NYC ‘S’ Motor
An Old Maude -even when brand new....
The New York Central railroad was going to build an electric locomotive anyway when a disastrous accident forced their hand. The design for the new loco was typically american of the period. It had "BiPolar" motors and was not exactly pretty... Nevertheless they proved to be study beasts and the next accident was not exactly the fault of the original designers of the loco -but rather the smooth running of it...
As designed the 'S' motor was a 1-D0-1 and was capable of very high speed running (for the time) so much so that the drivers were often convinced that they were in fact travelling far slower than they actually were. The result was that the front axle spread the gauge on a curve at high speed and the resulting derailment caused more deaths than the original accident that brought them into being...
They were re-designed as a 2-D0-2 and they lasted in this configuration right through their very long lives!!!
The following scans show the locomotive in its original 1-D0-1 and the later 2-D0-2 formats. The drawings come from Henry Greenlys book: "Model Electric Locomotives and Railways". (I have the 1928 edition).
The "BiPolar" motor was also used by the "Chicago, Milwaukee and St Paul RailRoad" in their huge freight locomotives. It has the advantage of being very efficient at high speeds -something that a geared motor is not. However it does have the huge problem of the huge electromagnet that picks up any magnetic object and then deposits it when the field is switched off. There are stories of "S"motors picking up things along their way and then there being a crash bang clatter as the scraps fell onto the sleepers at Grand Central station. My favourite one is of the "S" motor that collected several sets of "Ladies Stays" on its travels and deposited them there...
Due to the use of the "BiPolar" motor in the original, the spacing between the driving axles is "cramped" to say the least. The only place to connect them to the motors is at the end. I am going to use an idler gear to transfer power to the inner axles, this may be a rather noisy -but out in the garden I think that it might not be noticed, (well at least by me!)
The basic plywood chassis has been cut and awaits "plating" with ABS sheet. The 2 SLA batteries (6Volts 4.5Ah) will live in the end compartments and have lift off rooves for easy access. I am going to change the design somewhat from the original and give it a pantograph on the central roof. This has been done in several of the preserved 'S' motors to provide them with a working "modern" electrical supply -so I don't feel at all guilty about it...
Because it will have a short rhombic pantograph to work from an imaginary 1500Volt overhead supply the short "steeple" 600Volt pantographs of the rebuilt 'S' motors will not be present, nor will the collector arm for the 3rd rail. The short pantograph was for work in tunnels where the 3rd rail was on the tunnel ceiling -as a safety measure, and where the long gaps in the pointwork would cause the the third rail layout too many problems.
The rebuilt 'S' motors has a front bogie of the Adams type -so I have sat down and calculated the design requirements from the formulae. This basically uses the total length of the wheelbase and the fixed length of wheelbase plus the curvature of the corner that it has to move through to produce a diameter from the centre of the wheelbase. Here is my creation in the metal (no it is not Mecanno -despite appearances!)
This is how an Adams Bogie works... When the loco enters the curve the force on the front axle causes the bogie to pivot on its central axis. The next thing that happens is that the inclined spring on the outer side of the curve is relaxed thus making the other spring (on the inner side) more tense. The net result is that the bogie moves towards the direction of the inner curve and physically moves across the loco. The more the loco corners the more the bogie moves to the direction of the inner curve. Thus the bogie acts as if the centre of rotation of the bogie moves towards the centre of the curve.
The front and rear lids for the battery compartments have been fabricated from MDF and strengthened with 5mm sq pine strip. 1mm ABS sheeting forms most of the exterior shell and I have drilled the fronts to take the pins -so that the lids pivot outwards. The windows have been punched out by a combination of "chain drilling" and a craft knife. The holes then squared up with a grit block and some sandpaper. The roof shape has been roughed out by placing a saucepan lid over some balsa and cutting around it. The exact shape of the roof is formed by having a 30cm hack saw DELICATELY drawn across the balsa ribs until it touches the ply ends, thus giving a series of slots which can be joined up with a craft knife and then smoothed over with sandpaper.
The roof itself will be made from two 1mm thick sheets of balsa, laminated onto the ribs with "Croyd Aero" cement. The final layer of the roof will be 0.5mm thick ABS sheet held on with epoxy glue thinned down with meths to a brushable consistency.
Here you can see the ABS clad model with the working drawing beneath it. It is hard to see, (white on white with flash...), but I have carved in the side doors and the set of extractor grills at each "nose" of the loco. The drawing is for the original pre 1907 1-D0-1 configuration -I do have a set of drawing for the 2-D0-2 chassis to go underneath it -but this has yet to be fully dimensioned.
The chassis frame will be piece built in brass and aluminium, that is made from strips -not cut from a single sheet. Certain features will be "appliqued" into position -and then epoxied. Others will have to be silver soldered (such as the horn blocks and grease boxes) and some pieces will actually be riveted into position -but with 3mm and 4mm "pop" rivets. I do have a set of "snaps" but I lack the small thumbs -in short I have large hands!!!
Well a couple of days have passed and I have made some use of my time. The bulk of the superstructure is complete and has been primed and wet sanded to death!!! I have used an oblique flash shot and (hopefully) all the carved detail that was invisible last time has revealed itself in the shadows.
The dimensions for the chassis have been (finally) worked out, the main problem was getting wheels of a small enough diameter but with a gauge 3 profile -however Brandbright wagon wheels are pretty close -so that this is what I have based my calculations on.
The transverse I beams will be made from two U sections of aluminium extrusion epoxied together, the main chassis "bar" will be a single sheet of 64 thou brass with the horn guides bolted to it, (this will hold it in place while I hit it with the silver solder)... The front bar work will have to built in a jig, then silver soldered together. The "doughnut" will be the point where the differing parts of the frame join, (with a pop rivet), and I intend to epoxy the other end of the frame to the transverse I beam. This part of the chassis is actually decorative as the Adams bogie is fixed to the floor of the superstructure and makes no contact with the chassis at all.
I have spent a very taxing Sunday Afternoon applying stuff to the outside of the "S" Motor. The "Applique" material is a combination of Cambrian and Garden Railway Specialist "G64" stuff. Non of which was ever intended to fit an Edwardian era American locomotive -but by dint of main force, deft filing and a knife can be made to look as if it should be there!!!
The door handles and such like are Cambrian mouldings, the external riveted iron work is GRS stuff. The holes drilled into the bodywork show where the handles and stand off for the railings fit.
A pencil line is drawn in the primer then cross marked with a pair of compasses (the dent made by the point is hidden under the rivet). The rivets are then cut off the sprue and arranged face up with a paint brush. A length of wire is dipped into THICK CA and delicately "dobbed" at the cross points. The rivets are then pushed into the dobs of CA and set there. I found that doing more than 4 at a time caused the glue to set by the time I was on the 5th... The gaps between the rivets are at 4mm intervals -a scale 3 inches. I know the rivets are slightly over scale at 1 inch across, but to be honest if anyone would like to file them to the correct radius -they are welcome to do so!
The method leaves a slight "halo" of CA around the rivet -this can be attacked with either a scalpel -or a small piece of soaped wet and dry. I will admit to being in two minds about doing the rivets. I have always found the dome head rivets to be visually very messy and I much prefer the smooth sides of welded panels and flush head riveting.
However as my wife pointed out; "This is an american locomotive and if that's how they do things then that's how it has to be!"
Do I like it? No... but I do have to admit that it is a fundamental part of the look of the locomotive, so I just have to accept it.
As I am one of those people with an almost lethal sense of humour I have decided to apply it to the "S"motor. After having shared my thoughts with T.S.Ruby MSc -I will explain what I intend to do here...
This circuit has been around since I was at College (in fact I think it comes from the J Lindsey Hood Cassette deck design in Wireless World). Anyway it is simple, rugged, and cheap -all the best circuits are!!!
The 10k resistor is added to prevent small fingers turning the knob too far... What I intend to do is mimic the collection of resistors on the roof of the "S"motor and the switching system for it. To this end I will produce "fake" resistors on the roof, but hidden inside the "fake" resistors -will be real 470 ohm 1/4 watt metal films...
The collection of metal film resistors will be step switched to replace the 22k potentiometer in (2x) 470 ohm steps. If this sounds strange then I actually have a pre-amplifier that uses exactly the same technique(!) They will be made from lengths of plastic tube with "button thread" wound around them. This should look like the resistance wire that the original had -the real resistors can be then poked into the tubes and soldered into the Veroboard that is underneath the roof. This is going to take some precision drilling and marking out. Recently I have not been doing too well at the latter. Both of my "clutch pencils" have got rather sticky due to them being dropped into coffee and despite repeated washing still do not feel "clean" to my fingers...
Well as my father told me; "If you want to produce something repeatably -then you have to use a jig. So, take great care when you build one. A true jig will produce precise and exact copies, a poor jig will produce precise and exact SCRAP"
So several hours have been spent with lengths of K&S section and drawings to produce what you see above... Several lengths of 5mm sq pine stuck to a couple of scraps of MDF. HOWEVER they are all specific lengths and distances apart. I can thus drop the required pieces into the jig and then drill them -knowing that they will not move and the pieces will all be fixed in position while the CA sets. The top jig is the main chassis system -the horizontals hold the frame beam and the verticals will hold the horn guides. The jig below, (with the 50p coin), is the one for the end assemblies. There will be four of these, one at each end of the main chassis beam. The end result should be -two sets of mirror images.
When everything is fixed with M3 nuts and bolts, it will be time to hit it with the silver solder and the MAPP gas. I use MAPP in preference to Propane because it is hotter and the burner flame is so much "cleaner" than with either Propane or Butane. I tend to use Silver-Flo55 rather than the more common Easi-Flo2, because for some reason -I seem to be able to get a far neater joint with it(?) There is no difference in price, the melting point is 630°C (roughly 10°C higher than Easi-Flo2), or the type of flux used.
The K&S order should come sometime towards the start of next week. Then it is down to precision sawing, filing and drilling. I have never assembled a US style bar frame chassis before -nor do I know anyone who has. However I do have a small but curious audience who are wondering how much over the comming week is going to be; planning, guesswork and of course -pure fluke!!!
The pantograph fitted to the S motor is a pure home brew creation... The brass strips are actually stantions for model boats, (I found them in the Robbe catalogue). The ends are drilled out to 2.5mm from 1mm and then 3mm crimp connectors are soldered to the "plug end" of the stantion. The whole lot is then cobbled together with some M2.5 and M3 nuts and bolts.
A little dressing up and it will sit on the rear of the S motor...
Well another productive Sunday Afternoon....
The shot below shows the partially silver soldered "horns" for the pantograph -the impromptu jig is actually one I use quote frequently for hold thin pieces into position(!)
The "forge" is actually a fire brick from a loco which I got for a donation at "Butterley".
The next shot shows the collector plate now in position on top of the pantograph. The pantograph is held aloft by a spring rather than air pressure as in the original. The steel shaft slides up and down the brass bearing tube through the rear "nose" of the "S" motor.
The carbon greasers will be added when everything is ready to roll after some filing and suitable decoration!!!
One more to go
Well at this point in time I am looking at:
1 BOX of 1x12x64thous strip
1 BOX of 1/2x12x64thous strip
1 BOX of 1/4x12x64thous strip
1 BOX of 3mm brass set screws
1 BOX of 3mm brass nuts
2 lengths of J&M silver flo24 silver solder 710C
2 lengths of J&M silver flo55 silver solder 610C
I suppose what I should explain how I intend to assemble this collection of designer offcuts. The main beams will be cut from the 1 inch wide strip and then the horn guides cut from the 1/2 inch strip. The beam is then placed in the jig and the guides then CA'ed to them. The other side is then assembled in the jig -but as a mirror image i.e. the horn guides are placed into the jig and the main beam glued on top of them.
This produces two pieces that are "true" to themselves
The two assemblies are them placed back into the jig and the 3mm locking holes drilled through both pieces. This again produces two "true" pieces. The brass setscrews and nuts are then inserted and tightened up. Next the I solder with the Silver Flo24 which has a higher melting point than the Silver Flo55. I solder the backs of the setscrews and then grind off the heads leaving a flush finish. The CA has burnt off during this so it is only the soldered nuts and screws that are holding everything together. Next I hit it with the Silver Flo55 which has a far lower melting point and thus the threads remain firmly seated in their holes. I will solder up the horn guides at the top and bottom and then flash the nuts with ordinary tin solder -they will not move after that!
The horn blocks will have to be assembled by sandwiching them out of ? inch strip (two 1 inch long and one piece ? inch long). The 4.5mm hole for the journal will be drilled through as will the 2.5mm holes for the grease box. Next, a thick black graphite pencil line is drawn around the holes in the horn blocks, this stops the solder from flowing into the drilled holes -and plugging them... The horn blocks are then CA'ed together and the 2.5mm setscrews fitted and tightened up. The whole assembly is then heated to dull red heat and the Silver Flo24 solder applied. This is very liquid at high temperatures and will creep across the whole sandwich, the other alloy would not penetrate as far and leave voids.
The carbon greasers have been added to the top and the electrically conductive epoxy is holding them well. The "drop test" shows that they can conduct 6 Amperes so the pair of them should have no problem feeding power to the motors. The greasers are simply 2 old blocks of graphite armature connectors that I grooved with a set of clay scrapers.
The next shot shows the underside of the cab roof where I have started assembling the power control system. The relay on the left is the Fwd/Rev and the one on the right is the main power feed. Both of them are rated at 20 Amperes at 12 Volts. The hardwiring from the coils connects to the slide switches on the roof. The main PCB will sit to the right of the relays. Holes will be bored through the roof to connect to the resistors on it. The roof electronics connect to the lower power supplies by male Lucar "spades", this means that when the roof is taken off -there is no chance of a short from the power bus bars below.
The system will be a hybrid with 12 volt electronics and 6 volt motors, (both sets of motors will be coupled in series). As normal I will leave the front and rear windows unglazed -this provides a cooling draught of air to the electronics as the loco moves!
Well I initially imaged that there would be quite a lot of egg on my face -but the fact is that this does seem to be coming together far easier than I thought possible. It is now nearly 10pm and this evening everything has gone very well!!!
I started out with my collection of brass strips.
And after some sawing with my hacksaw I ended up with the main beam cut from 1 inch strip and the horn guides from 1/2 inch strip, all together in the jig.
Each of the horn guides was drilled with 3mm holes at 7mm and 18mm intervals.
The completed drilled horn guides are then returned to the jig and the main beam bored from them.
The whole thing is assembled with 3mm nuts and bolts and it is now ready for soldering.
Note; brass nuts and bolts are used so that when the assembly is heated prior to silver soldering, the assembly expands and contracts at the same rate -this will reduce twisting and warping.
It is just after 7:30pm and the evening was a nasty as expected!!! Silver soldering is not hard, I would say actually it is very easy -even when compared to electrical soldering. The main problem is that everything operates at dull red heat...
Having sawn all the sections to size and tacked them together with CA I loaded them onto the "forge".
I then opened all the doors and windows!!!
The safety sheet for MAPP (Methyl Acetyl Propadyne) says that is is safe to use indoors -however the smell may be objectionable. The smell is not unlike sweaty socks and ripe drain...
Anyway with my green safety glasses and my red gloves I lit my bottle torch and began. I torched up all four of the end pieces and duly threw them into the bucket of water at the end of the process -this cracks off most of the flux and saves on cleaning time. The flux I use is one I learned with at school, equal parts Borax and Olive oil, sticky, smokey -but it cuts through any oxide layer!!!
I then torched the horn guides to the main beam, and dunked them.
The end pieces are joined by the one top joint, this makes handling them until the bottom bar is in place -slightly fraught!
At the end of 2 hours work I have transformed the beautiful brass in the pictures above into the blackened, sooty and flux stained assembly below:
So, after having got this far I have to comment of the two very different types of frame construction -the bar type and the plate type. The bar type is very labour intensive but is actually surprisingly easy to assemble -however the strength of it comes from its shape rather than the pieces. The plate frame is not very labour intensive but is far more difficult to assemble and requires far more "fiddling" to get just right. The plate frame is however far easier for the small modeller to handle -up until the last few pieces of a bar frame are in place -it is all rather delicate...
The chassis rails have been soldered together and the assembly epoxied to the base of the 'S' motor. You can see the horn blocks in the horn guides.
The shot below shows the grease boxes (U shaped channels of Aluminium) have been bonded to the horn guides. They will be bolted with 2mm nuts and bolts to the hornguides hopefully by the end of this week. The bottom bar of the chassis frame has been fitted and it holds the horn guides against the pressure of the springs. These sit in a typical home made assembly of: 6mm washer, spring, 6mm washer, length of brass tube, 6mm washer. The central shaft is 4mm brass tube tapped to 2.5mm and the this is then bolted through the grease box. The shaft is "damped" by having the brass tube above (which it slides up and down in) packed with greased felt. The net result is not unlike an inverted "McPherson Strut".
I had some fun and games with Hookes Law working out the suspension springs... The bogie has to have more pressure at the rear, the combined forces of the front bogie plus the external power axle must equal the force on the internal power axle!!! (There are times when I wish I was 15 again -I remember it as all being so easy)...
The two motors have been fitted to the cab these have been installed transversely and will drive the power axles via cogged belts after having been stepped down 8:1 with gearing. A version of the "Silent Block" soft start system to ease the strain on the take from the motor will also have to be fitted. But as I have done this before on my EF-1 it is not going to be that hard -except for the space limitations!!!
Today is Friday the 13th.... This simple fact explains why so much has gone wrong today!!!! I blew up a motor -this has never happened before and these particular motors I am very well versed with. I also seem to have lost my temperature controlled soldering iron -not much you may think -but it is about 30cm square...
Anyway enough with the gripes -back to the Build Log.
As I am now down to one motor I have had to re-jig the drive system. The motor drives a 15 tooth spur to a 60 tooth spur, on the same shaft is an 8 tooth sprocket. This then drives, via a ladder chain, a 16 tooth sprocket. The final drive to the wheels is taken from this shaft. The net reduction is 1:8 which is, I think, still a bit high and I am contemplating dropping it down to a ratio of 1:16 by interspacing a second 8 tooth sprocket on the output shaft and then taking this down to the drive axle system.
According to Henry Greenly a ratio of 1:6 is quite adequate for a 2 1/2 inch gauge loco, but I do rather like my locos to run slowly and smoothly... After having played around a bit with 16mm models I am actually quite amazed at how different the Gauge 3 models are. The scale is smaller but the gauge is larger. The sheer MASS of a Gauge 3 model is at least 10 times that of the typical 16mm model that I have built. Even without its SLA power bricks the model weighs in at 2Kg easily.
I will need to step down the final drive to 1:16. The the maths shows that the torque curve from the single motor is wrong for starting from a standstill. If I simply increase the voltage the 'S' motor will take off like a scalded cat -rather than smoothly accelerating to its final velocity.
But I did however find my soldering iron -it was in the oven...
The shot below shows that some of the power and lighting wiring has been installed. The power is taken from two 6 volts SLA batteries arranged as +6 and -6 volt line feeds, (there is a reason for this!)
Above the piece of tag board there is the main power fuse (6 Amps) in the line between the two batteries on what is (nominally) the Zero Volt line. I have used my std colour coding for the wiring -which may look a little strange to other eyes...
Red and Black are negative and positive DC.
Blue and Yellow are DC lines of variable polarity -but always of opposite polarity.
Green and Orange are '0' and '1' TTL voltages.
The relays all use 12 Volts.
The Motor uses 0-6 Volts fed from a serial controller.
The serial controller is fed from a 12 Volt line.
The lighting LEDS are 5V and hence all use TTL.
When the loco reverses the relay flips the DPDT relay on the supply line to the lighting circuit and all the lighting LEDs that have been forward biased turn off and those that are reverse biased -turn on(!)
The reason I am using a relay is the fact that the LEDs are all running from a 5Volt TTL line and if I simply connected them to the 12Volt line the voltage would swamp the diode effect, and they would conduct, (for a "short" while....) The ditch lights/stop light LEDs are a dual red/yellow LED with three legs and a common anode.
I also prefer to isolate and test individual circuits -which I can do very easily with a relay. You can feel a relay "clunk" something you cannot do with bistable flip flop chip!
The morning post has delivered all the wheels required for the 'S' Motor. So on the kitchen work top there are eight 42mm wheels and eight 32mm wheels (2-D0-2). All have been supplied as seperate wheels and axles, (as I requested to Brandbright).
The next job is the drill the axles on the 42mm wheels to take the 3mm bolt that will act as the "pin" to the pairs of 16 tooth sprockets that will be assembled around it. The 32mm wheels will be the wheels for the front and rear bogies. These will be of the "compensated" type with the compensation springing being a torsion bar and there will be no vertical springing. This will force all the weight of the loco onto the eight driving wheels.
This is the time that I really have to decide wether I want to fit an English type "instanter" coupling or a US style "knuckle". There are pluses and minuses to both answers... If I fit an "instanter" then it is in keeping with the period and premise of a Colonial Railway and all my wagons and carriages will couple to it! If I fit a "knuckle" then I would have to build a converter wagon -but I would know that it was correct!!!
At the end of a feverish bout of activity on a wet and windy Sunday Afternoon -don't you just love the "English Summer".... The 'S' Motor now sports four completed drive axles and sprocket assemblies. The axles were drilled by the usual trick of placing a scrap of plywood on top and drilling through that -to prevent the drill from "wandering" as it bit into the curved top of the axle.
The sprockets were step drilled up the required bore of 6.5mm and then fastened around the 3mm bolt with cross 3mm bolts. This gives a "cage" assembly that will rock slightly. The "take up" of the cage is damped by it having rubber grommets bear on the pin -sort of a "silent block" set up!!!
The following shot shows the 'S' Motor sat for the first time on its wheels -the chassis is not loaded with the batteries so sits slightly "up" from where it will normally stand.
Here is a, (slightly blurry -sorry!), shot of the underside -showing the dual chain sprockets and the axles.
Fitting the wheels to their axles is now routine. As they are a "taper fit", I would imagine you are supposed to either have to compress the wheels onto the axles with a press or a big bench vice. My method uses two reels of solder and a 5Kg sledge hammer, dropping the head onto the top reel from 1 metre height ensures a perfect fit first time!!!
Another Sunday afternoon has passed and I have been hard at work... The front and rear bogies are complete (but they will need some work in the artistry dept). They are at the moment just raw offcuts of brass sheet with holes in the right places, later this week I intend to treat them to a grind wheel and a pierceing saw to make them more realistic. They are fitted to the front mounts with 4mm bolts and some twiddling was needed to get them to have "just the right" amount of play in them.
The LEDs have been wired up to the roof relays, the feed from the main power switch energises the fwd/rev and lights relay as well as the ESC. Thus there are no live circuits when the power switch is "off". I will admit though that I have blown more than a few fuses this morning...
Although it is not very clear from this shot the front white LED and the Ditch Lights are "on"
Here the reverse has been selected and the stop lights are "on"
A little tidying up and the model is now ready for the paint pots!!!
A couple of months have passed since the last entry and "Maude" has been painted, (but not detailed yet), and she has even been out on "Pukkha" Gauge 3 track at a Gauge 3 Get Together.
Here is Maude in her Lilac.
And here she is at the "Get Together".
Here is the drawing that I used to build her with.
The drawing is scaled for 13.5mm to the foot.
I am grateful to Mr. Scott Baxter for a photograph of the original "Maude" NYC 6000. It still exists -but alas in a very rusting condition with boarded up windows and doors. He cannot remember who took the photograph but we do at least know when and where...
