Krauss-maffei Aktiengesellschaft

Peter Moelzer

Gregor Trummer

Juergen Pollner

Karl Fichtner

A braking system for an aircraft towing vehicle which supports the nose wheel of an aircraft in a raised position and firmly clamps it to the vehicle. The braking force generated by the front wheels of the towing vehicle is greater by about 2:1 to 8:1 than the braking force at the rear wheels. The braking system has two hydraulic circuits employing identical braking cylinders at all four wheels of the vehicle. The number of cylinders per wheel are varied and different effective lever arms are used to generate like braking forces at each side of the vehicle, and the relatively greater braking force at the front wheels, even if one of the hydraulic circuits fails. The system limits the braking force at the front and rear wheels to maximum values to prevent excessive forces from damaging the nose gear of relatively smaller aircraft. The load carried by the vehicle is hydraulically sensed by tapping into the hydraulic leveling system to increase the braking forces that are generated when towing relatively heavier aircraft which is able to withstand such greater forces.

Braking system for aircraft towing vehicle

An aircraft towing vehicle has a frame with a rearwardly open, U-shaped recess for receiving the nose wheel of an aircraft and a lifting and securing mechanism for raising the nose wheel off the ground and securing it to the towing vehicle in the raised position. The lifting and securing mechanism, in particular a hold-down mechanism and/or a lifter mechanism secure the nose wheel after it has been fully engaged by applying a wheel clamping force of a predetermined magnitude to the periphery of the wheel. The clamping force is selected to substantially prevent relative nose wheel movements while the aircraft is being towed.

Aircraft towing vehicle having a mechanism for substantially preventing

An aircraft towing vehicle has a frame with a rearwardly opening, U-shaped recess for receiving the nose wheel of an aircraft. A lifting and securing mechanism is disposed within the recess and includes a ramp and a stop plate carried by the frame, a lifter which pushes the nose wheel from behind up the ramp into abutment with the stop plate, and a pivotable hold-down mechanism mounted above the ramp. In its rest position the hold-down mechanism is set at a distance from the ground which is less than the diameter of the smallest nose wheel of the types of aircraft that can be towed. It contacts the periphery of the nose wheel being engaged at an upper forward guadrant of the wheel's periphery and passively moves in tandem with the nose wheel as it is being pushed up the ramp into its secured position. At the end of the engaging operation, the hold-down mechanism applied a downwardly directed force of a predetermined magnitude against the nose wheel, which is generated by a hydraulic actuator. The pressure remains sealed in the hydraulic actuator so that the clamping force is applied to the nose wheel throughout the towing operation. A sensor is provided for detecting any pressure drop in the hydraulic actuator and triggering a corresponding alarm signal.

Hold-down system for an aircraft towing vehicle

An aircraft towing vehicle is equipped with an aircraft nose wheel lifting and securing mechanism. The nose wheel is received in a U-shaped recess of the vehicle chassis, the lifting mechanism being constructed to grip the wheel from behind and underneath and to then push it up a ramp. The tilt angle of the lifting mechanism as it advances towards the wheel is controlled by a steering linkage such that the lower, freely movable segment of the lifting mechanism is tilted farther forward and beneath the nose wheel at the beginning of the nose wheel engaging operation, while conversely, a rigid upper segment is tilted farther forward as the engaging operation continues to completion.

Aircraft towing vehicle having steered nose wheel lifting mechanism

An aircraft towing vehicle has a rearwardly opening recess adapted to receive the nose wheel of an aircraft to be towed. A nose wheel lifting and clamping mechanism has two nose wheel lifters which can be pivoted from a retracted position, in which they are parallel to sides of the vehicle frame, into an operative position, in which they extend into the recess for engaging the aircraft nose wheel. The lifters pivot on rocker arms which themselves pivot about a horizontal axis and are power driven by hydraulic actuators. A separate hydraulic swivel drive motor is provided for each lifter. The pressure increase which takes place when the swivel drive reaches the end of its path is used to initiate the delivery of pressurized fluid to the actuator. A crank arm driven by the hydraulic motor is connected to the support for the lifter with a low back pivot, self locking linkage to positively prevent even excessive forces generated during the nose wheel lifting process from unintentionally moving the lifters towards their retracted positions.

Aircraft towing vehicle having swiveled nose wheel lifter

A shunting vehicle for maneuvering aircraft on the ground equipped with an ascent and arresting device for the aircraft front undercarriages which overcomes the problem of the stepping out of the undercarriage in the upward direction and tilting off of the rear and, secondly, the problem of accepting front undercarriages equipped with stone guards. A pivoting ramp with automatically pivoting cams which pivot as a function of the pivoting motion of the ram is provided. Additional stationary and mobile elements of the arresting device prevent escape of the bow wheels in the upward or rearward directions. The ramp, and thus the cams, are actuated by a piston-cylinder unit, two toggle lever systems, and a sliding link guide.

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Schawbhausen, Germany

Peter Moelzer