I'd swear we had a thread discussing various clutch or non-contact drives, but I can't find the discussion.
There was a thread April 21, 2004 that discussed a few of the alternatives starting from the early Fifties, when low-speed voltage-controlled DC motor response was abysmal. (PWM, skew-wound armatures, better field magnets and the like relieved the problem according to Bill Schweber).
Some of the early approaches, in the era of Fluid Drive, implemented a simple fluid-flywheel approach, where a pump turbine close to a runner induced rotation in the fluid between, which in good designs could be changed out to get the effect of different viscosities. Of course their structure constituted an effective flywheel, too. Supposedly these had a tendency to leak over time, etc. and would have been somewhat fragile internally, although I can think of ways to manage the thrust issues.
Later versions of the same principle were done with permanent magnets (strangely none with modulated electromagnets that I know of) both as opposed magnetic 'gear teeth' and to induce eddy currents in a driven disc that increased with nominal input speed.
There were also drives with some sort of centrifugal clutch, which I'd think would start to slip-engage and then increase locking force with speed. I believe Lindsay made one on the flyweight-governor principle, slthough how it was faced and whether or not it locked up to direct at some speed I don't know.
Perhaps the most logical device class, although I never actually made one, is a magnetorheological clutch, a fluid clutch in which the fluid changes viscosity quickly when a magnetic field is applied. (Some of you probably have vehicles with shock absorbers using this principle). This promises to be just as effective in allowing controlled 'slip' between input and output speeds as it was in the late '40s, or in the '70s applied to mechanical steam-locomotive
Note that few if any of these do the job of fine motor control as well as 'good' high-frequency PWM. The question which follows is whether some form of torque multiplication could be made to work at model scale, in other words whether the power of higher input-shaft speed (and in a DC motor, power) could be applied to slower-turning output without slip. This would involve making a small version of a torque converter rather than fluid clutch. This might add dramatically to flexible performance with heavy loads.
Note that there's a family of devices, developed and patented by Thomas Bowes, that could be miniaturized and adopted for this purpose -- one of these was the Ingalls Shipbuilding 'secret weapon' for 140mph passenger locomotives prior to the ICC order after the Naperville wreck that ended the party.
Recently, t was in this thread
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I do remember seeing the centrifugal clutch advertised. Not sure if it was Lindsey or someone else, but it may very well have been.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Working on a full sized clutch is no fun and they are fussy a all get out. Would not want to go anywhere nearr one that small.
Mike
Earliest reference I can find is an April 1951 editorial by John Page on investigating the potential of fluid drives. He followed that up the next moth with a mention of something pulled from a British magazine with what appears to ba a cetrifugal style clutch.
March 1952 Trade Topics reviewed the Centriclutch by American Railway Models Inc.
A June 1952 Hobbytown ad lists an optional centrifugal clutch for the drive. In December 1953 the price came down from $3.95 to $2.95
In December 1957 Trade Tropics reviewed the W&T planetary cluth, which combined a centrifugal clutch and a planetary gearbox. The descrition of how it works makes it sound like some power cna get through even with the clutch not touching the drum, but as more force is applied by increasing the motort speed, the output shaft turns closer and closer to the soeed of the input shaft. It says at full speed the clutch is fully engaged and there is no slippage. There's a completely disassembled view accompanying the review, pretty intricate piece of machining. Although the text says the tolerances are a bit sloppy in places so it vibrated a bit at high speed. It is sized to fit in HO locos.
There's probably more but I did a rather loose search in the 75 year collection so there are several pages of hits (I included ads) and I don't feel like digging in to any more.
it acts similar to momentum ... but really isn't worth anything ...
never did take off to any extent, except for some screwballs ..
OvermodSupposedly these had a tendency to leak over time
I seem to remember those. I think they were called Harleys.
"I got a leak in my engine."
"Go ahead, it's your engine."
Disclaimer: This post may contain humor, sarcasm, and/or flatulence.
Michael Mornard
Bringing the North Woods to South Dakota!
Bayfield Transfer Railway"I got a leak in my engine." "Go ahead, it's your engine."
Harleys don't hold a candle to British products, I think -- both two and four-wheeled. If I recall correctly some of this was actual porosity in the cases, not just unfortunate 'choices' for seal and gasket design. I resigned myself to tiling puppy pads on the garage floor (and carrying a pack or two along to 'preclude misunderstandings' when visiting someone's driveway), but this may be more widespread an occupational accommodation.
Baldwin locomotives in particular seemed to have fallen foul of the oil gods. Where EMD relied as much as possible on bolted, gasketed connections, Baldwin had little hoses everywhere, some of them disturbingly reminiscent of the water-pump bypass hose on a Ford 385-series engine; then a lot of the electrical wiring was put cleanly under the deck in chases ... with only indifferent drains, but plenty of ipportunities for gravity and capillary action to do its evil work. I remember a story about an NYC crew with what I recall was one of the Babyface units; they had stopped on a bridge to fish and observed the drip, drip, drip of various fluids in the water beneath...
Again this doesn't hold a candle to some Britannia locomotive practice, most notably Bulleid who had a couple that actually caught fire from all the thrown lubricant...
It's not the leak that is the problem. It is when it stops leaking that you have the problem. At least that is what I was told
A pessimist sees a dark tunnel
An optimist sees the light at the end of the tunnel
A realist sees a frieght train
An engineer sees three idiots standing on the tracks stairing blankly in space
The old British car joke basically goes "Why do the British like warm beer" "Because Lucas makes refigerators, too". Former coworker had a 75 Triumph he restored - guy was a fanatic, polished every nut and bolt even when they couldn't be seen - he brought the wiring diagram in one say to ask for my help is figuring it out. As drawn, there is zero chance the thing could ever have charged the battery. It's not just that they (as is typical) didn;t show the frame as one side of the circuit, there was also no hot connection back to the battery from the charging circuitry and voltage regulator.
At least with those fluid drive locos you wouldn't have to paint a fake oil strip down the center of the track.
Ever notice those people with the fancy fully finished garages with the fancy floors and all never have any British cars?
You will notice I left the Prince of Darkness out of it -- that company's connection to lubricants being, as far as I know, tenuous (and fuel leaks not counting) .
I am still not quite sure about the rationale for positive ground -- which may be the reason you didn't see an explicit 'hot' return; I think the wires are the current source in positive ground -- in some of those things. It was an interesting idea in practice but weird things could start happening when the typical-British-'quality' metallurgy in the frame grounds and such began to answer its own call of nature.
I was driving the Land Rover down a benighted stretch of industrial 1 and 9 somewhere south of where PRR comes out of the tunnels when my high beams came on unexpectedly, dash indicator and all, and I started smelling something hot. Imagine my surprise to find the speedometer drive cable glowing orange its full visible length.
Perhaps the weirdest part (and British in a different sense): I sat while it cooled down, then thought 'well, I might as well see if I can nurse it back to Englewood' -- started right up, high beams worked fine, speedometer worked just fine... drove home.
I can guess - a body ground came loose, so the speedo cable sheath was the only metal between the dash and chassis. Though it fixing itself...well, who knows.
In a vehicle, psitive ground/negative ground really is a matter of choice, One's not necessarily better than the other. But when you have vehicles made one way for many years and then at some point switch over - it can really catch you out. Plenty of American vehicles ran pisitive ground back in the day. Which way makes sense I guess depends if you subscribe to the electron theory or conventional theory.
It's not just the British - my TYoyota Truck uses a wacko system of supplying a common hot from the headlight relay to the lights, with two grounds, selected by the beam switch. This makes it all but impossible to install better headlights (the stock ones are like taping two flashlights to the hood - it's nearly undrivable at night except on well lit roads). You need to use a pair of relays in a wiring harness to convert it over to plug normal lights into the thing if switchign to LEDs. I was goign to do it, but since the frame is pretty much risted away in critical suspention points (Toyota makes great bulletproof drivetrains, but their bodies and frames are made with junk metal - and the fram in my truck came from Dana, it's not made in Japan!). So basically I have a really solid motor, gearbox, and transfer case, attached to almost nothing.
Hello All,
As "Exhibit 'A'" I turn your attention to the Krauss-Maffei ML 4000.
If it wasn't successful in the prototypical world, how and or why could it, would it, be used in a miniature version for reliability over novelty.
Hope this helps.
"Uhh...I didn’t know it was 'impossible' I just made it work...sorry"
They actualy weren;t unreliable at all. They just had inadequate trnasmission cooling for pulling long US style traisn up steep grades. Still happens today if you pull a heavy trailer with even a 1 ton pickup over the Rockies - even if your tow package includes a beedef up transmission cooler. In flatland service, the K-M locos were VERY reliable. What doomed them was the US builders coming up with higher horsepower units (the K-M diesels were among the highest HP units at the time they were first delivered), using the same standard style prime movers the railroad were used to instead of the oddball (in the use) Maybachs, which were relatively high-revving as well.
Diesel-hydraulic locos were much more common in Europe. Shorter, more frequent, and faster trains, and not in the steep mountain areas liek the Alps. And many small industrial locos used hydraulic drives, here and there. Voith transmissions like those in the K-M ML 4000's are used in thousands of buses. They're still around.
They just weren;t made for AMerican-style railroading, long slow drags of 100+ cars.
jjdamnitIf it wasn't successful in the prototypical world, how and or why could it, would it, be used in a miniature version for reliability over novelty.
A lethal issue was maintenance. All the expensive German-spec oil in all the final drives was supposed to be changed every 30 days, or the warranty was void. The reverse was mechanical, and interlocked for 'mechanical integrity' -- and of course, utterly unlike a diesel-electric, couldn't be done with the locomotive moving. So you had to come to a stop and wait, ka-think, ka-thunk, ka-thunk, ka-thunk for all four boxes to settle, and confirm engagement, before the interlock would release and you could start engaging the first converter. This would get old fast. If I remember correctly the high-speed engines had tunnel roller-bearing cranks, a double whammy for low joints or other severe road shock with hjgh-speed inertial forces against the engine tribology...
Then we get into the long-term maintenance of C trucks with the axles all geared together to turn at the same speed...but with all the usual reasons to wear wheels to different diameters. Bone up on your underfloor lathe skills Or Else!
The Amerika-Loks were a wonderful try, but they were NOT really the same way to high single-unit power that the SD45 (and C636 and U36C) would be not too much later.
In any case, the torque converter principle isn't what the 'model' fluid drives seemed to involve; they were all basically slip clutches allowing either motor windup before pulling started, or softening motor response to primitive controls. What might be needed is something actually capable of torque multiplication under load.