Hello again. I'm considering purchasing Bachmann's DDA40X - the DCC-equipped model recently released.  I read that it comes with two motors, but only 12-wheel drive as opposed to 16-wheel drive.  Does anyone have any insight as to why Bachmann didn't just make it all-wheel drive like the older Spectrum models?  Also - is it 16-wheel electrical pickup?  I'd like to know this stuff before buying.  Thanks so much!

Quote from: Sasha on May 29, 2012, 07:03:43 PM
Hello again. I'm considering purchasing Bachmann's DDA40X - the DCC-equipped model recently released.  I read that it comes with two motors, but only 12-wheel drive as opposed to 16-wheel drive.  Does anyone have any insight as to why Bachmann didn't just make it all-wheel drive like the older Spectrum models?  Also - is it 16-wheel electrical pickup?  I'd like to know this stuff before buying.  Thanks so much!

Obvious Man told me cost, it should be obvious. The loco is so long, the wheels with pickups are quite a ways apart.
To my knowledge, all the indicated wheels will pickup or everyone would be asking the same question about all the Bachmann locos.

Rich

I don't think it's obvious... they already had the towers from the Spectrum models - why spend the money on engineering an entirely new tower (especially when the new one isn't as functional as the one it's replacing)? I don't mean to say anything against the new locomotive, I'm just asking the questions. I'm really interested in buying one before my preorder for another version of the train is released.

My question is - What difference does it make 12 or 16? It has enough pulling power.

16-wheel drive locomotives have an inherently better adhesion to the rails. I just want to know a few things before I buy. It makes a difference to me.

Thanks. 

I have the new version with factory Dcc and it is all wheel drive. All 4 axles on each truck.
For power pick up it only has 2 axles with pick up on each truck. They are the ones spaced the farthers apart. The pick up strips  runs the full length of the truck so it wouldn't be hard to add more but i don't think you will need them.
If you want to increase pull there is plenty of room inside to add weight. With 2 motors this should be no problem.

Bob

Thank you, Bob. I wonder why some retailers advertise this locomotive as "12-wheel drive"? Their mistake, their loss, I suspect.

This made my decision to purchase a lot easier and I appreciate your useful reply.

Sasha,

QuoteI appreciate your useful reply.

My question was not meant to be demeaning in any way. I was wondering myself as I watch a friend of mine's DD40AX has extremely good pulling power and I can not believe 16 vs. 12 would make any difference on this loco. You won't be disappointed with it if you plan on pulling a load.

Jerry

Jerry-

I didn't think your response was intended to be a put down but I did wonder if it might be taken that way. Partly that's because of the way you worded your reply, but mostly it was because there are a few sarcastic and/or condescending inhabitants of the board who are offensive and snide with their responses, although not outrightly aggressive. (Too honest for them?). I think they tend to taint all of us when they work their unpleasant manner on newbies or those with the temerity to ask questions which are (as they see it) far to stupid to warrant common courtesy.

These folks are especially likely to do their dirty work when the question is elementary, easily answered by the OP's own Google search or manual reading (they may have a point here at times), or just generally below their dignity. Sometimes they set their responses for a quick disappearance so an OP who doesn't seek their wisdom immediately is denied their munificent words. They may complain later about a lack of feedback from the OP although the OP may not have come back quickly enough to even have seen the reply, much less test it and report back. Sometimes these posters just make a borderline rude referral to Google and sometimes they give answers which appear to be crafted by or for Yoda: indirect, arcane, vague and with the implication that they have some special knowledge which persons outside of their lofty sphere will never truly understand or appreciate. I suspect you know who I'm referencing but I'd bet my eye teeth those posters themselves don't. My belief is that they hold themselves in such high regard that none of this would remind them of who lives inside their skin with them.

NB: No, I don't dislike Yoda, although I do think he'd be more of a mensch if he'd use a simple declarative sentence now and then. Yoda's style works great for the little fella; he comes across as sincere, wise and tolerant of the less well informed. Yoda's style used on this board, however, strikes me as artifice, self-importance and a fundamental lack of good upbringing.

Soapbox broke. Gotta get off now.
                                                            -- D

sasha,

if i have read your posts correctly, you intend to operate your trains on a closed loop with no grades. in that case, whether your locomotive has 12 or 16 wheel drive won't make a difference . here's why:

consider my bachmann gp7. it has 8 wheel drive. i have a grade of 4% on my layout, which effectively gives this locomotive 1/6 the pulling power it would have on level track. it can pull 7 or more cars on this grade. that is the equivalent of 42 cars on the level. with ONLY 8 wheel drive.

most cars to-day come with plastic knuckle couplers. at some point, the weight of the train will cause these couplers to fail. plastic is simply not as strong as the metal aftermarket couplers many of us use. what the point of failure is i don't know offhand. but, longer trains are alsoprone to derailments on curves (stringlining) or due to slack action when starting or stopping.

some experiments i did with my dad and grandfather in the 1970s may shed some light. we did successfully run a 60 car train on my grandfather's layout. however, to do so required locomotives to be placed throughout the train to keep the train from stringlining on the (24"r) curves. on my dad's layout, we also tried backing a 40 car train. the results were disasterous, even on carefully laid track. it should be noted these trains used metal couplers on all cars.

thus, my recommendations are to run no more than 40 cars, which a single gp7 will pull on level track. your dda40x will have no problems doing this.

Quote from: jward on May 31, 2012, 12:49:50 PM
most cars to-day come with plastic knuckle couplers. at some point, the weight of the train will cause these couplers to fail. plastic is simply not as strong as the metal aftermarket couplers many of us use. what the point of failure is i don't know offhand.

I knew that couplers like the McHenry et al were plastic and not metal like the Kadees, but fail?  As in the knuckle comes apart, like real trains occasionally do?  Due to weight??? 

I would have thought that the plastic couplers would have been sufficient to pull pretty much anything that wouldn't derail, especially on most relatively imperfect model railroaders' track.

I think most of us are lucky to have 15 foot long passing sidings and yard tracks. If I punched my calculator correctly, that's about 25 older freight cars or maybe 12-13 passenger cars inclusive of motive power necessary to get such a train up a reasonable model railroad grade (say, 3-4% compensated?). Under conditions such as this, say, 25-30 freight cars on a grade with all the power at the head end, how far from breaking the couplers are we?

with 25 car trains you won't exceed the strength of the couplers, even on a 4% grade.

coupler failure can come in two forms, due to train weight. in n scale, i noticed a problem on trains of over 50 cars, where the plastic knuckle couplers would ride over each other and ciome apart. often the pulling faces of the knuckles have a mold taper from the center of the knuckle, upward and downward  to the top and bottom of the knuckle. under strain, the knuckles try to slip past each other. it was enough of a problem that micro trains designed a "reverse draft angle" coupler whose pulling faces are concave. a quick solution would also be to file the pulling faces flat, to eliminate the taper altogether.

which brings us to the next problem. under extreme weight, the plastic knuckles have been known to actually straighten under load and release their grip on the next car.

both of these problems can be eliminated by either running shorter trains or switching to metal couplers.

Thank you guys for the replies and discussion.  The truth is: my loops are a little size-restricted, particularly the inner tracks, but I am still going to run big Union Pacific power on all five lines.  I won't be running any record-breaking freight consists, but I just like to know that my engines won't be too labored.  At the moment, I won't be constructing any grades or bridges.  That can always be changed, though.

Thanks again for the talk.  I love reading all the knowledge!

Quote from: jward on May 31, 2012, 01:45:06 PM
with 25 car trains you won't exceed the strength of the couplers, even on a 4% grade.

coupler failure can come in two forms, due to train weight. in n scale, i noticed a problem on trains of over 50 cars, where the plastic knuckle couplers would ride over each other and ciome apart. ... which brings us to the next problem. under extreme weight, the plastic knuckles have been known to actually straighten under load and release their grip on the next car.

Well, 50 modern freight cars is about 32 feet including motive power, 25 feet with older 40' cars. (Obviously I'm working with HO here.) Those lengths strongly imply a mainline run of over 600 feet, which is pretty unlikely for me given "only" about 600 square feet in the layout rooms.

For those of us in larger scales than N, is there realistically much risk of coupler failure on the types of trains we can run on less-than-hyperbolic sized layouts?

The majority of my rolling stock has Kadee couplers, but to be blunt since I have not had a lot of trouble on the limited amount of track I can run now, I haven't been replacing couplers that seem to work well. I haven't liked the looks of the ones that come in AccuRail kits, so they get Kadees right as they get built, but for example the ones that Branchline use seem pretty good once the heights get resolved properly.

i would say that yes, there is that risk. n scale cars are relatively light compared to the much larger HO cars. i don't know about anybody else, but i tend to weight my cars heavier than nmra standards. free rolling trucks counteract this additional weight somewhat, but it is still a factor to be considered.

while i agree with your calculations on train length, i don't see how you got the figure of 600 feet of mainline for the layout they would run on. very few of us have 600 feet of track in the entire layout, let alone as a mainline run. on the railroad we experimanted with a 60 car train, the mainline run was 89 feet long.