DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after May 19, 2022, is being examined under the first inventor to file provisions of the AIA .
Drawings
The drawings are objected to under 37 CFR 1.83(a). The drawings must show every feature of the invention specified in the claims. Therefore,
In claim 2, line 1, “a guide structure” is not shown in the figures 1 to 8. The feature must be shown, or the feature(s) canceled from the claim(s). No new matter should be entered.
Corrected drawing sheets in compliance with 37 CFR 1.121(d) are required in reply to the Office action to avoid abandonment of the application. Any amended replacement drawing sheet should include all of the figures appearing on the immediate prior version of the sheet, even if only one figure is being amended. The figure or figure number of an amended drawing should not be labeled as “amended.” If a drawing figure is to be canceled, the appropriate figure must be removed from the replacement sheet, and where necessary, the remaining figures must be renumbered, and appropriate changes made to the brief description of the several views of the drawings for consistency. Additional replacement sheets may be necessary to show the renumbering of the remaining figures. Each drawing sheet submitted after the filing date of an application must be labeled in the top margin as either “Replacement Sheet” or “New Sheet” pursuant to 37 CFR 1.121(d). If the changes are not accepted by the examiner, the applicant will be notified and informed of any required corrective action in the next Office action. The objection to the drawings will not be held in abeyance.
Claim Rejections - 35 USC § 112
The following is a quotation of 35 U.S.C. 112(b):
(b) CONCLUSION. —The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
Claim 14 recites: “the piston rod” in line 21 without providing proper antecedent basis for this term. Claim 14 introduces a damper “including a piston,” but does not previously introduce or define a piston rod, nor does it establish any structural relationship between the piston and a piston rod. nevertheless, the claim later recites:
“Movement of the piston rod in the first direction…”
“Movement of the piston rod in the second direction…”
Because “the piston rod” lacks antecedent basis and is not otherwise defined in claim 14, the scope of the claim is unclear. It is therefore impossible to determine the structure whose movement is being resisted by the fluid acting on the piston. As a result, the metes and bounds of the claim cannot be reasonably ascertained. Accordingly, claim 14 is indefinite.
Claim 20 recites the limitation “the damping force”. There is insufficient antecedent basis for this limitation in the claim.
Any claim not specifically addressed under 112(b) is rejected as being dependent on a claim rejected under 112(b).
Claim Rejections - 35 USC § 103
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4.Considering objective evidence present in the application indicating obviousness or non-obviousness.
Claims 1-12 are rejected under 35 USC 103 as being unpatentable over Tsao et al. (US Pat. 4991862; hereinafter, “Tsao”) in view of Manuel et al. (US Pub. 20140353098 A1; hereinafter, “Manuel”).
Regarding claim 1, Tsao discloses: a tow bar (“universal tow”, ‘Abstract’) for towing an aircraft (‘Title’, page 1), the tow bar comprising: a first structure (18, fig. 3) having a first connector (20, fig. 1 or 6) that is adapted to be connected to a selected one of a landing gear (gear shaft 20, fig. 1) of an aircraft or a tow vehicle [col. 3, lines 35-45 discloses: “tow bar is aligned with nose wheel probe 19 as explained above tow vehicle is advanced toward the aircraft until member 18 engages shoulder of probe 19 at point 27”];
a second structure (15, fig. 1) having a second connector (link 14, col3, lines 10-15) that is adapted to be connected (via point 13, fig. 1) to the other of a landing gear of an aircraft and a tow vehicle (10, see fig. 1); and
a shock assembly (hydraulic line 6, fig. 1) operably interconnecting the first and second structures (18 and 15, fig. 1) and providing damping forces that resist movement of the first and second structures towards one another and when the first and second structures move away from one another [fig. 1 and col. 5, lines 10-16 teaches: “an internal hydraulic cylinder means for extending and reducing the length of said towbar by admitting and releasing hydraulic pressure to said hydraulic cylinder means from a control valve in tow vehicle; thus, and providing damping forces that resist movement of the first and second structures towards one another and when the first and second structures move away from one another], the shock assembly (6) including:
Tsao teaches the damper and damping action, a first spring, but fails to explicitly disclose a first spring, a second spring biasing the first and second structure, damper with first fluid chamber, a second chamber, piston dividing first chamber and remaining limitations as required by claimed 1; however
Manuel in another selective fixed chamber similar to the Tsao teaches that a first spring (94 or 370, [fig. 15]) biasing the first and second structures (structure at end 26 and opposite end 82) away from each other (figs. 1);
a second spring biasing (98 or 372, fig. 15) the first and second structures (fig. 15) towards each other (fig. 1), whereby the first and second structures are biased to an initial position relative to each other [ para. 0106 teaches that the first spring 370 and the second spring 372 bias the valve (orifices) in opposite directions to position the valve assembly, and thus the piston assembly relative to the outer tube. In this example, the first spring and the second spring bias the piston assembly in a mid-travel position (‘an initial position relative to each other’ as claimed) where the piston assembly is midway between a fully extended position and a fully retracted position];
a damper (10. Fig. 1 and [0057]) comprising a first fluid chamber (42, [0047]) having fluid therein (‘hydraulic fluid’, [0057]) and a second fluid chamber (18), wherein the second fluid chamber (18) is in fluid communication with the first fluid chamber (via valve assembly 38, [0057]) through a plurality of spaced- apart orifices [as depicted in fig. 1, plurality of spaced apart cavity (orifices) 106 and 110 are formed in the side wall of the inner tube formed by 42 where orifices are evenly spaced from one another, all of the orifices are the same size and are arranged in a line parallel to an axis of the inner tube] that restrict flow of fluid between the first fluid chamber and the second fluid chamber [para. 0057 teaches: “forcing the valve assembly 38 to move through hydraulic fluid in the inner tube 42 (first fluid chamber) slows movement (equivalent to ‘restrict’) of the rod 22”], the damper including a piston rod (22, fig. 1) extending through at least a portion of the first fluid chamber (42, fig. 1) and a piston (22 of 14) in the first fluid chamber (18) that moves with the piston rod (22 and [para. 0047 teaches: “the valve assembly 38 and a portion of the rod 22 are received within an inner tube 42; thus, the first fluid chamber 18 that moves with the piston rod]), wherein the piston (14) sealingly engages an inner surface of the first fluid chamber (42; [para. 0047 teaches that the valve assembly 38 and a portion of the rod 22 are received within an inner tube 42 (first fluid chamber); thus, the piston sealingly engages an inner surface of the first fluid chamber]) whereby the first fluid chamber (42) is divided into first and second portions (118, 118A, annotated fig. 1 below and fig. 4) by the piston (fig. 1 shows the feature that the first fluid chamber is divided into first and second portions (118A) by the piston rod 22 of assy. 14) such that: 1) movement of the piston (14) in the first fluid chamber (42) in a first direction (left direction, annotated fig. 1 below) causes fluid in the first portion (118, fig. 4) of the first fluid chamber to be pressurized and flow out of the first portion (118) of the first fluid chamber (42) through at least one orifice (via valve assembly 38 and orifice 110 and 106, fig. 1) and into the second fluid chamber (18), and then through at least one orifice (110) into the second portion (118A) of the first fluid chamber (42), whereby the fluid acts on the piston (14) to resist movement of the piston rod (rod 22) in the first direction (left direction, annotated fig. 1 below) ; and 2) movement of the piston (14) in the first fluid chamber (42) in a second direction (right , annotated fig. 1 below) that is opposite to the first direction (left direction, annotated fig. 1 below) causes fluid in the second portion (118A, annotated fig. 1 below) of the first fluid chamber (42) to be pressurized and flow out of the second portion (118A) of the first fluid chamber (42) through at least one orifice (106) into the second fluid chamber (18) and then through at least one orifice (106) into the first portion (118) of the first fluid chamber, whereby the fluid acts on the piston (14 with rod 22) to resist movement of the piston rod (22) in the second direction [ para. 0057 expressly discloses that the hydraulic fluid moves through and around the valve assembly 38 between a cavity 106 and a cavity 110 as the piston assembly 14 moves relative to the outer tube 18. Forcing the valve assembly 38 to move through hydraulic fluid in the inner tube 42 slows movement of the rod 22 and the remaining portions of the piston assembly 14. The hydraulic fluid moves through the valve assembly 38 between the cavity 106 and the cavity 110]; Also see figs. 1-5 for those movements; Also, para 0061 teaches that he inner tube 42 establishes a groove 118 that permits a bypass flow of the hydraulic fluid from the cavity 106 to the cavity 110 around the valve assembly 38 at 108; thus, Manuel teaches the claimed limitation above.
and wherein a number of orifices (110, 106) fluidly interconnecting the first portion (118) of the first fluid chamber (42) and the second fluid chamber (18) changes as the piston (14) moves in the first direction (left direction, fig. 1), and also changes as the piston (14) moves in the second direction (right direction as depicted in annotated fig. 1 below, also see fig. 4);
and wherein a number of orifices (110, 106 and 38 valves) fluidly interconnecting the second portion (114, [0059]) of the first fluid chamber (42) and the second fluid chamber (18) changes as the piston (14) moves in the first direction (left direction as depicted in annotated fig.1 below), and also changes as the piston (14) moves in the second direction (right direction, annotated fig. 1 below), such that a restriction on the flow of fluid through the orifices (110, 106) varies as a function of a position of the piston (14) in the first fluid chamber (42) [ see para. 0059 for the detail where “38 to restrict or permit flow” is disclosed; thus, a restriction occurs via 38 on the flow of fluid through the orifices (110, 106) varies as a function of a position of the piston (14) in the first fluid chamber (42)]
and wherein: 1) the piston rod (22) is connected to the first structure (at end 26) the first fluid chamber and the second fluid chamber (42, 18) are part of the second structure (at end 82, fig. 1), such that movement of the first structure (at end 26) relative to the second structure (82) moves the piston in the first fluid chamber (42) and the
piston thereby causes a damping force (via first spring 94; [0056]) tending to resist movement [see para. 0059 for the detail where “38 to restrict or permit flow” is disclosed] of the first structure (at end 26) relative to the second structure (at end 82), wherein the damping force (“damp the force”; [0056]) varies as a function of a position of the first structure (at end 26) relative to the second structure (at end 82) and as a function of a velocity of the first structure relative to the second structure [ ‘Abstract teaches that an example method for operating a lockable damper includes moving a valve assembly together with a piston assembly between a retracted position and an extended position relative to a tube, the moving unassisted by the lockable damper [note that: The lockable damper includes an unlocking mechanism that is actuated by movement of the piston rod between a retracted position and an extended position. The unlocking condition depends upon the velocity between the first and the second structure at opposite ends of the damper, such velocity-dependent damping behavior would be readily understood by a person of ordinary skill in the art.]
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to incorporate a spring-bias and various damping features as taught by Manuel above similar to the claimed invention, sinch such components and their arrangement are routinely employed to provide restorative force and motion attenuation in analogous mechanical system, because doing so represents a predictable use of known elements to improve stability and control in any towbar for the aircraft in order to advantageously design enhanced variation of well-known technology and manufacture those to restrict the moving of towbar during towing of aircraft by restricting the flow of hydraulic fluid through the valve assembly to limit the moving [ 0003 of Manuel].
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Annotated fig. 1 of Manuel
Regarding claim 2, Tsao as modified above further teaches that the second structure includes a guide structure (29, fig. 5) that slidably engages a bearing (ball 28) of the first structure (18) to form a linear bearing operably interconnecting the first structure (18) and the second structure (15); [col. 3, lines 54-56 teaches that locking balls 28 to groove 29 at point 35; thus, the tow bar is firmly secured to the aircraft probe 19 in this locking position; thus, a guide structure (29, fig. 5) that slidably engages a bearing (ball 28) of the first structure to form a linear bearing operably interconnecting the first structure and the second structure.]
Regarding claim 3, Tsao as modified above teaches the guide structure (29) and the bearing (28), but fails to teach that comprises a tube; a bushing having an inner surface that slidably engages an outer surface of the tube; however,
Manuel teaches that the guide structure comprises a tube (“damper tube”); the bearing comprises a bushing (stop member 86, fig. 1) having an inner surface that slidably engages (fig. 1) an outer surface of the tube (“damper tube”) [ para. 0051 teaches that the stop member assembly (bushing) 86 establishes an aperture 90 that slidably receives the rod 22; thus, a bushing having an inner surface that slidably engages.]
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have the modified Tsao to integrate the teaching of Manuel and configure the guide structure as a tube and to provide a bushing having an inner surface that slidably engages the outer surface of the tube, as such tube-and-bushing arrangements are a well-known and predictable technique for guiding linear motion while reducing friction and maintaining alignment in mechanical assemblies.
Regarding claim 4, Tsao as modified above does not appear to further teach that the tube comprises an outer tube; and including: an inner tube disposed inside the outer tube whereby the first fluid chamber comprises an interior space of the inner tube, and the second fluid chamber comprises a space between the inner tube and the outer tube; however
Manuel teaches that the tube (fig. 1) comprises an outer tube (tube constituted by 18; [0047]); and including: an inner tube (tube constituted by 42) disposed inside the outer tube (fig. 1) whereby the first fluid chamber (42) comprises an interior space (fig. 1) of the inner tube (tube constituted by 42), and the second fluid chamber (18) comprises a space between the inner tube (fig. 1 shows space between tube constituted by 18 and tube constituted by 42) and the outer tube (tube constituted by 18).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have the modified Tsao to incorporate the teaching of Manuel and provide inner and outer tube with space, such that the first fluid chamber comprises an interior space of the inner tube, and the second fluid chamber comprises a space between the inner tube and the outer tube with a reasonable expectation of success in order to advantageously optimize design and represents a predictable use of known concentric-tube structures to define separate fluid chambers, since such tube-within-tube arrangements are commonly used to separate fluid volumes in analogous mechanical systems.
Regarding claim 5, Tsao as modified above does not appear to teach that the first and second plugs engaging opposite ends of the inner and outer tubes; and wherein the piston rod extends through openings in the first and second end plugs whereby the piston rod moves linearly relative to the first and second end plugs; however,
Manuel teaches that the first and second plugs (ring seal 122, fig. 11 and stop member 86, fig. 4) engaging opposite ends (46, 50) of the inner and outer tubes (tube formed by 18 and tube formed by 42); and wherein the piston rod (22) extends through openings in the first and second end plugs (122 and 86) whereby the piston rod moves linearly relative to the first and second end plugs.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have the modified Tsao to incorporate the teaching of Manuel and provide the first and second plugs engaging opposite ends of the inner and outer tubes; and wherein the piston rod extends through openings in the first and second end plugs whereby the piston rod moves linearly relative to the first and second end plugs with the reasonable expectation of success in order to advantageously optimize design and seal the tube ends while permitting guided axial rod movement in fluid-actuated assemblies. Such an arrangement is well known in hydraulic fluid chamber design and would have been readily implemented by a person of ordinary skill in the art without requiring inventive insight.
Regarding claim 6, Tsao as modified above does not appear to teach that the second spring comprises a compression spring having a first end that engages the second structure, and a second end that engages the piston rod; however,
Manuel teaches that the second spring (372, fig. 20 and [0104]) comprises a compression spring (fig. 18 shows compression spring) having a first end that engages the second structure (fig. 15), and a second end that engages the piston rod [ as depicted in fig. 15, one end of spring at zone C2 is engaged with the second structure and the other end is engaged to the piston rod.]
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have the modified Tsao to incorporate the teaching of Manuel and provide the second spring comprises a compression spring having a first end that engages the second structure, and a second end that engages the piston rod; such as the first spring and the second spring bias the piston assembly in a mid-travel position where the piston assembly is midway between a fully extended position and a fully retracted position. The example damper is thus considered a "self-centering" damper [para. 0106 of Manuel].
Regarding claim 7, Tsao as modified above does not appear to teach that the first structure comprises a first tubular end portion; the second structure comprises a second tubular end portion; a first end of the piston rod is disposed inside the first tubular end portion, and a second end of the piston rod is disposed inside the second tubular end portion; however,
Manuel teaches that the first structure (fig. 15) comprises a first tubular end portion (326 or 26, fig. 1 or 15) or; the second structure (fig. 15) comprises a second tubular end portion (350 or 82 (fig. 1 or 15) or ; a first end of the piston rod is disposed inside the first tubular end portion, and a second end of the piston rod is disposed inside the second tubular end portion ( see fig. 15 of Manuel for the detail.)
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have the modified Tsao to incorporate the teaching of Manuel and to arrive at the feature recited in claim 7, as the modification represents a predictable use of known elements to achieve expected functional results.
Regarding claim 8, Tsao as modified above does not appear to teach that the second end of the first spring engages the first end plug; the first end of the second spring engages the second end plug; however,
Manuel teaches that the second end of the first spring (94 or 370, fig. 15) engage (via release mechanism, fig. 15) the first end plug (86); the first end of the second spring (98 or 372) engages the second end plug (122); [ see fig. 13].
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have the modified Tsao to incorporate the teaching of Manuel and integrate the second end of the first spring that engages the first end plug and the first end of the second spring engages the second end plug with a reasonable expectation of success in order to advantageously enhance the features that reduces drift or bias in one direction for smoother bidirectional response of the piston rod, thereby maintaining the radial positioning of the piston rod during movement of the piston assembly [ 0052 of Manuel].
Regarding claim 9, Tsao as modified above teaches the piston head bearing (ball 28 of Tsao) that slidably engages (via 29 of Tsao) the inner surface of the inner tube (fig. 5 of Tsao), but fails to teach that the piston comprises: 1) a piston head, 2) a piston ring that sealing engages an inner surface of the inner tube; however,
Manuel teaches that the piston (14) comprises: 1) a piston head (fig. 1 shows piston head), 2) a piston ring (66, [0050]) that sealing engages an inner surface of the inner tube (42) [para. 0050 teaches that the ring 66 establishes an aperture 70 that slidably receives the inner tube 42. The ring 66 slides over the inner tube 42 as the piston assembly 14 moves between extended positions and retracted positions, which stabilizes movements of the piston assembly 14 and the inner tube 42; thus, slidably engages the inner surface of the inner tube.]
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have the piston that comprises: a piston head, a piston ring of Manuel along with bearing of Tsao, thereby sealing and engaging an inner surface of the inner tube, as required by limitation of claim 9 with a reasonable expectation of success in order to advantageously enhance the features that reduces drift or bias in one direction for smoother bidirectional response of the piston rod, thereby maintaining the radial positioning of the piston rod during movement of the piston assembly [ 0052 of Manuel].
Regarding claim 10, Tsao as modified above further teaches the plurality of spaced apart orifices (110 and are formed in a sidewall of the inner tube [as depicted in fig. 1, plurality of spaced apart cavity (orifices) 106, 110 are formed in the side wall of the inner tube formed by 42 where orifices are evenly spaced from one another, all of the orifices are the same size and are arranged in a line parallel to an axis of the inner tube; see claim rejection 1 above.]
Regarding claim 11, Tsao as modified above further teaches that the orifices (106, 110, fig.1) are evenly spaced apart from one another, and all of the orifices are the same size [ see claim rejection 10 above.]
Regarding claim 12, Tsao as modified above further teaches that the orifices (106, 110, fig. 1) are arranged in a line parallel to an axis of the inner tube [see claim rejection 10 above.]
Claims 13-19 and 20 are rejected under 35 USC 103 as being unpatentable over Tsao in view of Manuel and further in view of Konakai et al. (US Pat. 10564071 B2; hereinafter, “Konakai”).
Regarding claim 13, Tsao in view of Manuel teaches the changes in restrictions of fluid flow through the orifices, but fails to explicitly teach the first structure relative to the second structure defines a stroke; however,
Manuel teaches that the first structure (“first structure”; fig. 15) relative to the second structure (“second structure”; fig. 15) defines a stroke [para. 0003 teaches that moving a valve assembly together with a piston assembly between a retracted position and an extended position relative to a tube; thus, defines a stroke];
Tsao in view of Manuel fails to explicitly teach that a magnitude of the damping force as a function of stroke distance forms a sawtooth pattern comprising a series of spaced apart peaks and minimums; however,
Konakai in another method and system for inspecting damping force variable mechanism similar to the modified Tsao teaches that a magnitude of the damping force (‘damping force’, ‘Abstract’) as a function of stroke distance (fig. 13) forms a sawtooth pattern (fig. 13) comprising a series of spaced apart peaks and minimums [ fig. 13 shows the stroke distance forms a sawtooth pattern over time and comprising series of space apart peaks and minimums.]
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to configure the towbar such that movement of the first structure relative to the second structure defines a stroke and a magnitude of the damping force as a function of stroke distance forms a sawtooth pattern as taught by Konakai into the invention of the modified Tsao comprising a series of spaced apart peaks and minimums due to the changes in restrictions of fluid flow through the orifices, as such variable-restriction damping profile are a predictable result of using orifices that open and close progressively during reciprocating motion.
Regarding claim 14, Tsao as modified above teaches: a tow bar (“universal tow”, ‘Abstract’) for towing an aircraft (‘Title’, page 1), the tow bar comprising: a first structure (18, fig. 3) having a first connector (20, fig. 1 or 6) that is adapted to be connected to a selected one of a landing gear (gear shaft 20, fig. 1) of an aircraft or a tow vehicle [col. 3, lines 35-45 discloses: “tow bar is aligned with nose wheel probe 19 as explained above tow vehicle is advanced toward the aircraft until member 18 engages shoulder of probe 19 at point 27”];
a second structure (15, fig. 1) having a second connector (link 14, col3, lines 10-15) that is adapted to be connected (via point 13, fig. 1) to the other of a landing gear of an aircraft and a tow vehicle (10, see fig. 1); and
a shock assembly (hydraulic line 6, fig. 1) operably interconnecting the first and second structures (18 and 15, fig. 1) and providing damping forces that resist movement of the first and second structures towards one another and when the first and second structures move away from one another [fig. 1 and col. 5, lines 10-16 teaches: “an internal hydraulic cylinder means for extending and reducing the length of said towbar by admitting and releasing hydraulic pressure to said hydraulic cylinder means from a control valve in tow vehicle; thus, and providing damping forces that resist movement of the first and second structures towards one another and when the first and second structures move away from one another], the shock assembly (6) including:
a first resilient member (A, annotated fig. 15 below) biasing the first and second structures away from each other (fig. 15 shows biasing the first and second structures away from each other);
a second resilient member (B, annotated fig. 15 below) biasing the first and second structures (fig. 15) towards each other, whereby the first and second structures (fig. 15) are biased to an initial position relative to each other 9fig. 15 showing the limitation required by the claim);
a damper (10. Fig. 1 and [0057]) comprising a first fluid chamber (42, [0047]) having fluid therein (‘hydraulic fluid’, [0057]) and a second fluid chamber (via valve assembly 38, [0057]), wherein the second fluid chamber (18) is in fluid communication with the first fluid chamber (42) through a plurality of spaced- apart orifices [as depicted in fig. 1, plurality of spaced apart cavity (orifices) 106 and 110 are formed in the side wall of the inner tube formed by 42 where orifices are evenly spaced from one another, all of the orifices are the same size and are arranged in a line parallel to an axis of the inner tube] that restrict flow of fluid [para. 0057 teaches: “forcing the valve assembly 38 to move through hydraulic fluid in the inner tube 42 (first fluid chamber) slows movement (equivalent to ‘restrict’) of the rod 22”] between the first fluid chamber (42) and the second fluid chamber (18), the damper including a piston (14) that sealingly engages an inner surface of the first fluid chamber (42; [para. 0047 teaches that the valve assembly 38 and a portion of the rod 22 are received within an inner tube 42 (first fluid chamber); thus, the piston sealingly engages an inner surface of the first fluid chamber]) such that: 1) movement of the piston (14) in a first direction (left direction, annotated fig.1 above) causes fluid in a first portion (118) of the first fluid chamber (42) to be pressurized and flow out of the first portion (118) of the first fluid chamber (42) through at least one orifice (106 or 110) and into the second fluid chamber (18), and then through at least one orifice (110) into a second portion (118A, annotated fig. 1 above) of the first fluid chamber, (42) whereby the fluid acts on the piston (14) to resist movement of the piston rod in the first direction (left direction, annotated fig. 1 above); and 2) movement of the piston (14) in a second direction (right direction, annotated fig. 1 above) causes fluid in the second portion (118A) of the first fluid chamber (42) to be pressurized and flow out of the second portion (118A) of the first fluid chamber (42) through at least one orifice (106 or 110) into the second fluid chamber (18) and then through at least one orifice (110 or 106) into the first portion (118) of the first fluid chamber (42), whereby the fluid acts on the piston (14) to resist movement of the piston rod in the second direction (right direction, annotated fig. 1 above);
and wherein: 1) the piston rod (22) is connected to the first structure (via tube end 82 at 26 end, [0051]), and 2) the first fluid chamber and the second fluid chamber (42, 18) are part of the second structure (fig. 15 for ‘second structure’), such that movement of the first structure (at 26) relative to the second structure (fig. 15) moves the piston (14) in the first fluid chamber (42) and the piston (14) thereby causes a damping force (via first spring 94; [0056]) tending to resist movement of the first structure relative to the second structure [see para. 0059 for the detail where “38 to restrict or permit flow” is disclosed] of the first structure (at end 26) relative to the second structure (at end 82), wherein the damping force (“damp the force”; [0056]), wherein the damping force varies (“damp the force”; [0056]) as a function of a position of the first structure (at 26 and fig. 15) relative to the second structure (at end 82 and fig. 15) and as a function of a velocity of the first structure relative to the second structure; wherein movement of the first structure relative to the second structure defines a stroke [para. 0003 teaches that moving a valve assembly together with a piston assembly between a retracted position and an extended position relative to a tube; thus, defines a stroke]; also [ ‘Abstract teaches that an example method for operating a lockable damper includes moving a valve assembly together with a piston assembly between a retracted position and an extended position relative to a tube, the moving unassisted by the lockable damper [note that: The lockable damper includes an unlocking mechanism that is actuated by movement of the piston rod between a retracted position and an extended position. The unlocking condition depends upon the velocity between the first and the second structure at opposite ends of the damper, such velocity-dependent damping behavior would be readily understood by a person of ordinary skill in the art.];
Tsao in view of Manuel teaches the changes in restrictions of fluid flow through the orifices, but fails to explicitly teach that a magnitude of the damping force as a function of stroke distance forms a sawtooth pattern; however,
Konakai in another method and system for inspecting damping force variable mechanism similar to the modified Tsao teaches that a magnitude of the damping force (‘damping force’, ‘Abstract’) as a function of stroke distance forms a sawtooth pattern (fig. 13) comprising a series of spaced apart peaks and minimums due to the changes in restrictions of fluid flow through the orifices [ fig. 13 shows the stroke distance forms a sawtooth pattern over time and comprising series of space apart peaks and minimums.]
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to configure the towbar such that movement of the first structure relative to the second structure defines a stroke and a magnitude of the damping force as a function of stroke distance forms a sawtooth pattern comprising a series of spaced apart peaks and minimums due to the changes in restrictions of fluid flow through the orifices as taught by Konakai into the invention of the modified Tsao, as such variable-restriction damping profile are a predictable result of using orifices that open and close progressively during reciprocating motion.
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Annotated fig. 15 of Manuel
Regarding claim 15, Tsao as modified above further teaches a number of orifices (106, 110 and 38) fluidly interconnecting the first portion (118A) of the first fluid chamber (42) and the second fluid chamber (18), changes as the piston moves in the first direction (left direction, annotated fig. 1 of Manuel above) , and also changes as the piston moves in the second direction (right direction, annotated fig. 1 of Manuel above); a number of orifices (106, 110 and 38) fluidly interconnecting the second portion (118A, annotated fig. 15 above) of the first fluid chamber (42) and the second fluid chamber (18) changes as the piston moves in the first direction (left direction), and also changes as the piston moves in the second direction (right direction), such that a restriction on the flow of fluid through the orifices varies as a function of a position of the piston in the first fluid chamber [ see para. 0059 for the detail where “38 to restrict or permit flow” is disclosed; thus, a restriction occurs via 38 on the flow of fluid through the orifices (110, 106) varies as a function of a position of the piston (14) in the first fluid chamber (42)]
a number of orifices ( fluidly interconnecting the first portion of the first fluid chamber and the second fluid chamber changes as the piston moves in the first direction, and also changes as the piston moves in the second direction; a number of orifices fluidly interconnecting the second portion of the first fluid chamber and the second fluid chamber changes as the piston moves in the first direction, and also changes as the piston moves in the second direction, such that a restriction on the flow of fluid through the orifices varies as a function of a position of the piston in the first fluid chamber [ see para. 0059 of Manuel for the detail where “38 to restrict or permit flow” is disclosed; thus, a restriction occurs via 38 on the flow of fluid through the orifices (110, 106) varies as a function of a position of the piston (14) in the first fluid chamber (42)].
Regarding claim 16, Tsao as modified above further teaches the second structure (18 of Tsao) includes a guide structure (29, fig. 5 of Tsao) that slidably engages a bearing (ball 28 of Tsao) of the first structure (18) to form a linear bearing operably interconnecting the first structure (18) and the second structure (15; [col. 3, lines 54-56 teaches that locking balls 28 to groove 29 at point 35; thus, the tow bar is firmly secured to the aircraft probe 19 in this locking position; thus, a guide structure (29, fig. 5) that slidably engages a bearing (ball 28) of the first structure to form a linear bearing operably interconnecting the first structure and the second structure.])
Regarding claim 17, Tsao as modified above further teaches that the guide structure comprises an outer tube; the bearing comprises a bushing having an inner surface that slidably engages an outer surface of the tube [ see claim rejection 3 above; note that: although this claim is unrelated dependency-wise to claim 3 above, identical/corresponding limitations have been discussed in the rejection of claim 3 above, including motivation for a person of ordinary skill in the art to modify.]; and including: an inner tube disposed inside the outer tube whereby the first fluid chamber comprises an interior space of the inner tube, and the second fluid chamber comprises a space between the inner tube and the outer tube [ see claim rejection 4 above; note that: although this claim is unrelated dependency-wise to claim 4 above, identical/corresponding limitations have been discussed in the rejection of claim 4 above, including motivation for a person of ordinary skill in the art to modify.]
Regarding claim 18, Tsao as modified above does not appear to teach that the first resilient member comprises a compression spring having a first end that engages the first structure, and a second end that engages the second structure; the second resilient member comprises a compression spring having a first end that engages the second structure, and a second end that engages the piston rod; however,
Manuel teaches that the first resilient member (A, annotated fig. 15 above) comprises a compression spring (94 or 370, [fig. 15]) having a first end that engages the first structure ( see fig. 15), and a second end that engages the second structure (see fig. 15); the second resilient member (B, annotated fig. 15 above) comprises a compression spring (98 or 372, fig. 15) having a first end that engages the second structure (fig. 15), and a second end that engages the piston rod [[ para. 0106 teaches that the first spring 370 and the second spring 372 bias the valve (orifices) in opposite directions to position the valve assembly, and thus the piston assembly relative to the outer tube. In this example, the first spring and the second spring bias the piston assembly in a mid-travel position (‘an initial position relative to each other’ as claimed) where the piston assembly is midway between a fully extended position and a fully retracted position].
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have the modified Tsao to incorporate the teaching of Manuel and configure the first and second resilient members as compression springs with their respective ends engaging the first structure, second structure, and piston rod as recited, since arranging spring ends to seat against adjacent structural components is a well-known and predictable techniques for establishing controlled biasing forces within reciprocating mechanical assemblies.
Regarding claim 19, Tsao as modified above further teaches the piston comprises: 1) a piston head, 2) a piston ring that sealing engages an inner surface of the inner tube, and 3) a piston head bearing that slidably engages the inner surface of the inner tube [ see claim rejection 9 above; note that: although this claim is unrelated dependency-wise to claim 9 above, identical/corresponding limitations have been discussed in the rejection of claim 9 above, including motivation for a person of ordinary skill in the art to modify.]
Regarding claim 20, Tsao discloses: a tow bar (“universal tow”, ‘Abstract’) for towing an aircraft (‘Title’, page 1), the tow bar comprising: a first structure (18, fig. 3) having a first connector (20, fig. 1 or 6) that is adapted to be connected to a selected one of a landing gear (gear shaft 20, fig. 1) of an aircraft or a tow vehicle [col. 3, lines 35-45 discloses: “tow bar is aligned with nose wheel probe 19 as explained above tow vehicle is advanced toward the aircraft until member 18 engages shoulder of probe 19 at point 27”];
a second structure (15, fig. 1) having a second connector (link 14, col3, lines 10-15) that is adapted to be connected (via point 13, fig. 1) to the other of a landing gear of an aircraft and a tow vehicle (10, see fig. 1); and
a shock assembly (hydraulic line 6, fig. 1) operably interconnecting the first and second structures (18 and 15, fig. 1) and providing damping forces that resist movement of the first and second structures towards one another and when the first and second structures move away from one another [fig. 1 and col. 5, lines 10-16 teaches: “an internal hydraulic cylinder means for extending and reducing the length of said towbar by admitting and releasing hydraulic pressure to said hydraulic cylinder means from a control valve in tow vehicle; thus, and providing damping forces that resist movement of the first and second structures towards one another and when the first and second structures move away from one another], the shock assembly (hydraulic line 6, fig. 1) including a damper comprising a first fluid chamber and a second fluid chamber that is in fluid communication with the first fluid chamber through a plurality of spaced-apart orifices; and wherein:
Tsao teaches the changes in restriction of fluid flow through the orifices fluidly interconnecting the first and second fluid chambers of the damper, but fails to teach that the movement of the first structure relative to the second structure defines a stroke; however,
Manuel teaches that movement of the first structure (“first structure”; fig. 15) relative to the second structure (“second structure”; fig. 15) defines a stroke [para. 0003 teaches that moving a valve assembly together with a piston assembly between a retracted position and an extended position relative to a tube; thus, defines a stroke];
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have the modified Tsao to incorporate the teaching of Manuel and configure the towbar such that movement of the first structure relative to the second structure defines a stroke, as defining a stroke through relative structural movement is a well-known and predictable design approach in reciprocating mechanical assemblies.
Tsao in view of Manuel does not appear to explicitly teach that the damper is configured such that a magnitude of the damping force as a function of stroke distance forms a pattern comprising a series of spaced apart peaks and minimums; however,
Konakai in another method and system for inspecting damping force variable mechanism similar to the modified Tsao teaches that a magnitude of the damper (‘damper’; ‘Abstract’) is configured such that a magnitude of the damping force as a function of stroke distance (fig. 13) forms a pattern (pattern in fig. 13) comprising a series of spaced apart peaks and minimums [ fig. 13 shows the stroke distance forms a pattern comprising a series of spaced apart peaks and minimums.]
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to configure the towbar such that a magnitude of the damping force as a function of stroke distance forms a pattern comprising a series of spaced apart peaks and minimums as taught by Konakai into the invention of the movement of the first structure relative to the second structure defines a stroke and changes in restrictions of fluid flow through the orifices of the modified Tsao, as such variable-restriction damping profile are a predictable result of using orifices that open and close progressively during reciprocating motion.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
US 20190309817 A1 to Juracek discloses: the orifice plate provides a fluid path (161) for fluidly coupling a first fluid chamber (171) with a second fluid chamber (172).
US 4685545 to Fannin discloses: this invention relates to hydraulic dampers with selectively variable damping force or resistance for controlling suspension spring action and ride motions of vehicles and more particularly to a new and improved damper having selectively registrable orifice valving in the piston thereof for varying damping characteristics.
Tow Bars _ Scheppstangen, published oct 07, 2022 retrieved from Wayback machine URL https://web.archive.org/web/20221007224155/https://www.hydro.aero/en/tow-bars.html/ on 02/19/2026.
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/NABIN KUMAR SHARMA/Examiner, Art Unit 3612
/VIVEK D KOPPIKAR/Supervisory Patent Examiner
Art Unit 3612
February 20, 2026