Description:1. Title of invention
Multi functional cross pin assembly with towing and jacking feature.
2. Field of invention
The present invention is related to mechanical engineering in general and more particularly to the aircraft landing gear system and design of a cross pin assembly which along with locating the main landing gear axle in the wheel lever combines the features of rearward towing and single wheel jacking of an aircraft.
3. Background of invention
An aircraft landing gear system design deals with the operational aspects of takeoff, landing, taxying and towing of aircraft. Landing gear design or position of wheels is based on aircraft CG location and flotation requirement. The type of landing gear required is based on various factors like the aerodynamic configuration of an aircraft, wing configuration, ground clearance requirement and space available to house the landing gear within the aircraft etc. Landing gear shall have the provision to tow the aircraft forward and rearward depending in the required conditions. Landing gear shall also have the provision for changing the aircraft wheel without jacking the aircraft.
In general, all military aircraft landing gears are equipped with the forward towing, rearward towing and domes for single wheel jacking. Forward towing is provided on the nose landing gear to facilitate the towing of aircraft in forward direction. Rearward towing provided is on the main landing gear to facilitate emergency towing in deep snow, sand and muddy conditions in cases where the aircraft swerves of the normal runway. All land based aircraft are provided with lugs or rings to permit securing the attachment of towline. On the other hand, changing of aircraft tyre or wheel requires ground support equipment for jacking up of aircraft and trained personnel to carryout this activity. Therefore, it is indeed that landing gear must be fitted with a jacking dome to permit the tyre, wheel and brake change without the hassle of .ground support equipment. The present invention discloses a novel system having technical advancements by means of single cross pin assembly with rearward towing and single wheel jacking features.
4. Brief Summary of invention
The present invention facilitates the multifunctional cross pin assembly with towing and jacking features. The cross pin assembly (10) ensures the position and location of the main landing gear axle (200) on the wheel lever (300). It has freedom to rotate about its own axis and has eye end (11) to connect the towing unit. The rotation about its own axis allows the cross pin assembly (10) to orient to the towing direction during rearward towing. There is a spherical head nut (2) which is part of cross pin assembly (10) that secures the cross pin (1) in position and enables to connect the single wheel jack with spherical adapter.
Cross pin assembly (10) comprises two major components a cross pin (1) with eye (11) at one end and a threaded spherical head nut (2) at other end, both are made up of high strength steel. Cross pin assembly (10) is installed on both LH main landing gear and RH main landing gear. It is mandatory to have the provision of rearward towing requirement of an aircraft, in cases of emergency condition where aircraft the aircraft swerves away from main runway during extreme weather condition of deep snow, sand and muddy conditions. With use of cross pin assembly (10) which forms the part of aircraft landing gear, it is possible to pull rearward on to the runway. Spherical head nut (2) which is part of cross pin assembly (10), allows for jacking up single wheel in conditions wherein there is a requirement to change the wheel (400) or brake (300) used in the landing gear of an aircraft.
Cross pin assembly (10) with rearward towing and single wheel jacking feature is basically aimed to combine the requirements of rearward towing and single wheel jacking on same unit.
5. Brief description of drawings
Fig-1 shows Cross pin assembly (10) embodied on an aircraft main landing gear comprising of wheel lever (100), axle (200), brake (300) and wheel (400), drop link (500), leg (600), special pin (700), direction bar (800), short link (900) and shock absorber (1000).
Fig-2 shows front view and sectional view detailing the mechanical interface of cross pin assembly (10) with wheel lever (100) and axle (200).
Fig-3 shows cross pin assembly (10) with spherical head nut (2) is assembled to cross pin with eye end (1) along with spacer (3) and a split pin (4) is used to lock the cross pin (1) with spherical head nut (2). Isometric exploded view shows the elements of cross pin assembly (10) and its assembling line.
Fig-4 shows the constructional features of the cross pin (1), eye end (11), top bearing surface (12), shaft (13), external undercut (14), cross pin - Split pin hole (15) and external thread (16), features of spherical head nut (2) with internal thread (17), bearing surface (18), spot face (19), spherical head nut - split pin hole (20), internal undercut (21) and spherical head (22).
6. Detailed description of invention
Refer Fig-1. It discloses the preferred embodiment of cross pin assembly (10) into the articulated main landing gear of a typical aircraft. A typical aircraft in general consists of the LH main landing gear, RH main landing gear and nose landing gear. The Fig-1 indicates the front, side and isometric views of main landing gear of the aircraft. The main landing gear consists of main landing gear leg (600) that connects to the fuselage of aircraft and drop link (500) through pins to make a revolute joint. Drop link (500) mechanically couples the leg (600) and wheel levers (100) through pins make revolute joints. Axle (200) is assembled to wheel lever (100) and same is located and positioned in wheel lever (100) by cross pin assembly (10). Shock absorber (1000) connected to wheel lever (100) through short link (900) and pins forms revolute joints. The direction bar (800) connects to the wheel lever (100) through special pin (700) whereas wheel (400) and brake (300) are assembled on the axle (200). The elements described above, mechanically assembled together along with cross pin assembly (10), constitute and function as a typical main landing gear system of an aircraft.
All military aircraft landing gears are equipped with the forward towing, rearward towing and domes for single wheel jacking provisions on landing gear separately. With the use of present invention cross pin assembly (10) aims to combine the requirements of rearward towing and single wheel jacking inplace of providing a separate rearward towing attachment and a separate single wheel jacking adapter thereby saving of additional weight and making the design simplistic.
Fig-2 shows front view and sectional view detailing the mechanical interface of cross pin assembly (10) with wheel lever (100) and axle (200) which forms the parts of landing gear system of an aircraft.
Fig-3 shows cross pin assembly (10) comprising of spherical head nut (2) assembled to cross pin(1) having eye end (11) along with spacer (3) and a split pin (4) used to lock the cross pin (1) with spherical head nut (2). Isometric exploded view shows the elements of cross pin assembly (10). The cross pin assembly (10) is made of up of high strength steel having eye end (11) at one end and a spherical head nut (2) at the other. The spherical head nut is mechanically coupled to the cross pin (1) through means of spacer (3) and split pin (4). The split pin (4) mechanically locks the cross pin(1) onto the spherical head nut(2) through holes provided on the external thread area of the cross pin (1) and holes provided on the internal thread areas of spherical head nut (2).
Refer Fig-3, the constructional feature of cross pin (1) comprises shaft (13) with an eye end (11) that provides a means for connecting the aircraft towing unit and has a top bearing surface (12) that acts as stopper and wearing surface during towing. The other end of shaft (13) is provided with an external undercut (14) that accommodates the spacer (3) and external thread (16) with split pin hole (15).
The spherical head nut (2) is provided bearing surface (18) with spot space (19) that facilitates mechanical coupling to the shaft (13). Internal undercut (21), internal thread (17) along with split pin hole (21) aid the mechanical coupling of shaft (13) to spherical head nut (2). The spherical head nut (2) is provided with spherical surface (22) to accommodate the spherical shape adapter used during the jacking of the aircraft. It aligns with the adapter in case of any misalignment.
During rearward towing, both the main landing gear rearward towing attachments are connected to the towing vehicle through wire rope set up to the eye end (11) of the cross pin assembly (10). The cross pin assembly (10) facilitates a feature wherein the towing attachment shall align to the direction of pulling.
The spherical head nut (2) provided on the cross pin assembly (10) accommodates the spherical surface adapter during jacking of aircraft thereby facilitating change of single wheel or tyre of an aircraft. Thereby, it is seen that the cross pin assembly (10) combines the feature of accommodating both the rearward towing and also the jacking feature.

7. Drawing numerals:
Item No. Description
1 Cross Pin
2 spherical head nut
3 Spacer
4 Split pin
10 Cross pin assembly
11 Eye end
12 Top Bearing surface
13 Shaft
14 External Undercut
15 Cross pin - split pin hole
16 External Thread
17 Internal thread
18 Beating surface
19 Spot space
20 spherical head nut - split pit hole
21 Internal Undercut
22 Spherical surface
100 Wheel Lever
200 Axle
300 Brake
400 Wheel
500 Drop link
600 Leg
700 Special pin
800 Direction bar
900 Short link
1000 Shock absorber , Claims:We claim:
1. Multi functional cross pin assembly with towing and jacking feature, to use during aircraft towing and jacking, assembled in the aircraft’s main landing gear, comprising:
- a leg (600) that is connected to fuselage of the aircraft;
- a drop link (500) that mechanically couples the leg (600) and a wheel lever (100);
- an axle (200) that is assembled to the wheel lever (100);
- a shock absorber (1000) that is connected to the wheel lever (100) through a short link (900);
- a direction bar (800) that is connected to the wheel lever (100) through a special pin (700);
- a wheel (400) and brake (300) assembled onto the axle (200); and
- a cross pin assembly (10) located and positioned in the wheel lever (100), characterized in that, the cross pin assembly (10) is made up of high strength steel and comprises a spherical head nut (2) assembled to a cross pin(1) having an eye end (11) along with a spacer (3) and a split pin (4), the eye end (11) provides the means for connecting the aircraft towing unit and has a top bearing surface (12) that acts as stopper and wearing surface during towing, a shaft (13) is provided with an external undercut (14) that accommodates the spacer (3) and an external thread (16) with a split pin hole(15), the spherical head nut (2) is provided with a bearing surface (18) with a spot space (19) that facilitates mechanical coupling to the shaft (13), a spherical surface (22) provided on the spherical head nut (2) accommodates the spherical shape adapter used during the jacking of the aircraft.
2. The multi functional cross pin assembly with towing and jacking feature, as claimed in claim 1, wherein, during rearward towing, both the main landing gear rearward towing attachments are connected to the towing vehicle through wire rope set up to the eye end (11) of the cross pin assembly (10), where the towing attachment shall align to the direction of pulling the aircraft.
3. The multi functional cross pin assembly with towing and jacking feature, as claimed in claim 1, wherein, the spherical head nut (2) provided on the cross pin assembly (10) accommodates the spherical surface adapter during jacking of aircraft, thereby facilitating change of single wheel or tyre of the aircraft, by this the cross pin assembly (10) combines the features of accommodating both the rearward towing and jacking feature.