Te lab
- 1. Thermodynamics Lab Group 2 Krishna, Rafsan, Mostafa, Omari, Rohan, Mahesh
- 2. Closing Fuel entry Important because it will prevent more fuel leaking into the carburettor. Not completely safe as some fuel is already inside
- 3. Engine check Making sure that it is in the off position
- 5. Air Flow Remove air filter The filter removes particles from the air before it flows down into the engine.
- 6. Remove Exhaust Manifold This helps reduce engine noise It much shorter than one found in a car and does not have a catalytic converter The small hole is allows condensed water from the exhaust emissions to escape
- 7. Remove Spark plug This ignites the air fuel mixture inside the piston
- 9. Rockers These are operated by the pushrods and control the valve positions The breather tube returns unused fuel to the inlet to improve efficiency
- 10. Remove air intake mount
- 11. Choke Controls air flow into engine Open for cold starts so a richer mixture is used Closed when engine is hot so fuel is used at a more efficient ratio
- 12. Throttle Concerned with power production; regulates the input of the air-fuel mixture
- 14. Fan The solenoid magnet creates the current for the spark plug by magnetic induction so no need for battery. Cord for initial start Not convenient for large vehicles because large start force needed There are 2 sparks per cycle, on the 2nd and 4th stroke, the 2nd spark is ‘wasted’
- 15. Engine Cooling Air is used for cooling and is sucked in by the fan. The cover is important because when it is started by hand, the grooves on the fan and cover connect and therefore the cord can spin the magnet and fan.
- 16. Engine Cooling Car engines are cooled by water, which is good because it has a much higher specific heat capacity however it is much heavier and would require a radiator as well.
- 17. Air + fuel mixed here Carburettor Choke restricts air but throttle regulates the mixture for power control. Fuel is sucked in from the tank by a pressure difference. Now cars have pumps because it is more controlled, more efficient and there are lower maintenance costs.
- 18. Crank Shaft Cam shaft Inside the crank case The diameter ratio is 1:2 so that the cam shaft rotates once when the crank shaft rotates twice A small hook splashes oil as the crank shift spins, for lubrication
- 19. Cylinder Head The small cavity seen is for the compressed gases
- 20. Timing Marks These allow the cam and crank shaft to be aligned properly so the different strokes occur at the correct moments
- 21. Piston rings These expand and form a seal inside the cylinder to prevent the oil and the fuel mixture from escaping. The second ring seen here is to scrape the oil back. They receive the most wear because they are in contact with the cylinder walls.
- 22. Pushrods They push the rocker which pushes the valves. They are not present in cars because they have overhead cams which push the valves directly. This is because car engines run at high speeds and the rods are liable to bending. The valves open once each out of synchronisation to prevent the mixture exiting as it enters
- 23. Cam shaft Here there is a spring and weight assembly which makes hand starting the engine easier by opening the exhaust valve slightly. This helps because the compression stroke is difficult by hand and this reduces the pressure. However, as the engine starts and the cam shaft begins to spin quickly, the spring no longer has an effect.
- 24. We then rebuilt it Successfully You guys can add stuff here about the rebuild, a few pics with a title. - I have done all the questions
- 25. Team 2