# US 12,179,901 B2 · Tail folding mechanism > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,179,901 B2 - Document ID: US12179901B2 - Status: Granted - Kind: B2 - Application number: 18/521,491 - Filed: 2023-11-28 - Published: 2024-05-30 - Granted: 2024-12-31 - Earliest claimed: 2022-11-30 - Assignees: Tusas- Turk Havacilik Ve Uzay Sanayii Anonim Sirketi - Applicants: Tusas-Turk Havacilik Ve Uzay Sanayii Anonim Sirketi - Inventors: Furkan Yilmaz - Web page: https://patentgrep.com/patent/US12179901B2 ## CPC - B64C 1/063: {Folding or collapsing to reduce overall dimensions, e.g. foldable tail booms} - B64C 27/04: Helicopters - B64C 27/82: characterised by the provision of an auxiliary rotor or fluid-jet device for counter-balancing lifting rotor torque or changing direction of rotorcraft - B64C 3/56: Folding or collapsing to reduce overall dimensions of aircraft - B64C: AEROPLANES; HELICOPTERS ## Abstract A folding mechanism for a tail located on a helicopter has a front region on the tail, a rear region connected to the front region can be folded around the axis on which it is supported, a first shaft located on the front region and a second shaft located on the rear region enables power to be transmitted to the tail rotor during the flight movement of the helicopter, a first coupling and a second coupling located on the first shaft with a threaded form, a first hub located on the first shaft surrounding the first coupling all around and is form-fitting to the first coupling to enable the first coupling to make at least a partial spherical rotational movement, and a second hub located on the second shaft is arranged opposite the second coupling and being form-fitting to the second coupling with a dampener located on the front region. ## Claims ### Claim 1 A tail folding mechanism (1) comprising: a tail (2) located on a helicopter, a front region (201) located on the tail (2), a rear region (202) connected to the front region (2) in such a way that it can be folded around an axis on which it is supported, a first shaft (3) located on the front region (201) and a second shaft (4) located on the rear region (202) enabling power to be transmitted to a tail rotor during flight movement of the helicopter, a first coupling (5) and a second coupling (6) located on the first shaft (3), both with a threaded form, a first hub (7) located on the first shaft (3) and surrounding the first coupling (5) all around, the first hub (7) form-fitting to the first coupling (5) so as to enable the first coupling (5) to make at least a partial spherical rotational movement, a second hub (8) located on the second shaft (4) so as to be arranged opposite the second coupling (6) and being form-fitting to the second coupling (6), a dampener (9) located on the front region, wherein the folding mechanism is configured to have: an active mode (A) in which power is transmitted from the first shaft (3) to the second shaft (4) by placement of the second coupling (6) in the second hub (8), a passive mode (P) in which power transmission from the first shaft (3) to the second shaft (4) is interrupted when the second coupling (6) is decoupled from the second hub (8) by folding movement of the rear region (202), wherein the dampener (9) is located in the first shaft (3) so as to be in contact with the first hub (7), and enabling the movement of the first hub (7) into the first shaft (3) to be at least partially dampened, thereby damping linear movement of the first hub (7) while it is switched from the passive mode (P) to the active mode (A). ### Claim 2 (depends on 1) The tail folding mechanism (1) according to claim 1, comprising a mouth (10) on a side of the first shaft (3) where the shaft is connected to a helicopter main rotor, and wherein the dampener (9) is configured to dampen the movement of the first hub (7) towards the mouth (10) when the second hub (8) slides from teeth of the second coupling (6) and gets placed in the first hub (7) while the front region (201) is brought from the passive mode (P) to the active mode (A) by a user. ### Claim 3 (depends on 1) The tail folding mechanism (1) according to claim 1, comprising a socket (11) located on the first hub (7) so as to extend into the first shaft (3), contacting an inner wall of the first shaft (3), at least partially surrounding the dampener (9) all around, and enabling the dampener (9) to be supported. ### Claim 4 (depends on 2) The tail folding mechanism (1) according to claim 2, wherein the dampener (9) is configured to move forward towards the rear region (202) in a direction from the first shaft (3) to the first coupling (5) while being switched from the active mode (A) to the passive mode (P) or becomes compressed towards the mouth (10) in the direction from the first shaft (3) to the first coupling (5) while the dampener is brought from the passive mode (P) to the active mode (A), thereby at least partially damping a load transferred to the front region (201). ### Claim 5 (depends on 3) The tail folding mechanism (1) according to claim 3, comprising a stopper (12) enabling the dampener (9) to be mounted so as to limit its movement into the first shaft (3), the stopper (12) being form-fitting to a cross-sectional area of the first shaft (3), and the stopper (12) located in a region close to a mouth (10) and limiting the movement of the socket (11). ### Claim 6 (depends on 1) The tail folding mechanism (1) according to claim 1, comprising a transmission element (13) extending monolithically from the first hub (7) so that the axis in which the first shaft (3) extends is the center axis, forming an inner wall of the first shaft (3), and surrounding the dampener (9). ### Claim 7 (depends on 3) The tail folding mechanism (1) according to claim 3, comprising a pin (14) located in the socket (11), centering the first coupling (5) and the second coupling (6), and enabling the pin (14) to be mounted to the socket (11) so that the dampener (9) and the first coupling (5) can be moved together. ### Claim 8 (depends on 3) The tail folding mechanism (1) according to claim 3, comprising at least one shoulder (15) in the form of a protrusion located on the socket (11), preventing the movement of a fastener(S) on the socket (11), making stationary a position of the dampener (9) in the socket (11), thus ensuring an almost complete linear motion damping. ### Claim 9 (depends on 7) The tail folding mechanism (1) according to claim 7, comprising at least one nut (16) removably mounted to the pin (14) for assembly/disassembly of the first coupling (5) and being located on the second coupling (6) so that it can be directly accessed by a user in the passive mode (P). ### Claim 10 (depends on 3) The tail folding mechanism (1) according to claim 3, comprising a fastener(S) having a conical form so that it can engage the inner wall of the socket (11). ### Claim 11 (depends on 1) The tail folding mechanism (1) according to claim 1, wherein the dampener (9) comprises a wave spring. ### Claim 12 (depends on 1) The tail folding mechanism (1) according to claim 1, comprising a sealing element (17) located between the first coupling (5) and the second coupling (6), acting as a seal and preventing entry of foreign substances such as water and dust into the first shaft (3). ### Claim 13 (depends on 6) The tail folding mechanism (1) according to claim 6, wherein: the first shaft (3) surrounds the transmission element (13), a first suspension bearing (18) enabling the first shaft (3) to be mounted to the front region (201), and a second suspension bearing (19) enabling the second hub (8) to be mounted to the rear region (202). ### Claim 14 (depends on 13) The tail folding mechanism (1) according to claim 13, comprising a hinge (20) connecting the first suspension bearing (18) and the second suspension bearing (19) to each other and enabling the second suspension bearing (19) to be rotated and moved around the axis on which it is connected. ### Claim 15 (depends on 1) The tail folding mechanism (1) according to claim 1, wherein the first coupling (5) and the second coupling (6) are produced monolithically.