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How much should an Engine weight? Is there a NMRA standered?

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How much should an Engine weight? Is there a NMRA standered?
Posted by cudaken on Tuesday, August 29, 2006 4:00 AM

 Have been playing with the old Athearn Blue Boxes some more and pulled out a E-bay win that had not been up to snuff. Ran well but pulling power was not great. It has the old style round motor and steel flywheels, it is a SPD-40 C&O.

 I hooked it up to a 39 car train that has to go up a 2% grade. An BB FP-45 will pull the same train but it is a strain. With the C&O I had to help it up the grade. It did feel lite but was running well so I added some weight.

 Added around 3 oz and would pull the train but was still a strain but will do it. My scale only goes up to 16 OZ's then 500 grams, must be a metric thing. With the weights I bureded the 500 grams and guessing around 19OZ's.

 Just wanted a idea too what one should weight. F-7A Super weight comes in right at 16OZ's.

 Went double headed SPD's and pulling well.

 Now thottle question? Is to much thottle bad? Thanks to Darrell I am running a MRC 2500 with 16VA out put. Doubled headed I have to crank it to 90% to get any kind of speed. Have a MRC 260 coming at 20 VA so I have a little more power.

 Now back to my stereo back ground. On a lower power amp when you drive it to hard something called CLIP happens.  Amps does not have the back up power to power a transtiant peak, power wave falls off, goes flat and blowes a speaker. In stereo world back up power is called Head Room. Amps is putting out say 150 Watts RMS but there is a passage that needs say 175 watts too sound right. Power caps store power so when it happens you have 175 watts +.

 Just wondering if anything like this happens with DC thottles, and if so will it fry a train motor?

 Well it is 4:00 AM and time to crash. But if the darn board was not running so well I would have hit the hay 3 hours ago. Round 150 hours with no problems, added 2 more rolling stock that has been worked. 

 This is getting to be fun again, Cuda Ken 

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Posted by Virginian on Tuesday, August 29, 2006 4:25 AM
No, there is no NMRA standard I am aware of on engine weights.  No, motors are not like speakers.  Overvoltage can indeed kill them.  Unless you are running sound or something I think your MRC 2500 is going, because I have 3 different 2400s and I can run three of anything I have and rarely need more than 60% throttle, and that's for fairly fast movement.
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Posted by Paul3 on Tuesday, August 29, 2006 11:09 AM

While there is no standard, remember that it's possible to add too much weight.

I have a all-cast metal DL109 (Athearn drive) that will not spin the wheels under any circumstances.  That's too much weight.

Your loco should have enough power to break traction.  Otherwise, you can easily overload the motor (by stalling it) and melt it.

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Posted by TomDiehl on Tuesday, August 29, 2006 11:11 AM

As Virginian said above, there is no standard for weight of locomotives, or cars for that matter. RP20.1 is a Recommended Practice and the NMRA goes to great lengths to differentiate between the two.

Not quite sure what you mean by "pull the train with a strain." Is the loco slipping?

Back in the old days (yes, I'm old enough to say that), locomotive models were made as heavy as possible for the best pulling power. Die cast metal bodies and boilers were the norm rather than the exception back then. I have several Tyco models of the Baldwin Shark with a die cast body shell. The body weighs slightly over a pound by itself. Couple a string of model cars behind this with the slippery plastic trucks made nowadays and these things can pull a heck of a train.

"Clipping" only happens with an AC voltage/signal, the top and bottom of the sine wave is "clipped off" best seen with an oscilloscope. The closest thing that would happen to a DC voltage is to overload the power source (too many Amps being drawn). The best ways to add weight to a locomotive safely (to prevent motor burnout) would be 1. insure that the locomotive drivers will still slip if you try to pull too many cars, 2. have an ampmeter connected with the power pack and insure you're not exceeding the rating of the motor (for old BB Athearns, I believe it was half Amp or 500 milliamps).

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Posted by BRAKIE on Tuesday, August 29, 2006 11:14 AM
My rule of thumb for my BB units is 6 pieces of stick on weight except the SW7 which gets 4.I stick these weights to the INSIDE top of the shell where they're out of the way.

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Posted by METRO on Tuesday, August 29, 2006 11:37 AM
There have been a couple of heavyweight preformers in modern model railroading as well. The P1K DL109 comes to mind, that thing can pull better than my Genesis F7s.

The only problem I've found with weighting the top of bodyshells on Athearn BBs is that it reduces their top speed around curves. I've got a few of the older BB C44-9Ws that came in kit form and the weight made them unstable on curves, so I had to put it lower on the frame.

Cheers!
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Posted by BRAKIE on Tuesday, August 29, 2006 12:21 PM

 METRO wrote:
There have been a couple of heavyweight preformers in modern model railroading as well. The P1K DL109 comes to mind, that thing can pull better than my Genesis F7s. The only problem I've found with weighting the top of bodyshells on Athearn BBs is that it reduces their top speed around curves. I've got a few of the older BB C44-9Ws that came in kit form and the weight made them unstable on curves, so I had to put it lower on the frame. Cheers! ~METRO

 

OOOOKAY..Never notice that problem at scale speeds..What type of weight did you add to the frame? That sounds interesting..I might be able to add some more weight..Wink [;)]

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Posted by Leon Silverman on Tuesday, August 29, 2006 12:46 PM

The rated stall current for a particular motor may not be available to you. In addition, this may not be a safe load limit for that motor anyway. Knowing it's value is important if you decide to install a decoder.  If the decoder has a lower rating than the motor's stall current, it will shut down without burning out your motor.  If the decoder's capacity exceeds the stall current of the motor, it can concievably burn out your motor by overloading it. 

    The safest way to determine the weight limit of an engine is to run it at full load (speed and train length for at least 1/2 and hour and feel the shell around the motor.  If it is cool to the touch, you can add weight.  Retest the engine at the higher weight and longer train length again for half an hour.  If it is still cool, you are OK.  This might be an issue with the older style opened frame motors.  Modern can-type motors should not be sensitive to added weight.

    Tom Dielh:

   I also had a Tyco Shark.  It had a single powered truck with traction tires and the motor actually inside the power truck and gearing directly to the wheeels.  This engine ran hot and eventually burned itself out.  A hobby shop proprietor told me that there was too much weight for that single motor to handle.  Considering the fact that this armature was buried inside the truck with no air circulating around it for cooling, I am not surprised.  I noticed later that Tyco offered an F-unit with the same type of drive, but it was dual motored.

    

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Posted by BRAKIE on Tuesday, August 29, 2006 2:04 PM
Leon,Just for this discussion I will mention that I remove the cab's side glass so air can reach my motor...I found this helps my locos  run cooler for longer periods of time..Of course removing the side glass in the cab isn't for everybody nor is it for the unskilled because some locomotives require cutting the side windows from the  windshield assembly.   

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Posted by Anonymous on Tuesday, August 29, 2006 2:22 PM

Locomotives never have enough weight.

As long they spin wheels when stalled they should do fine.

I usually add more locomotives to the consist until the train moves; it seems to be easier to have several motors sharing the load than one motor overburdened with weight.

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Posted by RicHamilton on Tuesday, August 29, 2006 2:39 PM
 Leon Silverman wrote:

The rated stall current for a particular motor may not be available to you. In addition, this may not be a safe load limit for that motor anyway. Knowing it's value is important if you decide to install a decoder. 

Yes it is.

If the decoder has a lower rating than the motor's stall current, it will shut down without burning out your motor.  If the decoder's capacity exceeds the stall current of the motor, it can concievably burn out your motor by overloading it. 

 

No don't do that.  The decoder has to be able to accept the stall current in order not to burn the decoder up.  If not you are pushing too much current through very delicate electronics, guess what, it fries itself.  Then you have to put in a new one.  A rule of thumb for HO is Athearn BB is 1.5 amp and 1 amp in other quality locos like P2K, Genesis, Kato and Atlas.  These motors will handle the excess power far better than the decoder.

 

 

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Posted by TomDiehl on Tuesday, August 29, 2006 3:07 PM

Leon,

I have six of the metal bodied shark A Units, and two B units. Three of the A's have the original drive and three have the Hobbytown drive. I got all these off Ebay, some came with the drive, some were just the body. The original drives run good but don't pull as well as the Hobbytowns, which have all wheels driven. The power truck from the later F Units (identified by the metal plate on the bottom) were some of the better ones for the money at that time. This was when Athearn had the rubber band drive locos, so the gear driven motor unit (called the MU-2 power truck by Mantua/Tyco) was a real advance, and only a bit more expensive than the Athearns of that time.

I still have most of them, and they all run well.

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Posted by CAZEPHYR on Tuesday, August 29, 2006 3:09 PM

It would be not make sense for the NMRA to give a minumum or standards for weight in a locomotive since a 4-4-0 tea pot may not be large enough to add a sufficient amount of weight to meet any univeral standard.  Traction tires are used in the case of plastic modles needing more weight.    

 

The interesting result of adding weight to a model is the adhesion factor of metal to most metals is normally around 25%.  If your model weights about 16ozs and all of the weight is on the driving wheels, the drawbar pull should be about 4ozs.  You need to add about four times of weight compared to the added amount of tractive effort achieved. 

  

 New models tend to be better pullers after some of the polish is off of the wheels.  Real prototypes normally fall in the same adhesion percentages except for the newer AC diesels using over slip electronics achieve a much higher adhesion factor.  Six axles usually pull better than four for the same overall weight.  I am sure there are exceptions to this, but it is a general physical characteristic of the metal to metal interaction.     

 

Traction tires alter this factor since they do not use metal against metal and offer much higher adhesion levels.  The model should always be able to spin its wheels at the stalling point to prevent the motor from damage.

 

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Posted by Leon Silverman on Tuesday, August 29, 2006 3:15 PM
I stand corrected regaqrding the decoder rating vs the motor stall current. One addition to the rule of thumb.  Dual motored locomotives, such as the Bowser T-1 and the Athearn DD40 dual motor, either use one decoder per motor or use a 3 amp decoder.  
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Posted by Don Gibson on Tuesday, August 29, 2006 7:51 PM

Simply put:

ADDING ENGINE WEIGHT does two things:  Motors overheat; if the wheels don't slip.

Manufacturers balance Pulling power/ Motor capacity/ with price. It's easy to add weight to an engine, but that increases the amps consumed, which increases CO$T. Each manufacturer has to guess how many cars YOU are going to pull - which determines how big the motor - which determines how much you willing to pay in a competative market?

SURPRISE: cheaper products are designed for the 'toy' market, and to pull only a few cars. Case in point: Bachman's 'Hogswart Express' engine. On the other side of the spectrum we have Kato and their 'cloned' Stewart, and InterMountain drives.Proto 2000's SD-60 was a heavy engine, 6 wheels, and geared to boot. Want a 'puller'? - look no further.

ANYONE wanting to add weight should have, and use, an Ammeter.

Old Athearn BB 'round' engines pulled 1 amp nominally, 1.75amps at startup, and 2 amps at stall. New Genesis' 1/2 - 1/4 that. I put an A-line 'Holland' motor replacement in a BB F-7 (with custom paint job) and it now STARTS at 0.12 amps.

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Posted by cudaken on Tuesday, August 29, 2006 8:45 PM

 I don't think the MRC 2500 is going bad, my engines are old. Few are more than likely from the 60's or best 70's.

 I am now running triple headed and running OK with a 6.5OZ dummy and 39 cars up the 2 % grade. Now I am at 100% thottle and guessing moving around 50 sMPH. So I guess more power would help, getting ready to throw in Super Weight to see what happens.

 When I said the FP-45 strggled to pull the train, it never stalled but went real slow up the grade. SPD before I added weights was spinning like heck, looked like a HEMI doing a 12 wheel burn out.

 Should I stall the engines to see if the wheels spin?

 Just threw in the F-7A Super Weight, well if you like slow this is great! Down to around 30 sMPH if not slower. But the Good news to me is the old MRC 1440 at 14 VA would have shut down in 30 seconds with the 3 BB's. With the new MRC 260 coming with 20 VA and using a second thottle on main line B I should be set till I go DCC.

 Oh, on the warm to touch, with out dragging any cars the older BB's I have feel warm after say 10 minutes. One of the reason I have up grade a few with newer motors.

 Enjoying MRR again, Cuda Ken 160 hours of trouble free rail hours. Life is good tonight.

 

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Posted by BRAKIE on Tuesday, August 29, 2006 8:56 PM

Don,I agree with the amp meter if one adds extreme weight to their locos and no wheel slippage.

Now in the case of adding 6 pieces of stick on weight there is no real danger of overheating the motor because the wheel slip is still there when the locomotive is coupled to more cars then it can pull.

One of Athearn's biggest problems is they never added the needed weight to their line of locomotives like Atlas,Kato,P2K,Stewart,Walthers and Bachman-Spectrum did.

Larry

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Posted by Darth Santa Fe on Tuesday, August 29, 2006 9:07 PM

I don't know of any NMRA standards for engine weight, but you should make sure the wheels can slip if the engine can't pull a certain load. With Tyco's Power-Torque drive, that is unfortunately not possible because the motor's so weak. As long as you have a mechanism that runs freely and a good motor, you shouldn't have to worry about that.Smile [:)]

I think the reason you have to turn the throttle up to 90% just to get 2 Athearn's running is because the old oval-shaped Jet 400 motors draw so much current. They're probably drawing about 1.5 to 2 amps without a load, which over-loads most power-packs.

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Posted by BRAKIE on Wednesday, August 30, 2006 7:34 AM

Darth,Athearn hasn't used the Jet motors in years..In fact they use several different motors in the BB units since the days of the jet motor.

Quite the list isn't? No where near the Jet 400 and 500 days.Wink [;)]

84030 MOTOR, 1/2 ARMATURE(SWITCHERS & HUSTLER)
84040 MOTOR, 5/8 ARMATURE(LARGE LOCOMOTIVES)
84047 MOTOR, 5/8 W 3/4 FLYWHLS
84048 MOTOR, 1/2 W/FLYWHEELS
84049 MOTOR, 5/8 W 5/8 FLYWHEELS 
84060 MOTOR, C44-9W HI PERF
84067 MOTOR, C44-9W HP W 3/4 FW
84067 MOTOR HI PERF C44-9 W/FLYWHEELS
84070 MOTOR HI PERF AMD103
84077 MOTOR HI PERF AMD W/FLYWHEELS
84080 MOTOR HI PERF FOR DCC
84086 MOTOR HI PERF W/NEW FLYWHEEL FOR DC
84087 MOTOR HI PERF W/NEW FLYWHEELS
85043 SEE 90113

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Posted by Virginian on Wednesday, August 30, 2006 9:13 AM

In thirty some years of using traction tires, and adding as much weight as physics allowed, and piling on cars around the layout, I have lost a whopping three motors.  I have actually filled part of an old stocking with lead shot and balanced that on a steam engine just to see what it would do for tractive effort.  One old Canon ate up the brushes and the armature both, finally, after several attemps to arrest the deterioration along the way, and I finally just gave up and replaced it.  One was a Bachmann pancake that got sick from fighting out of quarter drivers repeatedly, and one was an old in-the-cab Rivarossi that used up the brushes and some idiot (who shall remain un-named) screwed up the repair job.  I think the risk of burning up motors is overblown, unless there is a complete absence of knowledge.

I have four old Athearn BBs, 2 Trainmasters and two Alco PAs, with the old metal sideframe trucks yet, and all four of them consisted together will go scary fast, I did not check exactly, but seemingly as fast as one alone, to the point I would not run them at close to full throttle for more than a partial straight stretch.  I did this to test a MRC 2400, and as I recall they were pulling something in the neighborhood of 2 plus amps.  I know it probably did not trip because I did not leave it at full throttle long.

Therefore, my point is, that if cuda is running locos and they are just crawling as he adds a load, I think there is a very good chance something is wrong.  I would definitely get an ammeter and see what the heck is going on.  The way the MRCs are designed you should not see a large drop in voltage due to added load right up until the point where the unit trips on overload.  Maybe the wheels are not slipping and he is indeed straining the motor, in which case it will eventually go, but I think something in wrong in any event.  When I finally started to lose an MRC 2400, the first sign was that the speed at any throttle setting started falling off with the same load.  On my layout you could run from one transformer district into another one, and you would see a negligible change in speed through the crossover, until the one unit started to go and then you would see a significant change.  I bought another one and went back to not seeing a speed change.

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Posted by Anonymous on Wednesday, August 30, 2006 3:01 PM

The manufactors should build a 10 foot stretch of 4% grade, build a 20 car train and see if their engines can haul the stuff all the way up without slipping.

Then add weight, bigger motors etc as necessary until thier engines can actually get that 20 car train over the top or even start one mid grade. All before sending the final production order to the factory.

Then they can sell that loco with confidence that it is adequately powerful and worth the cost.

In the meantime I rely on several locomotives to carry the load.

I really did not expect 4-4-0's, 4-6-0's etc to carry 20 over 4% but if they can get 5-10 cars rolling on the level it would be great.

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Posted by WSOR 3801 on Wednesday, August 30, 2006 7:01 PM
Part of the problem might be the old motor.  They take a lot more juice.  I have a newer F45 with 9 oz. added.  I've found that to be the optimum added weight for the stock Athearn motor.  More than that, it just doesn't run right. Haven't fried any athearn motors yet.  If I do, oh well, they are cheap.  Just make sure the wheels still spin if there is too much on the drawbar.

For weighing, weigh the shell, then the mechanism, then add it up.  I managed to find a digital food scale that weighs up to 5 lbs, I think, in 1/8 oz increments -- accurate enough for my needs.

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Posted by Don Gibson on Wednesday, August 30, 2006 8:40 PM

I agree. Todays S.S. power paks don't put out enough wattage (VA) to run old multiple BB lashups, since they pulled up to 2 amps each - .5 amps at best - depending on the motor.

Barra-Cuda Ken: The fact that you're running 20 - 50 MPH anywhere near* FULL THROTTLE tells me your power pack lacks 'Oomph' - Watts - VU's. DC *powerpacks lack 'tapered' speed controls, and you'll need around 2.5 amps to run those old BB's. That translates to 30 VA today. ALL power paks drop voltage as amps get near their capacity.  'Betcha you don't don't have the HP.

SAVE up your sheckels and you might get a good power pak while they still make them - or you can find one used. Look for an MRC AG 9500 @30VA.

 

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Posted by Darth Santa Fe on Wednesday, August 30, 2006 8:52 PM
 BRAKIE wrote:

Darth,Athearn hasn't used the Jet motors in years..In fact they use several different motors in the BB units since the days of the jet motor.

Yes, I know about the new motors, and even have a few Athearns with the gold motors.Big Smile [:D] I mentioned the Jet 400 motors because cudaken said his engines have the old round motors.

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Posted by cudaken on Thursday, August 31, 2006 12:13 AM

 Mopar! I love Mopar, let see I have a N 02 with a 150 HP plate and 20 pound bottle, or I could strap the 6-71 Blower to the MRC 2500.

 Well for he folks think I need wheels spining, I pulled out 1 oz and the wheels spin singel headed and a little doubled heaed.

 Then I threw on a PK Erie Bulit single headed and it stall and somke the wheels at the Apx of the track. Would cook at the lower part on the track say 100 sMPH.

 Next I threw in the B unit and it would pull the train, but at 50% power would stall and spin the weels at the Apx, or should I say high spot of the track. At 55% it makes the rounds on the B line. Threw on 2 Super Weight A&B's F-7's and with a light load and at 80% thottle they are moving very well, Super weight's with lite load say 80 sMPH and PK's Erie Bulit a round 70 sMPH.

 As far as the Rocket motor, Hum that is a Olds term and not a W-30 442. Not sure what it is but here is a PIC of the SPD that was weighted and lead engine.

          

 

 Don, as far as needing 30 VA, I think I will be OK. With running the 2500 16 VA on line A and 20 VA with the 280 I should be OK for now. Triple headed then quaded headed ws just to see what would happen.

 Oh, one thing I all most forgot to say. With only doubled headed BB's they pulled well and a lot faster than triple headed BB's.

               Cuda Ken                       

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Posted by twcenterprises on Thursday, August 31, 2006 12:47 AM

Sounds like your pack's "breaking down under load".  Simply put, VA=Watts.  Use 2.5 amps at 12 volts = 30 Watts.  Run the throttle up to about 90%, if you're still using the 2.5 amps, but with only 20 watts available on the 280, you'll only get about 8 volts.  Either that or you'll get the 12 volts, but only about 1.6 amps.

Prototype railroaders have similar problems, their equipment runs on 600 volts and up to 1000 amps +/- briefly. 

For a Really good power supply, just go on a get an MRC Control Master 20.  With 75 VA of power (in HO scale mode), that should handle almost anything.  I think I paid like $100 +/- for mine like 10 years ago.  These also handle G scale, with 85 VA of power in large scale mode.  It has walkaround and memory, should you like to have these features.

No, mine's NOT for sale.

As a rule of thumb, I try to get my engines fairly close to scale weight, a 200 ton SD40-2 should weigh about 9.75 ounces.  Even though my Proto 2000 E-8's weigh nearly 16 oz., I'm not changing those.

Brad

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Posted by Medina1128 on Thursday, August 31, 2006 2:37 AM

While there may not be an NMRA standard for locomotives, I plan on using the NMRA weight standard for the unpowered Athearn F7B in my consist. Why should the A&B units have to lug its big butt around? This will involve grinding weight out of it with my Dremel.

 

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Posted by Leon Silverman on Thursday, August 31, 2006 7:38 AM
 Don Gibson wrote:

I agree. Todays S.S. power paks don't put out enough wattage (VA) to run old multiple BB lashups, since they pulled up to 2 amps each - .5 amps at best - depending on the motor.

Barra-Cuda Ken: The fact that you're running 20 - 50 MPH anywhere near* FULL THROTTLE tells me your power pack lacks 'Oomph' - Watts - VU's. DC *powerpacks lack 'tapered' speed controls, and you'll need around 2.5 amps to run those old BB's. That translates to 30 VA today. ALL power paks drop voltage as amps get near their capacity.  'Betcha you don't don't have the HP.

SAVE up your sheckels and you might get a good power pak while they still make them - or you can find one used. Look for an MRC AG 9500 @30VA.

 

  Better yet, the MRC Control Master 20 is rated at 100 VA when operated at its' full voltage, but will still have plently of omph when operating at the lower voltage.

 

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Posted by BRAKIE on Thursday, August 31, 2006 8:40 AM
 Leon Silverman wrote:
 Don Gibson wrote:

I agree. Todays S.S. power paks don't put out enough wattage (VA) to run old multiple BB lashups, since they pulled up to 2 amps each - .5 amps at best - depending on the motor.

Barra-Cuda Ken: The fact that you're running 20 - 50 MPH anywhere near* FULL THROTTLE tells me your power pack lacks 'Oomph' - Watts - VU's. DC *powerpacks lack 'tapered' speed controls, and you'll need around 2.5 amps to run those old BB's. That translates to 30 VA today. ALL power paks drop voltage as amps get near their capacity.  'Betcha you don't don't have the HP.

SAVE up your sheckels and you might get a good power pak while they still make them - or you can find one used. Look for an MRC AG 9500 @30VA.

 

  Better yet, the MRC Control Master 20 is rated at 100 VA when operated at its' full voltage, but will still have plently of omph when operating at the lower voltage.

 

We been using the CM-20s at the club since the early 90s..I fully agree they have lots of omph at low voltage.

 Don,I doubt if the DC power packs will be going away any time soon..Theres still tens of thousands  DC users around.My old Tech IIs can handle 5 old BB units..

Larry

Conductor.

Summerset Ry.


"Stay Alert, Don't get hurt  Safety First!"

  • Member since
    August 2001
  • From: US
  • 261 posts
Posted by JonathanS on Thursday, August 31, 2006 11:06 AM
 Leon Silverman wrote:

The rated stall current for a particular motor may not be available to you. In addition, this may not be a safe load limit for that motor anyway. Knowing it's value is important if you decide to install a decoder.  If the decoder has a lower rating than the motor's stall current, it will shut down without burning out your motor.  If the decoder's capacity exceeds the stall current of the motor, it can concievably burn out your motor by overloading it.   

  

If you have a decent digital Ohm meter the stall current is easy to get.  Just measure the resistance across the motor.  Then divide that value into your maximum voltage and you have the stall current.

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