FORM 2
THE PATENTS ACT, 1970
(39 of 1970) & The Patents Rules, 2003
PROVISIONAL/COMPLETE SPECIFICATION
. (See section 10 and rule 13)
1. TITLE OF THE INVENTION
Design and Fabrication of Hydraulically operated Bush removal
device for Aircraft Landing Gears .
I i — i . L
2. APPLICANT(S)
(a) NAME: HINDUSTAN AERONAUTICS LIMITED
b) NATIONALITY: INDIAN
(c) ADDRESS: AMD, HAL, NASIK- 422206
3. PREAMBLE TO THE DESCRIPTION
PROVISIONAL The following COMPLETE The following specification
specification describes the particularly describes the invention and
invention. the manner in which is to be performed.
1
4. DESCRIPTION (Description shall start from next stage.)
Refer Annexure I
5. CLAIMS (Not applicable for provisional specification. Claims should start
with the preamble - "I/We claim" on separate page)
Refer Annexure II
6. DATE AND SIGNATURE (to be given at the end of last page of specification)
7. ABSTRACT OF THE INVENTION (to be given along with complete specification on separate page)
Refer Annexure III

Design and Fabrication of
Hydraulically Operated Bush
Removal Device for Aircraft
Landing Gears

1 Title of the Invention
Design and Fabrication of Hydraulically operated Bush removal device for Aircraft Landing Gears
2 Field of the Invention
This invention relates to removal bush from blind holes of barrel body of
. landing gears and can be applied across any platform where the bush is
pressed in blind holes. r
3 Background of the Invention
In aircraft landing gears during assembly there are several bushes which are cold pressed (after cooling in Liquid nitrogen) in blind hole of body there by ensuring interference fit. In these bushes the pivot pin are inserted and locked with body with some locking pin/bolt/screw which ensures that there is no rotation of pivot pin about body. However when these landing gears come for overhaul, they have to be dismantled and all the bushes which are worn out, have to be mandatorily replaced with new ■ one. However the challenge in removing these bushes are ,they are press fitted in blind hole not getting access from other end of hole to remove the bush neither there is gap between bush end and hole of body to insert some puller that can fit in the gap.
3.1 Prior Art
Bush removing devices are available to remove bushes from blind hole only when th'ere is gap between bush end and hole of body .Also such devices are manually operated/pulled which involves high labor and chances of scoring marks on body while removing bush.
However in this invention, the device is hydraulically operated thereby less laborious and no scoring marks on body while removal. Also this invention

can be used for all bushes even if there is no gap between bush end and hole.
4 Brief Summary of the Invention
This invention involves making use of a hydraulic jack(7), mandrel(3) which is inserted in the bush(2) and a pin(4) is inserted from hole of body(1) to move through hole of bush(2) and hole of mandrel(3) finally engaging with bush(2) and mandrel(3) only. In to. the mandrel(3), connecting rod(6) is threaded in and other end of connecting rod passes through cylinder(5) and is engaged in hydraulic jack(7). As we pump the hydraulic jack(7) the connecting rod(6) starts extending out which puts pressure on mandrel(3) and by newton's 3RD Law this creates an opposite force on cylinder(5) as result of which bush(2) tends to move in outer direction. As pumping progresses the bush(2) comes out of body progressively in smooth guided manner thereby preventing any scoring marks on body(1).
5 Detail Description of the Drawings
The invention can be better understood by following drawing reading the detail description of the disclosed embodiment followed by the accompanied drawings.
Figure 1 shows schematic of landing gear barrel assembly with barrel body(1)
Figure 2: Error! Reference source not found.shows schematic detailed view of bush (2) pressed in barrel body (1)
Figure 3: shows schematic of components of puller device to be manufactured.
Figure 4: Picture shows layout of how various components of device is connected physically.

6 Detail Description of the Invention
Design and Fabrication of Hydraulically operated Bush removal device for Aircraft Landing Gears. The following specification particularly describes the invention and the manner in which it is to be performed.
This invention can be used for removal of bush from blind holes in all cases where there is hole in bush and body in existing form. This hydraulic set up can also be used for removal of bush without hole by modifying mandrel provided there is gap at bush end and hole.
Whenever Landing gears come for overhaul, after pre-survey it is dismantled and all parts are subjected to micrometry. During this those bushes which are found to be worn out (Dimensions are out of tolerance limit) are to be mandatorily replaced with new bushes.
However removal of those bush which are cold pressed in blind holes of barrel body is challenge as there is no proper tool or device available for removal.of bush. A mechanical tool like puller tool was manufactured whose one end fitted, in hole and from other end pulling force was applied However this method had following disadvantages:
> Highly laborious and tiresome
> Time consuming
> Uniform force not getting applied
> Scoring marks noticed on barrel body
Proposed invention eliminates the manual pulling method by hydraulic jack (Old Unused Hydraulic Jack was restored and utilized thereby cost saving of new one) which ensures smooth removal of bush with minimum labor and time and without causing any scoring marks on body. In this invention a device was in-house designed and manufactured which consisted of following components which were manufactured in-house:

• Mandrel(3)
• Pin (4)
• Cylinder(5)
• Connecting rod(6)
• Hydraulic Jack(7)
During bush removal mandrel(3) is inserted in the bush(2) and a pin(4) is inserted from hole of body(1) to move through hole-of bush(2) and hole of mandrel(3) finally engaging with bush(2) and mandrel(3) only. In to the mandrel(3), connecting rod(6) is threaded in and other end of connecting rod passes through cylinder(5) and is engaged in hydraulic jack(7). As we pump the hydraulic jack(7) the connecting rod(6) starts extending out which puts pressure on mandrel(3) and by newton's 3RD Law this creates an opposite force on cylinder(5) as result of which bush(2) tends to move in outer direction. As pumping progresses the bush(2) comes out of body progressively in smooth guided manner thereby preventing any scoring marks on body(1).

7 Drawings
Figure 1


Figure 2


Figure 3



MANDRELI3) CYLINDER (5)
OLD UNUSED HYDRAULIC JACK WAS RESTORED AND USED


Figure 4 Bush removal device setup

Title: Design and Fabrication of Hydraulically operated Bush removal
device for Aircraft Landing Gears .
I Claim,
1. Hydraulically operated Bush removal device consists of
A. Hydraulic Jack (7) which is utilized for extending connecting rod.
B. Connecting rod (6) to pull the mandrel from the bush.
C. Mandrel (3) to engage with bush at one end and pulling rod at other
end.'
. D. Cylinder (5) to guide the mandrel and apply force such that bush is removed from barrel.
E. Locking pin (4) to engage mandrel with bush.

Title: Design and Fabrication of Hydraulically operated Bush removal device
for Aircraft Landing Gears