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  #26  
Old 9th March 2014, 17:59
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Varley Varley is offline   SN Supporter
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I am sure. Were you there when the ballast tanks parted company? As the RN would have it - character building! We also got Blue Fin and Yellow Fin from the same stable. I am sure they weren't 'easy' ships either but I didn't get to see either.
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  #27  
Old 9th March 2014, 18:29
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Originally Posted by Tmac1720 View Post
I've seen work done on a cylinder while the engine was run on the test bed in Harland and Wolff. The complete "engine unit" was stopped, lower con rod removed and cylinder isolated before engine re-started. In all my years there I only seen this happen once so can only assume it was some sort of test or demonstration. NOT a procedure I would like to replicate when at sea.

Forgive me - I was only a sparky - but I thought a unit and a cylinder were the same thing? Or am I being stupid?
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  #28  
Old 9th March 2014, 19:34
Plane Sailing Plane Sailing is offline  
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Originally Posted by Varley View Post
I am sure. Were you there when the ballast tanks parted company? As the RN would have it - character building! We also got Blue Fin and Yellow Fin from the same stable. I am sure they weren't 'easy' ships either but I didn't get to see either.

No, that happened before I was on her but I recall the story - like you say, character building. I was moved back to the chemical carriers after BB so missed the two Fin boats - if I recall correctly one of them suffered a very bad engine room fire?

Wasn't the Fiat main engine on BB prone to shooting the occasional piston bolt out the open scavenge and across the engine room?
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  #29  
Old 9th March 2014, 20:36
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Originally Posted by endure View Post
Forgive me - I was only a sparky - but I thought a unit and a cylinder were the same thing? Or am I being stupid?
They are but I was trying to keep things simple for non engineers who might be interested in this thread. (and your not stupid )

My error was adopting the old H&W KISS principal (Keep It Simple Stupid) Unfortunately engineers have a habit of speaking a language known only to them as in the Brotherhood of the Spanner.
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  #30  
Old 9th March 2014, 21:06
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Unfortunately engineers have a habit of speaking a language known only to them as in the Brotherhood of the Spanner.
You're not the only ones with secret words that you use to baffle the rest of the world with said the man from skywave
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  #31  
Old 9th March 2014, 21:24
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Originally Posted by endure View Post
Can one of you engineery people tell me how you can work on one unit while the engine is still running? Can you disengage it from the crankshaft? If not how do you do it?
To go back to square one . You cannot disengage it from the crankshaft while the engine is running .
A unit consists of a cylinder head with all its components ; a piston ; a liner and a piston rod and a crank driving the crankshaft .None of the above can be worked on while the engine is running .
I have explained what can be done after the engine has been stopped and the "bad " unit isolated .
While the engine is running the only work that can be effected would be to tighten cylinder head nuts or apply a coat of paint .
Which part of NO do you not understand .
Think I will go and poor a drink Derek
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  #32  
Old 9th March 2014, 21:31
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Originally Posted by Derek Roger View Post
Think I will go and poor a drink Derek
What about the rest of us?... don't we get any ?

By George !! (Derek) I think they've got it now...
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  #33  
Old 9th March 2014, 21:36
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Oh dear. I think I've upset Derek
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  #34  
Old 9th March 2014, 21:36
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Originally Posted by Tmac1720 View Post
What about the rest of us?... don't we get any ?

By George !! (Derek) I think they've got it now...
The question is similar to " can you replace a section of wire on a high tension grid wire of 400KV while it is still live "

Think about it . Derek
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  #35  
Old 9th March 2014, 21:50
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Originally Posted by Derek Roger View Post
The question is similar to " can you replace a section of wire on a high tension grid wire of 400KV while it is still live "

Think about it . Derek

From wiki

"Bare hand[edit]
Bare-hand, or potential working involves placing the worker in direct electrical contact with an energized overhead line. The worker might work alongside the lines, from a platform that is suspended from them, or may sit or stand directly on the line itself.[5] In all cases, the worker's body is maintained at the same voltage as the line. It is imperative that the worker maintain appropriate and adequate limits of approach to any part at a different potential.
The first procedures for barehand working were developed in 1960 by Harold L. Rorden, a high-voltage engineer for American Electric Power.[4] Techniques were further refined following field and laboratory tests.
There are a number of ways in which the worker can access the live parts:
The worker can access from a specialist type of mobile elevating work platform (MEWP) termed an insulating aerial device (IAD) which has a boom of insulating material and which all conductive parts at the platform end are bonded together. There are other requirements for safe working such as gradient control devices, a means of preventing a vacuum in the hydraulic lines, etc.
The worker can stand on an insulating ladder which is maneuvered to the line by means of non conductive rope.
The worker is lowered from a helicopter and transfers himself to the line.
The worker is brought alongside the wire in a hovering helicopter and works from that position.
As the lineman approaches the wire, an arc will form between them as the worker is charged. Although this arc carries no more than a few microamps, it is debilitating, and the worker must immediately bond himself electrically to the line to prevent further arcing.[5] A worker may use a conducting wand during the approach to first make the connection. Once on the line, the worker is safe from shock as both the lineman and the wire are at the same electric potential and no current passes through his body. This is the same principle that allows birds to safely alight on power lines.[5]
When the work is completed, the process is reversed to remove the worker safely from the wire. Barehand working provides the lineman with greater dexterity than the hot stick method, and may be the preferred option if conditions permit it.[6] With this technique, insulator strings, conductor spacers and vibration dampers can be replaced, or lines spliced, without any loss of supply.[6]
The strong electric field surrounding charged equipment is enough to drive a current of approximately 15 μA for each kVm−1 through a human body.[7] To prevent this, hot-hand workers are usually required to wear a Faraday suit. This is a set of overalls made from or woven throughout with conducting fibers. The suit is in effect a wearable Faraday cage, which equalizes the potential over the body, and ensures there is no through-tissue current.[8][9] Conducting gloves, even conducting socks, are also necessary,[10] leaving only the face uncovered.[5]
There is little practical upper voltage limit for hot-hand working, and it has been successfully performed at some of the highest transmission operating voltages in the world, such as the Russian 1150 kV system.[11]"
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  #36  
Old 9th March 2014, 21:58
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Quote:
Originally Posted by Derek Roger View Post
The question is similar to " can you replace a section of wire on a high tension grid wire of 400KV while it is still live "

Think about it . Derek
Weeeeellll you could but it or you wouldn't be live any more

Question... what's black and charred and hangs from the ceiling?


A Harland and Bluff spark repairing the lights (electrician for the uninitiated) NOW see what you've started Derek...
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  #37  
Old 9th March 2014, 22:57
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Quote:
Originally Posted by endure View Post
From wiki

"Bare hand[edit]
Bare-hand, or potential working involves placing the worker in direct electrical contact with an energized overhead line. The worker might work alongside the lines, from a platform that is suspended from them, or may sit or stand directly on the line itself.[5] In all cases, the worker's body is maintained at the same voltage as the line. It is imperative that the worker maintain appropriate and adequate limits of approach to any part at a different potential.
The first procedures for barehand working were developed in 1960 by Harold L. Rorden, a high-voltage engineer for American Electric Power.[4] Techniques were further refined following field and laboratory tests.
There are a number of ways in which the worker can access the live parts:
The worker can access from a specialist type of mobile elevating work platform (MEWP) termed an insulating aerial device (IAD) which has a boom of insulating material and which all conductive parts at the platform end are bonded together. There are other requirements for safe working such as gradient control devices, a means of preventing a vacuum in the hydraulic lines, etc.
The worker can stand on an insulating ladder which is maneuvered to the line by means of non conductive rope.
The worker is lowered from a helicopter and transfers himself to the line.
The worker is brought alongside the wire in a hovering helicopter and works from that position.
As the lineman approaches the wire, an arc will form between them as the worker is charged. Although this arc carries no more than a few microamps, it is debilitating, and the worker must immediately bond himself electrically to the line to prevent further arcing.[5] A worker may use a conducting wand during the approach to first make the connection. Once on the line, the worker is safe from shock as both the lineman and the wire are at the same electric potential and no current passes through his body. This is the same principle that allows birds to safely alight on power lines.[5]
When the work is completed, the process is reversed to remove the worker safely from the wire. Barehand working provides the lineman with greater dexterity than the hot stick method, and may be the preferred option if conditions permit it.[6] With this technique, insulator strings, conductor spacers and vibration dampers can be replaced, or lines spliced, without any loss of supply.[6]
The strong electric field surrounding charged equipment is enough to drive a current of approximately 15 μA for each kVm−1 through a human body.[7] To prevent this, hot-hand workers are usually required to wear a Faraday suit. This is a set of overalls made from or woven throughout with conducting fibers. The suit is in effect a wearable Faraday cage, which equalizes the potential over the body, and ensures there is no through-tissue current.[8][9] Conducting gloves, even conducting socks, are also necessary,[10] leaving only the face uncovered.[5]
There is little practical upper voltage limit for hot-hand working, and it has been successfully performed at some of the highest transmission operating voltages in the world, such as the Russian 1150 kV system.[11]"
A piece of Cake . Now try and work on a unit running at 120 RPMs ??
Explain How it could be done ????????????????????
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  #38  
Old 10th March 2014, 01:59
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Originally Posted by Derek Roger View Post
A piece of Cake . Now try and work on a unit running at 120 RPMs ??
Explain How it could be done ????????????????????
Dunno - I'm not an engineer. That's why I asked you
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  #39  
Old 10th March 2014, 02:45
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Originally Posted by Plane Sailing View Post
No, that happened before I was on her but I recall the story - like you say, character building. I was moved back to the chemical carriers after BB so missed the two Fin boats - if I recall correctly one of them suffered a very bad engine room fire?

Wasn't the Fiat main engine on BB prone to shooting the occasional piston bolt out the open scavenge and across the engine room?
I remember Harry Gilbert waxing lyrical about how long it took to summon the courage to re-enter after an engine room fire - one of the Fins that may have been but not, from memory, serious except in the commercial sense as far as I can remember (I hope that's right anyway).

I hadn't heard of the projectile boltsheding but little would surprise me of that GMT.
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  #40  
Old 10th March 2014, 18:39
berbex berbex is offline
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Derek thks for clarifying what is meant by 'unit', although it was evident from the beginning what Endure was asking about. But to some of us that is a 'line'. A unit is the whole engine. A six cylinder in-line is a unit with six lines and the cylinder/piston/head assembly is one 'line'. (and if you ask me an 18cylinder vee is a curse, and a square four fullagar......but that is something else.)

Re the high tension wire thing, the birds knew that long before wiki. They also knew never to sit on adjacent phases and flap wings. But 'sparkys' are also known to do insane things in tight situations-like pulling out an exploded circuit brkr from a live 11kv busbar. You start breathing only when the hissing in the contact spouts stops.
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  #41  
Old 10th March 2014, 19:00
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Originally Posted by A.D.FROST View Post
A Denholm ship sail across the Atlantic with one unit hung up on a 3cyl.Doxford!
As long as the lower piston pressure is good you can still get the beast to start.
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  #42  
Old 11th March 2014, 01:19
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If he posts like an Engineer he must be an Engineer- if he posts like a Deck man he is NOT an Engineer.

BW to all Engineers

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  #43  
Old 11th March 2014, 02:31
Fred Field Fred Field is offline  
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berbex - Two engine types I have only ever seen in books are the Fullagar and the Hurry & Worry double acting 4 stroke. I am quite happy about that the H&W single acting 4 stroke, optimistically described as 'under piston super charged' was bad enough.
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  #44  
Old 11th March 2014, 07:00
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Originally Posted by A.D.FROST View Post
It was a cylinder head stud that sheared (the narrator said it was a piston bolt?) No point in not to stop to tension a tie rod mainly on a Sulzer because of the main bearing tie bolts could come loose.(check out this forum https://www.shipsnostalgia.com/showth...ht=emma+mearsk )
Correct, cylinder head bolt on Emma Mearsk
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  #45  
Old 12th March 2014, 17:53
berbex berbex is offline
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berbex - Two engine types I have only ever seen in books are the Fullagar and the Hurry & Worry double acting 4 stroke. I am quite happy about that the H&W single acting 4 stroke, optimistically described as 'under piston super charged' was bad enough.
The fullagars i had to work with some years ago. Paired lines(units) have pistons cross connected by tie rods. Seen from inside crankcase when turned by air, it discouraged any work during operation. Still, since pistons were cooled by oil via telescopic pipes that were troublesome there was the occasional peek inside to see if something was wrong.

The Vee unit i had in mind is relatively modern. High power to weight ratio, it is highly stressed. Leads to many and frequent problems.

Not exactly what this thread asked, but then the type of engine was not indicated.
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  #46  
Old 12th March 2014, 23:17
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Originally Posted by berbex View Post
Derek thks for clarifying what is meant by 'unit', although it was evident from the beginning what Endure was asking about. But to some of us that is a 'line'. A unit is the whole engine. A six cylinder in-line is a unit with six lines and the cylinder/piston/head assembly is one 'line'. (and if you ask me an 18cylinder vee is a curse, and a square four fullagar......but that is something else.)

Re the high tension wire thing, the birds knew that long before wiki. They also knew never to sit on adjacent phases and flap wings. But 'sparkys' are also known to do insane things in tight situations-like pulling out an exploded circuit brkr from a live 11kv busbar. You start breathing only when the hissing in the contact spouts stops.
A six cylinder engine is an engine ; not a Unit . It consists of 6 units .
When in port the Chief Engineer or 2nd Engineer says we are going to pull number 3 unit ; all understand that the complete set of running gear ( Number 3 ) will be pulled for inspection and probably survey . I t will consist of the Cyl Head removal ; grinding of the lip inside the liner if necessary ; removal of the piston ( normally to be replaced by a spare ) Cly liner calibrations to be measured ; checking of liner lubricating quills . Overhaul od piston rod gland and piston cooling water glands . Cleaning of the scavenge space .
In section and measurement of cross head bearing wear ; inspection of con rod bearing and also the checking od a least one main crankshaft bearing plus taking a set o of crankshaft deflections . In the case of a Sulzer engine with rotary exhaust valves these would also be inspected and corrected as necessary and the timing set .
It would also be an opportunity to check the fuel pump spill to ensure that that particular unit was performing to specifications .
A very busy day . Cannot be done with and engine running as any idiot could understand .

I don't know why some have so much difficulty in understanding what a unit is .

Changed multitudes of the beggers .

Derek
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  #47  
Old 13th March 2014, 00:45
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Perhaps Berbex and Fred are deck wallahs

I'm not an engineer but I know the difference between an engine and a series of units or a unit.

But, there again I have no FOC experience or 2nd Mates tickets!


BW

J
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  #48  
Old 13th March 2014, 01:01
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Originally Posted by endure View Post
Forgive me - I was only a sparky - but I thought a unit and a cylinder were the same thing? Or am I being stupid?
Endure,
Don't let Varley catch you using the term 'only a sparky'!
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  #49  
Old 13th March 2014, 01:32
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Endure,
Don't let Varley catch you using the term 'only a sparky'!
Don't worry - I'd never do that. His beard frightens me too much
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  #50  
Old 13th March 2014, 02:13
stevie burgess stevie burgess is offline  
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Well said Derek...i was just a mere deckie on the box boats but we were gp's and had to muck in with the engineers when overhauling and we always regarded it as doing a unit. Wasn't just over excited about cleaning a scavenge space though!
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