Design of a double actlnq spring box mechanlsm of a tow-bor for towing an AIrcraff.
Fleld:
The present invention relates to mechanical design of o double acting spring box mechanism of a
tow-bar for towing an Aircraft.
Overvlew:
Aircraff ore usually kept inside the flight hangar and it should be towed to the tarmac for flight to carry out its mission. Once the aircraft has completed its mission and landed on the tarmac, it should be towed back to hangar. A tow-bar helps in doing this by connecting the Aircraft to a towing vehicle (Refer figure-1).
Brief description of the drawings:
Figure.1 is a isometric-view elevation schematic diagram of a double acting spring box mechanism design of a tow-bar using mechanical components; in accordance with embodiments of the present invention; the tow bar (incorporated with double acting spring box mechanism) is assembled with the aircraft (tail wheei portion of a helicopter) is shown.
Figure.2 is a top-view elevation and sectional view schematic diagram of a double acting spring box mechanism design of a tow-bar using mechanical components; in accordance with embodiments of the present invention; the assembly structure of a tow bar is shown.
Figure.3 is a sectional view schematic diagram of a double acting spring box mechanism design of a tow-bar of figure.2; in accordance with embodiments of the present invention; the assembly structure of a double acting spring box mechanism design is shown.
Figure.4 is a schematic diagram-of a double acting spring box mechanism design of a tow-bar of figure.3; in accordance with embodiments of the present invention; the double acting spring box mechanism under load conditions are shown.

DescrlpHon:
The construction of tow-bar (Refer figure-2) consists of a yoke assembly connecting io aircraft using a cross bolt, a long tubulär assembly to maintain distance between the aircraft and towing vehicle (usually a tractor), ihe spring box assembly is used to absorb the push & pull shock while towing and the eye end to connect with the towing vehicle. Design details are as given in figure-3.
The design of double acting spring box mechanism (Refer figure-3) consists of a hook pin which is the main supporting member and also transferring the pull load, two spring holders to Position the spring, a steel spring to absorb the towing shock loads, a guiding bush to glide on pin guider bush and the collar for transferring the push load. This spring box mechanism is accommodated inside the one end of aluminum tubulär assembly structure by means of two pin guider bush and a sleeve body.
Functiontng of double acting spring box mechanism:
The concept of double acting spring box mechanism is used to absorb the impact / shock generated while pulling and pushing the aircraft via tow-bar using a Single compression spring. This mechanism involves hook pin, steel spring, guiding bush, pin guider bush and the collar (Refer figure-3).
When the aircraft is pulled by the towing vehicle connected by tow-bar, the inner end of hook pin gets guided on pin guider bush and compresses the spring thru spring holders, which avoids jerk load getting transferred to the aircraft.
When the aircraft is pushed by the towing vehicle connected by tow-bar, the collar pushes the guiding bush and the guiding bush get guided on pin guider bush and compresses the spring thru spring holders, which avoids jerk load getting transferred to the aircraft.
Claims:
1. The design of double acting spring box mechanism is derived and used to absorb the impact / shock generated while pulling and pushing the aircraft via tow-bar using a Single compression spring.
2. A Single compression spring used for absorbing the impact/shock generated during towing in either direction i.e. push & pull.
3. The concept and methodology used for deploying compression spring.
4. The design of double acting spring box mechanism (refer figure-3) consisting of a hook pin which is the main supporting member and also transferring the pull load, two spring holders to position the spring, a steel spring to absorb the towing shock loads, a guiding bush to glide on pin guider bush and the collar for transferring the push load. This spring box mechanism is accommodated inside the one end of aluminum tubulär structure by means of two pin guider bush and a sleeve body.
5. The methodology of design of double acting spring box mechanism (refer figure-3) consisting of a hook pin which is the main supporting member and also transferring the pull load, two spring holders to position the spring, a steel spring to absorb the towing shock loads, a guiding bush to glide on pin guider bush and the collar for transferring the push load. This spring box mechanism is accommodated inside the one end of aluminum tubulär structure by means of two pin guider bush and a sleeve body.