Weak Bachmann Lyn motor

Do you have a problem? Here is the place to appeal for help
User avatar
ge_rik
Administrator
Administrator
Posts: 6497
Joined: Sun Oct 25, 2009 10:20 pm
Location: Cheshire
Contact:

Weak Bachmann Lyn motor

Post by ge_rik » Mon Mar 01, 2021 1:28 pm

I thought I'd take a video of the converted Bachmann Lyn in action but she just doesn't have any pulling power. I thought it might have something to do with the batteries but after a recharge it was no different and even replacing the batteries completely makes no difference, so I suspect the Buhler motor has had it. I can stall the loco with one finger. All my other locos will protest amid much wheel spinning under similar circumstances.

Has anyone else experienced anything like this?

Any ideas where in the UK I might be able to get a replacement motor?

Rik
------------------------
Peckforton Light Railway - Blog Facebook Youtube

User avatar
philipy
Moderator
Moderator
Posts: 5033
Joined: Sun Jan 30, 2011 3:00 pm
Location: South Northants

Re: Weak Bachmann Lyn motor

Post by philipy » Mon Mar 01, 2021 1:55 pm

ge_rik wrote: Mon Mar 01, 2021 1:28 pm

Any ideas where in the UK I might be able to get a replacement motor?

You could try these people they seem to be the UK agents for Buhler.
https://www.bancroft.co.uk/stock-motors.html
Philip

User avatar
ge_rik
Administrator
Administrator
Posts: 6497
Joined: Sun Oct 25, 2009 10:20 pm
Location: Cheshire
Contact:

Re: Weak Bachmann Lyn motor

Post by ge_rik » Mon Mar 01, 2021 2:07 pm

philipy wrote: Mon Mar 01, 2021 1:55 pm
ge_rik wrote: Mon Mar 01, 2021 1:28 pm

Any ideas where in the UK I might be able to get a replacement motor?

You could try these people they seem to be the UK agents for Buhler.
https://www.bancroft.co.uk/stock-motors.html
Thanks. Will investigate.
However, see next post......

Rik
------------------------
Peckforton Light Railway - Blog Facebook Youtube

User avatar
ge_rik
Administrator
Administrator
Posts: 6497
Joined: Sun Oct 25, 2009 10:20 pm
Location: Cheshire
Contact:

Re: Weak Bachmann Lyn motor

Post by ge_rik » Mon Mar 01, 2021 2:10 pm

I found this on the Bachmann.com forum
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.

The motor case is made in two halves, right and left. In order to get into the case the drivers must be pried from the nylon drive gears. Once that's done the case can be taken apart.

On balance, not a locomotive that would provide good service. It would be a shame to use a Lyn for a bash if its motor block was retained. All that work for a locomotive that won't pull much, melts its motor mounts, and is only comfortable at running at about Mach I.
So, it might just be a characteristic of the motor block. In which case, replacing the motor might make little difference. There is evidence of some overheating in the plastic of the clamshell housing so I wondered if the motor might have been cooked at some point.

Rik
------------------------
Peckforton Light Railway - Blog Facebook Youtube

User avatar
ge_rik
Administrator
Administrator
Posts: 6497
Joined: Sun Oct 25, 2009 10:20 pm
Location: Cheshire
Contact:

Re: Weak Bachmann Lyn motor

Post by ge_rik » Mon Mar 01, 2021 3:08 pm

Looks like there's some shared experiences on our forum - https://gardenrails.org/forum/viewtopic ... 4052#p4052

Rik
------------------------
Peckforton Light Railway - Blog Facebook Youtube

User avatar
philipy
Moderator
Moderator
Posts: 5033
Joined: Sun Jan 30, 2011 3:00 pm
Location: South Northants

Re: Weak Bachmann Lyn motor

Post by philipy » Mon Mar 01, 2021 3:33 pm

If the motor/block is as dodgy as it sounds, then would it be a better option to print a new housing to accomodate the motor/gears of your choice?
Philip

User avatar
ge_rik
Administrator
Administrator
Posts: 6497
Joined: Sun Oct 25, 2009 10:20 pm
Location: Cheshire
Contact:

Re: Weak Bachmann Lyn motor

Post by ge_rik » Mon Mar 01, 2021 3:54 pm

philipy wrote: Mon Mar 01, 2021 3:33 pm If the motor/block is as dodgy as it sounds, then would it be a better option to print a new housing to accomodate the motor/gears of your choice?
Possibly..... However, the wheels are mounted on stub axles with a square profile designed to fit into a nylon moulding which includes the worm wheels. Not sure if I will be able to use them with a different type of gearbox arrangement. :?

Rik
------------------------
Peckforton Light Railway - Blog Facebook Youtube

User avatar
ge_rik
Administrator
Administrator
Posts: 6497
Joined: Sun Oct 25, 2009 10:20 pm
Location: Cheshire
Contact:

Re: Weak Bachmann Lyn motor

Post by ge_rik » Tue Mar 02, 2021 11:56 am

Further to my previous posts - I've now tried another test run and discovered, curiously, that it runs better in reverse than going forwards. In reverse it's almost but not quite passable - but going forwards, skin and rice pudding springs to mind.

I've removed the motion to eliminate that as a possible cause.




Rik
------------------------
Peckforton Light Railway - Blog Facebook Youtube

User avatar
ge_rik
Administrator
Administrator
Posts: 6497
Joined: Sun Oct 25, 2009 10:20 pm
Location: Cheshire
Contact:

Re: Weak Bachmann Lyn motor

Post by ge_rik » Tue Mar 02, 2021 12:09 pm

ge_rik wrote: Mon Mar 01, 2021 3:54 pm .... the wheels are mounted on stub axles with a square profile designed to fit into a nylon moulding which includes the worm wheels. Not sure if I will be able to use them with a different type of gearbox arrangement. :?
Here's that the insides look like
Merged_document.jpg
Merged_document.jpg (1.92 MiB) Viewed 4443 times


Might be tricky to mount the wheels - unless I can find a worm which meshes with the existing worm wheels

Rik
------------------------
Peckforton Light Railway - Blog Facebook Youtube

User avatar
GTB
Driver
Driver
Posts: 1550
Joined: Sat Mar 05, 2011 2:46 pm
Location: Australia

Re: Weak Bachmann Lyn motor

Post by GTB » Tue Mar 02, 2021 1:33 pm

ge_rik wrote: Tue Mar 02, 2021 12:09 pm Might be tricky to mount the wheels - unless I can find a worm which meshes with the existing worm wheels
Bachmann and quality control have only a fleeting acquaintance from what I've seen........

I'm told they use Mabuchi motors, but I'm inclined to think it will be a cheaper chinese clone. The clone makers use Mabuchi motor codes and there should be a code printed on it somewhere. Usually in the form XX-nnn. There may also be a suffix letter if it's a special voltage, etc. Unless someone has replaced the original, the chance of Bachmann using Buhler motors would be somewhere between zero and none.

You need to establish the gear pitch of the axle gears, it's probably a standard metric gear in the range 0.5MOD - 1MOD from the look of it. You'll find websites that can take you through the measurement process, then you can find a matching worm.

My inclination of course would be to build a steel outside frame with a motor/gearbox and bevel gear final drive, probably with Walsall wheels. It would outlast me, but I realise you don't have the machinery for something like that.

It would be worth seeing if you can print a plain axle with square sockets and if your printer is up to that job, use them with the Bachmann wheels, plus a better motor and gears and print your own motor block.

Regards,
Graeme

User avatar
ge_rik
Administrator
Administrator
Posts: 6497
Joined: Sun Oct 25, 2009 10:20 pm
Location: Cheshire
Contact:

Re: Weak Bachmann Lyn motor

Post by ge_rik » Tue Mar 02, 2021 1:45 pm

Hi Graeme
It says it's a Buhler motor - unless it's a clever clone.
S1760015.JPG
S1760015.JPG (1.29 MiB) Viewed 4434 times

Rik
PS - You can see from the bulge in the side of the motor block that the motor (or its predecessor) has, in the past, got somewhat warm......
------------------------
Peckforton Light Railway - Blog Facebook Youtube

User avatar
-steves-
Administrator
Administrator
Posts: 2412
Joined: Thu Jul 28, 2011 1:50 pm
Location: Cambridge & Peterborough

Re: Weak Bachmann Lyn motor

Post by -steves- » Tue Mar 02, 2021 4:04 pm

Shame you don't have 32mm track as I am doing a FR Single Fairlie Taliesin next on my list, maybe you could just make a bogie to 45mm from my 32mm one, after all, it's only the width that would change? More room for stuff, lol.

Failing that, just make up your own complete drive unit from scratch, I assume the boiler area is hollow so you could fit a vertical motor?
The buck stops here .......

Ditton Meadow Light Railway (DMLR)
Member of Peterborough and District Association
http://peterborough.16mm.org.uk/

User avatar
Peter Butler
Driver
Driver
Posts: 5219
Joined: Sun Sep 09, 2012 10:33 pm
Location: West Wales

Re: Weak Bachmann Lyn motor

Post by Peter Butler » Tue Mar 02, 2021 5:40 pm

As a non-engineering person I wonder whether it would be possible to remove the worm gears from the drive shaft, fit them to a new, longer shaft with an outside motor attached, assuming there is space within the loco body?
The best things in life are free.... so why am I doing this?

User avatar
ge_rik
Administrator
Administrator
Posts: 6497
Joined: Sun Oct 25, 2009 10:20 pm
Location: Cheshire
Contact:

Re: Weak Bachmann Lyn motor

Post by ge_rik » Tue Mar 02, 2021 6:55 pm

Thanks chaps. I think my next option is to design and 3d print a new housing for the motor block. If the worm wheels are standard size, then maybe a motor with smaller diameter worms might give more thrust. I'm hoping that assumption is valid. The most obvious difference between the Bachmann block and lgb blocks is the diameter of the worms and all my lgb blocks perform far batter than this one does.

Rik
------------------------
Peckforton Light Railway - Blog Facebook Youtube

User avatar
philipy
Moderator
Moderator
Posts: 5033
Joined: Sun Jan 30, 2011 3:00 pm
Location: South Northants

Re: Weak Bachmann Lyn motor

Post by philipy » Tue Mar 02, 2021 7:00 pm

ge_rik wrote: Tue Mar 02, 2021 6:55 pm I think my next option is to design and 3d print a new housing for the motor block.
At the risk of teaching granny... ,if I were doing that I think I'd try to leave ventilation holes in the side plates, to allow for the motor gettinga bit warm?
Philip

metalmuncher
Cleaner
Cleaner
Posts: 95
Joined: Sat Oct 20, 2012 4:15 pm

Re: Weak Bachmann Lyn motor

Post by metalmuncher » Tue Mar 02, 2021 7:56 pm

ge_rik wrote: Tue Mar 02, 2021 6:55 pm If the worm wheels are standard size, then maybe a motor with smaller diameter worms might give more thrust. I'm hoping that assumption is valid.
With worm gears, the gear ratio is dependent on the number of starts of the screw, not the diameter of the worm. E.g. a single start worm used with a 40 tooth worm wheel has a ratio 40:1, no matter the diameter of the worm. Most of the worms I've seen on models are single start, but I can't really tell if the ones on your motor block are single or multi start. If it is multi start, swapping the worms for same-diameter single start versions would increase the gear ratio, giving more torque and less speed.

Since most worms are single start, to get more torque your best bet is to increase the number of teeth on the worm wheel, but for simple arrangements where the worm wheel is on the same axle as the wheels, your number of teeth on the worm wheel is limited by the size of the wheels, otherwise the worm wheel can foul the track.

User avatar
gregh
Trainee Driver
Trainee Driver
Posts: 566
Joined: Sun Apr 01, 2018 5:44 am
Location: Sydney, Australia
Contact:

Re: Weak Bachmann Lyn motor

Post by gregh » Wed Mar 03, 2021 5:45 am

Have you tried the Bachmann spare parts page? A quick search gave me this...
https://estore.bachmanntrains.com/index ... 3vmdta3l11

I think I mentioned before that I used two of the motor blocks in my red Garratt with no problems. I bought them in 1997 but they were labelled as Spectrum types so may be better quality.

If you apply finger pressure to the loco, do the wheels spin or stall? From the video it seems to stall.

The different operation in forward and reverse MAY be due to 'slop' on the main drive shaft allowing the worm gear to be pushed to one end and bind. I had to put a small brass shim behind the worm to hold it in place.

Can you measure the armature resistance with your multimeter? It could help determine if the motor is damaged. Expect resistance to be around 4 or 5 ohms. I can measure mine if it helps. And measure the milliamps the motor takes when running with its wheels in the air.

And the obvious - how much does it weigh and is the weight over the drivers or unbalanced at one end?
Greg from downunder.
The Sandstone & Termite's website: https://members.optusnet.com.au/satr/satr.htm

User avatar
ge_rik
Administrator
Administrator
Posts: 6497
Joined: Sun Oct 25, 2009 10:20 pm
Location: Cheshire
Contact:

Re: Weak Bachmann Lyn motor

Post by ge_rik » Wed Mar 03, 2021 9:06 am

metalmuncher wrote: Tue Mar 02, 2021 7:56 pm
ge_rik wrote: Tue Mar 02, 2021 6:55 pm If the worm wheels are standard size, then maybe a motor with smaller diameter worms might give more thrust. I'm hoping that assumption is valid.
With worm gears, the gear ratio is dependent on the number of starts of the screw, not the diameter of the worm. E.g. a single start worm used with a 40 tooth worm wheel has a ratio 40:1, no matter the diameter of the worm. Most of the worms I've seen on models are single start, but I can't really tell if the ones on your motor block are single or multi start. If it is multi start, swapping the worms for same-diameter single start versions would increase the gear ratio, giving more torque and less speed.

Since most worms are single start, to get more torque your best bet is to increase the number of teeth on the worm wheel, but for simple arrangements where the worm wheel is on the same axle as the wheels, your number of teeth on the worm wheel is limited by the size of the wheels, otherwise the worm wheel can foul the track.
I can see that I'd get the same reduction ratio regardless of the diameter of the worm, but how about the amount of thrust on each tooth. Say, for example, the worm was a metre in diameter. Wouldn't amount of effort needed to push each tooth be greater than if the worm was only 5mm in diameter - or will the amount of thrust remain the same? Sorry if I'm getting my forces terminology mixed up.

Rik
------------------------
Peckforton Light Railway - Blog Facebook Youtube

User avatar
ge_rik
Administrator
Administrator
Posts: 6497
Joined: Sun Oct 25, 2009 10:20 pm
Location: Cheshire
Contact:

Re: Weak Bachmann Lyn motor

Post by ge_rik » Wed Mar 03, 2021 10:18 am

gregh wrote: Wed Mar 03, 2021 5:45 am Have you tried the Bachmann spare parts page? A quick search gave me this...
https://estore.bachmanntrains.com/index ... 3vmdta3l11

I think I mentioned before that I used two of the motor blocks in my red Garratt with no problems. I bought them in 1997 but they were labelled as Spectrum types so may be better quality.
Thanks for this comprehensive reply Greg
I've now investigated the parts needed to replace the motor block. I'd also need a new wheel set as the gears on the new block are different. The total comes to £98 with shipping to the UK and I'd then need to pay 20% VAT so it would be nearly £120 overall. I think I'll see if there's a cheaper solution.
gregh wrote: Wed Mar 03, 2021 5:45 am If you apply finger pressure to the loco, do the wheels spin or stall? From the video it seems to stall.

The different operation in forward and reverse MAY be due to 'slop' on the main drive shaft allowing the worm gear to be pushed to one end and bind. I had to put a small brass shim behind the worm to hold it in place.
Yes, I can stall the loco with finger pressure. Something which is very difficult with my other locos. I'm going to try playing around with the block in its half assembled state to see if I can spot any sloppiness or binding. I'll give it a jolly good degrease and cleanup as well.
gregh wrote: Wed Mar 03, 2021 5:45 am Can you measure the armature resistance with your multimeter? It could help determine if the motor is damaged. Expect resistance to be around 4 or 5 ohms. I can measure mine if it helps. And measure the milliamps the motor takes when running with its wheels in the air.
Armature resistance is 6 ohms and it draws around 100 mA on tickover and around 180mA on full power with wheels in the air.
gregh wrote: Wed Mar 03, 2021 5:45 am And the obvious - how much does it weigh and is the weight over the drivers or unbalanced at one end?
I've placed the original weights from the Lyn in the side tanks. Slightly biased towards the cab so I might try adding something to the front end as per the Lyn.


Rik
------------------------
Peckforton Light Railway - Blog Facebook Youtube

User avatar
ge_rik
Administrator
Administrator
Posts: 6497
Joined: Sun Oct 25, 2009 10:20 pm
Location: Cheshire
Contact:

Re: Weak Bachmann Lyn motor

Post by ge_rik » Wed Mar 03, 2021 6:33 pm

Well folks! Thanks very much for all your kind thoughts, suggestions and contributions - both in words and, in one case, in posting me a replacement motor - which I maybe won't need to use. I think I have identified the problem and fixed it (let's hope that's not famous last words!).

By cleaning everything up and then closely scrutinising all the bits I figured out that the motor which was installed in the motor block was actually a replacement to the original. The original mountings for the motor had been filed away and the corners of the motor had also been filed to clear the worm wheels.
Merged_document.jpg
Merged_document.jpg (1.07 MiB) Viewed 4510 times

BY watching carefully, I discovered the motor twisted slightly (by only a couple of mm) when under power. This was sufficient for the motor can to rub against one of the worm wheels. I inserted a self-tapping screw through the clamshell housing to engage with a slot in the side of the motor can. This seems to have done the trick. The loco now runs as well (or as badly) going forwards as it does in reverse.



My next task is to design and 3D print a bespoke clamshell housing which include lugs to hold the motor more securely. The plastic of the original housing is so brittle that all the pillars for the self-tapping screws holding it together have either split or completely disintegrated.

Many thanks again to all those who contributed to the deliberations in this thread. To my mind, this sort of discussion is what a forum like this is all about.

Rik
------------------------
Peckforton Light Railway - Blog Facebook Youtube

Post Reply

Who is online

Users browsing this forum: No registered users and 5 guests