Mechanical · Automobile engineering · Final year project
3 Speed Gearbox Mechanism
A working model of a three-speed gearbox that shows how a single motor can deliver different output speeds and torques. Sliding gear pairs of different sizes mesh on parallel shafts inside a housing, and selecting each pair changes the gear ratio, just as in vehicles and machine tools.
What is the 3 Speed Gearbox Mechanism project?
A working model of a three-speed gearbox that shows how a single motor can deliver different output speeds and torques. Sliding gear pairs of different sizes mesh on parallel shafts inside a housing, and selecting each pair changes the gear ratio, just as in vehicles and machine tools.
Key facts
- Type
- Final year project · Intermediate
- Suitable for
- Diploma capstone and B.E / B.Tech final year
- Build time
- 4 to 6 weeks
- Estimated component cost
- ₹6,100 – ₹9,000
- Guidance from
- ₹9,999 (Hardware / IoT Final Year)
How the 3 Speed Gearbox Mechanism works
- The mild steel frame and fabrication forms the base that carries every other part, so it is designed first from the load and size of the machine.
- Motion is transmitted through gears / rack and pinion, ball bearings with housing and shafts, which set the speed, torque and direction at the working end.
- The parts are assembled, aligned and tested under load, and the readings are recorded for the results chapter.
Block diagram
Transmission
Gears / rack and pinionBall bearings with housingShafts (machined)Structure
Frame and mountsComponents list and cost
Typical prices from Indian online stores and electronics markets (Lamington Road, Budhwar Peth, SP Road). Buy from one store where you can to save on shipping.
| Component | Qty | What it does | Approx. cost |
|---|---|---|---|
| LEDs (assorted) | 1 | Indicate status. | ₹20 |
| Gears / rack and pinion | 1 | Transfer motion and change speed or torque. | ₹500 |
| Ball bearings with housing | 1 | Support rotating shafts with low friction. | ₹250 |
| Shafts (machined) | 1 | Transmit rotation and torque. | ₹400 |
| Mild steel frame and fabrication | 1 | Forms the main structure that holds all parts. | ₹2,500 |
| Welding, cutting and machining labour | 1 | Needed for this type of build. | ₹2,200 |
| Mounts, screws, nuts and small hardware | 1 | Enclosure, mounts and fasteners. | ₹300 |
| Paint, finishing and workshop consumables | 1 | Project overhead | ₹600 |
| Transport of material | 1 | Project overhead | ₹400 |
| Estimated total | Varies with brand, quality and city | ₹6,100 – ₹9,000 |
Prices are estimates for budgeting. We confirm the bill of materials when your design is frozen, and components are charged at actual cost with bills.
How much does this project cost?
| Option | What you get | Cost |
|---|---|---|
| Components only | You buy the parts and build it yourself | ₹6,100 – ₹9,000 |
| Hardware / IoT Final Year | Working model or guided build, Circuit diagram and bill of materials, Firmware / code with explanation | from ₹9,999 + components |
| Capstone Project (CPE) | Working project or model, Black book in MSBTE format, Step-by-step explanation | ₹9,999 + components |
| Diploma ITR | 100% working source code, Project report PDF, PPT | ₹1,999 + components |
No GST and no hidden charges. Use the cost calculator for a quote with your deadline and add-ons, or see all plans.
Download the project brief (PDF)
Summary, working, components and cost and viva questions on one branded PDF to show your guide or team. To get it developed, contact us on WhatsApp.
What you submit with this project
- Working model with circuit diagram and program code
- Project report or black book in your university's chapter order (block diagram, circuit, calculations, results)
- Presentation for the review and final viva
- Synopsis for topic approval, if your college asks for one
Mechanical viva questions on this project
What is the aim of the 3 Speed Gearbox Mechanism project?
A working model of a three-speed gearbox that shows how a single motor can deliver different output speeds and torques. Sliding gear pairs of different sizes mesh on parallel shafts inside a housing, and selecting each pair changes the gear ratio, just as in vehicles and machine tools.
Explain the working of your project in short.
The mild steel frame and fabrication forms the base that carries every other part, so it is designed first from the load and size of the machine. Motion is transmitted through gears / rack and pinion, ball bearings with housing and shafts, which set the speed, torque and direction at the working end. The parts are assembled, aligned and tested under load, and the readings are recorded for the results chapter.
Why is a resistor connected in series with an LED?
It limits the current to a safe value (about 10–20 mA). Without it, the LED would draw too much current and burn out. R = (supply voltage − LED voltage) ÷ current.
What is the gear ratio?
The number of teeth on the driven gear divided by the number on the driving gear. A ratio of 3:1 reduces speed three times and increases torque about three times.
Why are bearings used?
They replace sliding friction with rolling friction, reducing wear and power loss and keeping the shaft aligned.
How is a shaft diameter selected?
From the torque and bending moment it carries: d³ = 16 T ÷ (π × allowable shear stress) for pure torsion, with a factor of safety.
Why is mild steel used for the frame?
It is cheap, strong, easy to cut and weld and widely available. A frame of 25 mm square pipe is enough for most student models.
Which material did you select for the main parts and why?
Mild steel (MS) is used for the frame because it is strong, cheap, easy to cut and weld and available everywhere. Shafts are made of EN8 or bright mild steel for strength, and parts that do not carry load can be aluminium or acrylic to reduce weight.
What factor of safety did you take in your design?
A factor of safety of 2 to 3 is taken for static parts and 3 to 5 for parts under shock or fatigue loading. Allowable stress = yield strength ÷ factor of safety, and each part is checked against it.
How did you estimate the cost of the project?
The cost is the sum of raw material, bought-out parts, machining or fabrication and overheads. Our estimate for this model is about ₹6,100 to ₹9,000, depending on size, material and the workshop rates in your city.
Which manufacturing processes were used?
Cutting and grinding of sections, arc or MIG welding of the frame, drilling for mounting holes, turning of the shafts and fitting of bearings and the drive, followed by assembly, alignment and painting.
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Want to build 3 Speed Gearbox Mechanism?
Send your college, deadline and team size. We confirm the scope, cost and what you will submit.