With the rambling on another thread I thought I would start a separate thread with a single topic.
What are the criteria for best locomotive drive and why. Let’s keep this thread to steam to keep the thread on a single topic. We can do diesel later.
For example criteria mght include: power, gear ratio, reliability, performance…
Once we collect the criteria it might be interesting to compare the commercial locomotives currently in the marketplace to the desired criteria.
Stan Ames
The only criteria I have is no matter what it cost it should work "WITHOUT FAIL " out of the box period.
Stan,
good topic discussion, but really a little subjective. Firstly, what do we want from a drive? Do we want it to scale like Bachmann products of late or more ‘functional’ like Aristo-Craft drives?
Secondly, do we want it prototypical in its haulage capacity or do we want it to win tractor pull contests? Alas, for many ‘value’ is seen as how many cars the loco will pull, far in excess of prototype. This infers that the loco would need to be heavily weighted. I always felt the Aristo Pacific was far too heavy for normal operation and difficult to manhandle as a result.
Thirdly, do we want it to run at prototypical speed or a potential Hussein Bolt 100 metre candidate? Many would be disappointed with a maximum scale speed locomotive drive, even if prototypical.
Fourthly, comparing a standard gauge locomotive to a narrow gauge model is counterproductive. Thus there would need to be several categories of comparison. Many would scoff at the idea of doubleheading to move a few cattle waggons and yet such narrow gauge movements were common.
For me a drive needs to have a quality motor and gearbox, coupled with decent build quality. Axle quartering and drive rod dimensions within tolerance, not shoddy tolerances to make up for assembly line sloppiness. No point spending money on quality components only to see assembly line QC let the team down.
The drive needs to be rebuildable. No more supergluing the components together making disassembly prone to disaster.
Lastly, a drive needs to be proven in concept and testing before being released to the consumer. Single operator beta tests are not productive. The typical consumer these days is past the stage of ooh! ahh! when a new model is released. They want a quality model, reliable out of the box. The drive quality should match the cosmetic look of the locomotive.
Here are my “Givens and 'D’Ruthers.” They should work equally well for either Standard Gauge or Narrow Gauge.
Givens:
No electronics. I can add that later, if I want them. What I want will probably not be what the manufacturer has in mind, anyway. That includes a “socket.” Sorry, Stan, but you asked what I want. Screw posts rather than pin and socket, because I have bent a pin or two in the past.
Wiring done well with NO cold solders. Red insulation (not paint) for positive and black for ground. Other wiring can be of manufacturer’s choice, since there doesn’t seem to be any standard that I know of, but PROVIDE A COLOR CHART in the owner’s manual. Lionel used to check every one of their locomotive drives prior to final assembly, that should not add too much per unit to do that.
Drive wheels keyed to axles so they won’t slip out of “quarter.” Quality motor and gear box. Easy to tear down and rebuild should the need arise.
Pilot truck heavy enough to go around less than perfect track without derailing.
Straightforward disassembly. Please don’t use 5 different sizes of screws to hold the thing together, either. One size should be enough, if you plan properly.
I want the locomotive to start slowly, say at 1 scale mph, and then smoothly move up the speed curve. It is unlikely that I will ever get my steamers over 35-40 scale mph, even on long straights, so the low end is more important than the top end.
A Standard Gauge locomotive of say 2-8-0 size should be able to handle 10 cars and a caboose without wheezing. A Narrow Gauge loco should be able to handle 6 cars and a caboose.
D’Ruthers:
Enough detail to keep things interesting, but not so much that I will be afraid to take it outside for fear of leaving important “bits” in the ballast. I want a robust locomotive that I can operate on my outdoor layout, and that I can had the controller to my grandson without trepidation.
The model should include, or there should be the ability to purchase different detail parts like stacks, domes, and interchangable oil, coal or wood tender loads where appropriate.
Scale size engineers and firemen that actually fit inside the cabs.
I really don’t care if there is a light in the cab, or if the firebox glows, save your pennies by not including those features. I don’t use smoke, either. since I run battery. I really don’t like having to pay for the smoke feature that really doesn’t work.
I do operate at night. Having a head and backup light that will illuminate the track a bit ahead, and can be seen from 20 feet away is important to me.
A 2-8-0 is the largest Standard Gauge locomotive that i am interested in.
There, 7 Givens and 6 D’Ruthers. I have to stop there, because I am going outside to run some trains.
Nick, Tim, Steve
Thanks for contributing to this thread. I think Nick sums it up rather well that the locomotive must work without fail out of the box.
True some of this such as speed range is subjective but subjective items are key as well. We hear a lot that a product has a “ good drive” or a “poor drive” but we seldom define what we mean by those terms.
I do wish to keep this thread on topic so issues such as features, electronics or detail while key to making a purchase do not contribute to the basic drive. It is fair however to add the running gear to the equation as the drive and running gear are highly related to a good operating locomotive.
Top speed is a real hard topic. For me the locomotive needs a good top speed at 24 V that is faster than typical garden operating speeds but must do this without compromising low speed performance. Subjective and hard to achieve.
I would add two items to the list.
Ability to run smoothly on uneven track (those of us who float our track can relate to this need)
Ability to run with a full load in the heat in direct sun and not damage the motor or drive. (A good test for this is operating at slip into a wall in the sun at 100degree F)
So let’s sum up what we have so far
Works without fail out of the box
A drive needs to have a quality motor and gearbox, coupled with decent build quality. Axle quartering and drive rod dimensions within tolerance, not shoddy tolerances to make up for assembly line sloppiness.
Drive wheels keyed to axles so they won’t slip out of “quarter.” Quality motor and gear box. Easy to tear down and rebuild should the need arise.
Pilot truck heavy enough to go around less than perfect track without derailing.
Straightforward disassembly. Please don’t use 5 different sizes of screws to hold the thing together, either. One size should be enough, if you plan properly.
The locomotive to start slowly, say at 1 scale mph, and then smoothly move up the speed curve. It is unlikely that I will ever get my steamers over 35-40 scale mph, even on long straights, so the low end is more important than the top end.
Good top speed at 24 V
A Standard Gauge locomotive of say 2-8-0 size should be able to handle 10 cars and a caboose without wheezing. A Narrow Gauge loco should be able to handle 6 cars and a caboose.
Ability to run smoothly on uneven track (those of us who float our track can relate to this)
Ability to run with a full load in the heat in direct sun and not damage the motor or drive. (A good test for this is operating at slip into a wall in the sun at 100degree F)
What additional qualities should we add to the list.
Stan
I follow along with Steve on most points, A biggie is a drive that is bullet proof ( BBT ) and go along with the low end performance for good starts and smooth switching. Added Elect. Thingies that I can do my self and All wiring going to and coming from a single point with screw connectors. Charge me $10 more but make it all easily accessible and adaptable
A little loose fit on the rods and the timing works would be ok, so as that the need to maintain precision doesn’t require constant maintenance.
And I will toss in All wheel pick up.
$.02
I’ll add another one to my “Givens.”
Dave Taylor said:
I follow along with Steve on most points, A biggie is a drive that is bullet proof ( BBT ) and go along with the low end performance for good starts and smooth switching. Added Elect. Thingies that I can do my self and All wiring going to and coming from a single point with screw connectors. Charge me $10 more but make it all easily accessible and adaptable
A little loose fit on the rods and the timing works would be ok, so as that the need to maintain precision doesn’t require constant maintenance.
And I will toss in All wheel pick up.
$.02
Stan, reliable, easy to fuss with wiring is part of a reliable drive mechanism, like it or not. You just can’t have a reliable drive mechanism without reliable wiring.
Steve Featherkile said:
I’ll add another one to my “Givens.”
- Keyed, or otherwise securely attached, metal gearing. No more plastic fantastic gearing that splits the first time someone sneezes, or opens the door.
Steve
Good addition. Added it to the list.
I did not add electornics to the list. Not because it is not important to the overall locomotive but because it is not part of the drive mechanism itself. For example you can purchase a BBT drive and you get a drive with virtually no wiring (unless you request pickups). I happpen to think this is an example of an exelent drive. Bachmann also sells the drive for several of its locomotives as a seperate item as well and these also have no electronics included. Good electronics or the detail of the model are key to the overall quality of the model but not the drive itself.
Since track pickups are most often part of the drive chasis/motor/gearbox bundle I have added that to the list
As a compromise I also added “wiring from the motor and track pickups that can handle the maximum current draw of the drive.”
Current list follows.
Stan
So let’s sum up what we have so far
Works without fail out of the box
A drive needs to have a quality motor and gearbox, coupled with decent build quality. Axle quartering and drive rod dimensions within tolerance, not shoddy tolerances to make up for assembly line sloppiness.
Drive wheels keyed to axles so they won’t slip out of “quarter.” Quality motor and gear box. Easy to tear down and rebuild should the need arise.
Pilot truck heavy enough to go around less than perfect track without derailing.
Straightforward disassembly. Please don’t use 5 different sizes of screws to hold the thing together, either. One size should be enough, if you plan properly.
The locomotive to start slowly, say at 1 scale mph, and then smoothly move up the speed curve. It is unlikely that I will ever get my steamers over 35-40 scale mph, even on long straights, so the low end is more important than the top end.
Good top speed at 24 V
A Standard Gauge locomotive of say 2-8-0 size should be able to handle 10 cars and a caboose without wheezing. A Narrow Gauge loco should be able to handle 6 cars and a caboose.
Ability to run smoothly on uneven track (those of us who float our track can relate to this)
Ability to run with a full load in the heat in direct sun and not damage the motor or drive. (A good test for this is operating at slip into a wall in the sun at 100degree F)
Keyed, or otherwise securely attached, metal gearing
Reliable and electrically sound track electrical pickups
Wiring from the motor and track pickups that can handle the maximum current draw of the drive."
Sounds like a reasonable enough list for me (though I must admit I’m a bit more simplistic; I don’t really care how it runs smoothly and reliably, just that it does.)
I would amend #4 in that I want the front pilot truck to be able to push through a closed spring switch without derailing. Bane of my existence, that one.
Later,
K
I’ll guarantee that over time most people really DO care HOW it runs smoothly, because a good design will evidence itself by working well.
So HOW a driver is attached to an axle WILL eventually show up in reliability.
Greg
The test for point 10 is ludicrous. For how long would you run such a test? Till something breaks? At a minimum, it wouldn’t take long to wear drivers and leave divots in the track.
Gosh, Geoff, thanks for your positive input.
How would you test for ability to run at full load in the heat in direct sun and not damage the motor or drive?
“I’ll guarantee that over time most people really DO care HOW it runs smoothly, because a good design will evidence itself by working well.”
Greg, what I’m saying is that there’s always more than one way to skin the proverbial cat. For instance, Barry makes a complete chassis and he makes a gearbox system to drop in an existing frame. LGB’s motor blocks (though clunky looking) also allow for smooth operation. I’ve also had good luck with Aristo’s “prime mover” design. These are four very different approaches for how to get the wheels turning on a locomotive, but all of them can result in very smooth operation.
The rest of the system needs to be engineered properly as well–suspension, wheels, quartering, etc., and that can “make or break” a system as much as the motor/gear/axle interface. But–like the motors–there’s more than one way to do that as well. Fully sprung frame, just equalize the front axle, make the whole shootin’ match rigid… I’ve got locos with all these “systems” on them and they all meet my expectations for smooth, reliable operation.
That’s what I’m driving at when I say “I don’t care how…” The precise mechanism doesn’t matter so long as it works, and there numerous ways to make it work. (There are numerous ways to screw it up, too.) For me it’s the end result that matters.
Later,
K
You have the manufacturer test it… I think the IDEA behind the comment is good, if the loco can do full load then you know it won’t overheat in Arizona, or have such a weak drive train that it won’t last long.
Doing this test would of course put wear on the drivetrain, but this is a test.
But of course, no one is going to volunteer their loco other than the manufacturer… and can you be sure they did the test? But there is really no other option, unless the magazines will test… (oh the days of real tests)
I know of a manufacturer who “tests” their locos on DC only even though they have a socket and make an R/C system that goes in the socket.
A recent batch of locos had what amounted to a miswired socket, so that even the manufacturer’s OWN decoder was plugged in, it did not work.
So, I surely don’t think that #10, asking for a bit of a torture test is “ludicrous”…
Greg
Geoff Ringle said:
The test for point 10 is ludicrous. For how long would you run such a test? Till something breaks? At a minimum, it wouldn’t take long to wear drivers and leave divots in the track.
Geoff
Let me try to explain why to me this is one of the most important test of a drive. Lets use the Bachmann Connie as an example.
While running into a wall is admittedly a hard test, it is not that much different then pulling a full load and is easier to perform. On our railroad, tt can take more the 40 minutes to climb our 2% grade and if a Connie starts out with a full load, the stock motor will burn out long before the locomotive reaches the top of the hill. The reason is that as the motor heats up, the plastic motor end gets soft and the armature will move out of alignment. The locomotive can put on quite a smoke show when that happens.
Ideally a locomotive should shut down long before any damage occurs or be designed so that it can survive a long time wheel slip in the hot sun. It can get real hot in a black boiler in the hot sun.
Stan
Kevin Strong said:
Greg, what I’m saying is that there’s always more than one way to skin the proverbial cat. For instance, Barry makes a complete chassis and he makes a gearbox system to drop in an existing frame. LGB’s motor blocks (though clunky looking) also allow for smooth operation. I’ve also had good luck with Aristo’s “prime mover” design. These are four very different approaches for how to get the wheels turning on a locomotive, but all of them can result in very smooth operation.
The rest of the system needs to be engineered properly as well–suspension, wheels, quartering, etc., and that can “make or break” a system as much as the motor/gear/axle interface. But–like the motors–there’s more than one way to do that as well. Fully sprung frame, just equalize the front axle, make the whole shootin’ match rigid… I’ve got locos with all these “systems” on them and they all meet my expectations for smooth, reliable operation.
That’s what I’m driving at when I say “I don’t care how…” The precise mechanism doesn’t matter so long as it works, and there numerous ways to make it work. (There are numerous ways to screw it up, too.) For me it’s the end result that matters.
Later,
K
Kevin
While there are a large number of ways to mess things up, Not all ways you mention result in a high quality drive and mechanism.
For example a rigid long wheelbase requires very good and cross level track. Great for indoor use but not as great outside. I believe there needs to be at least some play in the frame to allow the wheels to track.
Some locomotives look absolutely fantastic but can be a real pain to operate on a typical garden railroad.
Stan
PS I am surprised that no one to date has mentioned wheel profile. A poor wheel profile can also result in a very poor runner.
Just wanted to address pilot design. The Bachmann stock pilot (early version) was the bane of my life, took me 15 years to find the solution.
The four wheel pilot that I produce now is a flexible frame that does not require weight to stay on the track. The two wheel pilot, which I make for my Big Hauler 2-8-0 conversion does benefit from added weight. Unfortunately, I have no feed back on how either pilot succeeds or fails on push switches open.
Adding weight to the 4 wheel pilot can be problematic. Keeping the flex feature means the weight would have to be added to each side rail, equally.
Barry
Stan,
Yes a locomotive should be able to run in the heat without damage if it is operating within its limits. I think running the locomotive against a wall is a test that you can not learn much from, that’s all. Operating any locomotive at full slip for a long period will produce damage. I would say that if your engine is experiencing long time wheel slip, you have exceeded it limits by definition.
Designing testing procedures & parameters that replicate real usage takes some thought, time and money. So I would suggest that you leave #10 as: Ability to run with a full load in the heat in direct sun and not damage the motor or drive.
However, full load might need to be defined. One car less than causes engine driver slippage might cover it and would take grades into account
Stan,
I went through wheel profile evaluations nearly twenty years ago. What worked best for me was a modified Sierra Valley wheel profile with about .020 added to the height of the flange.
I was given permission to use this profile from Gary Watkins and it has proven to be very successful. I also have cutting tools for finescale and semi-finescale flanges (for special applications).
This profile has a good fillet from flange to tire and a proper (working) taper on the tire.
Also want add a comment on wheel mounting, we’ve all seen some silly methods, but I wanted a mounting method which would help in quartering, allow me to send a set of wheels to a customer requiring the slightest instructions as to how to exchange with the wheels he already has from me.
This required an axle with cross drilled holes for roll pins to locate the wheel and aid in locking it in place, the locating also determined the back to back dimension. I also determined that rim insulation would be most problematic, so I designed a Delrin hub for the wheel. This hub started out with one slot all of the way across the hub, later another slot was added 90 degrees out from the first slot. The slot is lined up with the rod pin location, therefore automatically quartered.
Barry