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Recreating LYN
Progress log
updated 12/02/2012 |
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I have been contracted by The 762 Club to work with Ian Gaylor to produce the working drawings required to recreate this Baldwin Locomotive.
The version of the loco that we are creating is the later version after its rebuild by Southern as shown on the right in the heading photos. The plan is to create loco in a "looks like, works much better" version incoporating a number of the improvements in steam loco design that have happened since the original was cutup. Amongst the "improvements" will be :-
a superheater, Increased boiler pressure, rolling bearings, a "gas producer" coal firing design, reduced friction valve design.
These changes will produce a loco that is much more efficient, uses less fuel, makes less smoke, doesn't throw sparks up the chimney, uses less water, pulls more weight but still recaptures the look and feel of the original loco.
For more info on the gas producer firing system as used on the kirklees Light Railway go here
and
here
for a good description on how it was applied to existing locos.
I have just started the process and I plan to keep this page as a log of my progress. I am using a 3D CAD package to produce a 3D model of each of the parts prior to creating the drawing of the part in order to ensure that the potential for errors to creep in is significantly reduced.
Currently I am producing a 3D model of the boiler. This is not the documentation that will be used, as the boiler manufacturer, Bennett Boilers, will produce their own documentation and be responsible for the delivery of a working boiler. The boiler is the core of the locomotive and this model will be a huge help in ensuring that the rest of the assemblies fit and work as expected. Click on any of the images for a full size version.
Modelling progress up to 18th Feb 2011
Section through boiler 18th Feb 2011 |
View of boiler 18th Feb 2011 |
Close up of firebox area 18th Feb 2011 |
Modelling progress up to 28th Feb 2011
All the currently modelled bits put together. The frames are modelled from the original drawings and will be subject to changes to make them acceptable to the modern standards. The cab is now finished ready for installation |
Current work is to model the cowcatcher - a much trickier modelling exercise than it looks |
Modelling progress up to 8th March 2011
Well, I have been working on the boiler cladding and I guess that I am half way through the modelling. The Firebox backhead cladding was a real challange and the model is still reporting a problem(et) but I know what the problem is and I think that I may be able to force the program to model it correctly with a bit of cunning!
This is the latest jpg of the loco complete with the cladding |
The firebox backhead has has to be modelled using the sheetmetal tools so that the flat pattern can be created easily ready for lasercutting before bending. |
The firebox backhead cladding flat pattern for lasercutting. |
Modelling progress up to 11th March 2011
The boiler cladding is now broadly finished. The backhead cladding model is now OK with no errors and I have done the detail drawing and a DXF file for it to be lasercut. The cladding clamping straps are modelled. I have added the sand domes, only a rough guess at present but I will firm them up when we have decided how to make them and have the final dimensions to hand.
This is the latest jpg of the loco with the cladding finished and the temporary sand domes in place. |
The cladding is now modelled and the detailing of the parts has started. |
detail of the clamping straps for the boiler cladding. |
This is probably as far as I can go for a while as there are some decisions that need to be made before we start some of the other elements.
Modelling progress up to 12th April 2011
I have been getting on with the water tank modelling. Ian has provided an outline design and I have been filling it out into a 3D model. I quess I am about 3/4 of the was through. I have been doing the drawings as I go along so I am close to being able to issue all the tank drawings for quotation. We won't release any for manufacture until some of the other areas have been modelled so that I can be sure that it will all fit.
Modelling progress up to 11th May 2011
The water tank is now modelled and the drawings are ready for issuing for quotation. I have also finished the drawings of the smokebox and smokebox door ready for quotation.
The firebox door has been redesigned to better reflect the shape of the original round door although this does compromise the efficiency of the gas producer firing system somewhat. We have tried to provide the capability for controlling the drawing in of air above the fire in the door assembly rather than the original idea of controlling the opening of the door with a lever and foot pedal. The new design is fully modelled but I will wait to detail it until after our design review meeting at the end of the month.
The cladding is in the process of being detailed and should be finished ready for quotation this month. There may be a few changes as we havent sourced the boiler water gauges and the positions of the mounting holes for these will need to be incorporated
The sand domes are partially designed and the internal sand containment and delivery parts are being modelled.
This is the latest design of the firebox door in the closed position the door is opened with the handle shown and a cam system holds it either open or closed. The small lever at the top of the door controls the air into the top of the firebox (shown in the fully open position). |
The tubes shown are to make this incoming air swirl to improve the efficiency. |
This is a cross section thro the firebox showing the main features. The deflector pushes the incoming swirling air down to mix it with the burning gas and ensure complete combustion. |
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Modelling progress up to 26th May 2011
The super heater is now modelled and the improved boiler mounting completed. I have also updated the chassis to have the main wheel axles and cranks fitter. The steam valve and attendant parts have been up dated and are now nearer to the final design. The main effort has been to get the superheater modelled so that we can have a design review at the end of the month.
This is a complete cross section showing the current state of the model. |
This is the superheater. |
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Modelling progress up to 3rd June 2011
Well, we had the design review and it does look as though we are going in the right direction from a technical viewpoint. There are a few non-technical things that will be addressed over the next couple of weeks. In the meantime I have been pressing on with modelling the buffer assemblies. I won't be doing the drawings for this assembly as the plan is to purchase it finished from the Ffestiniog Railway Company as they are already having some identical items made for their own use. There is a reasonably good drawing from around 1925 when the L&B was in Southern Railway ownership and I have been able to use this to create an accurate model (see below)
This is a complete assembly of all the components. On LYN the front assembly and the rear assembly were different. |
This is the buffer assembly as fitted to the front of LYN. Only the hook is fitted. In use the hook was lifted clear by a chain to protect it. |
This the assembly as fitted to the rear of LYN. The hook is not fitted but the parts for tensioning the coupling are there. |
Modelling progress up to 20th June 2011
The detail drawings for the firedoor are now complete and ready for sending out for quote, The cladding drawings are complete and also ready for quotation. The cowcatcher is finished and detailed as is the smokebox. all of these are subject to changes when we check the drawings and finish other areas. I have started the design work for the pony trucks. There is very little information on the pictures and drawings that I have available but I have been much helped by Stephen Phillips, a 762 Club member and an excellent draughtsman as well as a keen L&B historian who has done a lot of research in this area and created a couple of excellent illustration of the leading and trailing trucks. The model of the trailing truck shown below is still quite speculative and will be firmed up as more info is obtained. It also has to cope with the deeper firebox that will be fitted to the loco.
The cowcatcher model shown below doesn't try to replicate the actual shapes of the forged ends as they will depend on the actual forging process and can't be modelled precisely. The drawings show only the important dimensions.
This is a picture of the current model of the trailing truck. |
The cowcatcher is now complete subject to checking. |
The firebox door is finished also subject to checking. The tubes shown are part of the gasproducer system and allow good control of the secondary air to improve combustion and reduce smoke and sparks. |
Modelling progress up to 15th July 2011
Not as much progress this month as we are waiting for the boiler order to be placed. I have offered to do the detailing of the boiler to save both time and money. I already have a nearly complete model of the boiler and will update this with input from the boilermaker. I have made a good start to the simplified (non-rocking) grate assembly and, once we have had a design review (Ian and I) I will be able to finish the modelling and do the detailing.
This is the current model of the ashpan exploded. |
This is the current model of the ashpan. |
Modelling progress up to 20th August 2011
The boiler order is still to be placed but I have high hopes that a meeting in the next couple of days will get that underway. I have been working on the draughting of the engine. This is one of the more important elements that needs to be right to ensure that the engine delivers the performance required and is easy to fire and control. Ian has done the calculations and provided a sketch layout of the Lempor system. I have now done most of the detail design and am ready to start the detailing.
This design is quite interesting. The Exhaust steam from the cylinders is directed up the blast stand (the blast stand is split into 2 channels one from each cylinder) and is merged in a Kordina before being ejected through 4 carefully shaped nozzles into the chimney. This design gives the 2 main benefits of sucking the fire gasses through the boiler tubes and creating a low pressure pulse to the other cylinder thus improving the power delivery by minimising exhaust back pressure. There are some compromises to the ideal geometry because of the shape of Lyn's chimney but the result should be a much better steaming performance than would be achieved with a conventional single blast nozzle and conventional chimney.
The small supplementary steam pipe is used either to assist the draught via 4 small blower nozzles when the engine is stationary and there is no exhaust to power the Lempor or, by connecting to a compressed air source, to provide some draught when firing up the engine from cold.
Cross section through the Chimney and Lempor assy. |
Picture of the current model of LYN. |
Modelling progress up to 3rd September 2011
We are still waiting for the boiler order to be placed but I think that it is much nearer. One thing that has been thrown up is that the plate thickness has been increased from 10mm to 12.5mm not a big change but it has had a significant impact on the 3D model of the design. The waterlegs of the boiler are now too narrow (they were already close to the minimum) and increasing these has required the boiler barrel to increase from 875mm diameter to 937 diameter. This won't change the outside dimensions of the cladding but it will mean that the insulation will be reduced. We have taken the opportunity to increase the waterlegs by more than the minimum which should give the boiler a better performance. Another change has been the change to remove the expensive formed flange curves from the boiler design and to change it to a "cut and shut" style.
Cross section through the engine. |
Modelling progress up to 11th November 2011
The boiler order is now placed and also the build contract With Alan Keef. I have taken on the drawing of the boiler in order to reduce the cost (this is unpaid work in addition to the drawings I am contracted to create). I have started the boiler drawings and am working with the boilermaker to ensure that they are correct and able to pass the insurance requirements.
I have now completed some 296 drawings (including the first pass boiler and superheater drawings) representing some 930 parts. So you can see that LYN is progressing OK so far.
I have started the design and detailing of the coal bunker (another job that wasn't part of my original work program) and you can see what it looks like on the picture below. It is interesting that this assembly has gone through a number of changes over the years. The addition of the top rails to increase the coal carrying capacity are the biggest change and even those have been tweaked to further increase the capacity. Luckly the 1929 version that we are aiming for has the largest coal capacity.
The design for the saddle and cylinders has started. Currently the torch is with Ian Gaylor. He is producing the design layout and doing the calculations to ensure that we get a really good performing loco!
Latest side view. |
Modelling progress up to 2nd December 2011
The Saddle is now modelled and awaiting completion of the design for the cylinders before detailing can start. The model of the saddle won't have the welds and some of the rads shown due to the limitiations of the CAD package (software engineers really don't understand welding).
Saddle. |
Saddle section. |
Section through the smokebox. |
Modelling progress up to 5th December 2011
I've gone as far as I can with the modelling of the saddle and it is now ready for detailing. There has been a number of modifications to the draughting now that the blast stand is finished and connected to the saddle and these are mostly complete (subject to a design review with Ian). As I am now held up till the cylinders and valve gear are laid out, I have taken the opportunity to have a first pass at the front pony truck. Still a bit more to do to it but it should be a bit more straight forward than the trailing truck as that has the deeper firebox to cope with. I am reasonably confident that the basic size of the main frame of the truck is as close to the original as possible as I have been able to scan part of the original erection drawing, put it as a back drop to a drawing, drag it to close to actual size by comparing the few dimensions on the drawing to real CAD dimensions and then trace over the shapes. The drawing is quite old and there is some evidence that there has been a lot of "draftsman's license" taken with the scaling. Still, the drawing was only done to enable the kit of parts to be assembled.
Leading Pony Truck. |
Section of the Original Erection Drawing. |
Side view of LYN with all its wheels on. |
Modelling progress up to 22th December 2011
I have been working hard to get the boiler certification drawing completed. This drawing is an example of the limitations of the modern 3D CAD drawing systems. Because the drawing has to give sufficient information for the insurance companies engineers to sign off the boiler as safe and fit for purpose, but they (apparently) can't/won't cope with the more usual approach of a single drawing for each part and an assembly drawing to show how they are put together so, on the advice of the boilermaker, I have produced a drawing for the completed boiler that I hope achieves the requirement. The thing that make this type of drawing so demanding is that every component has to be fully modelled including all the stays and even the welds as SolidWorks is pants at doing the welds on welded structures. This means that the simplest change can take 10 minutes as the rebuild time of all the components is done.
The image below of the initial version of this drawing will be updated once the drawing is approved. If any one wants a copy for their wall let me know and I will provide a PDF for printing at A0.
Modelling progress up to 27th January 2012
The cylinder assembly design layout is broadly complete so I have been able to get the assembly modelled. Ian and I have had a first pass at a design review of the cylinder design and I am currently updating the model to the latest thinking.
We have a major design review later in February and I am aiming to have the model completed for that.
Section of the left hand cylinder through the cylinder. |
Section of the left hand cylinder through the valve. |
left hand cylinder. |
Modelling progress up to 12th February 2012
The cylinder is complete and looks to be able to deliver the performance needed according to the calculations that Ian has done.
We have a major design review at Alan Keef's works tomorrow and I have the full model completed up to date for that.
The boiler certification drawing has been completed and issued to the certifying authorities. I have also issued a set of detail drawings to the boiler maker so that quotes can be obtained and material ordered - a total of 60+ drawings!.
Also issued for quotation and ordering materials are the set of part drawings for the smokebox. This is also being made by Andy Bennett at Bennett Boilers .
Once the design review is completed and providing that no major issues are identified we should be able to detail the saddle and the cylinders for manufacture. I understand that these components will be the first to be manufactured despite being the last detailed.
Drawing of LYN at 12th Feb 2012. |
LYN model view 12th Feb 2012. |
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