Patent Publication Number: US-7725217-B2

Title: Ammunition loading vehicle and method

Description:
This application is a continuation of copending application Ser. No. 10/150,493, filed May 20, 2002, the entire disclosure of which is incorporated herein by reference. 

   FIELD OF INVENTION 
   The present invention relates to the loading of aircraft. 
   More particularly, the invention provides a wheeled vehicle for collecting, transporting and raising a load such as a bomb, rocket, pylon or fuel tank for attachment to an aircraft, typically under the wing thereof, or under the belly. 
   BACKGROUND OF THE INVENTION 
   One of the tasks in servicing military aircraft is to replace items such as bombs, rockets and fuel tanks which have been ejected in a previous mission. Bombs and rockets are usually carried externally and are releasably held by appropriate pylons under the aircraft wings. While small ordnance items could be assembled manually, the attachment of heavy items, for example bombs weighing hundreds of kilograms, requires the use of a mechanical loader. For this purpose vehicles have been developed which have a low long front to allow access under an aircraft wing, and a hydraulic boom between the front wheels to which the required item is attached and then raised in a position allowing attachment to the aircraft pylon. The loader vehicle may then be used to collect, transport and raise further items. Such vehicle will henceforth be referred to as a bomb loader, or simply as the vehicle. 
   Hydraulically operated bomb loaders are in service in many countries, but the functioning thereof leaves much to be desired. A bomb loader must meet somewhat contradicting requirements. Fast execution of its task is essential when the aircraft to be loaded is to carry out several successive missions in a tight time frame. However, due to the nature of the loads being handled, it is mandatory that highest possible safety standards are adhered to. Furthermore, the bomb loader is often required to maneuver in restricted space areas such as aircraft hangars wherein aircraft and servicing equipment leave little free space. Meeting these requirements is the primary aim of the present invention. 
   A patent search carried out failed to produce any relevant prior art. However it is known that the British firm “Portsmouth Aviation Ltd.” manufactures a motorized bomb loader as well as a Trolley Weapon Loading device referred to as Type R Mk2. Hydraulic power is provided by a hand pump, and the trolley naturally requires a tractor for locomotion. 
   A further prior-art bomb loader is known as the MJ-1, which is however not equipped with safety features which are an important part of the present invention. This vehicle also has a turning circle twice as large as the subject of the present invention. 
   It is therefore one of the objects of the present invention to obviate the disadvantages of prior art bomb loading vehicles and to provide a bomb loader which is more maneuverable than previously known vehicles. 
   It is a further object of the present invention to provide multiple safety features aimed at carrying out the allotted task without mishap. 
   The present invention achieves the above objects by providing a motorized hydraulically-operated and driven aircraft loading vehicle particularly suited for the loading of bombs, the vehicle being provided with a pair of hydraulically-operated arms for raising and lowering a load, the vehicle having two selectable operation modes, a first, working mode providing four-wheel hydraulic steering and enabling the vehicle to be driven at a small turning radius, and at a speed of up to 10 km/h, and a second, traveling mode wherein the rear wheel steering system is automatically locked at straight orientation and the vehicle can be road driven at a speed of up to 20 km/h. All systems of the vehicle are computer controlled. 
   In a preferred embodiment of the present invention there is provided an aircraft loading vehicle wherein two independent braking systems are provided, a first braking system of conventional design for normal use and a second braking system hydraulically operated and automatically applied in case of loss of hydraulic pressure. 
   In a further preferred embodiment of the present invention the systems are electrically controlled and not mechanically. 
   In a most preferred embodiment of the present invention there is provided an aircraft loading vehicle further including an emergency hand-operated pump, the pump being usable to release the second braking system and to operate the arms upwards or downwards. 
   Yet further embodiments of the invention will be described hereinafter. 
   It will thus be realized that the novel device of the present invention makes significant progress over the prior art in providing a bomb loader that is faster, safer and easier to maneuver than previously known vehicles for this purpose. A further advantage of the present bomb loader is that the diesel engine driving the hydraulic system when idle runs at only 900 rpm, thus reducing noise, fuel consumption and engine wear. Computer  95  converts the engine speed signal into an automotive drive characteristics to control the non feed back proportional axial piston pump, plus an electric two speed bent axis motor. 
   The computer  95  controls the axial piston pump via two proportional pressure reducing valves. The automotive control curve, is a function of the engine speed measured with the integral pulse pickup mounted on the pump. 
   Two driving modes conditions. 
   selected via mode switch: 
   
       
       
         
           A. Working mode/Combined front and rear steering. 
           B. Traveling mode/Front steering only. 
         
       
     
  
   It will further be understood that the vehicle is not limited to the previously-specified duties but can be used for lifting and transferring loads for many other purposes, and easily be adapted for lifting a person, for example a maintenance technician. 
   The invention will now be described further with reference to the accompanying drawings, which represent by example preferred embodiments of the invention. Structural details are shown only as far as necessary for a fundamental understanding thereof. The electrical and hydraulic circuits show only essential features and do not include items of conventional vehicle design. The described examples, together with the drawings, will make apparent to those skilled in the art how further forms of the invention may be realized. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a preferred embodiment of the bomb loader according to the invention; 
       FIG. 2  is a diagram of a hydraulic circuit for driving a road wheel; 
       FIG. 2   a  is a detail of the displacement pump illustrating the electric operation thereof. 
       FIG. 3  is a plan showing the 4-wheel steering being used to achieve a tight turning circle; 
       FIG. 4  is a block diagram representing the two braking systems; 
       FIG. 5  is a diagrammatic view of the hand pump circuit; 
       FIG. 6  is a schematic representation of the no-driver safety system; 
       FIG. 7  is a schematic representation of the emergency switch arrangement; and 
       FIG. 8  is a hydraulic circuit for a safety valve for preventing accidents in case of hydraulic failure. 
   

   DETAILED DESCRIPTION OF PREFERRED EXEMPLARY EMBODIMENTS 
   There is seen in  FIG. 1  a motorized hydraulically-operated and driven vehicle  10  particularly suited for the loading of aircraft with bombs, rockets fuel tanks and other items within its rated capacity. The illustrated vehicle can raise and transport up to 1500 kg, the driver sitting at the rear of the vehicle in seat  90 . The vehicle  10  is provided with a pair of hydraulically-operated arms  12 , seen between the front wheels  14 , for raising and lowering a load  16 . The arms  12  are shown in their lower position, usually used for loading and traveling. The vehicle is powered via hydraulic circuits, an example of which is seen in  FIG. 2 , by an internal combustion engine  18  coupled to a hydraulic pump  20 , receiving oil from a reservoir  44 . 
   The vehicle  10  has two operation modes, selectable by means of a mode switch  21  seen in  FIG. 6 . 
   A first, working mode providing four-wheel hydraulic steering, as seen in  FIG. 3 , and enabling the vehicle to be driven at a small turning radius, and at a speed of up to 10 km/h. 
   A second, traveling mode may be selected wherein the rear wheel steering system (not seen) is automatically locked at straight orientation and the vehicle can be road driven at a speed of up to 20 km/h. 
   With reference to the rest of the figures, similar reference numerals have been used to identify similar parts. 
   The working mode is controlled by a computer  95  which converts the engine speed signal into an automotive drive characteristics to control the non feed back proportional axial piston pump, plus an electric two speed bent axis motor. 
   Referring now to  FIG. 2 , there is seen one of the hydraulic circuits  22  driving one of the road wheels  24  (seen in  FIG. 1 . The circuit  22  is typical of several other circuits which are not shown). A reversible variable displacement pump  20  is driven by the internal combustion engine  18  ( FIG. 7 ) connected to its input shaft  26 . 
   In the main circuit  28  oil flows between the pump  20  and the hydraulic motor, which is in the present circuit, a fixed displacement motor  30 . The rate of oil flow in the main circuit  28 , and consequently the motor speed, is determined by the pump displacement which is proportional to the pump swash-plate  32  angle. The direction of oil flow depends on whether the swash-plate angle is negative or positive. Thus the direction of vehicle travel can be selected. A variable displacement motor (seen in  FIG. 8 ) is used in circuits which require a larger range of output speeds. High pressure relief valves  34  are built into the pump  20  to limit output torque. 
   A charge pump  38  functions to replenish oil lost in the main circuits  28  through leakage. The charge pump  38  supplies oil at constant pressure for use of the servo control valve  40 . When the pump swash-plates  32  are in neutral position, the charge pump flow which is not required for replenishing leaked oil passes through the charge relief valve  42  into the pump  20  and back to the reservoir  44 . In forward or reverse drive the charge pump  38  supplies oil through the charge check valve  34  on the low pressure side  48  of the main circuit  28 . Oil from the low pressure side  48  flow to a heat-exchanger  54 , and then to the reservoir  44 . 
   The servo control valve  40  maintains the constant swash-plate angle. The pump swash-plate  32  is held in a mechanical neutral position by pre-compressed springs  58  within the servo-control cylinders  60 , thus locking the wheels  24  if hydraulic power is lost, for example due to damage of a hydraulic tube. 
     FIG. 3  again illustrates the aircraft bomb loading vehicle  10  seen in  FIG. 1 . The good maneuverability of the vehicle  10  is due to its small turning radius  64 , made possible because both front  14  and rear wheels  24  can be steered. The turning radius measured at the inner face of the vehicle is about 1.6 meters. Measured externally the turning circle radius is just over 3.3 meters. 
   Seen in  FIG. 4  is a block diagram of a further embodiment of the bomb loader. At least one pair of the road wheels  24  of the vehicle are provided with two independent braking systems  66 ,  72 . 
   A first braking system  66  includes a caliper  68  disk  70  brake of conventional design for normal use. 
   A second braking system  72  is spring  74  operated. To release the brake, hydraulic pressure is applied to overcome the spring  74 . 
   Consequently, loss of hydraulic pressure results in the spring  74  immediately locking the wheels  24 . Release of the parking brake push button  76  allows hydraulic pressure to enter a cylinder  78  which opposes the spring  74  and reopens the failsafe brake  72 . 
   Referring now to  FIG. 5 , there is depicted a detail of an embodiment of the aircraft loading vehicle further including an emergency hand-operated hydraulic pump  80 , operated by the handle  82 . The pump  80  is intended for use if normal hydraulic pressure is lost, for example as result of a hose failure. 
   A selector valve  84  enables the pump  80  to be used either to release the second braking system  72  seen in the previous figure, or to send oil through a directional control valve  86  to a hydraulic cylinder  87  whereby it is possible to operate the arms  12  upwards or downwards. 
     FIG. 6  diagrammatically shows details of a further embodiment of the aircraft loading vehicle. 
   As a further safety measure, there is further provided a switch element  88  activated by the weight of the driver sitting in his seat  90 . 
   If for any reason the driver is not in his seat  90 , the switch  88  deactivates a solenoid operated hydraulic valve  92  to divert hydraulic fluid from driving the road wheels  24 , to the reservoir  44  seen in  FIG. 7 . 
   Also, a second valve  94  diverts hydraulic fluid from the second brake system  72  seen in  FIG. 4  thus allowing the springs  74  to apply the brake system  72  used for parking, and halting the vehicle. 
   The computer  95  coordinates all these functions. 
     FIG. 7  diagrammatically illustrates a detail of a bomb loader provided with a hand-operated emergency switch  96 . 
   Operation of the switch  96  shuts down the internal combustion engine  18  powering the hydraulic systems. Hydraulic pressure is retained in the actuators  87  (seen in  FIG. 5 ) raising the hydraulically-operated arms  12 , which are locked in place. 
   Furthermore, power is cut from the solenoid-operated valve  97  which then diverts hydraulic fluid from the hydraulic cylinder  78 , thus causing the springs  74  to apply the parking brake  72  and halting the vehicle. 
   Seen in  FIG. 8  is a detail of a bomb loader further including a rupture valve  100  in the hydraulic system  102  operating the hydraulically-operated arms  12  seen in  FIG. 1 . The rupture valve  100  prevents the falling of the arms  12  if hydraulic pressure thereto is lost. The arms  12  are normally operated by the electric proportional directional control valve  104 . 
   The vehicle according to the invention, the First working mode unable precise and safe working up to 10 km/h with 4-wheel steering which allows extremely small turning radius (1.5 m) and very high maneuverability required in hangars and other limited areas. This reduces the total loading time by 50% in comparison to other bomb loaders. 
   The operation of the vehicle is as follows: 
   After work mode is chosen, when the front wheel steering system reaches straight position, automatically the front and rear steering systems combine together into one unit. In this mode the hydrostatic pump receives a flat and precise command from the computer. 
   The traveling mode operation, up to 20 km/h, operates only with 2 front wheel drive system for high stability at higher speeds on open road. 
   When traveling mode is chosen, automatically by means of the Computer when the front and rear steering systems go into straight and parallel position, the rear steering system locks and the front steering system is still in operation. In this mode the hydrostatic pump receives a 45° curve from the computer and the hydrostatic motor goes into second speed up to 20 km/h. 
   The scope of the described invention is intended to include all embodiments coming within the meaning of the following claims. The foregoing examples illustrate useful forms of the invention, but are not to be considered as limiting its scope, as those skilled in the art will readily be aware that additional variants and modifications of the invention can be formulated without departing from the meaning of the following claims.