WO1988006121A1

WO1988006121A1 - A transfer device, equipped with wheels, for moving an aircraft

Info

Publication number: WO1988006121A1
Application number: PCT/FI1988/000023
Authority: WO
Inventors: Matti Sinkkonen
Original assignee: Tana-Jyrä Ky
Priority date: 1987-02-20
Filing date: 1988-02-16
Publication date: 1988-08-25
Also published as: FI75535B; FI75535C; AU1298588A; FI870710A0

Abstract

Transfer device, equipped with wheels, for moving an aircraft (1) on a base (2), which transfer device includes at least one so-called self-wedging friction roller (3) which is pressed against the wheel (6) of the aircraft (1) to be moved, beneath its axle, and by rotating which from its point of contact upwards the aircraft (1) is moved, and which transfer device includes a device to rotate the friction roller (3). It is the intention of this invention to achieve a new transfer device, equipped with a so-called wedging friction roller, which will reliably follow the wheel (6) of the aircraft (1). In accordance with the invention the transfer device includes a bar roller (4) to be placed on the other side of the wheel (6) of the aircraft (1) to prevent the aircraft from breaking away and/or to stabilize the transfer, and that the bar roller (4) is adapted to be normally either completely clear of, or at most in light contact with, the wheel (6) of the aircraft (1).

Description

A Transfer Device, Equipped with Wheels, for Moving an.Aircraft

The object of the invention is a transfer device, equipped with wheels, for moving an aircraft on a base, which transfer.device includes a so-' called self-wedging friction roller that is pressed'against at least one of the aircraft's wheels below the axle, and by turning which from its point of contact upwards the aircraft is moved, and which transfer device includes a device for rotating the friction roller. The transfer device is also intended for moving various wheeled vehicles. In this the friction

10 roller also means a series of rollers or a tracked mat, located on the same side.

Tug tractors, which must be constructed to be heavy in order to give them the necessary traction, are usually to used to move aircraft around airfields. As the size of sircraft increased so increasingly large tug J tractors are required, with a heavy construction, large wheels, powerful brakes, and sturdy axles.

The construction of the transfer device can be substantially lightened when the rotational force is transferred to the aircraft's own wheel from a drive wheel or friction roller belonging to the transfer device. This o presupposes that the drive wheel is pressed against the aircraft wheel with such a force that is normally a few percent of the weight coming onto the wheel. The most normal solution in connexion with a transfer de¬ vice of this kind is that the transfer device is attached to the aircraft bogie or the ends of the axle by means of suitable connecting members in 5 order to achieve a sufficient counter-force to the pressure. Transfer de¬ vices of this kind cannot be used to move any type of aircraft whatever, because there must be correspoding counter-members in the bogie of the aircraft to make the connexion of the transfer device possible. Jhe.mon- struction of completely all-purpose light transfer device is presented in 0 the Finnish Patent Application FI 833275 (partly corresponding W085/01265) This does not require any contact with the bogie of the aircraft to press . the drive wheel against the wheel. The pressure is achieved by means of the mutual movement of pressure wheels that are connected by an inter- mediate member, and placed around the wheel of the aircraft. 5 This invention is particularly concerned with transfer devices equipped with so-called self-wedging friction rollers, which are known for example from the following patent publications SE 437137, GB 845,105, and US 4,125,029. The transfer device shown in the US publication differs considerably from the two previously mentioned in that the transfer device is applicable only to pulling a vehicle to be moved. In the case of the two previously mentioned as in the case of this invention the matter is of a pushing transfer device equipped with a friction roller. In these the aforementioned pressure is achieved through the common effect of torque and the transfer device's own wheels. The friction roller attempts to pull itself beneath the wheel of the aircraft, when the horizontal" forces of the pressure and the tangential friction cancel one another, but in a vertical direction they achieve a double resultant force, which the wheels of the transfer device itself must carry.

In transfer devices equipped with pushing friction rollers one problem among others is that the aircraft being moved may suddenly break free from the grip of the friction roller. This happens for example due to unevennesses in the airfield. The basic cause of this breaking free may also be the difficulties of the know wedging transfer devices in follow¬ ing an aircraft. The known transfer devices must be continually steered so that they remain attached to the wheel of the aircraft. Naturally it is also possible to regard the lack of a pulling possibility in them as a fault, or in the case of the US publication, the lack of a pushing pos¬ sibility.

It is the intention of this invention to achieve a new transfer device equipped with a so-called wedging friction roller, from which'the afore¬ mentioned problems have been removed. The principal characteristics of the invention appear in the accompanying Patent ClaimH.. According to the invention the bar roller is not under pressure so that it advantageously only comes into contact if the friction roller loses its grip on the air¬ craft wheel or the transfer device is no longer driven stcajigj-t. The form of application in accordance with Patent Claim 2 shows a simple solution of the transfer device, which is applicable for both pushing and pulling an aircraft. In this the "pull" is arranged in reality also by means of the the pushing friction roller. It must be noted that in this only one of the friction rollers is can always transmit the moment to the wheel of the aircraft. Even though the friction roller on the pulling side would be in contact with this wheel, it canno.t in practice transmit drive power at all, because the compression is any in case small. The form of application in accordance with Patent Claim 3 improves the steering effect of the transfer device significantly. By using rollers of this form two significant advantages are gained. First of all the transfer device's own steering, mentioned above, is improved, so that it is able to grip the wheel of the aircraft reliably, on the other hand the compression is more evenly distributed on the surface of the wheel of the aircraft. The rollers of a transfer device that grips one wheel are most advantageously formed in accordance with Patent Claim 4, by which relaible self-steering is ensured. In what follows the invention is illustrated with the aid of examples by reference to the accompanying figures, in which

Figure 1 shows the transfer device seen from above Figure 2 shows the situation in Figure 1 seen from the-^side Figure 3 shows the principle of the form of the rollers in a transfer device that grips one wheel.

The transfer device shown in Figures 1 and 2 is intented to move an aircraft 1 on an airfield 2. In the figures the aircraft 1 is shown by only a part of the landing gear and the wheels 6. The transfer device is equipped with its own drive, which, however, is disconnected when the drive is transmitted to the wheel of the aircraft. The device is driven round the double wheels 6 of the aircraft 1 when the front friction rollers are drawn to the side. In the position in Figures 1 and 2 the transfer device is pushing the aircraft 1, that is, the rear friction rollers 3 are in operation. The direction of rotation of the driving friction rollers is extremely important to the operation of the transfer device, as is its point of contact, as stated previously.

The front friction rollers 4, that is in this situation the bar rollers are not in contact with wheel 6. If, however, the driving friction roller 3 loses its grip on wheel 6, the bar roller 4 prevents it from breaking away completely. On the other hand if the transfer device turns to a ' slight angle in relation to wheel 6, the bar roller also comes into con¬ tact with wheel 6 at its edge and returns the transfer device to the cor- rect position. When the direction of movement changes the front friction rollers are brought into contact with wheel 6 and their turning begins. From an operational point of view the rear friction rollers 3 now act as bar rollers. If the transfer device is driving ^>,a pair of wheels its steerability. is naturally good. In order to ensure the grip of the transfer device it is only necessary to thin the rollers a little in the centre, so that move- ment that takes place directly laterally is prevented. In the case of a transfer device that turns one wheel the situation is more complicated. Figure 3 shows a hroizontal cross-section through the rollers. At this level the principle of the advantageous form is apparent. The transfer device attempts to turn around the wheel 6. When the circle 5 is drawn from the central position using the diameter obtained from wheel 6 it can be seen ttώt this is the slackest position. The edges of the rollers 3 - and 4 resist the turning and thus return the transfer device to the cen¬ tral position if it moves into an angle. When the entire aircraft turns the transfer device follows it with a^' small deviation.

Claims

Patent Claims

1. A transfer device equipped with wheels especially for moving an aircraft (1) on a base (2), which transfer device includes at least one so-called self-wedging friction roller (3) that grips the whel (6) of the aircraft (1.) to be moved, beneath its axle, and which transfer device also includes a device for rotating the friction roller (3), characterized in that the transfer device includes a bar rolle (4) to be placed at the other side of the wheel (6) of the aircraft (1) in order to prevent the aircraft breaking away and/or to stabilize the transfer, which bar roller is adapted to be normally either completely clear or only in light contact with the wheel (6) of the aircraft (l).

2. A transfer device in accordance with Patent Claim 1, characteriz ed in that the bar roller (4) is essentailly another symmetrically located friction roller, and that the transfer device in¬ cludes devices for connecting rotation in different directions alterna-i tively to the friction rollers (3,4) on either side.

3- A transfer device in accordance'with Patent Claims 1 or 2, characteriz ed in that both the friction roller (3) and the bar roller (4) are self-centering, i.e. that their edge diameters are sub¬ stantially greater than the centre diameters and that their form is thus adapted to the wheel (6) of the aircraft (l) to be moved so that the slack- est position is when the wheel (6) of the aircraft (l) is straight between them, in which case' they return to the central position if due to some disturbance they come to be at an angle.

4. A transfer device in accordance with Patent Claim 3 which grips one wheel, characteriz ed in that the forms of both the frictio roller (3) and the bar roller (4) from the centre to the edges are adapted so that in the operating position cross-section, i.e. in the cross-section of both rollers (3,4) the projection edge line of the rollers (3,4) at the edges remains for the greatest part within such a circle (5) the diameter (d) of which is the size of the diameter of the wheel (6) in this cross- section.