1. Title of the invention
Mechanism to accommodate axis shift in mating holes.
2. Field of invention
This invention is related to assembly of mechanical parts where precision of mating hole axis are of importance.
3. Use of invention
This invention is used in mechanical assemblies where both the assembly parts are having holes (one or more) and any change in axis of mating holes in either of the assembly parts causes rejection of the parts.
4. Prior art
Mechanical assemblies are commonly used in most of the machines, automobiles and aerospace industry. Such parts are assembled using bolts and in places where load bearing is involved bushes are used. For a perfect assembly the holes in both the parts are to be co-axial. In most of the during service of such parts due to distortions the holes does not come in same axis. This shift in axis leads to change in one or either of the parts. One way to overcome such anomaly is to remove the bushes and enlarge the basic hole and introduce a new bush of an oversize with respect to the shift.
5. Draw backs of prior art
The replacement of bushes to oversize leads to
1. Excessive man power, material, money and time.
2. Causing an effect on the characteristics of design due to less margin from the bush outer diameter to the edge of the part.
3. Change in load bearing characteristics which are undesireable.
4. Change of one or either of the parts though the part may have not been damaged.

6. Comparison between prior art and present invention
As indicated above in Draw back section, use of this mechanism will accommodate any change in misalignment of the holes.
7. Aim of the invention
Aim of the invention is to decrease the rejection of parts due to axis shift.
8. Summary of the present invention
The present invention contains 2 eccentric bushes enclosed in a cylindrical bush. The 2 eccentric bushes work in tandem to allow the movement of the center bush hole across the fixed range of diameter.
9. Brief description of drawings

10. Statement of invention
This invented method is highly useful for production, Repair and overhaul industry, where assemblies having mating holes are involved. In cases where the hole axis of parts are misaligned by a larger difference, this eccentric bushes can be rearranged to change their position and align the hole axis.
11. Detailed description of invention
Outer bush A holds the inner 2 bushes B & C. Each Inner bush has eccentric hole. Bush C contains the hole in which fastener is passed for assembly. Bush B can be rotated in the inner hole axis of bush A. Offset hole axis of Bush B revolve around the hole axis of bush A. Bush C can be rotated in the offset hole axis of bush B. The mating hole or Offset hole axis of Bush C revolve around the offset hole axis of bush B. Mating hole axis can be shifted by rotating the bush B & C together or independently giving flexibility to re-center the hole axis to any new position in a given range. Invented mechanism can be installed in one of the mating part of the assembly. During servicing if the mating hole of either of the mating parts is shifted, the holes can be aligned by rotating the bushes B & C simultaneously or independently. To achieve maximum allowance for hole alignment, larger sizes of bushes have to be used. For a given diameter of bush combination, to get the maximum range of hole shift inside the bush, the minimum wall thickness area of the eccentric bushes should be maintained as minimum as possible. Eccentric hole diameter in bush B is the average of outer diameter of bush B and inner eccentric hole diameter of bush C.

We Claim
1. The design and fabrication of the eccentric bushes with a feature of shifting the bush centre or hole axis as and when required.
2. The wide range of area within the bush where the centre of the assembly axis can be shifted to new position.
3. The design of mechanism utilizing two bushes and three bushes.