Lesson 27 – So, how does it work?
Summary
Describing a typical process in an office.
The topic of this lesson is describing office processes. I have opportunity to :
- explain a process that takes place in an office
- learn vocabulary related to product manufacture
- practise passive forms
- practise intonation when listing items.
[Linking words – explain a process]
Going back to …
Before we begin, let’me ask/tell…
To start, we could …
Firstly, …
Next, …
Following on from this/that …
After that, …
Later on, …
Following this/that …
Subsequently, …
Finally, …
How does a four-stroke, piston engine work?
Firstly, by the helping of induction system, air is induced to carburetor.
After that, the air will be mixed with the fuel to become fuel-air mixture in correct ratio.
Next, when the inlet valve is opened by the controlling of camshaft, the fuel-air mixture is ushered into the cylinder – this process is called “Intake stroke”
Then, the fuel-air mixture is compressed when the piston is moving from TDC to BDC – this process is known as “Compress stroke”
Following this, a spark is provided by the spark plug and then the fuel-air mixture would be ignited. – this process is the “Power stroke”
Later, the outlet valve is opened while the inlet valve is closed, so the spend gas could be expelled. – this is the “Exhaust stroke”
As both camshaft and connection rod is connected to the crankshaft while the spark is continuously provided by spark plug once the engine is started with enough rpm. Subsequently, piston is keeping moving from TDC to BDC while the crankshaft is keeping converting linear motion into rotatory motion. Finally, in case fixed-pitch propeller, as it is directly connected to the crankshaft. Therefore, the chemical energy in fuel is converted in to heat and mechanical energy.
