Design and Fabrication of GearBox

Design and Fabrication of GearBox

Department of Mechanical and Automobile Engineering,

Institute of Technology and Management, Gurgaon26/11/2009

AIM: To design and fabricate a automobile gearbox

Objectives•To design a Helical gear box•Study of various gear manufacturing processes•Fabrication of gear box

Department of Mechanical and Automobile Engineering,

Institute of Technology and Management, Gurgaon26/11/2009

Representation of Gearbox

Department of Mechanical and Automobile Engineering,

Institute of Technology and Management, Gurgaon26/11/2009

Motor

Gear box Gear

Market research was done at following places regarding type and cost calculation of the Gearbox.

•Sokhi heli-wom gears pvt.ltd in Ghaziabad•Hi-tech gears in Manesar•Junk market in Mayapuri

Department of Mechanical and Automobile Engineering,

Institute of Technology and Management, Gurgaon26/11/2009

Market Survey

Gearbox A transmission or gearbox provides speed and torque conversions from a rotating power source to another device using gear ratios, including for a motor vehicle partly because of the limitations of internal combustion engines. Torque converters, hydraulics, electrical power and hybrid configurations may also be used for the same purpose.

Department of Mechanical and Automobile Engineering,

Institute of Technology and Management, Gurgaon26/11/2009

Uses of Gearbox

Department of Mechanical and Automobile Engineering,

Institute of Technology and Management, Gurgaon26/11/2009

•Gearbox has different uses at different places. •In Automobiles, engine speed is about 5000 rpm ,but wheels rotate at 1000 rpm.Machine tool spindle rotates at 50 rpm while the motor is at 1440 rpm.•Automobile gearbox can have variable output and input speeds ,and few reduction ratios in between.

Gearbox typesIt can be classified as •Manual •AutomaticManual Gearbox can be further divided as 1.Synchromesh and Non SynchromeshNon synchromesh includes :sliding mesh type

Department of Mechanical and Automobile Engineering,

Institute of Technology and Management, Gurgaon26/11/2009

Synchromesh GearBox

Constant Mesh Gearbox where diagonal cut helical gear sets are constantly "meshed" together, and a dog clutch is used for changing gears. On synchromesh boxes, friction cones or "synchro-rings" are used in addition to the dog clutch. This type of gearbox is used in modern cars and trucks these days.

Department of Mechanical and Automobile Engineering,

Institute of Technology and Management, Gurgaon26/11/2009

Material Selection

Department of Mechanical and Automobile Engineering,

Institute of Technology and Management, Gurgaon26/11/2009

• Keeping in mind cost effectiveness. It was intended to design a general purpose Gearbox, where cheaper materials would be used.

• So, Plain Carbon Steel will be used for moving components and Cast iron for Frames and bodies ,because of intricate shape they can be easily casted.

Materials contd.• Plain Carbon Steel with 0.4% carbon or EN8

material is selcted for shaft.• Further,Hot rolled being cheaper than cold rolled

and heat treated materials , hot rolled will be selcted.

• For gears : 30 Ni 4 Cr 1 is selected with Sut=1500Mpa

• For gears, additonal cheap alloying element,such as manganese (0.87%),to make it Strong , giving ultimate strength of 600 Mpa.(P.S.G Design data book 1.13)

Department of Mechanical and Automobile Engineering,

Institute of Technology and Management, Gurgaon26/11/2009

Automatic Gearbox

Department of Mechanical and Automobile Engineering,

Institute of Technology and Management, Gurgaon26/11/2009

• This type of transmission are easy to use. Automatic transmission will select an appropriate gear ratio without any operator intervention .

• Sun and planet gear are mainly used

Design of Automobile Gearbox• Gearbox are incorporated to match performance

of variable speed internal combustion engine.• Lowest reduction ratio is needed at highest

speed of operation, and vice versa, values of these reduction ratio lies b/w 3.5 to 4.5 for cars and 5 to 7 for commercial vehicles.Gearbox provides reduction ratio between 1:1 to 1:4 for cars to 1:1 to 1:7 for commercial vehicles.

Department of Mechanical and Automobile Engineering,

Institute of Technology and Management, Gurgaon26/11/2009

Special features of Automobile Gear box

• Universally accepted number of gear ratios is 4.These four are in geometric progression, However ,overdrive gear is provided to enhance performance at higher speeds

• Additional reduction ratio is provided to enhance performance during higher gradient operation.

Department of Mechanical and Automobile Engineering,

Institute of Technology and Management, Gurgaon26/11/2009

Results Obtained

Department of Mechanical and Automobile Engineering,

Institute of Technology and Management, Gurgaon26/11/2009

Gear Ratios1st gear ratio 4:1

2nd gear ratio 2.52:1

3rd gear ratio 1.58:1

4th gear ratio 1:1

5th gear ratio 1.58:1

6th gear ratio 2.52:1

7th gear ratio 4:1

Department of Mechanical and Automobile Engineering,

Institute of Technology and Management, Gurgaon26/11/2009

Layout

Department of Mechanical and Automobile Engineering,

Institute of Technology and Management, Gurgaon26/11/2009

Results

Gear Pair Velocity(km/hr)

GH 33.9

AB 67.9

CD 57

EF 44.7

Department of Mechanical and Automobile Engineering,

Institute of Technology and Management, Gurgaon26/11/2009

Pitch line velocities for different gear pairs

Gantt Chart

Department of Mechanical and Automobile Engineering,

Institute of Technology and Management, Gurgaon26/11/2009

Task Start Date End Date Days Completed Days Remaining

1. Problem Formulation 09/01/09 09/30/09 21 0

2.Literature and market survey 10/01/09 10/31/09 31 0

3.Design of gears and shafts 11/01/09 11/30/09 25 5

4. Cutting of gears 01/20/10 02/28/10 0 38

5. Gear assembling and casing 03/01/10 03/31/10 0 31

6. Final Report 04/01/10 04/30/10 0 30

Conclusion

Designing of gears and shafts has been done and near future we will be starting with fabrication of gearbox.

Department of Mechanical and Automobile Engineering,

Institute of Technology and Management, Gurgaon26/11/2009

AcknowledgementProject Advisor : Mr Pawan Taneja Help also taken from: • Raman Rawal : Graduate Student• Pankaj Sharma : Graduate Student

Department of Mechanical and Automobile Engineering,

Institute of Technology and Management, Gurgaon26/11/2009

Bibliography

Department of Mechanical and Automobile Engineering,

Institute of Technology and Management, Gurgaon26/11/2009

•P.S.G Design Data book•Handbook for engineers •Material Science By Rk Rajput•Mechanical System Design By S.P . Patil•Theory of machine By Khurmi & Gupta•Machine Design By Khurmi & Gupta