Wright writes.....

[Enterprisingwestern]

 

 

 

 

The main thing is the layout works, and works as 'perfectly' as I could hope for. I hope visitors will testify to that, always accepting that the limiting factor is me, and my making too many mistakes.

 

Isn't that the whole point of the hobby?

 

Mike.

[corneliuslundie]

I think two things have been missed in the DC v DCC debate.

 

First, DCC has the advantage that there is a constant 16V being supplied to the loco, rather than a variable voltage which one increases from zero, to the point where the loco will start to move, and then increases to achieve the required speed. This means that pick-up should be more reliable for DCC.

 

Secondly, there are cases where DCC is the only option. I mentioned earlier that I had attended a meeting of the American Railways modular group. That meeting would simply not have been possible without DCC. Each module had a standardised two wire connection to adjacent modules. It didn't matter what the modules were, who had built them or anything else. And yes, my son operated the loco he was running from his phone. Which was just as well as we roamed around a large room following it.

 

I have also operated a large BR WR layout which uses DCC. While it made it easy to operate I didn't see any advantage over DC for this layout. And the same applies to "Down The Line", a excellent WW! layout which was at our show last Saturday.

 

Three other comments.

 

First, I am not enthusiastic about sound. But it can have its place (though not usually at the next stand to your at an exhibition!)

 

Secondly, those juicers do have a role though not I believe simply to power crossings. My son's module at the above mentioned meeting had a diamond crossing of two running lines for which he used a juicer, obviating any need for manual switching, though it is really a fudge which relies on detecting a short circuit caused by a loco arriving to put things right, so to speak (have I got that right?), not a technique either he or I really like. 

 

Thirdly, I was always told that Portescaps need pure DC, which is why the Pentroller was developed and is what I use.

 

That said I have no intention of using DCC myself because I simply do not see any advantage for the type of layout I am likely to build.

 

As said above, it is horses for courses, like OO/EM/P4. 

 

And I am glad to hear about someone who once used Wrenn fibre based track. I started with the three rail version of this so I could run my AC Trix Twin locos, and wired the layout so that it could be operated three or two rail, though I jumped over Hornby 3-rail to straight 2-rail. Now Trix Twin - that was an interesting system to operate where dirty track could lead to the loco stopping or even instantly reversing. For those less than a century old, like DCC it had a small constant alternating current to the track, and interrupting the current turned a small commutator which was used to reverse the wiring of the AC motor.

 

And finally (didn't someone called Paul use that phrase rather often in his writings, usually about half way through a letter?), on wiring. I have always advocated using colour coding for wiring, and of course writing down what one has done (but where do you put the piece of paper so you can find it later?), only to be brought up short at the local club by two groups. The first is really only one person but he is colour deficient. The second is several ex GPO engineers who swear by numbering everything and won't touch colour coding because their experience is of the multiple twisted pairs in GPO cables which have the colours repeated frequently. My problem with those little plastic numbers is that they seem to have a habit of dropping off the wire as soon as you turn your back and disappearing down a crack in the floor. Is there a better way?

 

And really finally, lovely to see some wagons on this thread.

 

Jonathan

[LNER4479]

Talking of wiring, i briefly mentioned my Carlisle layout project, when talking about foam sprung track a few pages back. Well here are pics of the main control panel, the whole thing is about 6ft long, divided into three sections. There are also other mini panels for Canal Shed, Canal Yard and Upperby Shed. There's a scaled-down and fictitious version of Kingmoor Shed by the l/h ammeter on the main panel. The layout was built on two levels, passenger lines and Citadel station on top, goods lines below and underneath, with connecting lines and branches to both levels. Who needs DCC?!  :-))

                               Cheers, Brian.

 

CarlisleCitadel003 - Copy.jpg

CarlisleCitadel004 - Copy.jpg

CarlisleCitadel005 - Copy.jpg

Ah c'mon now Brian - you're getting to be a tease. Layout photos required please! (ideally on its own thread). I intend Carlisle to be the basis for my own 'one day, last great project' layout.

[Focalplane]

I am reasonably sure that some RTR DCC locos come with a switch.  In fact I think I own one or two in my HO Southern Pacific collection.  This allows the locomotive to bypass the decoder if run on a DC wired layout.

 

The problem for metal kit builders is that there is no ready to buy piece of circuit board that could emulate this.  It would be simple enough to design and produce but the market for it is probably too small to justify the economics.

 

For what it is worth I have successfully added a DCC chip to a Bachmann split chassis Royal Scot (original Fowler).  Here is a post to prove it:

 

http://www.rmweb.co.uk/community/index.php?/blog/1565/entry-14968-an-old-scot-gets-dcc/

 

I note that I said there is no such thing as a locomotive that cannot be converted to DCC.  I still stand by that.  The term DCC Compatible actually should be interpreted as "Easy to add a decoder".  Note that the TCS decoder I installed is a relatively large one but it has a plug and socket, so it would be very easy to remove the decoder and replace it with a plug that connects the wires from the pickups directly to the motor terminals.  I haven't done this because I haven't needed to.  But I could!

 

Most modern RTR locos have a DCC socket, either in the tender or inside the boiler.  "DCC ready" means there is a blank plug of exactly this description sitting there.  But some disassembly would be required each time a change of DCC to DC was needed.  The switch referred to above obviates this.

 

I hope this helps?

[Allegheny1600]

4, Do any kit manufacturers supply the 8 or 21 pin socket and wires for installation or do the chips have to be hard wired? 

 

8, Most important, have some FUN with your modelling. 

#4 You can certainly buy 6 or 8 pin sockets pre-wired, which is what I always use if there is space available.

Why hard wire a socket in?

Not all decoders are the same and one make will run one loco better than another*, the socket allows you to easily swap out decoders.

#8 I totally agree!

Cheers,

John E.

 

* I don't have the neccessary knowledge (skill) to alter any of the CV's required to modify 'motor characteristics' and if I did, I'm still sure that one decoder manufacturer does differ from another. All I can really say is that the higher quality decoders do give better performance!

[Brian Kirby]

 Please, all of you, feel free to destroy any of these. 

 

1. Compensation/springing makes no difference to what a locomotive will pull, but it could improve pick-up. Weight is all-important in haulage ability.

 

2. It is not a good idea to run a DC locomotive on a DCC system. 

 

3. Not all DCC systems are compatible (though in the case of the Heljan chip frying, I think that was more because of the chip's temporary installation than the system).

 

4. Most locomotive kit-builders I know of do not like the 'fuss' entailed in installing decoders in all-metal locomotives, be they for clients or for themselves. 

 

5. Fiddle yard wiring (where function/reliability is paramount) can be installed quite happily surface-mounted, as long as its neat, doesn't snag and doesn't catch on passing trains. In fact, surface-mounted point motors and micro switches are highly-desirable, especially as one gets older. 

 

6. It's preferable if one can do most of the wiring/installation jobs oneself (even if it's not completely understood). The same is so for making locos and installing decoders, and laying track/installing signals. These are things which have to work properly and be maintained so they continue to. Structures and scenery do not have to 'work', other than visually, so those who commission work by others and/or who aren't members of a team can rest easy with the latter. However, they're a hostage to fortune if the former items go wrong. 

 

7. There should be a great vote of thanks given to all those who've contributed to this thread with so much knowledge.

 

8. Any more?

 

In answer to Q1: I disagree, the more wheels touching the track is better for adhesion, current collection, allows for twists in the track and above all, rides the more smoothly. Just push a compensated coach over joints, bumps and pointwork, it feels smoother. Just like when we were kids riding our bikes, on encountering rough terrain, we would stand on the pedals, thus compensating our bike chassis for a smoother ride, with the bottom bracket acting as the central pivot. With a rigid chassis on badly twisting track, it will encounter the tipping point, where it rocks to the opposite side (and back). I would never say compensate everything, i'm no chassis snob, but some wheel arrangements cry out for "a bit of give", notably 0-4-4Ts, back in the old days when far more people built kits, problems with the latter were known as suffering from "ohfourfouritis". There must be an equation as to whether the stock needs compensation/set against the extra complication and time required to build it - i.e. Is it worth it in each case? I've never liked fully sprung chassis, being akin to a kid's "bouncy castle", but the odd sprung axle, beam or pivot does help.

 

In answer to Q2: Firstly, if you place an analogue DC loco on a DCC layout using the '0' address, the high-pitching whining noise is caused by the motor armature vibrating, you can get away with limited running, but it's not good in the long term.

 

In answer to Q4: Fitting chips is straightforward, minimum only four wires to connect, slightly better (and safer) on dead chassis, older chips with plain wiring easier for kit installation, although modern chips are smaller, insulation is easy, most now come with rubber sleeves, biggest problem is always where to put the damned thing? I've always held the view, that DCC is more appropriate and useful on modern diesels and electrics, with their cab and headcode lights, etc. Can't remember the last time i saw a 4mm kitbuilt steam loco with working lights, older chips could never handle the current of a smoke unit, and had to be by-passed, so a regular chip was only used as a command address (although your coach lights will all stay on). However, there's a better case for steam with chips, if you want working sound, lots of modern RTR is now designed to accept it, but kit conversion is tricky, just where do i put that speaker?

 

In answer to Q5: Hmmm! When you had your central heating installed, were all the pipes kept above the flooring, or were they neatly concealed below the floor? The Romans were even neater, they didn't bother with radiator panels and water, they hid everything below the floor. On the other hand cabling on prototype railways is invariably positioned above the baseboard, so i suppose there's an argument for both methods?

 

I agree with everything else!

                                                            Cheers, Brian.

Edited October 26, 2015 by Brian Kirby

[polybear]

My greatest thanks, Andy,

 

As for the new motor/gearbox Phil describes; this was brilliant. The prototype was fitted to a King which passed through my 'shop'. After minor chassis/pick-up adjustments, it ran superlatively

Hi Tony,

 

I believe Comet Models went to Wizard Models ( a.k.a. "Major Clanger" on RMWeb). Do you have any idea what became of this motor/gearbox design? It would be sad if all Geoff's work on the design has been lost.

 

Brian

[Horsetan]

..... Do you have any idea what became of this motor/gearbox design? It would be sad if all Geoff's work on the design has been lost....

The gearbox, ref. MG1, with a Maxon coreless motor attached, should also have passed to Andrew Hartshorne at Wizard Models along with everything under the Comet name. The gears were crossed helicals plus spurs, supplied specially by ABC Gears, who are known more for their 7mm scale work.

 

The size of the gears was such that the assembly would only really fit large engines such as the Duchess or Princess, but it was definitely a step in the right direction of having an efficient drivetrain and strong coreless motor.

[corneliuslundie]

"On the other hand cabling on prototype railways is invariably positioned above the baseboard". Really?

 

A pity they didn't do it on the GW main line some 30 years ago. If they had they wouldn't now be hand digging holes for electrification masts because they don't know where cables are buried. At least we don't have that problem.

 

Jonathan

[Brian Kirby]

"On the other hand cabling on prototype railways is invariably positioned above the baseboard". Really?

 

A pity they didn't do it on the GW main line some 30 years ago. If they had they wouldn't now be hand digging holes for electrification masts because they don't know where cables are buried. At least we don't have that problem.

 

Jonathan

 

Looks a lot neater buried though dunnit? I s'pose burying cables also puts off the wretched cable thieves, at least we don't have that problem in 4mm? Whatever happened to "Mercontrol" point operation (25g steel wire in copper tubing, also with cranks and lever frames), it used to be all the rage in the 1960s and 70s, for remote hand or motor operation, did it disappear with Gem?     BK

[glo41f]

I never tire of the (in the main) erudite and learned topics on this thread. So many things I can identify with. (I too have had Portescap motors "fry" and it is not funny as the whole unit has to be replaced. On the DCC topic I have to confess to being impressed with the technology involved especially when sound is used well. (I do think that sound on steam outline locos is often weak as it is difficult to synchronise the chuffs with the wheels and I have yet to be convinced of the sound of a three cylinder type). I have also witnessed  expensive chips go up in smoke to the chagrin of the loco owner. However, I cannot help but feel that DCC is a halfway house as it still is dependent on the Achilles Heel of model railways namely the need to pick up current from the track. The way ahead must be for the prime mover units to be self contained as to power with batteries or some other (yet to be discovered) method of transmitting power over the ether to the model from a control unit. Only then will our trains replicate the full size article and we will be released from the chores of cleaning wheels and track and rummaging around under baseboards for loose wires etc. in an attempt to get things running. As a complete numpty with regard to electrics, (I lost it when the power connector clip came in with Tri ang Series 3 track system!), I cannot help being in admiration of you chaps who understand the world of wiggly amps and can get it all right. 

 

Please  carry on with my education chaps.

 

Martin Long

[The Stationmaster]

"On the other hand cabling on prototype railways is invariably positioned above the baseboard". Really?

 

A pity they didn't do it on the GW main line some 30 years ago. If they had they wouldn't now be hand digging holes for electrification masts because they don't know where cables are buried. At least we don't have that problem.

 

Jonathan

They did do it on the GW mainline 60 years ago and earlier, then from the late 1950s in new work it went into concrete troughing in the cess or trenches well away from the cess, trouble is someone is else came along and buried teh troughing or the markers used for trenched cable.

Looks a lot neater buried though dunnit? I s'pose burying cables also puts off the wretched cable thieves, at least we don't have that problem in 4mm? Whatever happened to "Mercontrol" point operation (25g steel wire in copper tubing, also with cranks and lever frames), it used to be all the rage in the 1960s and 70s, for remote hand or motor operation, did it disappear with Gem?     BK

 

Most recently has been PTFE tube with steel wire, and although Hamblings and GEM were always the main proponents of Mercontrol you can still buy Mercontrol branded components and GEM lever frames (which are nowadays built around cast instead of pressed metal) components.  

[AndyID]

In answer to Q1: I disagree, the more wheels touching the track is better for adhesion

 

 

Hi Brian,

 

Yes, that seems to be a common misconception. It would be nice if that were true though.

 

The total traction only depends on two things: The coefficient of friction between the wheels and rails which is different for different materials, and the total force pressing down on the driven wheels (and that's the result of gravity and the weight of the locomotive).

 

When you add more wheels you are sharing the total traction over a larger number of wheels, but the total remains the same. Of course, if you add a wheel with a very different coefficient of friction (e.g. rubber) it will make a huge difference to the traction.

 

Cheers!

Andy

[Brian Kirby]

I can see your argument, but i'd rather have all wheels down on the rail, when negotiating twisted track, rather than have an odd wheel flying through the air doing nothing (if you'll forgive the exaggeration, it's barely perceptible). It also depends on where, and with how much, weight is bearing down on the axles. One complication with a compensated chassis using bars, is too often there is not enough weight at the fixed axle end, which will cause wobble and loss of contact. Where wheels are out of contact with the rails, this will cause sparking, which in turn attracts dirt, witness for example the front drivers on the RTR Hornby M7, where insufficient weight is pushing down on the front axle and the whole thing rocks on the inner driving axle (we're back to rigid "ohfourfouritis" again).

 

                                                                           Cheers, Brian.

[billbedford]

1. Compensation/springing makes no difference to what a locomotive will pull, but it could improve pick-up. Weight is all-important in haulage ability.

 

 

Not true. For about 15 years before 2001 the Scalefour Society ran a competition which was aimed at improving the performance of locos (the Deputy Chairman's Cup). Part of this competition tested the drawbar pull as a percentage of the adhesive weight. I found the results for 1997 an these show that the drawbar pull varied between lest 10% to over 25% of the adhesive weight.

[Izzy]

As regards layout wiring, whatever the system used, DC or DCC, I do firmly believe that it is best if the layout owner(s) wire it themselves or at least understand how it is wired. This goes back many years to a time when as a teenager I joined a local model railway club. They were engaged at the time in constructing a fairly large layout depicting a local line, and on low wages I and a friend were unhappy that all the 'subs' we paid were being spent on the complicated and expensive electrical controls which were being undertaken by one individual because he was 'clever' and seemed to be the expert in such matters.

 

Of course you can probably guess what happened. He lost interest and left the club to do other things. Despite several attempts no one else at the club had the slightest clue about how to complete the wiring, nothing could be run on what had been made to that juncture, and eventually it transpired that the whole lot got scrapped. Both of us were appalled at this outcome, seeing some of our meagre hard earned wages wasted in such a manner, that we left the club, and vowed never to belong to another. Although my friend later ran/owned a model shop for a good few years and I have fiddled about making the odd loco for others I don't believe that either of us ever have

 

I recenty read an account of a similar present day situation. Circumstances that I feel need preventing whether the layout belongs to a club, or an individual. Building any layout takes considerable amounts of time, energy, and money and none of it needs wasting because of such an occurrence.

 

Izzy

[billbedford]

Yes, that might be the case for a locomotive with multiple independent traction motors, but I'm referring to model locomotives, and not too many of them have multiple motors. 

 

The same is true of the coupled wheels of ta steam loco, either model or full size. 

 

Consider the force between the rail and the lightest loaded wheelset.

 

The maximum force that the wheelset can apply to the rail is given by the weight on the wheelset x the coefficient of static friction.

 

If this maximum force on the wheelset is exceeded, the wheelset slips, and the coefficient of friction changes from static to sliding and the force exerted by the wheelset drops.

 

Since the driving force doesn't change, the difference between the maximum and the new sliding force the wheelset can supply is divided between the other wheelsets.

 

If the force transferred from the slipping wheelset brings the next lightest loaded set above the maximum adhesive force, then that wheelset will slip too. And so on until all the axles are slipping.

[Theakerr]

To add to the DC vs DCC debate, I suggest we need to look into our respective crystal balls.  At the rate technology is advancing I suggest that in 10 years our locos will be battery powered.  Said locos will either use direct inductive charging (as the loco runs) or direct charging from some sections of powered track where only two wires really WOULD be the case.  The technology is actually with us today in the developmental stage (see this forum).  I will not list the advantages because they are so obvious, but as an example the exit from Newcastle with all the curved crossings could actually be made to work.  Also since track contact would be a low order priority it might even eliminate the need for compensated chassis.   Thats my crystal ball anyway

Edited October 26, 2015 by Theakerr

[AndyID]

 

Since the driving force doesn't change, the difference between the maximum and the new sliding force the wheelset can supply is divided between the other wheelsets.

 

 

Hi Bill,

 

I see where you are going, but because all the driven wheels are synchronized, either by gears or coupling rods, they are all now experiencing sliding friction. The opposite is also true. If the coefficient of friction drops at one wheel due to contamination for example, that wheel can be prevented from sliding/slipping by the other wheels.

 

It's really a bit more complicated than that anyway. If the locomotive is running on curved track, the wheels are all slipping to some extent - not much of course, but it's not exactly static friction either.

 

Cheers!

Andy

[newbryford]

 

 

Most modern RTR locos have a DCC socket, either in the tender or inside the boiler.  "DCC ready" means there is a blank plug of exactly this description sitting there.  

 

Most of my RTR locos have a decoder socket, but as they don't have either a tender or boiler..........

 

 

Cheers,

Mick

Edited October 26, 2015 by newbryford

[newbryford]

Looks a lot neater buried though dunnit? I s'pose burying cables also puts off the wretched cable thieves, at least we don't have that problem in 4mm? Whatever happened to "Mercontrol" point operation (25g steel wire in copper tubing, also with cranks and lever frames), it used to be all the rage in the 1960s and 70s, for remote hand or motor operation, did it disappear with Gem?     BK

 

Only once used motor operation with mercontrol. There was so much friction in the system that only the large H&M motors would work with it. The lights in the room used to dim as each point motor was fired.

 

Cheers,

Mick

[AndyID]

Not true. For about 15 years before 2001 the Scalefour Society ran a competition which was aimed at improving the performance of locos (the Deputy Chairman's Cup). Part of this competition tested the drawbar pull as a percentage of the adhesive weight. I found the results for 1997 an these show that the drawbar pull varied between lest 10% to over 25% of the adhesive weight.

 

Hi Bill,

 

I don't doubt that they saw improvements, but unless they went to considerable lengths, the causes for the improvements might have been obscured.

 

It would be interesting to see the test setup. Did they take a particular locomotive and run it both with and without suspension and ensure that nothing else had changed that might have affected the coefficient of friction? Did the locomotives have additional carrying wheels (bogies etc.)? Did they run the tests in both directions?

 

Suspension can also make a big difference to electrical contact. To make sure contact has nothing to do with it I would like to see the tests run with the motors hard-wired to the controller.

 

Cheers!

Andy

[Tony Wright]

Not true. For about 15 years before 2001 the Scalefour Society ran a competition which was aimed at improving the performance of locos (the Deputy Chairman's Cup). Part of this competition tested the drawbar pull as a percentage of the adhesive weight. I found the results for 1997 an these show that the drawbar pull varied between lest 10% to over 25% of the adhesive weight.

Thanks Bill,

 

I too remember the Deputy Chairman's Cup. If my memory serves, part of the competition involved a loco negotiating an obstacle course consisting of out-of-gauge track, out-of alignment track, inconsistent radii and other such impediments. I seem to recall it was 0-4-0s which did best at that. One year there seemed to be a prize for how slowly a loco could travel without stalling, the winner being the one which took the longest to travel, say, a yard of straight track. Since I know of no CME who was knighted for how slowly his locos could travel, it seemed a bit futile to me.

 

May I ask this question, please? Why does my fully-compensated WC not pull as much or slip far more readily than the rigid chassis one I built using exactly the same kit, weighted to exactly the same amount, with exactly the same motor? 

[bbishop]

About a year ago, Tony and I conducted a civilized debate on this thread regarding the pros and cons of DCC.  Our final position was that we happily agreed to disagree.

 

Something that hasn't been considered this time, is the simplified wiring that can be achieved with DCC.  My German prototype exhibition layout (Höchstädt) is 100% DCC.  Droppers connect every piece of track to the DCC busbar, then the layout is set up as follows:

 

1. check that all the Cobalt point motors have three wires attached

2. set up boards

3. connect the DCC busbars with blue and red banana plugs and sockets

4. connect the DC busbars with green and orange banana plugs and sockets

5. connect the AC transformer and Lenz box to the layout

6. connect the ExpressNet

7. connect the DC transformer to the layout

 

Stages 3. to 7. take about five minutes, and I've never had to lie under the layout with a hot soldering iron.

 

Bill

Edited October 26, 2015 by bbishop

[Brian Kirby]

 

 

May I ask this question, please? Why does my fully-compensated WC not pu as much or slip far more readily than the rigid one I built using exactly the same kit? 

 

I think you are in need of a good plumber Tony.

 

On a serious note, assuming your compensated water closet has one rigid axle (for the gearbox), the chassis will require more weight at that end. I assume you are not pulling our chains, whilst flushed with such success?    BK