Possible motor problem with Bachmann Lyn

PhilP said:
How much is your time worth?
Plus the cost in 'bits'...

For £35 you could buy a new LGB twin-ended motor.. :nerd:
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But like all model building, it is the fun of the challenge, and if you can afford it sourcing the items to build with. The final "glee" being "I built this", the fact that you could have bought it quicker and cheaper is irrelevant, until SWMBO find out ;)
 
AustrianNG said:
Not wishing to chuck a grenade in here, but replace the motor block with an LGB block..........

(Ducks for cover) :)
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Hi Paul
If I had one, I probably would. But having got two Bachmann blocks with motors, I'd hate to waste them. ...

Rik
 
PhilP said:
How much is your time worth?
Plus the cost in 'bits'...

For £35 you could buy a new LGB twin-ended motor.. :nerd:
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I've got one - donated by another fellow modeller - but the LGB worms don't mesh with the Bachmann worm wheels..... Curses!!
And I do hate to waste a decent motor in the remotored Bachmann block ...... :eek:

Rik
 
Well to say the least, I am confusingly dissappointed --- and certainly feel your "pain" Rik. But like JimmyB, the Quest for a solution (or at minimum, the cause of the dilemma) is almost too tantalizing to not pursue. I wish I could offer something more practical towards the Quest but can only compare this situation to a classic mystery novel and I can't wait to see "Who done it?"
 
ge_rik said:
The two motor blocks (original and modified) give almost the exact same performance so I don't think it can be the replacement motor which is the problem.
Rik
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Hi Rik, I am aware that you're getting equal performance from to original and replacement motor types.
However, as the original motors were pretty poor pullers even when new, my suggestion of trying to find out the origin of the replacement motor was to check that it was not from an equally poor puller. (Such as a LGB toytrain.)
see quote below regarding early Lyn performance:
Paul.

Lyn loco​
hi guys,i see a lyn loco on ebay,as new not run,is this loco a good runner,i want to copy a model of our famous puffing billy,which is 2-6-2,the wheel config is not big problem,is the running gear the same as the new porter,im not sure,any help is good help,thanks peter
Smiley
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Jon

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« Reply #1 on: December 08, 2007, 09:59:22 AM »​
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The motor block of the Lyn does not even come close to that of the new side tank or saddle tank Porter.

The Lyn was introduced sometime around late 1993 or early 1994. It was Bachmann's first offering to carry the designation of Spectrum. The Lyn was never catalogued, to the best of my knowledge. The locomotive was sold in a regular Bachmann box with a sleeve that has the picture of the Lynn and the Spectrum 'G' designation.

They are very poor runners, by my estimation. Geared way too high. They will not pull much and have no low speed power. Being geared so high they run like a scalded dog, overheat the motor, melt the motor mounts, and at that point end up on the rip track.

The motors have very large diameter brass worm gears. Bachmann's claim at the time they were introduced was that these heavier worm gears would act as flywheels. Maybe so, but they sure did not help locomotive performance.
 
ge_rik said:
And so the saga continues ...... :(

After reassembling the loco, I gave her a test run. Still very disappointing in terms of pulling power. Even with a standard load of eight goods wagons the loco really struggled up my 1:40 gradients which my other locos gallop up. It also slowed appreciably on curves; the curve on the gradient brought it to a snail's pace on full power. I discovered the gauge on the drivers was slightly wide, but pushing the wheels tighter on to the gears to bring them to gauge made minimal difference. I stripped the motor block down to see if my clamshell was rubbing on anything. Nothing evident but I filed possible pinch points just in case. I reassembled and found there was very little improvement.

In desperation, I assembled the motor block which JimmyB had kindly sent me - which looks almost new.

Another test run and exactly the same outcome! Too little power to cope with a standard train!!

I can only assume that, for whatever reason (friction and/or my leverage theory), the large worms seriously impede the motor's ability to transmit power.

My next resort is to see if I can replace the worms with smaller diameter versions. I've ordered a gear puller and have found out how to calculate the mod value of the worm wheels. I just hope I can find a couple of replacements somewhere......

I will not be defeated!! :eek::wasntme:

Rik
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One thing I learned way back in the days of GSM with my first battery build, was that motors use less current when they're spinning freely - they require a lot, and are therefore presumably less efficient, at bottom end grunt. So, lower gear ratios are better, and a good starting point is 1:30. My scratch built 2-6-2 with slightly larger drivers (designed for a 16mm:1ft L&B 2-6-2 ) has a gearbox with a 1:50 ratio.

The Yeti, in its latest and most successful guise with 28mm wheels is running 1:32 :nod: :nod:
 
JimmyB said:
But like all model building, it is the fun of the challenge, and if you can afford it sourcing the items to build with. The final "glee" being "I built this", the fact that you could have bought it quicker and cheaper is irrelevant, until SWMBO find out ;)
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Oh yes, but to be a professional cheapskate, you must always look at what appears to be the cheapest option first ........... even if the final answer then costs you three or four times more :emo::emo: Trust me, I know >:)>:)
 
Rik, I believe that the smaller worm is the solution, but I do not believe anybody has mentioned what the issue (apologies if you have and I have missed it), I think this is all to with "moments around a point".

The centre of the motor spindle is the fulcrum, and the motor provides the power which is a constant (assuming constant voltage input) the the further you move from the fulcrum, less load is required to equal the power output, ergo the larger the worm the less power drive you have.
 
JimmyB said:
Rik, I believe that the smaller worm is the solution, but I do not believe anybody has mentioned what the issue (apologies if you have and I have missed it), I think this is all to with "moments around a point".

The centre of the motor spindle is the fulcrum, and the motor provides the power which is a constant (assuming constant voltage input) the the further you move from the fulcrum, less load is required to equal the power output, ergo the larger the worm the less power drive you have.
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Thanks Jim. That's how I was trying to explain it in earlier posts, but far less eloquently.

Something else which Gregh has just pointed out to me is that I would need a matching pair of left and right handed worms. It's proving difficult to find standard 2.5mm bore 0.5M worms so I've decided to go for a single worm with a 3mm bore and use 3mm brass tube as a reducer. I can then use the coupling rods of the loco to transmit power to the other drivers.

All good fun!

Rik
 
ge_rik said:
Thanks Jim. That's how I was trying to explain it in earlier posts, but far less eloquently.

Something else which Gregh has just pointed out to me is that I would need a matching pair of left and right handed worms. It's proving difficult to find standard 2.5mm bore 0.5M worms so I've decided to go for a single worm with a 3mm bore and use 3mm brass tube as a reducer. I can then use the coupling rods of the loco to transmit power to the other drivers.

All good fun!

Rik
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Yep - the biggest issue facing the scratchbuilder in this scale is a lack of consistency in shaft and axle diameters - it is the thing that really holds us back.

You wouldn't necessarily need a handed pair of worms if the motor shaft were long enough for you to mount one with the grub screw 'inboard' and the other 'outboard'.

However, I think you're right - get the gear ratio right one end and let the con-rods do their job :nod: :nod:
 
ge_rik said:
Thanks Jim. That's how I was trying to explain it in earlier posts, but far less eloquently.

Something else which Gregh has just pointed out to me is that I would need a matching pair of left and right handed worms. It's proving difficult to find standard 2.5mm bore 0.5M worms so I've decided to go for a single worm with a 3mm bore and use 3mm brass tube as a reducer. I can then use the coupling rods of the loco to transmit power to the other drivers.

All good fun!

Rik
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I don't think you need different handed worms, one worm on each end turning in the same direction, if one worm is L/H and one R/H then the driven gears will turn in opposite directions, check out your original ones (I have just looked at your photos) and both worms look the same :)
 
Rhinochugger said:
Yep - the biggest issue facing the scratchbuilder in this scale is a lack of consistency in shaft and axle diameters - it is the thing that really holds us back.

You wouldn't necessarily need a handed pair of worms if the motor shaft were long enough for you to mount one with the grub screw 'inboard' and the other 'outboard'.

However, I think you're right - get the gear ratio right one end and let the con-rods do their job :nod: :nod:
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JimmyB said:
I don't think you need different handed worms, one worm on each end turning in the same direction, if one worm is L/H and one R/H then the driven gears will turn in opposite directions, check out your original ones (I have just looked at your photos) and both worms look the same :)
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Doh! Of course, why didn't I think of that?


Anyhow, I think I'll try it with just one worm anyway. I might try redesigning the motor block housing to tilt the motor thereby giving clearance for the motor can over the worm wheel and obviating the need for an idler gear between the worm and worm wheel.

Rik
 
ge_rik said:
Doh! Of course, why didn't I think of that?


Anyhow, I think I'll try it with just one worm anyway. I might try redesigning the motor block housing to tilt the motor thereby giving clearance for the motor can over the worm wheel and obviating the need for an idler gear between the worm and worm wheel.

Rik
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Apologies if this has been mentioned before. In my opinion the original version's cranks and coupling rods are a little flimsy and have a bit of play. This may even be an advantage with both axles motor driven but may cause issues when the cranks and coupling rods transmit power.
 
ge_rik said:
Doh! Of course, why didn't I think of that?


Anyhow, I think I'll try it with just one worm anyway. I might try redesigning the motor block housing to tilt the motor thereby giving clearance for the motor can over the worm wheel and obviating the need for an idler gear between the worm and worm wheel.

Rik
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Tricky one - the purpose of an idler gear is to reduce the stresses on the drive train.

I've lost count of how many gearboxes I tried on the Yeti, before I splashed out on an expensive G1 item.

That said, the most successful simple drive box before the super-duper version was the home made one that was formed out of a strip of ally bent in a vice to a U shape and with all the axle holes and motor mount holes drilled by hand. The motor was slightly skew to the axle, and it performed a dream o_Oo_Oo_Oo_O Its only drawback was that the second hand gears that I salvaged were an inappropriately high ratio and while the loco would run on level track with a short train, it wouldn't deal with the gentle grades on the current line.
 
Paul2727 said:
Nope. Just comes up with:
Oops! We ran into some problems.
Please enter a valid message.
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Just leave it, and go and do something else - as long as there's no text it will eventually sort itself with no embarrassment to the mis-poster ;););)
 
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