Title of Invention

HYDRAULICALLY OPERATED TOE-OUT/TOE-IN AND MANUAL LOCKING MECHANISM ON MAIN LANDING GEAR

Abstract

To obtain wheel swivel function on deck based main landing gear, a swivel axis is created by introducing a turning tube between piston tube and barrel. A mechanical lock is introduced between the fixed barrel and the turning tube. Toe-out or toe-in of the wheel is performed by a hydraulic actuator connected between the barrel and turning tube. Hydraulic power is . supplied from an external hand pump and is not drawn from the hydraulic system of the helicopter. The spring loaded lock is unlocked manually by lifting the plunger using Allen key and can stay unlocked by rotating the plunger and gets locked automatically, when the plunger is turned back and released prior to reaching to final position, in toe-out position or in fore-and- aft position.

Full Text

PURPOSE OF INVENTION Pivoting the main wheels of an aircraft is a rarity. But there are occasions that require moving the direction of main wheels when the aircraft is stationary. One such requirement comes from the need for turning the I helicopter on ship deck with harpoon engagement point on deck as the pivot point. Then prior to rotating the helicopter, the nose and main wheels have to be tumed such that the planes of rotation of the wheels are normal to harpoon engagement point. This action would allow the wheels to rotate without skidding while the helicopter is tumed with respect to harpoon engagement point. This requirement on a deck-based helicopter has led to the design of main landing gear with toe-out & toe-in facility along with locking provision in either position. PRIOR ART AND DRAWBACKS Sea Lynx helicopter-, driven by similar requirements, has provision for manual toe-out of the wheel on main landing gears by mechanical means. But, since the wheel pivoting has to be done manually, it is laborious, difficult and time consuming. To avoid these disadvantages, a hydraulically operated wheel toe-out system is conceived. MAIN OBJECTIVES The main landing gear of a deck based helicopter has to reorient the direction of main wheels and lock the wheels in this toe-out position to facilitate spot turning the helicopter with the harpoon as pivot point. The objective is to create a swivel hinge for wheels, un-lock the fore-and-aft lock, power swivel the main wheel to toed-out position, and lock the wheel at toe-out position. The reverse procedure should be possible to bring back the wheels from toe-out position to fore-and-aft position (toe-in position) after spot tuming the helicopter to desired direction. Fig. 1 to 3 show positions of main wheels of the landing gear and helicopter during the j process of tuming the helicopter. The objective is not to use hydraulic power of helicopter for the toe-out operation. This gives the advantage of tuming the helicopter in engine-off condition when hydraulic power is not available. In fact the helicopter need not have hydraulic system if the hydraulic power is not required by any other utility. Instead, ground crew can use external hand pump for this purpose. Another objective is to have a manual lock which is capable of : locking the wheel in toe-out position as well as in toe-in (or fore-and-aft) ; position. There should be provision to keep the lock in disengaged position as long as needed during the process of toe-out operation. Yet another objective is to make the lock engage at the end of toe-out operation automatically. All these objectives are set to make the toe-out operation (and the toe-in operation) simple, quick, effective, less cumbersome with least labour and with least weight penalty on the helicopter. To suit the above functional requirements and performance objectives the invention is made the description of which is given in subsequent section. SYSTEM DESCRIPTION Normally there is a piston and cylinder (or barrel) along with toggle links in the shock absorber of main landing gear. To create the swivel (or ; toe-out) axis, a turning tube 1 is added in the present arrangement (Refer Fig. 4) in between the barrel and piston tube. In this case the shock absorber is contained within the turning tube and piston tube along with toggle links. : The entire shock absorber (consisting of turning tube, piston tube, toggle links, wheel axle, wheel, tyre and brake) can, now, rotate inside a fixed barrel 2. A lug 3 is created at the bottom end of the barrel inside which a lock 4 is provided. The lock is used to lock the locking lug 5 of the turning tube 1 on to the barrel 2. The shaft of the body of toe-actuator 6 is attached to the barrel lugs 7. The piston end of the toe-actuator is attached to a fork end 8 on tuming tube 1. In an embodiment of present invention, hydraulically operated toe-out/toe-in and manual locking mechanism on main landing gear comprises of the tuming tube of the shock absorber, barrel, toe-actuator and lock as described above. The lock 4 (Refer Fig. 5) is manually operable with a spring loaded plunger 10. The lock 4 contains a light alloy housing 11 with threaded ends on both sides. One side is used for inserting the housing inside the lug 3 of the barrel 2 and for securing with a lock nut 12. The plunger 10 is inserted inside the housing 11 and further the spring 9 is placed with a spacer 13 at bottom end and the plunger guide 14 on top. The plunger guide 14 (Also refer Fig.6) has two slots 15 diametrically opposite to each other and they enter into two corresponding lugs at the end of housing 11. A top cover 16 is screwed on to the housing to keep the plunger under preload of the spring. The top portion of the plunger has two projecting lugs 17 (Also refer Fig. 7) and they slide in corresponding slots of plunger guide 18, which guide the plunger. In another embodiment of present invention, at the bottom end of the plunger a hexagonal bore 19 is made. An Allen key is inserted into this hexagonal bore and the plunger is pushed up to release the locking between barrel 2 and tuming tube 1. This arrangement avoids usage of integral handle or lever to release the lock. In another embodiment of present invention, in released position, if the plunger 10 is rotated, it does not fall down keeping the lock in unlocked position because the projecting lugs 17 of the plunger 10 at upper end sit on the top surface of the plunger guide 14. In yet another embodiment of the present invention, two stoppers 20 are provided on top surface of the plunger guide 14 (Refer Fig.6) at 90° positions such that the plunger cannot be unduly tumed through more angle. To release the lock, the plunger 10 is tumed back again such that the projecting lugs 17 of plunger 10 re-enter into the slots of the plunger guide 18. In addition to the above, the shaft of the jack body 21 of a two chamber hydraulic toe-actuator 6 (Refer Fig. 8) is attached to the barrel 2 through two lugs 7. In an embodiment of the present invention, this forms the rotating hinge for the toe-actuator 6 and avoids the usage of additional links or levers when the actuator is pin mounted at both the ends. Inside the jack body 21 a piston rod 22 with seals is placed and the end of the jack body 21 is covered by an end cap 23. The end cap is secured by lock nut 24, An adjustable threaded eye end 25 is assembled into the piston rod 22 and is secured by a locking washer 26 and locking nut 27. A spherical ball bearing 28 is inserted inside the eye end 25. The eye end 25 is attached to the fork end 8 of tuming tube 1 by means of bolt 29, nut and split pin 30. This hydraulic toe-actuator is used to rotate the tuming tube 1, intum ^he shock absorber with wheel and tyre, with respect to the fixed barrel 2. The tyre, wheel, brake and wheel axle are attached to the piston tube of shock absorber (Refer Fig. 4). The piston tube is connected to the turning tjube by means of a pair of toggle links. This arrangement ensures that a linear movement of the piston rod 22 of the toe-actuator 6 rotates the wheel $xle with the shock absorber axis as the hinge line. An integral locking lug 5 is made on the tuming tube 1 (Refer Fig. 9&10) with two holes corresponding to fore-and-aft position (toe-in position) and toe-out position of wheel axle. When the plunger of lock enters into one of these two holes, then the wheel is locked in that position. OPERATION Operationally the requirements are two. They are a) to toe-out the Wheel and b) to bring the wheel back to fore-and-aft position. These functional requirements are carried out as given below. a() Toe-out function To start with, the main wheels are in fore-and-aft position and locked (Refer Fig. 9). The sequence of operations involved to bring the wheel to toed out position is unlocking the lock and keeping it in unlocked position, supplying hydraulic power to toe-actuator to initiate toe-out operation of wheel, release the plunger of the lock onto the locking lug, further rotating the wheel to toe-out position by pumping fluid to the extension chamber of the toe-actuator and stopping supply of hydraulic fluid upon watching the entering of the plunger into toe-out locking hole of locking lug which ensures wheel locked status. To obtain the above functionality, the plunger of the lock is lifted up ; from fore-and-aft locking hole against spring load by an Allen key to release the lock between fixed barrel and turning tube. Then the plunger is turned to 90° to keep the plunger in unlocked position. Later hydraulic power is given to the extension port of the toe-actuator through a hand pump to extend the toe-actuator to about half the distance, which in turn rotates the wheel connected through turning tube, toggle links and wheel axle. At about the midway of the wheel tuming (or toe-out) operation the plunger of the lock is released which comes and sits on the locking lug waiting for the toe-out locking hole. The extension of the actuator is continued further till the plunger finds the toe-out locking hole on the locking lug of the tuming tube and smoothly enters in due to spring load which ensures locked status of wheels in toe-out position (Refer Fig. 10). In yet another embodiment of the present invention, the above procedure of automatic locking at toe-out position (as well as in toe-in position, as described further) ensures simplicity of operation. b) Turning to fore-and-aft position (toe-in position) The main wheels are in toe-out position and locked initially (Refer Fig 10). In this configuration helicopter can be rotated on the spot with the harpoon engagement point as pivot point by applying yawing moment on helicopter through tail rotor thmst (Refer Fig. 2 and Fig. 3), After completion of rotation of helicopter to desired position, the wheels have to be turned back to fore-and-aft position from toe-out position. The sequence of operations is similar to that given earlier for toe-out operation except for that they have to be followed in reverse order. To satisfy this functional requirement, the plunger of the lock is lifted up and turned through 90^ to unlock and the wheel is turned towards fore-and-aft position by giving hydraulic power to the closure port of the toe-actuator. Before the toe-actuator piston reaches its closed position, the plunger of the lock is unturned such that the plunger falls onto the locking lug. When the wheel reaches fore-and-aft position, the plunger enters the fore-and-aft locking hole of the locking lug of turning tube. This completes the swiveling of the main wheels to fore-and-aft position and locking in that position. ADVANTAGES Swiveling of the main wheels manually is cumbersome and laborious. The swiveling of wheels can be done by using hydraulic toe-actuator as an integral unit on the main landing gear and extemal hand pump. Unlocking and locking can be done manually. Ground crew can perform these operations quickly and effectively. APPLICATION This system can be employed in landing gear design of helicopters, which are ship deck based, and where a hydraulic harpoon is used to augment the stability of the helicopter on deck at adverse sea-state conditions. This design has been successfiilly used on Advanced Light Helicopter (ALH). CLAIMS We claim 1. A hydraulically operated toe-out / toe-in and manual locking mechanism on main landing gear with pivoting wheel that can be easily and quickly tumed by a hydraulic toe-actuator for which the power is supplied by extemal hand pump and mechanically locked in toed position, comprising of turning tube of shock absorber, barrel, toe-actuator and lock. 2. The body of toe-actuator claimed in claim 1 is moimted on a swivel axis to avoid additional linkages needed. 3. The means of supplying hydraulic power to toe-actuator of main landing gear claimed in claims 1-2 for toe-out and toe-in through extemal hand pump which avoids integrated hydraulic system on the helicopter. 4. The means of supplying the hydraulic power to toe-actuator of main landing gear claimed in claims 1-3 for toe-out and toe-in through extemal hand pump which does not require the helicopter to be in engine-on condition to utilise the on board hydraulic power. 5. The spring loaded mechanical lock of the main landing gear claimed in claims 1-4 containing the mechanism to keep the locking pin in withdrawn position when tumed through 90*^. 6. The mechanical lock of the main landing gear claimed in claims 1-5 that does not have integral handle or lever to disengage or to engage the lock. 7. The stopper of the mechanical lock of the main landing gear claimed in claims 1-6 that prevents the plunger of lock being unduly tumed through more angle. 8. The spring loaded mechanism of automatic mechanical locking of the locking plunger of the main landing gear claimed in claims 1-7 when the toe-actuator completes the toe-out or toe-in operation.

Documents:

0058-che-2004-abstract.pdf

0058-che-2004-claims duplicate.pdf

0058-che-2004-claims original.pdf

0058-che-2004-correspondnece-others.pdf

0058-che-2004-correspondnece-po.pdf

0058-che-2004-description(complete) duplicate.pdf

0058-che-2004-description(complete) original.pdf

0058-che-2004-drawings.pdf

0058-che-2004-form 1.pdf

0058-che-2004-form 19.pdf

0058-che-2004-form 3.pdf

0058-che-2004-form 5.pdf