Modifications to FCAF Garratt No 2

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This page has been lifted from the 5AT Project website, www.5AT.co.uk, with full permission of webmaster Chris Newman - cheers Chris ! I have subtly altered the page to suit this site. To see the full unadulterated original page click here.

Every time we used to build up speed with this engine a part of the valve gear normally fell off!

Shaun has provided the following information on past, current and planned modifications to the locomotive No.2.

STAGE 1 - 2001/2002

STAGE 1 OUTSTANDING WORK - TO BE INCLUDED IN 2003 WINTER MAINTENANCE SCHEDULE.

The work carried out at stage 1 should allow us to obtain some 22,000 km from the current driving wheels before they begin to break up in the same way as the originals did. This allows us some 3 operating years in order to finalise all design work for the stage 2 modifications and even time to prepare the components for fitting with the engine remaining in traffic rather than manufacturing and fitting as has been the case up to date. Likewise it would be convenient to use the allocated time in order to design the new components for Camilla stage 2 work and the new locomotive LVM 803 so that manufacturing can also take place in parallel at designated factories and workshops so as to reduce costs.

STAGE 2 - 2005/2006.

The above list of work raised a few of questions in Chris's mind which he addressed to Shaun.  The answers are much more interesting than Chris expected, hence their publication.

Q: Why boiler rebuild in 2005 when a new boiler was fitted in 2001? Weren't there sufficient funds to do the full job first time round, or were there other reasons for doing it in stages?

A: The spare boiler was fitted in 2001 because the original boiler showed signs of a warped crownsheet. This was caused by former crews carrying to low a water level in the original boiler in days pre 1999. The crews here had not been trained properly and were not aware of the risks involved with boilers. It is amazing that no accident occurred during those years. Neither of the boilers were fitted with fusible plugs and only one means of determining the water level in the boiler. The original idea was only to raise the old boiler and modify the spare fully before fitting at a future date. Time and circumstances did not permit such. Therefore I am left with the original boiler at Ushuaia. I had the barrel tested and such is okay, this means that as time and money allows we can modify this boiler (lets call it No.1) to include a high degree of superheating, belpaire firebox, feed water heater (feed pump to be fitted), auxiliary manifold fitted outside of the cab and foam height meter. The smokebox will need extending so as to accommodate the new superheater header and feed water heater (something along the lines of Porta's 1816 in Cuba) and this will mean an extension of the engine as a whole so some careful redesign work needs to be done here. Boiler pressure to be raised along with a redesign of the boiler stays. Some 75% of the new tubeplate area will be taken up by the superheater flues, the remaining smoke tubes will be fitted with an economiser (superheater booster). As you mention the stage work was a crucial part of the plan to improve the FCAF as a whole hence stage 1 modifications to Camila, Nora/Porta, issuing of train operating regulations, maintenance systems, plant & machinery, track, infrastructure etc. We are now in stage 2 of the development which means completing in a fully professional manner all that was begun during stage 1 (1999 to 2002). A realistic timescale (taking into account where we are and the singularity of Argentine businesses) for carrying out all stage 2 work at FCAF would be 2003 to 2007.

Q: What modifications did you make to the drive crank and eccentric crank? You draw attention to them in but they don't look anything special or unusual to the untrained eye;

A: If you look closely at old photos of No.2 (Hugh Odom has a good one on his website with Porta standing next to it taken December 2001) you will see that the drive cranks are now a slightly different shape. They were redesigned and manufactured new in Argentina during 2002. Due to time and financial restrictions during 2001 (we were trying to get the engine ready for the world conference which was to held at Ushuaia during October 2001 and we had begun the work to No.2 with next to no planning and budgeting due to its mechanical failure on 20/2/2001 which meant the whole plan of work being brought forward by 1 year) we did not carry out investigative work with respect to the original design and manufacture of the drive cranks and we re fitted such to the new wheelsets as was. The originals were (as the boilers 1 & 2) not designed or manufactured to any given code of practice and had been sleeved so as to fit on the journal. The sleeving allowed minimum crank web thickness and the result was a very embarrassing failure in traffic on February 4th 2002. I redesigned the cranks to AAR standard practice during March of last year and they were complete for fitting in August. The eccentric cranks were of the same nature so at the same time I redesigned these and had them manufactured along with the new drive cranks and axleboxes so as to reduce production cost (don't forget that all this was taking place at the height of our economic crisis in Argentina when we did not know what was happening day to day!). Again if you have a close look at the photos you will see a difference in shape and section.

Q: Why is insulation of the exhaust steam pipes necessary? I can guess a vague sort of answer to that, but would like to know the real reason.

A: The energy conserved in the exhaust steam is of the highest importance in order to maximise the draughting capacity of the exhaust ejector. The more energy that the steam has on striking the Kordina wall (which is a first stage ejector in itself) the better it will contract in the converging section of the Lempor nozzle and hence expand in the diverging section of such. The releasing through the diverging (top) section allows a greater velocity to be achieved (in excess of the speed of sound in the case of the Lempor ejector) thus higher draughting capacity (smokebox vacuum in simple terms of testing reference for the engine). In the case of No.2 the problems of energy conservation are made more difficult because we are dealing with a Garratt locomotive that has long exhaust steam pipes with an increased flow section in order to streamline the exhaust circuit, thus reducing back pressure. In simple terms the biggest problem associated with this type of engine (the problem increasing with the size of such) is the total pressure drop between the boiler to the steam chests and from the exhaust chambers to the blast nozzles. Apart from the length of the pipes concerned we are dealing with a saturated boiler as far as No.2 is concerned, NOT YET superheated (see boiler notes above). So, our problem of the exhaust steam having enough energy to perform draughting work at the ejector is compounded. This is also very noticeable at lower pressures (see steam charts). The live and exhaust steam pipes are therefore insulated so as to conserve as much energy as possible. In the Porta modern compounding system, re superheating takes place between HP and LP cylinders and when we get around to designing and building the LVM 803 for FCAF this will be the case.

Q: What's the steam sampling system for and what does it do?

A: This amounts to nothing much more than a 'Liebig Condenser'. A sample of the steam can be taken straight from the dome and the condensed steam then analysed for contamination etc. The most interesting part of this testing is that steam samples can be taken at varying outputs of the locomotive (i.e. different steaming rates).

Q: Is the flange lubrication system for going round tight curves? If so, how do you prevent loss of traction from lubricant getting on the rail head? (Or is that what the rail cleaning jets are for?)

A: The subject of rail adhesion is a very large one. Traction is lost due too contamination at the rail head and not rails being necessarily wet. The flange lubricators use condensed steam direct from the auxiliary manifold and when correctly used apply a steady trickle of water to the flange. Yes they help reduce tyre and rail wear on sharp curves without the requirements of grease flange lubricators which cause a great deal of slipping for all types of traction. The steam jets are really rail head decontaminaters (anti slipping device). They also de ice the rail heads in sub zero climatic conditions and can be used in reverse application as de-sanders. The 'water lubricators' were pioneered in Peru. One of my many tasks at the moment is to write a detailed technical paper on this subject which gives practical applications of such.

Q: What happened to the original driving wheels that caused them to break up, and why do you expect the current wheels to follow suit?

A: Poor castings combined with un-tyred wheelsets. The current wheels as fitted were manufactured at the same time (1994) to the same standards so these will follow suit. New wheels are to be designed and manufactured (fully balanced and tyred of course!).

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