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2ND Class EK Gen

Posted: Wed Jun 22, 2016 2:52 pm
by Tazok58
Hello folks, I just wrote my 2nd class general exam and I am worried about one of the questions I did not answer (virtually guaranteeing it will be on my oral), it was the metallic packing gland for the piston rod of a 2 stroke (not much time spent on 2 strokes) so if anybody knows the basics about them (how they are lubricated, and inspected at layup) it would be greatly appreciated.


Re: 2ND Class EK Gen

Posted: Wed Jun 22, 2016 7:21 pm
by Revolver
Stuffing Box - built of 2 halvs
Channels in the stuffing box (4-5 or so)
'scrapers' in each of the channels, consisting of...probably...3 pieces @ ~120 degrees of reach around the piston rod (or 4 @ 90, depends on design I guess)
scrapers have 'lamella' inserts which are designed to 'softly' scrape the oils from the piston rod separating cyln oil from C.C oil.
(those inserts often have a high zinc content, so if you take drip samples from the stuffing box and the zinc levels are up, it might be a clue they're starting to wear/break down)
On the outside of the scraper pieces have a circular groove to fit garder springs around them to keep them taught to the piston rod to apply pressure to scrape the oil but not excessive pressure.

Stuffing box is fitted into position by securing it to the piston rod, slowly turning-gear it up into place. A flange is then secured below it to ensure it holds in place.

Then you could go on to say how the segregation of comb. space and C.C via the stuffing box is an incredible advantage because specific oils for the both applications, and 'no' products of combustion should go into the C.C.

If you're ever going to open/inspect/replace be sure to give the under piston space a real good cleaning because it's going to be full of oil and carbon and just crappy stuff, which you don't want to fall into the C.C when you pull it down.

AND be sure to include all safety related concerns when doing works like this. Permits, lock/tag out, sniff it, clean the C.C, harnesses in the C.C it's also working at height, controller of the turning gear is the one in the engine so they know whats going on in the inside if it's ever moving, proper lighting, watch keeper outside the confined space yadda yadda..lots of safety stuff.

I don't have my 2nds, still need plenty of sea time for that, so it may not be an adequate response - but it was all off the top of my head.
Good luck.

Re: 2ND Class EK Gen

Posted: Thu Jun 23, 2016 4:41 am
by JK
It is important to answer the question as a 2nd engineer. I know someone who failed his 1st because he answered as a watchkeeper.

Re: 2ND Class EK Gen

Posted: Thu Jun 23, 2016 9:27 am
by Tazok58
Thanks for the info everybody

Re: 2ND Class EK Gen

Posted: Fri Jun 24, 2016 5:26 pm
by Revolver
Jollyjack, would you put a 'tick' by that answer if you were the examiner? Ha

Re: 2ND Class EK Gen

Posted: Tue Jun 28, 2016 9:25 am
by JollyJack
Not bad for a 3rd's answer :)

Re: 2ND Class EK Gen

Posted: Tue Jun 28, 2016 9:32 pm
by Revolver
Good to know.
I mean; I wouldn't go into the exams with 'off the top of my head' answers haha, but I'll be sure to include a lot more than that if it comes up during my time for those exams.

Re: 2ND Class EK Gen

Posted: Wed Jun 29, 2016 7:53 am
by JollyJack
You wouldn't find it in EKG though, that's more a Motor question. General is more like "How do you forge, harden and temper steel?" or "Explain, with sketches, how to obtain steel from iron ore" or "List 5 tests to which boiler shell steel may be subjected, Explain one of them in detail". General questions on everything you know about Engineering, in a general sense. EKM is all about motors, the majority about Diesels, but there is some Gasoline engine stuff and gas turbine in there.

A wee tip, don't attempt a question, the subject of which you know nothing, nor have ever come across because you only read it in a book. Stick to what you know, what you've done, what caused hammer rash or skinned knuckles.

Re: 2ND Class EK Gen

Posted: Thu Jun 30, 2016 5:08 pm
by Revolver
Well that just makes sense, things you have worked on would certainly be the first questions you'll be attempting.
Even though I haven't skinned my knuckles doing a stuffing box I'll still offer any knowledge I think I have, which is always open to harsh criticism - being told your wrong is a great way to remember something the proper way haha
If you're faced with a question you haven't had your hands actually on, you can at least offer what you think you understand of it and keep an open mind about what else comes with it.

It's all a learning experience...this whole career...