Since the last entry, the liners Pedro has worked his magic and the liners have arrived from sunny spain.
4 brand spanking new standard size Sulzer liners manufactured to the original drawings
The Liner interior showing the cross hatching and the carbon brake the end of the cross hatching marks the top of the travel for the top piston ring. At the top of the stroke the piston crown is roughly flush with the top of the liner.
The liners themselves are spun cast iron (not machined from tubing) the spun casting means that when the molten iron is poured into the mould the spinning action ensures a perfectly circular bore, and a completely even thickness across the liner walls, an uneven liner wall will crack prematurely.
The reason for the cross hatching is to give the oil somewhere to go as it comes out from the piston rings, without the cross hatching the oil would gravitate to the to combustion area, but also could lead to something called excessive scraping, where effectively the oil is scraped during the stroke completely from the piston leading to piston ring where and at worse the piston jamming in the liner, which will lead to the rod exiting stage left through the crankcase leading to massive engine failure. too much oil in the combustion area leads to excessive carbon build up, dirty oil, and poor combustion, high oil consumption, and a general inefficient engine. Inevitably when cold some oil does get burnt and this is a where the carbon brake comes in and oil that does get burnt will carbonise and start to rise up to the top of the liner, when it gets to the carbon brake the carbon then falls off and can be ejected during the exhaust phase of the 4 stroke cycle so effectively the engine keeps itself clean. A common issue with preserved engines however is quite often the engine isn't stressed enough to dislodge this carbon, eventually it builds up and floods the carbon brake leading to a dirty exhaust and excessive wear on the fuel injectors.
The distance between the carbon brake and the top of the cross hatching indicates the area of the piston stroke where the maximum power is generated and is therefore under the highest stress, and highest temperature.
6LDAs like all sulzers are NON interference engine, in that if the timing were to be incorrect (which is pretty impossible) then the valves and the pistons will never meet causing a bent valve and a very badly damaged cylinder heads. This is why on a car the cam belt is vitally important, it keeps the timing correct, it always keeps the valves and pistons away from each other. Car engines are normally interference engines.
However what is vitally important is that the liners are the correct orientation, you can see at the side of the liners a cut out, and this is where the valves go when they open, conversely you can see a cut out on the piston crown which is also where the valves go.
The cylinder liners therefore have a mark which lines up with a mark on the block which ensures the liner is in the correct rotation.
The mark on the liner.
There are 3 sizes of liner
Standard - Classes 24,25,26,27
.5mm Oversize Class 33
1mm Oversize Class 45 and Class 47
As built all sulzers Baby, Juvenile and Big used the same liner, over time bore damage was observed on the higher powered engine as a result of excessive wear 45s and 47s it was commensurate with the size of the trains they were hauling, and the time they were spending at full power, 33s reflected the fact that they were running at a higher rpm due to the ETH, this meant that the liner vibrated in the bore and left an impression on the internal bore, this lead to sealing issues and damage to liners (fretting) so as a result the engines were bored to the sizes above to reset the issue.
Elsewhere the bodywork continues as we follow the step by step guide to increasing your class 26s route availability by cutting out all the filler, rot and general detritus they are carrying around.
B Side, the area we saw in the last post now completely welded up with new steel and framework in the area we saw in the last post, investigations revealed the source of the water ingress (the cantrail grills and this metal has been cut back to make a modification which will drastically cut down the water ingress into the locomotive in future., a few other areas of localised corrosion further down have been cut out, this is caused by the internal fire bottles sweating, and creating condensation on the bodyside.
There are 2 problems at the cantrail level
The first is the bodyskin has been applied too far up and riveted to the grills themselves, steel on aluminium is never ever a good combination causing electrolytic corrosion, this weakens the aluminium, although it has been cleaned you can see evidence of this, the other issue is that you will as a result of this process never ever get a water tight seal, you can see where the body was originally riveted on the girder. instead of riveting though we will seam welding (along the line of the original rivets), ensuring a strong 100% seal, an aluminium strip will then be applied to take the skin up to the bottom of the grills and then sealed to them with a very strong mastic, to cover the join a finishing strip of D profile aluminium will then be put over the join to cover it, this has the further advantage of disturbing the flow of rainwater off the roof and keeping it off the bodyside.
Further down by the radiators we can see pooling water behind the skin has pushed it away from the frame which make it just look downright ugly, this is a process known as rust jacking.
On the other side of the locomotive more is present because of the same issues this will be needle gunned before the frame is primed.
The next area for cutting this is the opposite side in the boiler compartment to the picture you saw with the new plate welded in. However this rot isn't thought to be as bad this side hence the smaller amount to be removed.
Cutting starts with the lower portion to be retained due the unique profile the bodyside is 3mm steel its very very difficult to recreate this with 3mm steel so this steel which is pretty much rust free is being re-used.
What did surprise us was the sheer amount of detritus in a sealed area under the floor ( I say sealed because this had a cover which has been cut off to reveal this) it is full the brim with dirt flies, nuts and bolts and general crud believe it or not very little deep corrosion is present, it is though that this area has never been exposed since the locomotive was built.
The now cleaned out area, and evidence of the larger lumps on the floor, the smaller dust filled the vacuum cleaner twice, this area will be needle gunned, and primed with a 2 pack zinc primer, the outer guttering (which was too corroded to retain on the other side, will be retained this side. The pipes are from brake frame which controls all of the locomotives air and vacuum systems.
A Side prior to cutting, the cant rail will be cut just like the other side as well.
26043 is the gift that just keeps giving and we knew an issue was present at No1 end, on a previous blog we had an similar issue at no1 end, we knew at the time No2 was similarly affected but ran out of time to correct it, we patched it up and hoped to look at it next winter....of course after that fateful oil change....we have all the time in the world...., you can see myself with a suitable appendage knocking out the filler to expose random steel plates beneath which are padding out a rather large dent!!!
Dent marked out for cutting
you are looking at what's left of the communications doors that 26s were built with, when the headlights were removed poor welding (too much heat) caused the metal to bow inwards due to expansion, when it cooled the weld prevented it from contracting back to its normal position, so to fill the dent they flooded with filler (over an inch!!!) and padded it out with steel plates which were held in place with a self tapping bolt. The tank was fitted when the 26s were dual braked.
hopefully the next blog will show no more cutting and an re-assembly of the engine in progress.
Edited by pheaton