Clas 2 Motor exam Questions

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LIGO
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Clas 2 Motor exam Questions

Postby LIGO » Thu Oct 04, 2012 3:55 pm

Class 2 Motor Exam 2011 qustions
1. i)Purpose of a Flywheel
ii)How & why weight of flywheel is reduced?

2. i)Why a 2 stroke diesel engine exhaust is open earlier than a 4 stroke diesel engine exhaust?

ii) Draw a 2 stroke & 4 stroke timing diagram

3. i) Sketch and describe a valve operating gear for a 4 stroke diesel engine
ii) If wear on a cam lobe, what will be the effect on engine operation?


4. i)Why are compressors fitted with coolers?
ii) How is an intercooler tested?.
iii) What type of compressors are fitted with coolers?


5. i) Describe , how you would withdraw the liner of a two stroke diesel engine?
ii) Describe, how water seal is effected in the liner?

6. i)Describe an auxiliary boiler feed water system.
ii) Explain all the fittings in the system.


7. Describe , how you will clean a fuel oil settling tank and ready it for hot work

8. Sketch and describe a LO system for a main engine
i) Explain all devices and fittings
ii) How many types of pumps are there in the system and why?

9. i) Sketch and describe a rotary type of pump suitable for LO duties , driven by a main engine
ii) When the engine is reversed how the direction of flow is maintained in the pump?

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JollyJack
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Re: Clas 2 Motor exam Questions

Postby JollyJack » Thu Oct 04, 2012 7:16 pm

Not quite accurate, close, but no cigar. A little misleading at some points. :)
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The Dieselduck
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Re: Clas 2 Motor exam Questions

Postby The Dieselduck » Sat Oct 06, 2012 7:03 am

I don't understand the thread here.

Ligo, are you offering an example of a recent exam you have taken, or are you looking for answers to the questions?
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LIGO
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Re: Clas 2 Motor exam Questions

Postby LIGO » Mon Oct 08, 2012 3:52 pm

The questionsare from the exam taken in feb2011 - LIGO

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JollyJack
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Re: Clas 2 Motor exam Questions

Postby JollyJack » Mon Oct 08, 2012 5:48 pm

Where was the exam taken Ligo?
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astat101
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Re: Clas 2 Motor exam Questions

Postby astat101 » Mon Nov 02, 2015 6:05 am

Hi,

just reading through some posts associated with charge air coolers, I work for a company called Vestas aircoil who design and manufacture charge air coolers for large diesel engines. When you ask "how is a charge air cooler tested" do you mean tested for performance or tested to ensure its manufactured correctly? i do know that they a are pressure tested with water to ensure that the tubes are ok and not leaking.
Hope this helps.

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Re: Clas 2 Motor exam Questions

Postby Revolver » Mon Nov 21, 2016 7:10 am

LIGO wrote:Class 2 Motor Exam 2011 qustions

9.
ii) When the engine is reversed how the direction of flow is maintained in the pump?


JJ, is this a question that would be asked here in Canada - and what I mean is, would it be worded that way? ("Engine is reversed")

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JK
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Re: Clas 2 Motor exam Questions

Postby JK » Mon Nov 21, 2016 7:51 am

Yes, that was a question at one time, for directly connected engines with engine driven pumps.

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D Winsor
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Re: Clas 2 Motor exam Questions

Postby D Winsor » Mon Nov 21, 2016 11:08 am

JK wrote:Yes, that was a question at one time, for directly connected engines with engine driven pumps.


Everyone used to use the reversing valve block for the oil pump on a reversible Fairbanks as their example. The water pumps didn't need any kind of reversing valve due to the shape of discharge volute and the impeller. What was fun was trying to explain the reversing gear for the blower or how the injection timing was changed with the timing chain and idlers.
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Re: Clas 2 Motor exam Questions

Postby Revolver » Mon Nov 21, 2016 11:19 am

Okay very good; fully reversible with engine driven pumps, gotcha.
That's how I read it, but just verifying because I don't think that set up is too common these days, eh?

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D Winsor
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Re: Clas 2 Motor exam Questions

Postby D Winsor » Mon Nov 21, 2016 11:51 am

I haven't heard of any vessel built with reversible medium speed engines with engine driven pumps since the late 60's. I think the last Canadian Coast Guard ships built like that were the Alert (Reversible Fairbanks), Bartlett and Provo Wallis (Reversible 4 Stroke Merlees) and JK may be able to confirm that. It was also the understanding at the time that where all these ships also had CP Propellers, the Senior Management of the Day at Transport Canada questioned the reliability of the CP Propellers and specified that the main engines be made reversible so vessels could still be maneuvered with a failed CP System. It was also my understanding that the reversing gear was eventually removed from the engines but the reversing fluid control valves remained.
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Re: Clas 2 Motor exam Questions

Postby Revolver » Mon Nov 21, 2016 4:26 pm

Merlees! That was the name I was trying to remember, I just couldn't put my finger on ha

Yeah, my exp with reversible was MAN 2-S fixed pitch prop.

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Re: Clas 2 Motor exam Questions

Postby D Winsor » Tue Nov 22, 2016 4:31 am

I forgot to mention in my previous post that there were a number of fishing trawlers built in the mid to late 60's with direct reversible Deutz, or Stork Werkspoor engines and fixed pitch propellers. I'm not too certain about the Stork engine but I know the Deutz engine had engine driven pumps with a fluid flow reversing valve system connected to the suction and discharge of the oil pump

Today it is extremely rare to find a reversible engine other than Slow Speed 2 Stoke engines like Sulzer and MAM/B&W and in most if not all cases the oil and water pumps for these engines are electrically drive.

On smaller vessels with medium speed engines and fixed pitch props you are more likely to find either a marine transmission or some sort of double clutch reversing gear box controlling the reversing duties.
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JK
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Re: Clas 2 Motor exam Questions

Postby JK » Tue Nov 22, 2016 4:46 am

The CCGS Alert was built with reversing Fairbanks Morris, gearbox and CPP. Those engines were actually quite interesting in that they were also fitted with blowers and turbochargers. The blowers supplied air at low RPM. As a result the engines had a lot of stuff hanging off of them.
The Alert was sold and was renamed Ocean Alert. I happened to run across a post on another site where it was stated that the ship had suffered engine seizures after overhaul. I'm willing to bet they had overhauled the LO pumps incorrectly.
The old Thomas Carleton was direct drive if I remember correctly as well with reversing FM. She was decommissioned and purchased by Sea Shepard and renamed the Cleveland Amory. They painted her black, loaded one barrel of engine oil and headed out the harbour for the seal hunt. The ship suffered an engine failure on the way out and was reduced to one shaft. The thing with FM was was they would run with the crankshafts out of timing, they'd leak like a sieve, but the engineers had to know something to keep them going.
The Provo had reversing Mirlees, oil clutches and CPP. The engines never were reversed, so when the engines were rebuilt in the early 90s, the reverse camshafts were switched from one engine to the other as one engine always run in the opposite direction. For years before, the fuel pumps had to have the stroke adjusted to make up for wear in the cam lobe.
It's funny, looking back, at some of the decisions made in the late 60s and early 70s. I dealt with a ship with a gearbox fitted with babbit bearings. The L&S gearbox had been designed for ball bearings but someone didn't trust that new-fangled technology. The problem was by 2006, pouring and scraping of babbit bearings was a bit of a lost art. Nevermind having 2 of the only gearboxes in existence.

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JollyJack
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Re: Clas 2 Motor exam Questions

Postby JollyJack » Wed Nov 23, 2016 8:41 am

Well I guess that's covered pretty well! :)
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