member is disposed between the nut and an end of the cylinder.

[0020] In any embodiment, the linear actuator further comprises a nut in threaded engagement with a threaded portion of the gland. A third damping member is disposed between the nut and an end of the cylinder.

[0021] Another embodiment of a linear actuator includes a cylinder having a central cavity, a gland mounted to the cylinder and having an aperture extending therethrough, and a piston slidably disposed within the central cavity. The piston includes a body and a piston seal mounted to an outer surface of the body and sealingly engaging the cylinder. A rod is mounted to the piston and slidingly extends through the aperture of the gland. The actuator further includes a nut in threaded engagement with a threaded portion of the gland and a first damping member disposed between the nut and an end of the cylinder.

[0022] In any embodiment, the gland includes a recess extending axially toward the piston, the linear actuator further comprising a second damping member mounted within the recess of the gland and slidingly engaging the rod.

[0023] In any embodiment, the linear actuator further comprises a gland seal mounted to an inner surface of the aperture of the gland and sealingly engaging the rod; a third damping member mounted to the outer surface of the body and engaging the cylinder, wherein the third damping member comprises a different material than the piston seal; and a fourth damping member mounted to the inner surface of the aperture of the gland and engaging the rod, wherein the fourth damping member comprises a different material than the gland seal.

[0024] In any embodiment, one or both of the first and second damping members comprises a fiberglass isolation pad or nitrile rubber.

[0025] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This summary is not intended to identify key features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

DESCRIPTION OF THE DRAWINGS

[0026] The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:

[0027] FIGURE 1 shows a landing gear door installation reciprocated between an open position and a closed position by a known linear actuator, wherein the landing gear door assembly is in the closed assembly;

[0028] FIGURE 2 shows the landing gear door installation of FIGURE 1 in the open position;

[0029] FIGURE 3 shows cross-sectional side view of the actuator of FIGURE 1 in a retracted position;

[0030] FIGURE 4 shows a cross-sectional view of the actuator of FIGURE 1 in an extended position;

[0031] FIGURE 5 shows a partial detailed view thereof as indicated in FIGURE 4;

[0032] FIGURE 6 shows a cross-sectional view of an actuator according to an embodiment of the present disclosure, wherein the actuator is in a retracted position; and

[0033] FIGURE 7 shows a cross-sectional view of the actuator of FIGURE 6 in an extended position; and

[0034] FIGURE 8 shows a partial detailed thereof as indicated in FIGURE 7. DETAILED DESCRIPTION

[0035] Disclosed embodiments of a linear actuator have improved damping as compared to known actuators.

[0036] Referring now to FIGURES 3-5, the actuator 100 shown in FIGURES 1 and 2 will be described. The cylinder 110 of the actuator 100 comprises an elongate body having an inner cavity 112. One end of the inner cavity 112 is delimited by a cylinder wall, and a gland 160, which is fixedly secured to the cylinder 110, delimits the other end of the cavity. A lug 124 is formed on the end of the cylinder 110 proximate to the cylinder wall, i.e., at the end of the cylinder opposite the gland 160.

[0037] In the illustrated embodiment, the lug 124 is provided with a spherical bushing 126 that enables the lug to be pivotally coupled about a pivot point 106 to corresponding structure. It will be appreciated that the lug 124 may include a cylindrical bushing, one or more flanged bushings, or any other joint components to enable rotational, pivotal, or any other suitable mounting configuration to couple the cylinder 110 to the corresponding structure. In some embodiments, the lug 124 is a fixed or adjustable rod end mounted to the cylinder 110.

[0038] A piston 140 is slidably disposed within the cavity 112 for reciprocating travel along the centerline 102 of the actuator 100. The piston 140 includes a cylindrical body 142 with an outer surface 144 that engages a radial surface 114 of the cavity 112 to divide the inner cavity into an extension chamber 116 and a retraction chamber 118. As best shown in FIGURES 3 and 4, the extension chamber 116 extends between the end wall of the cylinder and the piston 140, and the retraction chamber 118 extends between the piston 140 and the gland 160. As the piston 140 moves toward the gland 160, the volume of the extension chamber 116 increases, and the volume of the retraction chamber 118 decreases by a corresponding amount. Conversely, as the piston 140 moves toward the end wall of the cylinder 110, i.e., away from the gland 160, the volume of the retraction chamber 118 increases, and the volume of the extension chamber 116 decreases by a corresponding amount.

[0039] A small clearance exists between the radial surface 114 of the cavity 112 and the piston 140 to allow the piston to move within the cylinder 110. The radial surface 114 typically has a diameter that is in the range of 0.004-0.011 inches greater than the outer diameter of the piston 140. In some embodiments, the clearance may be greater or less than this range. [0040] As the piston 140 reciprocates within the cylinder 110, the primary contact between the piston and the radial surface a sliding metal-to-metal contact. To reduce wear, in some embodiments, the piston is made from a bearing material, such as Aluminum Bronze, Aluminum-Nickel-Bronze, or any other suitable bearing material. As best shown in FIGURE 5, in order to provide sealing engagement of the piston 140 with the radial surface 114 of the cylinder 110, one or more seals are mounted to the piston. In an embodiment, one or more circumferential recesses 146 are formed in the piston 140, and a dynamic seal 148, such as an elastomeric O-ring is partially disposed within each recess. The seals 148 engage both the piston 140 and the cylinder 110 to provide a dynamic seal therebetween.

[0041] One or more extension ports 120 extend through the cylinder 110 and are configured to provide a fluid connection between the extension chamber 116 and a fluid source (not shown). Similarly, one or more retraction ports 122 extend through the cylinder 110 and are configured to provide a fluid connection between the retraction chamber 118 and a fluid source (not shown). To move the actuator 100 to the extended position of FIGURE 4, pressurized working fluid is added to the extension chamber 116 through the extension ports 120, and fluid from the retraction chamber 118 is discharged through the retraction ports 122. The resulting pressure difference between the extension chamber 116 and the retraction chamber 118 moves the piston 140 toward the gland 160.

[0042] To move the actuator 100 to the retracted position of FIGURE 3, pressurized working fluid is added to the retraction chamber 118 through the retraction ports 122, and fluid from the extension chamber 116 is discharged through the extension ports 120. The pressure in each of the extension chamber 116 and retraction chamber 118 acts upon a corresponding face of the piston 140, which results in a net force that moves the piston 140 away from the gland 160.

[0043] In some embodiments, the actuator 100 is a pneumatic actuator, and the working fluid is air or any suitable gas or mixture of gases. In some embodiments, the actuator 100 is a hydraulic actuator 100, and the working fluid is a liquid, such as a petroleum-based hydraulic fluid, or any other suitable liquid or combination of liquids. It will be appreciated that the working fluid is not limited to any particular fluid or fluids, and any suitable working fluid may be utilized with embodiments of the disclosed actuator 100. [0044] The rod 130 is fixedly mounted at one end to the piston 140. The rod 130 extends from the piston 140 along the centerline 102 through an aperture 164 formed in the gland 160. A lug 134 is formed on the end of the rod 130 opposite the piston 140.

[0045] In the illustrated embodiment, the lug 134 is provided with a spherical bushing 136 that enables the lug to be pivotally coupled about a pivot point 104 to corresponding structure. It will be appreciated that the lug 134 may include a cylindrical bushing, one or more flanged bushings, or any other joint components to enable rotational, pivotal, or any other suitable mounting configuration to couple the rod 130 to the corresponding structure. In some embodiments, the lug 134 is a fixed or adjustable rod end mounted to the rod 130.

[0046] Referring now to FIGURE 5, the gland 160 comprises a body 162 fixedly positioned relative to the central cavity 112. In the illustrated embodiment, the gland 160 is at least partially received within the central cavity 112. A recess 172 is formed within the outer surface of the body 162 and is sized and configured to receive a seal 174, such as an elastomeric O-ring. The seal 174 engages the radial surface 114 of the cylinder 110 to provide a seal between the body 162 of the gland 160 and the radial surface 114 of the cylinder 110.

[0047] The gland 160 includes a threaded portion 176 disposed at an end of the body 162. A recess 178 extends axially inward from the end of the gland to be at least partially surrounded by the threaded portion. A nut 180 threadedly engages the threaded portion 176 of the gland 160 and bears against an end of the cylinder 110. A lock ring 182 engages an outer portion of the gland 160 and an inner portion of the cylinder 110. Engagement of the nut 180 against the cylinder 110 cooperates with the engagement of the lock ring 182 with both the cylinder 110 and the gland 160 to fixedly secure the gland 160 to the cylinder 110. It will be appreciated that the disclosed embodiment is exemplary only and should not be considered limiting. In this regard, the gland 160 may be fixedly and sealingly secured to the cylinder 110 in any suitable manner, and such configurations should be considered within the scope of the present disclosure.

[0048] Reciprocating movement of the piston 140 within the cylinder 110 drives reciprocating movement of the rod 130 through an aperture 164 that extends axially through the gland 160. A small clearance exists between the outer surface 132 of the rod 130 and the surface 166 of the aperture 164 to allow the rod to move within the aperture 164 of the gland 160. The aperture 164 typically has a diameter that is in the range of 0.004-0.010 inches greater than the outer diameter of the rod 130. In some embodiments, the clearance may be greater or less than this range.

[0049] The primary contact between the rod 130 and the surface 166 of the aperture 164 is a sliding metal-to-metal contact. To reduce wear, in some embodiments, the gland 160 is made from a bearing material, such as Aluminum Bronze, Aluminum-Nickel-Bronze, or any other suitable bearing material. Still referring to FIGURE 5, in order to provide sealing engagement of the rod 130 with the surface 166 of the aperture 164, one or more seals are mounted to the gland 160. In an embodiment, one or more circumferential recesses 168 are formed in the aperture 164 of the gland 160, and a dynamic seal 170, such as an elastomeric O-ring is partially disposed within each recess. The seals 170 engage both the rod 130 and the gland 160 to provide a dynamic seal therebetween.

[0050] As previously noted, the primary contact between the piston 140 and the cylinder 110 and between the rod 130 and the gland 160 is sliding metal-to-metal contact. This contact provides no structural damping. The dynamic seals 148 and 170 provide some damping, but this damping is limited and does not provide meaningful mitigation of fatigue caused by vibration.

[0051] Referring now to FIGURES 6-8 an embodiment of a linear actuator 200 with damping features according to aspects of the present disclosure will be described. The damping features provide damping of vibrational loads not provided in known linear actuators. By damping vibrational loads, the magnitude and frequency of occurrences of oscillations are reduced, which in turn increases service life, decreases inspection and service intervals, and/or allows for lighter actuators.

[0052] For the sake of brevity, the illustrated embodiment will be described with the understanding that elements shown in FIGURES 3-5 and indicated with reference numbers 1XX correspond to elements shown in FIGURES 6-8 and indicated with reference numbers 2XX, and the corresponding components thereof are similar excepts as otherwise noted. For example, the cylinder 210, piston 240, and gland 260 shown in FIGURES 6-8 (and their components) are similar to the cylinder 110, piston 140, and gland 160, respectively, shown in FIGURES 3-5 except as described.

[0053] As best shown in FIGURE 8, a circumferential recess 250 is formed in the outer surface 244 of the body 242 of the piston 240. A damping member 252 in the form of bearing liner is positioned within the recess 250 and is sized and configured to have an outer diameter larger than that of the body 242 of the piston 240 when mounted thereto. That is, the damping member 252 extends beyond the outer surface 244 of the piston 240. In some embodiments, the damping member 252 maintains contact with the radial surface 214 of the cavity 212.

[0054] The damping member 252 is formed from a material or combination of materials with suitable damping characteristics to at least partially dissipate energy from the vibration of the actuator 200. At the same time, the damping member 252 has suitable durability to withstand the operating conditions of the actuator 200. In some embodiments, the damping member 252 is formed from a known glass fiber pad, i.e., a fiberglass isolation pad designed for noise, shock, and high frequency vibration isolation. In some embodiments, the damping member 252 is formed of nitrile rubber, an elastomeric material, or any suitable material of combination of materials.

[0055] In the illustrated embodiment, the damping member 252 has the form of a sleeve that surrounds a portion of the piston 240. In some embodiments, more than one damping member 252 is mounted to the piston 240. In some embodiments, separate damping members 252 are elongate strips extending in an axial direction and arranged around the circumference of the piston 240. In some embodiments, the damping member 252 includes any number of damping elements having any suitable shape and/or position relative to the piston 240.

[0056] Still referring to FIGURE 8, a recess 290 is formed in the body 262 of the gland 260. The recess 290 extends radially outward from the surface 266 of the aperture 264. A damping member 292 is disposed within the recess 290 and has an inner diameter that is smaller than the diameter of the aperture 264. Accordingly, the damping member 292 extends radially inward from the surface 266 of the aperture 264. In some embodiments, the damping member 292 maintains contact with the outer surface 232 of the rod 230.

[0057] The damping member 292 of the gland 260 can be made of any of the materials of combinations of materials used for the previously described damping member 252 of the piston 240. In some embodiments, the damping member 292 is made of the same material or materials as the damping member 252 of the piston 240. In some embodiments, the damping member 292 is made from a different material or materials than the damping member 252 of the piston 240. [0058] In the illustrated embodiment, the damping member 292 has the form of a sleeve that surrounds a portion of the rod 230, however, it will be appreciated that the damping member can be otherwise configured. In this regard, the damping member 292 can include any suitable number of separate elements that are suitable shaped and positioned on the gland 260, and such embodiments should be considered within the scope of the present disclosure.

[0059] In the illustrated embodiment, an annular damping member 294 is positioned between the nut 280 and the end of the cylinder 210. The damping member 294 may be shaped like a flat washer sized and configured to receive the threaded portion 276 of the gland 260 therethrough. In some embodiments, the damping member 294 has the shape of a torus. In some embodiments, the damping member 294 includes a radial split and/or does not extend around the entire threaded portion 276 of the gland 260. The damping member 294 can be made of any of the materials of combinations of materials used for the previously described damping members 252 and 292. In some embodiments, the damping member 294 is made of the same material or materials as the previously described damping members 252 and 292. In some embodiments, the damping member 294 is made from a different material or materials than the previously described damping members 252 and 292.

[0060] In the illustrated embodiment, another annular damping member 296 is disposed within the recess 278 of the gland 260. An inner surface of the damping member 296 slidingly engages the outer surface 232 of the piston 230. The outer surface of the damping member 296 engages the circumferential surface of the recess 278. The damping member 296 can be made of any of the materials of combinations of materials used for the previously described damping members 252, 292, and 294. In some embodiments, the damping member 296 is made of the same material or materials as one or more of the previously described damping members. In some embodiments, the damping member 296 is made from a different material or materials than the previously described damping members 252, 292, and 294.

[0061] The described damping members 252, 292, 294, 296 cooperate to provide damping through the full range of extension and retraction of the actuator 200. Damping members 252 and 292 address sliding motion, and damping members 294 and 296 address transverse oscillations. When the actuator 200 is in the retracted position of FIGURE 6, the damping member 294 between the nut 280 and the cylinder 210 and the damping member 296 between the rod 230 and the gland recess 278 provide most of the damping As the actuator 200 moves toward the extended position of FIGURES 7 and 8, wherein the piston 240 and gland 260 are closer together, the damping member 252 mounted to the piston 240 and the damping member 292 mounted to the gland 260 engage the cylinder 210 and the rod 230, respectively, to provide a greater portion of the damping.

[0062] Embodiments of the disclosed linear actuator are illustrated with four damping members. It will be appreciated that the number and position of the damping members can vary within the scope of the closure. In some embodiments, the actuator includes more or less than the disclosed four damping members.

[0063] As previously noted, embodiments of the disclosed linear actuators are suitable for use with various aircraft systems, including landing gear doors. However, it will be appreciated that the use of the disclosed linear actuators is not limited to any particular aircraft system. In this regard, the described linear actuators may be utilized with any suitable kinematic system that may be driven by linear input. Further, the use of the disclosed actuators is not limited to aircraft systems but can include any system that utilizes linear actuation.

[0064] The detailed description set forth above in connection with the appended drawings, where like numerals reference like elements, are intended as a description of various embodiments of the present disclosure and are not intended to represent the only embodiments. Each embodiment described in this disclosure is provided merely as an example or illustration and should not be construed as preferred or advantageous over other embodiments. The illustrative examples provided herein are not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Similarly, any steps described herein may be interchangeable with other steps, or combinations of steps, in order to achieve the same or substantially similar result. Moreover, some of the method steps can be carried serially or in parallel, or in any order unless specifically expressed or understood in the context of other method steps.

[0065] In the foregoing description, specific details are set forth to provide a thorough understanding of exemplary embodiments of the present disclosure. It will be apparent to one skilled in the art, however, that the embodiments disclosed herein may be practiced without embodying all of the specific details. In some instances, well-known method/process steps have not been described in detail in order not to unnecessarily obscure various aspects of the present disclosure. Further, it will be appreciated that embodiments of the present disclosure may employ any combination of features described herein.

[0066] The present application may reference quantities and numbers. Unless specifically stated, such quantities and numbers are not to be considered restrictive, but exemplary of the possible quantities or numbers associated with the present application. Also, in this regard, the present application may use the term “plurality” to reference a quantity or number. In this regard, the term “plurality” is meant to be any number that is more than one, for example, two, three, four, five, etc. The term “about,” “approximately,” etc., means plus or minus 5% of the stated value. For the purposes of the present disclosure, the phrase “at least one of A and B” is equivalent to “A and/or B” or vice versa, namely “A” alone, “B” alone or “A and B.”. Similarly, the phrase “at least one of A, B, and C,” for example, means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C), including all further possible permutations when greater than three elements are listed.

[0067] Throughout this specification, terms of art may be used. These terms are to take on their ordinary meaning in the art from which they come, unless specifically defined herein or the context of their use would clearly suggest otherwise.

[0068] The principles, representative embodiments, and modes of operation of the present disclosure have been described in the foregoing description. However, aspects of the present disclosure, which are intended to be protected, are not to be construed as limited to the particular embodiments disclosed. Further, the embodiments described herein are to be regarded as illustrative rather than restrictive. It will be appreciated that variations and changes may be made by others, and equivalents employed, without departing from the spirit of the present disclosure. Accordingly, it is expressly intended that all such variations, changes, and equivalents fall within the spirit and scope of the present disclosure as claimed.

Claims

CLAIMS The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A linear actuator (200), comprising: a cylinder (210) having a central cavity (212); a gland (260) mounted to the cylinder (210) and having an aperture (264) extending therethrough; and a piston (240) slidably disposed within the central cavity (212), the piston (240) including: a body (242); a first seal (248) mounted to an outer surface of the body (242) and sealingly engaging the cylinder (210); and a first damping member (252) mounted to the outer surface of the body (242) and engaging the cylinder (210), wherein the first seal (248) comprises a different material than the first damping member (252).

2. The linear actuator (200) of Claim 1, wherein the first damping (252) member has the form of a sleeve that surrounds the piston (240).

3. The linear actuator (200) of Claim 1, wherein the first damping member (252) comprises a fiberglass isolation pad or nitrile rubber.

4. The linear actuator (200) of Claim 1, further comprising: a rod (230) mounted to the piston (240) and slidingly extending through the aperture (264) of the gland (260); a second seal (270) mounted to an inner surface of the aperture (264) of the gland (260) and sealingly engaging the rod (230); and a second damping member (292) mounted to the inner surface of the aperture (264) of the gland (260) and engaging the rod (230), wherein the second seal (270) comprises a different material than the second damping member (292).

5. The linear actuator (200) of Claim 4, wherein the second damping member (292) has the form of a sleeve that surrounds the rod (230).

6. The linear actuator (200) of Claim 4, wherein the first damping member (252) and the second damping member (292) comprise a fiberglass isolation pad or nitrile rubber.

7. The linear actuator (200) of Claim 6, wherein each of the first seal (248) and the second seal (270) comprises an elastomeric material.

8. The linear actuator (200) of Claim 6, wherein each of the first seal (248) and the second seal (270) is an O-ring.

9. The linear actuator (200) of Claim 4, wherein the gland (260) includes a recess (278) extending axially toward the piston (240), the linear actuator (200) further comprising a third damping member (296) mounted within the recess (278) of the gland (260) and slidingly engaging the rod (230).

10. The linear actuator (200) of Claim 9, further comprising: a nut (280) in threaded engagement with a threaded portion of the gland (260); and a fourth damping member (294) disposed between the nut (280) and an end of the cylinder (210).

11. The linear actuator (200) of Claim 4, further comprising:

A nut (280) in threaded engagement with a threaded portion of the gland (260); and a third damping member (294) disposed between the nut (280) and an end of the cylinder (210).

12. A linear actuator (200), comprising: a cylinder (210) having a central cavity (212); a gland (260) mounted to the cylinder (210) and having an aperture (264) extending therethrough; a piston (240) slidably disposed within the central cavity (212), the piston (240) including: a body (242); and a piston seal (248) mounted to an outer surface of the body (242) and sealingly engaging the cylinder (210); a rod (230) mounted to the piston (240) and slidingly extending through the aperture (264) of the gland (260); a nut (280) in threaded engagement with a threaded portion of the gland (260); and a first damping member (294) disposed between the nut (280) and an end of the cylinder (210).

13. The linear actuator (200) of Claim 12, wherein the gland (260) includes a recess (278) extending axially toward the piston (240), the linear actuator (200) further comprising a second damping member mounted (296) within the recess (278) of the gland (260) and slidingly engaging the rod (230).

14. The linear actuator (200) of Claim 13, further comprising: a gland seal (270) mounted to an inner surface of the aperture (264) of the gland (260) and sealingly engaging the rod (230); a third damping member (252) mounted to the outer surface of the body (242) and engaging the cylinder (210), wherein the third damping (252) member comprises a different material than the piston seal (248); and a fourth damping member (292) mounted to the inner surface of the aperture (264) of the gland (260) and engaging the rod (230), wherein the fourth damping member (292) comprises a different material than the gland seal (270).

15. The linear actuator (200) of Claim 13, wherein one or both of the first and second damping members (294, 296) comprises a fiberglass isolation pad or nitrile rubber.