A double-shaft double-wheel holding wheel mechanism, an airplane towing vehicle and a towing method

Abstract

The present application relates to the technical field of aircraft traction, in particular to a double-shaft double-wheel wheel-holding mechanism, an aircraft tractor and a traction method. The wheel-holding mechanism comprises a first wheel-holding component and a third wheel-holding component in the middle part, which are oppositely arranged with the front wheel-holding assembly to form a first wheel-holding space; a second wheel-holding component and a fourth wheel-holding component in the middle part, which are oppositely arranged with the rear wheel-holding assembly to form a second wheel-holding space; and the first wheel-holding space and the second wheel-holding space can realize the holding operation of the double-shaft double-wheel wheel pair. The aircraft tractor comprises the wheel-holding mechanism. The traction method can realize automatic wheel holding by combining a remote controller, a signal receiver, a hydraulic control system and a steering adjustment system during the wheel holding operation, can satisfy the holding operation of the double-shaft double-wheel wheel pair of different sizes, and can realize the overall traction of the aircraft.

Description

Technical Field

[0001] The present invention relates to the technical field of aircraft towing, and in particular to a dual-axle dual-wheel holding mechanism, an aircraft towing vehicle and a towing method. Background Art

[0002] Existing wheel-holding aircraft tractors often use a wheel-holding mechanism consisting of a front wheel-holding assembly and a rear wheel-holding assembly, which is used to hold and tow a single-axle, two-wheel structure. However, these mechanisms are unable to hold and tow the dual-axle, two-wheel structure of heavy aircraft. Therefore, a dual-axle, two-wheel wheel-holding mechanism, an aircraft tractor, and a towing method are needed to address the problem of existing wheel-holding mechanisms being unable to hold and tow the dual-axle, two-wheel structure of heavy aircraft. Summary of the Invention

[0003] The present invention aims to provide a dual-axle dual-wheel holding mechanism, an aircraft tractor, and a tractor method. The specific technical solutions are as follows:

[0004] In a first aspect, the present invention provides a dual-axle dual-wheel holding mechanism, comprising a mounting slot, a front holding assembly, a middle holding assembly, and a rear holding assembly;

[0005] One end of the mounting groove in the length direction is an open end, and the other end is a closed end;

[0006] The front wheel-holding assembly can be opened and closed on the open end of the mounting slot; the rear wheel-holding assembly can be slidably arranged in the closed end of the mounting slot and can be arranged closer to or farther away from the front wheel-holding assembly;

[0007] The middle wheel-holding assembly includes a middle first wheel-holding component and a middle second wheel-holding component; the middle first wheel-holding component and the middle second wheel-holding component are respectively slidably arranged close to or slidably arranged away from each other in the width direction of the mounting groove; the middle first wheel-holding component includes a middle first wheel-holding part and a middle second wheel-holding part; the middle second wheel-holding component includes a middle third wheel-holding part and a middle fourth wheel-holding part; the middle first wheel-holding part and the middle third wheel-holding part are arranged facing each other with the front wheel-holding assembly to form a first wheel-holding space; the middle second wheel-holding part and the middle fourth wheel-holding part are arranged facing each other with the rear wheel-holding assembly to form a second wheel-holding space.

[0008] Optionally, the first middle wheel-holding component further includes a first support frame slidably arranged in the mounting groove; the first middle wheel-holding component includes a first upper support shoe cylinder, a first upper wheel-holding piece, a first lower support shoe cylinder and a first lower wheel-holding piece; the first upper wheel-holding piece is arranged above the first lower wheel-holding piece; the first upper support shoe cylinder and the first lower support shoe cylinder are respectively arranged on the first support frame from top to bottom; the first upper wheel-holding piece is connected to the operating end of the first upper wheel-holding piece; the first lower wheel-holding piece is connected to the operating end of the first lower wheel-holding piece;

[0009] The second wheel-holding component in the middle part further includes a second support frame slidably arranged in the mounting groove; the third wheel-holding component in the middle part includes a third upper gripper cylinder, a third upper gripper piece, a third lower gripper cylinder and a third lower gripper piece; the third upper gripper piece is arranged above the third lower gripper piece; the third upper gripper cylinder and the third lower gripper cylinder are respectively arranged on the second support frame above and below; the third upper gripper piece is connected to the operating end of the third upper gripper cylinder; the third lower gripper piece is connected to the operating end of the third lower gripper cylinder;

[0010] The first upper wheel holding piece, the first lower wheel holding piece, the third upper wheel holding piece and the third lower wheel holding piece are arranged facing the front wheel holding assembly to form a first wheel holding space.

[0011] Optionally, the middle second wheel holding component includes a second upper wheel holding shoe cylinder, a second upper wheel holding piece, a second lower wheel holding shoe cylinder and a second lower wheel holding piece; the second upper wheel holding piece is arranged above the second lower wheel holding piece; the second upper wheel holding shoe cylinder and the second lower wheel holding shoe cylinder are respectively arranged on the first support frame from top to bottom; the second upper wheel holding piece is connected to the operating end of the second upper wheel holding shoe cylinder; the second lower wheel holding piece is connected to the operating end of the second lower wheel holding shoe cylinder;

[0012] The fourth middle wheel-holding component includes a fourth upper wheel-holding cylinder, a fourth upper wheel-holding plate, a fourth lower wheel-holding cylinder, and a fourth lower wheel-holding plate; the fourth upper wheel-holding plate is arranged above the fourth lower wheel-holding plate; the fourth upper wheel-holding cylinder and the fourth lower wheel-holding cylinder are respectively arranged on the second support frame from top to bottom; the fourth upper wheel-holding plate is connected to the operating end of the fourth upper wheel-holding cylinder; the fourth lower wheel-holding plate is connected to the operating end of the fourth lower wheel-holding cylinder;

[0013] The second upper wheel holding piece, the second lower wheel holding piece, the fourth upper wheel holding piece and the fourth lower wheel holding piece are arranged facing the rear wheel holding assembly to form a second wheel holding space.

[0014] Optionally, the first central wheel-holding member further includes a first propulsion cylinder; a housing of the first propulsion cylinder is disposed on the mounting slot, and an operating end thereof passes through the mounting slot and is connected to the first support frame;

[0015] The second middle wheel-holding component also includes a second propulsion cylinder; the shell of the second propulsion cylinder is set on the installation groove, and its working end passes through the installation groove and is connected to the second support frame.

[0016] Optionally, the first central wheel-holding member further includes a first telescopic connecting member; one end of the first telescopic connecting member is a first fixed end, which is fixedly disposed on the mounting slot through the first telescopic end, and the other end is a first telescopic end, which is telescopically disposed relative to the first fixed end, and the first telescopic end is connected to the first support frame;

[0017] The second middle wheel-holding component also includes a second telescopic connecting member; one end of the second telescopic connecting member is a second fixed end, and is fixedly arranged on the mounting groove, while the other end is a second telescopic end, and is telescopically arranged relative to the second fixed end, and the second telescopic end is connected to the second support frame.

[0018] Optionally, the front wheel holding assembly includes a base plate, a front baffle, a telescopic cylinder, a rotating cylinder and a locking cylinder; the base plate can be rotatably set on the open end of the mounting slot; the shell of the rotating cylinder is connected to the mounting slot, and its working end is connected to the base plate; the front baffle can be rotatably set on the base plate; the shell of the telescopic cylinder is hinged to the base plate, and its working end is hinged to the front baffle; the shell of the locking cylinder is connected to the mounting slot, and its working end is connected to the base plate.

[0019] Optionally, the rear holding wheel assembly includes a slide rail, a rear baffle, an auxiliary baffle, a third thrust cylinder and a fourth thrust cylinder; the slide rail is arranged in the closed end of the mounting slot along the length direction of the mounting slot; the rear baffle is arranged in the closed end of the mounting slot, and a slide groove adapted to the slide rail is arranged on the rear baffle; the shell of the third thrust cylinder is fixedly connected to the closed end of the mounting slot, and the working end is connected to the rear baffle; the auxiliary baffle is arranged above the rear baffle and can be rotatably arranged on the closed end of the mounting slot; the shell of the fourth thrust cylinder is fixedly connected to the closed end of the mounting slot, and the working end is hinged to the auxiliary baffle.

[0020] In a second aspect, the present invention provides an aircraft tractor including the dual-axle dual-wheel wheel-holding mechanism, further comprising a tractor trolley; a mounting opening communicating with the rear end of the tractor body is provided on the tractor trolley; the dual-axle dual-wheel wheel-holding mechanism is provided on the mounting opening;

[0021] It also includes a full-vector travel unit and a lifting drive assembly; the number of the full-vector travel units is multiple, and they are evenly arranged in pairs at the bottom of the traction trolley through connecting shafts; the number of the lifting drive assemblies is at least two groups, and they are symmetrically arranged on both sides of the bottom of the traction trolley; each group of the lifting drive assemblies includes a first connecting rod, a second connecting rod and a lifting cylinder; one end of the first connecting rod is hinged to the connecting shaft through a first connecting seat, and the other end is hinged to one end of the second connecting rod; the end of the second connecting rod away from the first connecting rod is hinged to the bottom of the traction trolley through the second connecting seat; the shell of the lifting cylinder is connected to the first connecting seat, and the working end is connected to the second connecting seat;

[0022] It also includes a cab provided on the tractor trolley; the top of the cab is flush with the top of the tractor trolley, and the bottom of the cab is flush with the bottom of the tractor trolley;

[0023] It also includes a remote control and a control room arranged on the traction trolley; a hydraulic control system, a steering adjustment system and a signal receiver are arranged in the control room; the first upper shoe cylinder, the first lower shoe cylinder, the second upper shoe cylinder, the second lower shoe cylinder, the third upper shoe cylinder, the third lower shoe cylinder, the fourth upper shoe cylinder, the fourth lower shoe cylinder, the first propulsion cylinder, the second propulsion cylinder, the third propulsion cylinder, the fourth propulsion cylinder, the telescopic cylinder, the rotating cylinder, the locking cylinder and the lifting cylinder are all connected to the hydraulic control system; each of the full-vector driving units is connected to the steering adjustment system; the hydraulic control system and the steering adjustment system are both connected to the signal receiver; the signal receiver is wirelessly connected to the remote control;

[0024] It also includes a ventilation port which is arranged on the traction trolley and communicates with the control room.

[0025] In a third aspect, the present invention provides a towing method using the aircraft towing vehicle, comprising:

[0026] In step S1, the operator drives the tractor trolley close to the aircraft's dual-axle dual-wheel wheelset, and uses the remote controller to send a signal to lower the tractor trolley, which is transmitted to the hydraulic control system via the signal receiver. The hydraulic control system controls the lifting cylinder to lower the tractor trolley for subsequent wheel-holding operation; the operator uses the remote controller to send a signal to open the front wheel-holding assembly, which is transmitted to the hydraulic control system via the signal receiver. The hydraulic control system controls the rotating cylinder to open the bottom plate, and controls the telescopic cylinder to open the front baffle; at the same time, the operator uses the remote controller to send a reverse signal, which is transmitted to the steering adjustment system via the signal receiver. The steering adjustment system controls the tractor trolley to reverse to the aircraft's dual-axle dual-wheel wheelset position, and continues to reverse until the dual-axle dual-wheel wheelset abuts the rear baffle, and then stops reversing;

[0027] In step S2, the operator uses the remote control to send a signal to retract and lock the front wheel-holding assembly, which is transmitted to the hydraulic control system via the signal receiver. The hydraulic control system controls the rotating oil cylinder to link the base plate to retract, and controls the telescopic oil cylinder to link the front baffle to retract; then, the hydraulic control system controls the locking oil cylinder and the base plate to lock; if there is a gap between the dual-axle dual-wheel wheelset and the front baffle, the operator uses the remote control to send a signal to start the movement operation of the rear wheel-holding assembly, which is transmitted to the hydraulic control system via the signal receiver. The hydraulic control system controls the third propulsion oil cylinder to link the rear baffle to move along the slide rail toward the front baffle until the dual-axle dual-wheel wheelset abuts against the front baffle, and controls the fourth propulsion oil cylinder to link the auxiliary baffle to abut against the dual-axle dual-wheel wheelset, thereby realizing the clamping operation of the dual-axle dual-wheel wheelset;

[0028] Step S3: The operator uses the remote controller to send a signal to start the operation of the middle wheel-holding assembly. The signal is transmitted to the hydraulic control system via the signal receiver. The hydraulic control system controls the first propulsion cylinder and the second propulsion cylinder to respectively link the first middle wheel-holding component and the second middle wheel-holding component to move toward each other to the middle of the mounting groove.

[0029] The hydraulic control system controls the first upper gripper cylinder to be linked to the first upper wheel-holding plate, controls the first lower gripper cylinder to be linked to the first lower wheel-holding plate, controls the third upper gripper cylinder to be linked to the third upper wheel-holding plate, and controls the third lower gripper cylinder to be linked to the third lower wheel-holding plate to move closer to the front wheel-holding assembly to form a first wheel-holding space, thereby clamping the two-wheel wheelset on one axle of the two-axle two-wheel wheelset.

[0030] The hydraulic control system controls the second upper gripper cylinder to be linked to the second upper wheel-holding plate, controls the second lower gripper cylinder to be linked to the second lower wheel-holding plate, controls the fourth upper gripper cylinder to be linked to the fourth upper wheel-holding plate, and controls the fourth lower gripper cylinder to be linked to the fourth lower wheel-holding plate to move closer to the rear wheel-holding assembly to enclose a second wheel-holding space, thereby achieving the clamping of the two-wheel wheelset on the other axle of the two-axle two-wheel wheelset;

[0031] Step S4: The operator drives the towing trolley to tow the aircraft toward the target location.

[0032] Optionally, the towing method further comprises in step S4 that, after the towing trolley leaves the aircraft, an operator uses the remote controller to send a signal to raise the towing trolley, which is transmitted to the hydraulic control system via the signal receiver, and the hydraulic control system controls the lifting cylinder to raise the towing trolley in conjunction with the lifting cylinder to avoid hitting obstacles during towing;

[0033] The towing method further includes step S5, wherein the step S5 includes using a corresponding number of the towing trolleys according to the number of the dual-axle dual-wheel wheelsets of the aircraft, and connecting adjacent towing trolleys via the connecting frame to achieve overall towing of the aircraft.

[0034] The application of the technical solution of the present invention has at least the following beneficial effects:

[0035] (1) The present invention provides a dual-axle dual-wheel holding mechanism, wherein a first wheel holding space is formed by a middle first wheel holding component and a middle third wheel holding component and a front wheel holding assembly being arranged opposite to each other; a second wheel holding space is formed by a middle second wheel holding component and a middle fourth wheel holding component and a rear wheel holding assembly being arranged opposite to each other; the first wheel holding space and the second wheel holding space are used to realize the holding operation of the dual-axle dual-wheel wheel pair, thereby solving the problem that the existing wheel holding mechanism cannot hold the dual-axle dual-wheel structure of a heavy aircraft tightly.

[0036] (2) The present invention provides an aircraft tractor including the dual-axle dual-wheel gripping mechanism, which solves the problem that the existing gripping mechanism cannot grip and tow the dual-axle dual-wheel structure of a heavy aircraft.

[0037] (3) The present invention provides a towing method for an aircraft tractor, which can achieve automatic wheel holding by combining a remote control, a signal receiver, a hydraulic control system, and a steering adjustment system during wheel holding operations. This towing method can meet the needs of holding operations for dual-axle dual-wheel wheelsets of different sizes. Specifically, according to the size of the gap between the dual-axle dual-wheel wheelset and the front baffle, the hydraulic control system is used to control the third propulsion cylinder to link the rear baffle and move along the slide rail toward the front baffle until the dual-axle dual-wheel wheelset abuts the front baffle, and the fourth propulsion cylinder is controlled to link the auxiliary baffle to abut the dual-axle dual-wheel wheelset, thereby achieving holding operations for dual-axle dual-wheel wheelsets of different sizes. This towing method can also achieve the overall towing of an aircraft. Specifically, according to the number of dual-axle dual-wheel wheelsets of the aircraft, a corresponding number of the towing trolleys are used, and adjacent towing trolleys are connected by the connecting frame to achieve the overall towing of the aircraft.

[0038] In addition to the above-described objects, features and advantages, the present invention has other objects, features and advantages. The present invention will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0040] Figure 1 This is a schematic structural diagram of a dual-axle dual-wheel holding mechanism in an embodiment;

[0041] Figure 2 This is a structural schematic diagram of an aircraft tractor including the dual-axle dual-wheel holding mechanism in an embodiment;

[0042] Among them, 1. Mounting slot, 2. Front wheel holding assembly, 2.1. Bottom plate, 2.2. Front baffle, 2.3. Telescopic cylinder, 2.4. Rotating cylinder, 2.5. Locking cylinder, 3. Middle wheel holding assembly, 3.1. The first middle wheel holding component, 3.1.1. The first middle wheel holding component, 3.1.1.1. The first upper support shoe cylinder, 3.1.1.2. The first upper wheel holding piece, 3.1.1.3. The first lower support shoe cylinder, 3.1.1.4. The first lower wheel holding piece 3.1.2. The second middle wheel holding component, 3.1.3. The first support frame, 3.1.4. The first propulsion cylinder, 3.1.5. The first Telescopic connection, 3.2, second middle wheel-holding component, 3.2.1, third middle wheel-holding component, 3.2.2, fourth middle wheel-holding component, 3.2.3, second support frame, 3.2.4, second propulsion cylinder, 3.2.5, second telescopic connection, 4, rear wheel-holding assembly, 4.1, slide rail, 4.2, rear baffle, 4.3, auxiliary baffle, 4.4, third propulsion cylinder, 4.5, fourth propulsion cylinder, 5, traction trolley, 5.1, installation port, 5.2, full vector driving unit, 5.3, lifting drive assembly, 5.4, cab, 5.5, control room, 5.6, ventilation port. DETAILED DESCRIPTION

[0043] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention are within the scope of protection of the present invention.

[0044] Example:

[0045] See also Figure 1 A dual-axle dual-wheel holding mechanism includes a mounting slot 1, a front holding assembly 2, a middle holding assembly 3, and a rear holding assembly 4.

[0046] One end of the mounting groove 1 in the length direction is an open end, and the other end is a closed end;

[0047] The front wheel-holding assembly 2 can be opened and closed on the open end of the mounting groove 1; the rear wheel-holding assembly 4 can be slidably arranged in the closed end of the mounting groove 1 and can be arranged closer to or farther away from the front wheel-holding assembly 2;

[0048] The central wheel-holding assembly 3 includes a central first wheel-holding component 3.1 and a central second wheel-holding component 3.2; the central first wheel-holding component 3.1 and the central second wheel-holding component 3.2 are respectively slidably arranged close to or slidably away from each other in the width direction of the mounting groove 1; the central first wheel-holding component 3.1 includes a central first wheel-holding part 3.1.1 and a central second wheel-holding part 3.1.2; the central second wheel-holding component 3.2 includes a central third wheel-holding part 3.2.1 and a central fourth wheel-holding part 3.2.2; the central first wheel-holding part 3.1.1 and the central third wheel-holding part 3.2.1 are arranged facing each other with the front wheel-holding assembly 2 to form a first wheel-holding space; the central second wheel-holding part 3.1.2 and the central fourth wheel-holding part 3.2.2 are arranged facing each other with the rear wheel-holding assembly 4 to form a second wheel-holding space.

[0049] The first middle wheel-holding component 3.1 also includes a first support frame 3.1.3 slidably arranged in the mounting groove 1; the first middle wheel-holding component 3.1.1 includes a first upper wheel-holding cylinder 3.1.1.1, a first upper wheel-holding piece 3.1.1.2, a first lower wheel-holding cylinder 3.1.1.3 and a first lower wheel-holding piece 3.1.1.4; the first upper wheel-holding piece 3.1.1.2 is arranged above the first lower wheel-holding piece 3.1.1.4; the first upper wheel-holding cylinder 3.1.1.1 and the first lower wheel-holding cylinder 3.1.1.3 are respectively arranged on the first support frame 3.1.3; the first upper wheel-holding piece 3.1.1.2 is connected to the operating end of the first upper wheel-holding cylinder 3.1.1.1; the first lower wheel-holding piece 3.1.1.4 is connected to the operating end of the first lower wheel-holding cylinder 3.1.1.3;

[0050] The second middle wheel-holding component 3.2 also includes a second support frame 3.2.3 slidably arranged in the mounting groove 1; the third middle wheel-holding component 3.2.1 includes a third upper gripper cylinder, a third upper wheel-holding piece, a third lower gripper cylinder and a third lower wheel-holding piece; the third upper wheel-holding piece is arranged above the third lower wheel-holding piece; the third upper gripper cylinder and the third lower gripper cylinder are respectively arranged on the second support frame 3.2.3 from above; the third upper wheel-holding piece is connected to the operating end of the third upper gripper cylinder; the third lower gripper cylinder is connected to the operating end of the third lower gripper cylinder;

[0051] The first upper wheel holding piece 3.1.1.2, the first lower wheel holding piece 3.1.1.4, the third upper wheel holding piece and the third lower wheel holding piece are arranged facing the front wheel holding assembly 2 to form a first wheel holding space.

[0052] The second middle wheel holding component 3.1.2 includes a second upper wheel holding shoe cylinder, a second upper wheel holding piece, a second lower wheel holding shoe cylinder and a second lower wheel holding piece; the second upper wheel holding piece is arranged above the second lower wheel holding piece; the second upper wheel holding shoe cylinder and the second lower wheel holding shoe cylinder are respectively arranged on the first support frame 3.1.3 from top to bottom; the second upper wheel holding piece is connected to the operating end of the second upper wheel holding shoe cylinder; the second lower wheel holding piece is connected to the operating end of the second lower wheel holding shoe cylinder;

[0053] The fourth middle wheel holding component 3.2.2 includes a fourth upper wheel holding cylinder, a fourth upper wheel holding piece, a fourth lower wheel holding cylinder and a fourth lower wheel holding piece; the fourth upper wheel holding piece is arranged above the fourth lower wheel holding piece; the fourth upper wheel holding cylinder and the fourth lower wheel holding cylinder are respectively arranged on the second support frame 3.2.3 from top to bottom; the fourth upper wheel holding piece is connected to the operating end of the fourth upper wheel holding cylinder; the fourth lower wheel holding piece is connected to the operating end of the fourth lower wheel holding cylinder;

[0054] The second upper wheel holding piece, the second lower wheel holding piece, the fourth upper wheel holding piece and the fourth lower wheel holding piece are arranged facing the rear wheel holding assembly 4 to form a second wheel holding space.

[0055] The first central wheel-holding member 3.1 further includes two first propulsion cylinders 3.1.4. The housing of the first propulsion cylinder 3.1.4 is disposed on the mounting slot 1, and the operating end thereof passes through the mounting slot 1 and is connected to the first support frame 3.1.3.

[0056] The middle second wheel-holding component 3.2 also includes a second propulsion cylinder 3.2.4 (two in number); the shell of the second propulsion cylinder 3.2.4 is set on the installation groove 1, and its working end is set through the installation groove 1 and connected to the second support frame 3.2.3.

[0057] The first central wheel-holding member 3.1 further includes two first telescopic connectors 3.1.5. One end of the first telescopic connector 3.1.5 is a first fixed end that extends through and is fixedly disposed in the mounting slot 1, while the other end is a first telescopic end that is telescopically disposed relative to the first fixed end. The first telescopic end is connected to the first support frame 3.1.3. Specifically, the first telescopic connector 3.1.5 is a telescopic sleeve structure that facilitates auxiliary support of the first support frame 3.1.3.

[0058] The second central wheel-holding member 3.2 also includes two second telescopic connectors 3.2.5. One end of the second telescopic connector 3.2.5 is a second fixed end, extending through and fixed to the mounting slot 1. The other end is a second telescopic end, telescopically arranged relative to the second fixed end. The second telescopic end is connected to the second support frame 3.2.3. Specifically, the second telescopic connector 3.2.5 is a telescopic sleeve structure, which provides auxiliary support for the second support frame 3.2.3.

[0059] The front wheel holding assembly 2 includes a base plate 2.1, a front baffle 2.2, a telescopic cylinder 2.3, a rotating cylinder 2.4 and a locking cylinder 2.5; the base plate 2.1 can be rotatably arranged on the open end of the mounting groove 1; the shell of the rotating cylinder 2.4 is connected to the mounting groove 1, and its working end is connected to the base plate 2.1; the front baffle 2.2 can be rotatably arranged on the base plate 2.1; the shell of the telescopic cylinder 2.3 is hinged to the base plate 2.1, and its working end is hinged to the front baffle 2.2; the shell of the locking cylinder 2.5 is connected to the mounting groove 1, and its working end is connected to the base plate 2.1.

[0060] The rear wheel holding assembly 4 includes a slide rail 4.1, a rear baffle 4.2, an auxiliary baffle 4.3, a third thrust cylinder 4.4 and a fourth thrust cylinder 4.5; the slide rail 4.1 is arranged in the closed end of the mounting groove 1 along the length direction of the mounting groove 1; the rear baffle 4.2 is arranged in the closed end of the mounting groove 1, and a slide groove adapted to the slide rail 4.1 is provided on the rear baffle 4.2; the shell of the third thrust cylinder 4.4 is fixedly connected to the closed end of the mounting groove 1, and the working end is connected to the rear baffle 4.2; the auxiliary baffle 4.3 is arranged above the rear baffle 4.2 and can be rotatably arranged on the closed end of the mounting groove 1; the shell of the fourth thrust cylinder 4.5 is fixedly connected to the closed end of the mounting groove 1, and the working end is hinged to the auxiliary baffle 4.3.

[0061] Specifically, two rear wheel-holding grooves adapted for the dual-axle, dual-wheel wheelset are provided on the rear baffle 4.2, and the two rear wheel-holding grooves are separated by a protrusion provided on the rear baffle 4.2. The protrusion is used to provide abutment and support for the two adjacent side surfaces of the dual-axle, dual-wheel wheelset, ensuring a tight and supportive effect on the wheelset. There are two third propulsion cylinders 4.4, which are provided in a one-to-one correspondence with the two rear wheel-holding grooves; the rear wheel-holding grooves are arc-shaped, which improve the fit and tightness of the wheelset. There are two auxiliary baffles 4.3, which are provided in a one-to-one correspondence above the two rear wheel-holding grooves; specifically, the two auxiliary baffles 4.3 are rotatably provided on the closed end of the mounting groove 1 via a first rotating shaft; there are two fourth propulsion cylinders 4.5, which are provided in a one-to-one correspondence with the two auxiliary baffles 4.3.

[0062] Specifically, there are two front baffles 2.2, which are arranged in a one-to-one correspondence with the two rear wheel-holding grooves; the two front baffles 2.2 are rotatably mounted on the base plate 2.1 via a second rotating shaft. There are two telescopic cylinders 2.3, which are arranged in a one-to-one correspondence with the two front baffles 2.2.

[0063] See also Figure 2 An aircraft tractor including the dual-axle dual-wheel wheel-holding mechanism, further comprising a tractor 5; a mounting opening 5.1 communicating with the rear end of the vehicle body is provided on the tractor 5; the dual-axle dual-wheel wheel-holding mechanism is provided on the mounting opening 5.1;

[0064] It also includes a full-vector running unit 5.2 (specifically an omnidirectional steering wheel) and a lifting drive assembly 5.3; the number of the full-vector running units 5.2 is 16, and they form 4 pairs through connecting shafts and are evenly arranged at the bottom of the traction trolley 5, wherein each pair of full-vector running units 5.2 contains 4 full-vector running units 5.2; the number of the lifting drive assemblies 5.3 is 8 groups, and they are symmetrically arranged on both sides of the bottom of the traction trolley 5; each group of the lifting drive assemblies 5.3 includes a first connecting rod, a second connecting rod and a lifting cylinder; one end of the first connecting rod is hinged to the connecting shaft through a first connecting seat, and the other end is hinged to one end of the second connecting rod; the end of the second connecting rod away from the first connecting rod is hinged to the bottom of the traction trolley 5 through the second connecting seat; the shell of the lifting cylinder is connected to the first connecting seat, and the working end is connected to the second connecting seat;

[0065] The vehicle further comprises a cab 5.4 disposed on the tractor 5; the top of the cab 5.4 is flush with the top of the tractor 5, and the bottom of the cab 5.4 is flush with the bottom of the tractor 5, ensuring that the entire vehicle body is not affected by the height of the cab 5.4 and thus hindered from being raised or lowered.

[0066] The vehicle further comprises a remote controller (not shown) and a control room 5.5 provided on the tractor 5; a hydraulic control system (not shown), a steering adjustment system (not shown), and a signal receiver (not shown) are provided in the control room 5.5; the first upper gripper cylinder 3.1.1.1, the first lower gripper cylinder 3.1.1.3, the second upper gripper cylinder 3.1.1.3, the second lower gripper cylinder, the third upper gripper cylinder, the third lower gripper cylinder, the fourth upper gripper cylinder, the fourth lower gripper cylinder, the first thrust cylinder 3.1.4, the second thrust cylinder 3.2.4, the third thrust cylinder 4.4, the fourth thrust cylinder 4.5, the telescopic cylinder 2.3, the rotating cylinder 2.4, the locking cylinder 2.5, and the lifting cylinder are all connected to the hydraulic control system; each of the full vector travel units 5.2 is connected to the steering adjustment system; the hydraulic control system and the steering adjustment system are both connected to the signal receiver; and the signal receiver is wirelessly connected to the remote controller;

[0067] The tractor 5 further includes a vent 5.6 disposed on the tractor 5 and communicating with the control room 5.5 for facilitating ventilation and heat dissipation.

[0068] A towing method using the aircraft towing vehicle comprises:

[0069] In step S1, the operator drives the tractor 5 close to the aircraft's dual-axle dual-wheel wheelset so that the center axis of the tractor 5 and the center axis of the dual-axle dual-wheel wheelset are kept in a straight line as much as possible, and uses the remote controller to send a signal to lower the tractor 5, which is transmitted to the hydraulic control system via the signal receiver, and the hydraulic control system controls the lifting cylinder to link the tractor 5 to lower for subsequent wheel holding operation; the operator uses the remote controller to send a signal to open the front wheel holding assembly 2, which is transmitted to the hydraulic control system via the signal receiver, and the hydraulic control system controls the rotating cylinder 2.4 to link the bottom plate 2.1 to open, and controls the telescopic cylinder 2.3 to link the front baffle 2.2 to open; at the same time, the operator uses the remote controller to send a reverse signal, which is transmitted to the steering adjustment system via the signal receiver, and the steering adjustment system controls the tractor 5 to reverse to the position of the aircraft's dual-axle dual-wheel wheelset, and continues to reverse until the dual-axle dual-wheel wheelset abuts against the rear baffle 4.2, and then stops reversing;

[0070] In step S2, the operator uses the remote control to send a signal to retract and lock the front wheel-holding assembly 2, which is transmitted to the hydraulic control system via the signal receiver. The hydraulic control system controls the rotating cylinder 2.4 to link the base plate 2.1 to retract, and controls the telescopic cylinder 2.3 to link the front baffle 2.2 to retract; then, the hydraulic control system controls the locking cylinder 2.5 to lock the base plate 2.1; if there is a gap between the dual-axle dual-wheel wheelset and the front baffle 2.2, the operator uses the remote control to send a signal to start the movement operation of the rear wheel-holding assembly 4, which is transmitted to the hydraulic control system via the signal receiver. The hydraulic control system controls the third propulsion cylinder 4.4 to link the rear baffle 4.2 to move along the slide rail 4.1 toward the front baffle 2.2 until the dual-axle dual-wheel wheelset abuts against the front baffle 2.2, and controls the fourth propulsion cylinder 4.5 to link the auxiliary baffle 4.3 to abut against the dual-axle dual-wheel wheelset, thereby achieving the clamping operation of the dual-axle dual-wheel wheelset;

[0071] Step S3: The operator uses the remote control to send a signal to start the operation of the middle wheel holding assembly 3. The signal is transmitted to the hydraulic control system via the signal receiver. The hydraulic control system controls the first propulsion cylinder 3.1.4 and the second propulsion cylinder 3.2.4 to respectively link the first middle wheel holding member 3.1 and the second middle wheel holding member 3.2 to move toward each other to the middle of the mounting groove 1.

[0072] The hydraulic control system controls the first upper gripper cylinder 3.1.1.1 to be linked to the first upper wheel-holding plate 3.1.1.2, controls the first lower gripper cylinder 3.1.1.3 to be linked to the first lower wheel-holding plate 3.1.1.4, controls the third upper gripper cylinder to be linked to the third upper wheel-holding plate, and controls the third lower gripper cylinder to be linked to the third lower wheel-holding plate, so as to respectively move closer to the front wheel-holding assembly 2 to enclose a first wheel-holding space, thereby achieving the clamping of the two-wheel wheelset on one axle of the two-axle two-wheel wheelset;

[0073] The hydraulic control system controls the second upper gripper cylinder to be linked to the second upper wheel-holding plate, controls the second lower gripper cylinder to be linked to the second lower wheel-holding plate, controls the fourth upper gripper cylinder to be linked to the fourth upper wheel-holding plate, and controls the fourth lower gripper cylinder to be linked to the fourth lower wheel-holding plate to move closer to the rear wheel-holding assembly 4 to enclose a second wheel-holding space, thereby clamping the two-wheel wheelset on the other axle of the two-axle two-wheel wheelset.

[0074] Step S4: The operator drives the traction vehicle 5 to tow the aircraft toward the target location.

[0075] The towing method further includes, in step S4, after the towing trolley 5 leaves the aircraft, an operator using the remote controller to send a signal to raise the towing trolley 5, which is transmitted to the hydraulic control system via the signal receiver. The hydraulic control system controls the lifting cylinder to raise the towing trolley 5 in conjunction with the lifting cylinder to avoid hitting obstacles during towing.

[0076] The towing method further includes step S5, which includes using a corresponding number of the towing trolleys 5 according to the number of the aircraft's dual-axle dual-wheel wheelsets, and connecting adjacent towing trolleys 5 via the connecting frame (not shown in the figure) to achieve overall towing of the aircraft.

[0077] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A dual-axle dual-wheel holding mechanism, characterized in that: It comprises a mounting groove (1), a front wheel holding assembly (2), a middle wheel holding assembly (3) and a rear wheel holding assembly (4); One end of the mounting groove (1) in the length direction is an open end, and the other end is a closed end; The front wheel-holding assembly (2) is closably arranged on the open end of the mounting groove (1); the rear wheel-holding assembly (4) is slidably arranged in the closed end of the mounting groove (1) and is arranged close to or away from the front wheel-holding assembly (2); The middle wheel holding assembly (3) comprises a middle first wheel holding component (3.1) and a middle second wheel holding component (3.2); the middle first wheel holding component (3.1) and the middle second wheel holding component (3.2) are respectively slidably arranged close to or slidably away from each other in the width direction of the mounting groove (1); the middle first wheel holding component (3.1) comprises a middle first wheel holding part (3.1.1) and a middle second wheel holding part (3.1.2); the middle second wheel holding part (3.1.2) is provided with a plurality of intermediate portions. The wheel component (3.2) includes a third middle wheel-holding component (3.2.1) and a fourth middle wheel-holding component (3.2.2); the first middle wheel-holding component (3.1.1) and the third middle wheel-holding component (3.2.1) are arranged opposite to the front wheel-holding assembly (2) to form a first wheel-holding space; the second middle wheel-holding component (3.1.2) and the fourth middle wheel-holding component (3.2.2) are arranged opposite to the rear wheel-holding assembly (4) to form a second wheel-holding space; The front wheel holding assembly (2) comprises a base plate (2.1), a front baffle (2.2), a telescopic oil cylinder (2.3), a rotating oil cylinder (2.4) and a locking oil cylinder (2.5); the base plate (2.1) is rotatably arranged on the open end of the mounting groove (1); the housing of the rotating oil cylinder (2.4) is connected to the mounting groove (1), and its operating end is connected to the base plate (2.1); the front baffle (2.2) is rotatably arranged on the base plate (2.1); the housing of the telescopic oil cylinder (2.3) is hinged to the base plate (2.1), and its operating end is hinged to the front baffle (2.2); the housing of the locking oil cylinder (2.5) is connected to the mounting groove (1), and its operating end is connected to the base plate (2.1); The rear wheel assembly (4) comprises a slide rail (4.1), a rear baffle (4.2), an auxiliary baffle (4.3), a third propulsion cylinder (4.4) and a fourth propulsion cylinder (4.5); the slide rail (4.1) is arranged in the closed end of the mounting groove (1) along the length direction of the mounting groove (1); the rear baffle (4.2) is arranged in the closed end of the mounting groove (1), and a slide groove adapted to the slide rail (4.1) is arranged on the rear baffle (4.2); the shell of the third propulsion cylinder (4.4) is fixedly connected to the closed end of the mounting groove (1), and the operating end is connected to the rear baffle (4.2); the auxiliary baffle (4.3) is arranged above the rear baffle (4.2) and is rotatably arranged on the closed end of the mounting groove (1); the shell of the fourth propulsion cylinder (4.5) is fixedly connected to the closed end of the mounting groove (1), and the operating end is hinged to the auxiliary baffle (4.3).

2. The dual-axle dual-wheel holding mechanism according to claim 1, characterized in that: The first central wheel holding component (3.1) further comprises a first support frame (3.1.3) slidably arranged in the mounting groove (1); the first central wheel holding component (3.1.1) comprises a first upper support shoe cylinder ( 3.1.1.1), the first upper holding wheel (3.1.1.2), the first lower holding shoe cylinder ( 3.1.1.3) and the first lower wheel holding piece (3.1.1.4); the first upper wheel holding piece (3.1.1.2) is arranged above the first lower wheel holding piece (3.1.1.4); the first upper shoe cylinder ( 3.1.1.1) and the first lower gripper cylinder ( 3.1.1.3) are respectively arranged on the first support frame (3.1.3) and the first upper holding wheel piece (3.1.1.2) and the first upper holding shoe cylinder ( 3.1.1.1) is connected to the working end; the first lower holding wheel piece (3.1.1.4) is connected to the first lower holding shoe cylinder ( 3.1.1.3) operating end connection; The second wheel-holding component (3.2) in the middle also includes a second support frame (3.2.3) slidably arranged in the mounting groove (1); the third wheel-holding component (3.2.1) in the middle includes a third upper support shoe oil cylinder, a third upper wheel-holding piece, a third lower support shoe oil cylinder and a third lower wheel-holding piece; the third upper wheel-holding piece is arranged above the third lower wheel-holding piece; the third upper support shoe oil cylinder and the third lower support shoe oil cylinder are respectively arranged on the second support frame (3.2.3) from top to bottom; the third upper wheel-holding piece is connected to the operating end of the third upper support shoe oil cylinder; the third lower wheel-holding piece is connected to the operating end of the third lower support shoe oil cylinder; The first upper wheel holding piece (3.1.1.2), the first lower wheel holding piece (3.1.1.4), the third upper wheel holding piece and the third lower wheel holding piece are arranged facing each other with the front wheel holding assembly (2) to enclose a first wheel holding space.

3. The dual-axle dual-wheel holding mechanism according to claim 2, characterized in that: The second wheel-holding component (3.1.2) in the middle portion includes a second upper wheel-holding shoe cylinder, a second upper wheel-holding piece, a second lower wheel-holding shoe cylinder, and a second lower wheel-holding piece; the second upper wheel-holding piece is arranged above the second lower wheel-holding piece; the second upper wheel-holding shoe cylinder and the second lower wheel-holding shoe cylinder are respectively arranged on the first support frame (3.1.3) from top to bottom; the second upper wheel-holding shoe is connected to the operating end of the second upper wheel-holding shoe cylinder; the second lower wheel-holding shoe is connected to the operating end of the second lower wheel-holding shoe cylinder; The fourth wheel-holding component (3.2.2) in the middle portion includes a fourth upper wheel-holding shoe cylinder, a fourth upper wheel-holding piece, a fourth lower wheel-holding shoe cylinder and a fourth lower wheel-holding piece; the fourth upper wheel-holding piece is arranged above the fourth lower wheel-holding piece; the fourth upper wheel-holding shoe cylinder and the fourth lower wheel-holding shoe cylinder are respectively arranged on the second support frame (3.2.3) from top to bottom; the fourth upper wheel-holding shoe is connected to the operating end of the fourth upper wheel-holding shoe cylinder; the fourth lower wheel-holding shoe is connected to the operating end of the fourth lower wheel-holding shoe cylinder; The second upper wheel holding piece, the second lower wheel holding piece, the fourth upper wheel holding piece and the fourth lower wheel holding piece are arranged facing each other with the rear wheel holding assembly (4) to enclose a second wheel holding space.

4. The dual-axle dual-wheel holding mechanism according to claim 3, characterized in that: The first central wheel-holding component (3.1) further comprises a first propulsion oil cylinder (3.1.4); a shell of the first propulsion oil cylinder (3.1.4) is arranged on the mounting groove (1), and an operating end thereof is arranged through the mounting groove (1) and is connected to the first support frame (3.1.3); The middle second wheel-holding component (3.2) further includes a second propulsion cylinder (3.2.4); the shell of the second propulsion cylinder (3.2.4) is arranged on the installation groove (1), and the operating end thereof is arranged through the installation groove (1) and is connected to the second support frame (3.2.3).

5. The dual-axle dual-wheel holding mechanism according to claim 4, characterized in that: The first central wheel-holding component (3.1) further comprises a first telescopic connecting member (3.1.5); one end of the first telescopic connecting member (3.1.5) is a first fixed end, and is fixedly arranged on the mounting groove (1), while the other end is a first telescopic end, and is telescopically arranged relative to the first fixed end, and the first telescopic end is connected to the first support frame (3.1.3); The middle second wheel-holding component (3.2) further includes a second telescopic connecting member (3.2.5); one end of the second telescopic connecting member (3.2.5) is a second fixed end, which is fixedly arranged on the mounting groove (1) through the second fixed end, and the other end is a second telescopic end, which is telescopically arranged relative to the second fixed end, and the second telescopic end is connected to the second support frame (3.2.3).

6. An aircraft tractor comprising the dual-axle dual-wheel holding mechanism according to claim 5, characterized in that: It also includes a traction trolley (5); a mounting opening (5.1) communicating with the rear end of the vehicle body is provided on the traction trolley (5); the dual-axle dual-wheel holding mechanism is provided on the mounting opening (5.1); It also includes a full-vector form running unit (5.2) and a lifting drive assembly (5.3); the number of the full-vector form running units (5.2) is multiple, and they are evenly arranged in pairs at the bottom of the traction trolley (5) through connecting shafts; the number of the lifting drive assemblies (5.3) is at least two groups, and they are symmetrically arranged on both sides of the bottom of the traction trolley (5); each group of the lifting drive assemblies (5.3) includes a first connecting rod, a second connecting rod and a lifting cylinder; one end of the first connecting rod is hinged to the connecting shaft through a first connecting seat, and the other end is hinged to one end of the second connecting rod; the end of the second connecting rod away from the first connecting rod is hinged to the bottom of the traction trolley (5) through a second connecting seat; the shell of the lifting cylinder is connected to the first connecting seat, and the working end is connected to the second connecting seat; It also includes a cab (5.4) arranged on the traction trolley (5); the top of the cab (5.4) is flush with the top of the traction trolley (5), and the bottom of the cab (5.4) is flush with the bottom of the traction trolley (5); It also includes a remote controller and a control room (5.5) arranged on the traction trolley (5); a hydraulic control system, a steering adjustment system and a signal receiver are arranged in the control room (5.5); the first upper support shoe cylinder ( 3.1.1.1) The first lower support shoe cylinder ( 3.1.1.3), the second upper shoe cylinder, the second lower shoe cylinder, the third upper shoe cylinder, the third lower shoe cylinder, the fourth upper shoe cylinder, the fourth lower shoe cylinder, the first propulsion cylinder (3.1.4), the second propulsion cylinder (3.2.4), the third propulsion cylinder (4.4), the fourth propulsion cylinder (4.5), the telescopic cylinder (2.3), the rotating cylinder (2.4), the locking cylinder (2.5) and the lifting cylinder are all connected to the hydraulic control system; each of the full vector form driving units (5.2) is connected to the steering adjustment system; the hydraulic control system and the steering adjustment system are both connected to the signal receiver; the signal receiver is wirelessly connected to the remote controller; It also includes a ventilation port (5.6) provided on the traction trolley (5) and in communication with the control room (5.5).

7. A towing method using the aircraft towing vehicle according to claim 6, characterized in that: include: Step S1: The operator drives the traction trolley (5) close to the double-axle double-wheel wheelset of the aircraft, and uses the remote controller to send a signal to lower the traction trolley (5), which is transmitted to the hydraulic control system via the signal receiver. The hydraulic control system controls the lifting cylinder to link the traction trolley (5) to lower for subsequent wheel holding operation; The operator uses the remote control to send a signal to open the front wheel assembly (2), which is transmitted to the hydraulic control system via the signal receiver. The hydraulic control system controls the rotating oil cylinder (2.4) to link the bottom plate (2.1) to open, and controls the telescopic oil cylinder (2.3) to link the front baffle (2.2) to open; at the same time, the operator uses the remote control to send a reverse signal, which is transmitted to the steering adjustment system via the signal receiver. The steering adjustment system controls the tractor (5) to reverse to the position of the aircraft's dual-axle dual-wheel wheelset, and continues to reverse until the dual-axle dual-wheel wheelset contacts the rear baffle (4.2), and then stops reversing; Step S2: The operator uses the remote control to send a signal to retract and lock the front wheel assembly (2), which is transmitted to the hydraulic control system via the signal receiver. The hydraulic control system controls the rotating oil cylinder (2.4) to retract the base plate (2.1) and controls the telescopic oil cylinder (2.3) to retract the front baffle (2.2). Subsequently, the hydraulic control system controls the locking oil cylinder (2.5) to lock with the base plate (2.1). If there is a gap between the dual-axle dual-wheel wheelset and the front baffle (2.2), the operator A person uses the remote controller to send a signal to start the movement operation of the rear wheel holding assembly (4), which is transmitted to the hydraulic control system via the signal receiver. The hydraulic control system controls the third propulsion cylinder (4.4) to move the rear baffle (4.2) along the slide rail (4.1) toward the front baffle (2.2) until the double-axle double-wheel wheelset abuts the front baffle (2.2), and controls the fourth propulsion cylinder (4.5) to move the auxiliary baffle (4.3) abuts the double-axle double-wheel wheelset, thereby achieving the clamping operation of the double-axle double-wheel wheelset. Step S3: The operator uses the remote controller to send a signal to start the operation of the middle wheel holding assembly (3), which is transmitted to the hydraulic control system via the signal receiver. The hydraulic control system controls the first propulsion cylinder (3.1.4) and the second propulsion cylinder (3.2.4) to respectively link the middle first wheel holding component (3.1) and the middle second wheel holding component (3.2) to move toward each other to the middle of the installation groove (1); The first upper shoe cylinder is controlled by the hydraulic control system ( 3.1.1.1) links the first upper holding wheel (3.1.1.2) and controls the first lower holding shoe cylinder ( 3.1.1.3) Linking the first lower wheel holding piece (3.1.1.4), controlling the third upper holding shoe oil cylinder to link the third upper wheel holding piece, and controlling the third lower holding shoe oil cylinder to link the third lower wheel holding piece to move closer to the front wheel holding assembly (2) to enclose a first wheel holding space, thereby achieving the clamping of the two-wheel wheelset on one axle of the two-axle two-wheel wheelset; The hydraulic control system controls the second upper support shoe cylinder to be linked to the second upper wheel holding piece, controls the second lower support shoe cylinder to be linked to the second lower wheel holding piece, controls the fourth upper support shoe cylinder to be linked to the fourth upper wheel holding piece, and controls the fourth lower support shoe cylinder to be linked to the fourth lower wheel holding piece to be respectively close to the rear wheel holding assembly (4) to enclose a second wheel holding space, thereby achieving the clamping of the two-wheel wheelset on the other axle of the two-axle two-wheel wheelset; Step S4: The operator drives the traction trolley (5) to tow the aircraft toward the target location.

8. The pulling method according to claim 7, characterized in that: The traction method further comprises in step S4 that after the traction trolley (5) leaves the aircraft, the operator uses the remote controller to send a signal to raise the traction trolley (5), which is transmitted to the hydraulic control system via the signal receiver, and the hydraulic control system controls the lifting cylinder to link the traction trolley (5) to raise, so as to avoid hitting obstacles during traction; The towing method further comprises step S5, wherein the step S5 comprises adopting a corresponding number of the towing trolleys (5) according to the number of the double-axle double-wheel wheelsets of the aircraft, and connecting adjacent towing trolleys (5) via a connecting frame to achieve overall towing of the aircraft.

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