7/29/2019 Axle-FG

1/1

Axle (Fuel gauge)

Function /Purpose1. Its function is to transmit torque developed by resultant of magnetic field created by coils and magnet of fuel gauge

assembly.

2. It rotates with a torque proportional to resultant voltage developed by variable resistance.The fuel level in the tank varies

the resistance and thus voltage is developed in the coils proportional to fuel level.

3. Axle is held in the magnet by press fit arrangement.

4. Fuel gauge pointer is mounted on the axle.Possible Modes of Failure:

1. Torsional failure while transmitting torque.

2. Possibility of bending of axle during its fitment with magnet.

3. Possibility of bending of magnet while mounting of pointer on axle.4. Magnet may come out of axle during working of gauge.

5. Pointer axle rotation in non concentric (oval) manner.

6. Pointer may come out from axle.

7. Flickering of pointer.

8. Pointer axle loose in bobbin.

9. Axle may get jam in the bobbin top or bottom cover.

10. Interference of axle with bobbin assembly.

11.

Rusting of axle due to environmental effects.Design Procedure:1. Determine diameter of axle depending upon torque to be transmitted by axle.

2. The diameter of axle should not be uniform but of varying diameter to get inserted in magnet and pointer.

3. Press fit between axle and magnet should be assured.

4. Also press fit between axle and pointer bush should be assured.

5. Determine its length depending upon height of fuel gauge dial from bottom face of lower bobbin.

6. Specifically mention instruction on the drawing so as to control concentricity.

7. Provide adequate clearance between axle and hole provided in the bobbin assembly.

8. Provide adequate clearance between axle and inner face of lower bobbin.

9. Interference between pointer axle and bobbin assembly should be avoided.

10. Anti corrosive coating should be applied on axle surface to prevent its corrosion.

11.

Provide diameter to assure press fit between magnet- axle and pointer axle.12. The material should be selected based on its torsional strength, its machinability, corrosion resistance, elastic strength

required for press fit.

13. Mention specifically on drawing for nickel plating if steel is used as material for manufacture. Nickel plating ensures

protection from corrosion.

14. Provide surface finish required after nickel coating.

15. ID of magnet to be controlled and checked by gauge to avoid pointer flickering.

Material: Free Cutting Steel.

Properties of Material:

Properties Of Free cut ting Steel

14mNS14

TENSILESTRENGTH

(Kgf/mm2)

YIELDSTRENGTH

(Kgf/mm2)

%

ELONGATION

HARDNESS

(BRINNEL)C Mn Si S P

0.1-

0.18

1.2-

1.5

0.05-

0.3

0.1-

0.180.06 44-54 38 22 137

Properties Of Free cutting Steel40Mn2S12

TENSILESTRENGTH(Kgf/mm2)

YIELDSTRENGTH(Kgf/mm2)

%ELONGATION

HARDNESS(BRINNEL)

C Mn Si S P

0.35-

0.45

1.3-

1.70.025

0.08-

0.150.06 60-65 7-10 % 212