Monday, 2 May 2011
What is the purpose of a glow plug on a diesel engine?
The purpose of a glow plug is to heat up the combustion chamber and the air that comes through the inlet.
Monday, 11 April 2011
more questions 12/04/11
1.What is the firing order of a four stroke engine?
- the firing order is the sequence in which the pistons do their power stroke. for a four stroke engine the sequence is in order of pistons -1-3-4-2-.
2.What is the difference between a S.I and C.I engine?
- S.I ENGINE = spark plug ignition.
- C.I ENGINE = diesel compression ignition.
3.Is there any difference between a S.I and C.I piston if so what?
- yea the C.I engines pistons have to made to withstand the higher compression and heat. they tend to be larger and have a different shapped crown to the S.I pistons.
4.What year was the diesel engine invented and by whom?
- the inventor of the diesel engine was Rudolf Diesel and he invented it in the 1890's
5.What is the purpose of the oil jet on the connectng rod, and where does it spray?
- when the piston travels up to T.D.C the preasurised oil is sprayed up onto the thrust side of the piston so that it lubricates the bore for when the piston travel backs down to B.D.C.
6.On the connecting rod where is the big end and little end?
- the small end of the connecting rod is connected to the piston head and the big end of the connection rod is connected to the crankshaft.
7.What is the purpose of the thrush washers on the crankshaft?
- they prevent the play of the crankshaft from moving to much. but the crankshaft must have a small amount of play to be able to move the pistons properly.
8.On a diesel engine whats the difference between direct injection and a indirect injection type?
- the indirect injection works so that the fuel mixture is not injected straight into the combustion chamber but is injected into a prechamber that then combusts and follows through into the main combustion chamber, were as the direct injection just injects the fuel mixture directly into the main combustion chamber to combust.
9.Explan the term valve timming?
- valve timing is what the name says. its the timing in which the valves for the air intake and exhaust that lead to and from the combustion chamber, are opened and closed. this has to be very presise to make the engine run properly.
10.Why do we have valve clearance?
-
- the firing order is the sequence in which the pistons do their power stroke. for a four stroke engine the sequence is in order of pistons -1-3-4-2-.
2.What is the difference between a S.I and C.I engine?
- S.I ENGINE = spark plug ignition.
- C.I ENGINE = diesel compression ignition.
3.Is there any difference between a S.I and C.I piston if so what?
- yea the C.I engines pistons have to made to withstand the higher compression and heat. they tend to be larger and have a different shapped crown to the S.I pistons.
S.I piston
C.I piston4.What year was the diesel engine invented and by whom?
- the inventor of the diesel engine was Rudolf Diesel and he invented it in the 1890's
5.What is the purpose of the oil jet on the connectng rod, and where does it spray?
- when the piston travels up to T.D.C the preasurised oil is sprayed up onto the thrust side of the piston so that it lubricates the bore for when the piston travel backs down to B.D.C.
6.On the connecting rod where is the big end and little end?
- the small end of the connecting rod is connected to the piston head and the big end of the connection rod is connected to the crankshaft.
7.What is the purpose of the thrush washers on the crankshaft?
- they prevent the play of the crankshaft from moving to much. but the crankshaft must have a small amount of play to be able to move the pistons properly.
8.On a diesel engine whats the difference between direct injection and a indirect injection type?
- the indirect injection works so that the fuel mixture is not injected straight into the combustion chamber but is injected into a prechamber that then combusts and follows through into the main combustion chamber, were as the direct injection just injects the fuel mixture directly into the main combustion chamber to combust.
9.Explan the term valve timming?
- valve timing is what the name says. its the timing in which the valves for the air intake and exhaust that lead to and from the combustion chamber, are opened and closed. this has to be very presise to make the engine run properly.
10.Why do we have valve clearance?
-
Thursday, 7 April 2011
Wednesday, 6 April 2011
Question with Answers
What is taper and ovality in the bore, how is it caused how do you check it?
- Taper is the difference in width from the top of the cylinder to the bottom
- Ovality is the the change in shape of the cylinder from circular to oval shaped. this is a different in width of the cylinder commonly starting in the middle working up.
What is side clearance on a piston and how is it checked?
- side clearance is the movement of the piston ring on the piston as it is going through its strokes. as the piston is doing its compression stroke it is moving up compressing the fuel and air mixture. the piston ring is being pushed down. the ring stops the mixture and combusted gas from moving down into the sump. then as the piston moves down the ring is moved up. over time carbons can gather in this gap in the piston around the ring and stop the movement of the ring. this can cause the engine to sease. or taper and ovality.
How can you tell the difference between a inlet and exhaust vavle and why?
- the inlet valve is larger than the exhaust valve because the inlet need to suck as much air as it can into the engine but the exhaust is just to dispose of the combusted gas.
What sort of tempatures do the inlet and exhaust valves get upto?
- inlet = 250
- exhaust = 750
What temperatures and speeds must the piston be able to cope with?
Why do we have piston ring end gap clearance ?
What could the result be if the piston ring end gap is too small?
Why do aluminum cylinder heads usually have a steel shim (washer) between the valve spring and the cylinder head surface ?
What is meant by the terms S.I and C.I in a four stroke engine?
7/4/11 What is the purpose of the margin on the valve?
- Taper is the difference in width from the top of the cylinder to the bottom
- Ovality is the the change in shape of the cylinder from circular to oval shaped. this is a different in width of the cylinder commonly starting in the middle working up.
What is side clearance on a piston and how is it checked?
- side clearance is the movement of the piston ring on the piston as it is going through its strokes. as the piston is doing its compression stroke it is moving up compressing the fuel and air mixture. the piston ring is being pushed down. the ring stops the mixture and combusted gas from moving down into the sump. then as the piston moves down the ring is moved up. over time carbons can gather in this gap in the piston around the ring and stop the movement of the ring. this can cause the engine to sease. or taper and ovality.
How can you tell the difference between a inlet and exhaust vavle and why?
- the inlet valve is larger than the exhaust valve because the inlet need to suck as much air as it can into the engine but the exhaust is just to dispose of the combusted gas.
What sort of tempatures do the inlet and exhaust valves get upto?
- inlet = 250
- exhaust = 750
What temperatures and speeds must the piston be able to cope with?
Why do we have piston ring end gap clearance ?
What could the result be if the piston ring end gap is too small?
Why do aluminum cylinder heads usually have a steel shim (washer) between the valve spring and the cylinder head surface ?
What is meant by the terms S.I and C.I in a four stroke engine?
7/4/11 What is the purpose of the margin on the valve?
Tuesday, 5 April 2011
engine work done today
Todays work included measurements done on the piston and the slip rings along with measurements on the bore.
First thing was to do a visual check on the pistons and bores.
- piston 1 had a small chip out of it
- piston 4 had 3 small indents on the surface
- bore 3 had 3 pores rust marks around the centre on the stroke section
- bore 4 had 2 long scratches oposite each other on the stroke section. this looks like it has been corsed by someone not being more carefull when removing the piston from the bore.
Next i checked each pistons diameter. this measurement is taken from 90 degrees from the gudgeon pin.
- piston 1 = 78mm
- piston 2 = 78mm
- piston 3 = 78mm
- piston 4 = 78mm
next set of measurements were for the bores. each bore had to be measured 6 times. once at the T.D.C, once at the middle section and once at the B.D.C. then you must do this twice on X and Y of each bore.
First thing was to do a visual check on the pistons and bores.
- piston 1 had a small chip out of it
- piston 4 had 3 small indents on the surface
- bore 3 had 3 pores rust marks around the centre on the stroke section
- bore 4 had 2 long scratches oposite each other on the stroke section. this looks like it has been corsed by someone not being more carefull when removing the piston from the bore.
Next i checked each pistons diameter. this measurement is taken from 90 degrees from the gudgeon pin.
- piston 1 = 78mm
- piston 2 = 78mm
- piston 3 = 78mm
- piston 4 = 78mm
next set of measurements were for the bores. each bore had to be measured 6 times. once at the T.D.C, once at the middle section and once at the B.D.C. then you must do this twice on X and Y of each bore.
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