Wombat C30T

 
  Neville John Station Master

Location: Sydney
I've had the C30t for quite a while since it's inception from Wombat models. My problem with it is the noisy mechanism.It sounds like it's a tractor on a farm! I don't recall it being like this when I first bought it. I have added weights to it to improve traction but I don't believe this has affected the running qualities.
It's dc and non sound. (Sorry but I'm old fashioned and started well before dcc!)
It's a great runner but a noisy one!
Does anyone have any ideas?
Thank you in advance.
Neville.

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  Oscar Train Controller

My thoughts without answers.  At a certain speed the chatter starts on both of mine, (edit)more in reverse.  I've left one unaltered and have heavily messed around with the other one, 3004. I thought perhaps the motor was to blame but with a Mashima and non accurately bored out worm the noise was worse.  I've had other variations of motors like custom skewed OEM and NWSL both using stock unaltered worms and the the chatter still exists above a certain speed.  

There is tape underneath the OEM motor which I thought may dampen vibrations and I have experimented with a layer of squished blu tac and other tape to no avail.  Then there are those four metal plates which I can't remember off hand exactly where they go, but I think they go between the sides of the metal gear housing and the body, and they might dampen noise. But from memory there was still noise before I took them out so i haven't put them back in.

Then there's the gears.  I've only once disassembled everything. The worm, worm gear, reduction and drive gears (not sure of exact names), they all seem finely machined and mesh really well and the chassis finely machined to accept shafts in the right spots. I really can't tell where the chatter comes from except to say I think the gears cause the noise but I don't know where or why.

I've thought that perhaps fewer gears would make a difference. I've an unassembled FSM Z25 kit that has a fine pitched worm and drive gear without idlers. I look forward to seeing if that type of setup is noiseless. On the other hand a Lloyds C30 with worm, idler and drive gear in a NWSL gearbox is smooth and quiet.  The major difference is it drives the middle axle which makes the gear box visible. So in that respect the Wombat does well to conceal the gears and any attempt to change the gears to a more direct drive setup would require major and accurate work I'm incapable of.

So I don't know.  I'll have another look at this one day but the only thing I'd be prepared to do myself that probably goes against any advice of the more experienced and manufacturers is to liberally apply heavy grease to the teeth of all gears.  I'm not recommending you or anyone to do it, but I'll give it a shot for the greater good. Soon. Cool
  a6et Minister for Railways

My thoughts without answers.  At a certain speed the chatter starts on both of mine, less in reverse.  I've left one unaltered and have heavily messed around with the other one, 3004. I thought perhaps the motor was to blame but with a Mashima and non accurately bored out worm the noise was worse.  I've had other variations of motors like custom skewed OEM and NWSL both using stock unaltered worms and the the chatter still exists above a certain speed.  

There is tape underneath the OEM motor which I thought may dampen vibrations and I have experimented with a layer of squished blu tac and other tape to no avail.  Then there are those four metal plates which I can't remember off hand exactly where they go, but I think they go between the sides of the metal gear housing and the body, and they might dampen noise. But from memory there was still noise before I took them out so i haven't put them back in.

Then there's the gears.  I've only once disassembled everything. The worm, worm gear, reduction and drive gears (not sure of exact names), they all seem finely machined and mesh really well and the chassis finely machined to accept shafts in the right spots. I really can't tell where the chatter comes from except to say I think the gears cause the noise but I don't know where or why.

I've thought that perhaps fewer gears would make a difference. I've an unassembled FSM Z25 kit that has a fine pitched worm and drive gear without idlers. I look forward to seeing if that type of setup is noiseless. On the other hand a Lloyds C30 with worm, idler and drive gear in a NWSL gearbox is smooth and quiet.  The major difference is it drives the middle axle which makes the gear box visible. So in that respect the Wombat does well to conceal the gears and any attempt to change the gears to a more direct drive setup would require major and accurate work I'm incapable of.

So I don't know.  I'll have another look at this one day but the only thing I'd be prepared to do myself that probably goes against any advice of the more experienced and manufacturers is to liberally apply heavy grease to the teeth of all gears.  I'm not recommending you or anyone to do it, but I'll give it a shot for the greater good. Soon. Cool
Oscar
My Wombat 30T is back in its box, I took it out only to have a bopeep, and take the tail rods off the cylinders as mine is a Superheated version which did not have them, and I have not tried to run it yet.

I purchased the 30T to use only as a shunting engine and a relay work to an abatoirs section works, so no fast running will be had.  But no looking at this point of time as to the problems mentioned here. Although I am wondering after reading what you have said regarding the Lloyds C30 and nil noise, with the wombats body off does the same noise take place? or closer to the quieter Lloyds model.

I wonder if there is some internal flexing with the motors mount as the speed of the model increases, that causes the motor or gears themselves to move a bit in a side ways manner. How that would affect the gears or even positioning of them and or the motor may be part or all of the problem.
  Oscar Train Controller

Apologies for the late reply, be warned, it's gonna be a long one.....

Regarding body off, definitely less noise. When I was experimenting months ago I noticed louder with the body on, quieter when off, regardless if it was an OEM motor, Mashima or NWSL. It was as though the body can act as an amplifier of sorts, similar to how baseboards can amplify track sounds.  During testing on a rolling road and body off, even less noise is transmitted, but the noise is still there.  Generally it's faint whilst starting, nearly disappears at maybe quarter pace then gets louder all the way to full throttle.

I'll post a couple of exerts from older videos demonstrating the noise. I must correct a couple of things though.  The noise is a whir sound not chatter as I described it in the previous post. Also, running in reverse produces a louder sound not less as I previously typed.

Now regarding the flexing motor mount theory you mentioned, I admit I was dismissive when I read it a few days ago. But I gave it some more thought after going out and cleaning the track to get the locos running and I remembered the test with the Mashimas and rebored worm many months ago that there was more noise at speed than OEM motor and stock worm.  The reboring excercise was inaccurate and from that I suppose anything messing with the mesh of worm and worm gear will lead to more noise.  

So I had a look at a couple of other gear arrangements. The Lloyds C30 has a flexible tube coupling between motor and worm's shaft compared to the wombat with worm attached directly to the motor's shaft. That highlights another major difference whereby the Lloyds C30's worm shaft is held in place by bearings and bushes fore and aft in the NWSL gearbox.  Similarly an unassembled Ezi Kits Z24 has the same in its NorthYard gearbox. This approach leads to a secured and constant meshing of the worm and worm gear.  The wombat on the other hand has the worm attached to the end of the motor shaft with nothing anchoring the rear of the worm.  So the worm's position relies on that motor retaining clip and chassis bulkheads to keep the motor in one place and by extension, keep the mesh between the worm and worm gear.  If there was any vibration or freeplay perhaps there'd be a magnification towards the worm.  But I hasten to add it all seems pretty solid.  Only when I have removed the forward bulkhead and packing tape beneath the motor did I see movement of the motor under the retaining clip.

An obvious fix to this would be to add 1mm shafting from the worm through a bearing placed in a hole drilled into the rear of the gear housing.  Easier said than done but it's an interesting idea.  

Whilst it's possible that vibrations of a fast spinning motor and worm arrangement of the wombat might cause some additional noise it's my belief that it's the rest of the gear train that causes the whir.  The Lloyds 30 as mentioned before is quiet.  The fixed position of the worm inside the gearbox meshes it to a helical idler gear then helical drive gear.  The worm is fine pitched and reduction is 28:1 with a bigger Mashima 5 pole skew wound 1525 motor.  The wombat has a 1015 sized 3 pole motor with coarser pitched worm.  The matching helical gear has a straight cut reduction gear attached that's meshed to a straight cut idler gear and straight cut final drive gear.  Reduction is 50:1.

My take on all that is more gears and particularly straight cut have more potential to be noisy.  The smaller motor spins faster for reduction to be performed by the worm, first reduction gear and the idler to get the slow speeds rather than just the fine pitched worm of the Lloyds example and a torquier motor.  I wish I had the Z24 going but I assume it would be quiet based on the fine pitched worm producing reduction alone with no idler.  The worm gear is also the final drive gear.

So barring major mods I go back to my initial thoughts into reducing noise by using a sticky thick grease. Research into what to use is continuing.

Here's those snippets demonstrating the whirring noise. Click the links for the short versions or fast forward to 12 seconds and 1:42 respectively.



https://youtu.be/m6Mu_TvpLtk?t=12



https://youtu.be/xXaxmlvipXg?t=102
  Oscar Train Controller

Did a fair bit of testing over the weekend, results were negligible. I used INOX MX6 and MX8 on two mechanisms a 30T and Ixion 32.  Briefly about the greases - MX6 food grade type, is synthetic PAO with PTFE.  MX8 is lithium based with PTFE and much thicker.

The 30T always had a quieter spot which I said was around quarter throttle but after remapping the chip to a straight line to mimic a lineal DC like response, I discovered the mechanism was quieter between 50 - 90% throttle. I used MX6 first which had no effect.  After trying to remove some I repacked the area with MX8 and whilst I thought there was some improvement, now I'm not sure.

The 32 had just MX8 applied, repacked twice and it made no difference.  The 32 has the gear noise form zero to full throttle.  

I videoed and compared everything but they don't capture what you can hear. It's a bit of hit and miss and sometimes unfairly exaggerated so I've not cut a video together.  In short, overpacking with grease didn't really improve anything.

I will leave some photos of the mechanisms though because there's one more thing I'd like to try.
Before I greased the mechs I took photos of them just to check they were the same.
The 30T had a little more factory grease compared to the 32 but both were lubed enough IMO.  With them appearing the same I wondered why they sounded different.  The idler in both mechs can slide laterally and the 30T's idler could move more readily compared to the 32.  Perhaps the 30T is more run in. But I would like to try and see if adding bushings, washers and a spring to keep the idler in place will make a difference.  

The first two pics show the 30T with idler in different positions and the last is of the 32 showing the same gear arrangement. Helical cut gear and attached reduction are easily visible in the last pic.


https://flic.kr/p/2kXHRvv
https://flic.kr/p/2kXDpLA
https://flic.kr/p/2kXDpMn
  Neville John Station Master

Location: Sydney
Thank you both for the replies and a thank you to NSW3802 for the pm's. It was suggested that I apply some oil to the gears which I've done by only taking off the bottom plate. ( Labelle 107 ).I think this has made a little difference although after reading Oscar's extensive replies, perhaps I'm kidding myself?
It was also suggested that I remove the body and apply some oil on either end of the motor and perhaps the top bearings associated with the gears. I'll get around to doing that soon.
Thanks again.
Neville.
  a6et Minister for Railways

Did a fair bit of testing over the weekend, results were negligible. I used INOX MX6 and MX8 on two mechanisms a 30T and Ixion 32.  Briefly about the greases - MX6 food grade type, is synthetic PAO with PTFE.  MX8 is lithium based with PTFE and much thicker.

The 30T always had a quieter spot which I said was around quarter throttle but after remapping the chip to a straight line to mimic a lineal DC like response, I discovered the mechanism was quieter between 50 - 90% throttle. I used MX6 first which had no effect.  After trying to remove some I repacked the area with MX8 and whilst I thought there was some improvement, now I'm not sure.

The 32 had just MX8 applied, repacked twice and it made no difference.  The 32 has the gear noise form zero to full throttle.  

I videoed and compared everything but they don't capture what you can hear. It's a bit of hit and miss and sometimes unfairly exaggerated so I've not cut a video together.  In short, overpacking with grease didn't really improve anything.

I will leave some photos of the mechanisms though because there's one more thing I'd like to try.
Before I greased the mechs I took photos of them just to check they were the same.
The 30T had a little more factory grease compared to the 32 but both were lubed enough IMO.  With them appearing the same I wondered why they sounded different.  The idler in both mechs can slide laterally and the 30T's idler could move more readily compared to the 32.  Perhaps the 30T is more run in. But I would like to try and see if adding bushings, washers and a spring to keep the idler in place will make a difference.  

The first two pics show the 30T with idler in different positions and the last is of the 32 showing the same gear arrangement. Helical cut gear and attached reduction are easily visible in the last pic.


https://flic.kr/p/2kXHRvv
https://flic.kr/p/2kXDpLA
https://flic.kr/p/2kXDpMn
Oscar
Oscar, looking at the last pic, I gather the gears are some sort of synthetic/nylon or something rather than brass gears that were more common in previous models as I have not purchased anyloco's for some time, the Wombat 30T being the exception, I wonder if brass gears may be better?  Other thing I notice and maybe the photo's angle but the 3rd pic looks to me with the large gear to have minimal distance between the side of the gear and the metal side of the chassis/gear setting, could that mean the noise could be the gear rubbing against the metal, as the model increases speed?
  NSWRcars Assistant Commissioner

I can't believe that Nylon gears would be noisier than brass. I am also not surprised that packing grease makes no difference.
I have a re-motored Ixion C32 (similar mech to Wombat C30T) and it is quite noisy, particularly in reverse, but otherwise runs well since fitting a Mashima motor.
If there is a significant difference in noise between forward and reverse then one must suspect the helical gear that meshes with the worm, this will be thrust either left or right depending upon the direction of travel.
  a6et Minister for Railways

I can't believe that Nylon gears would be noisier than brass. I am also not surprised that packing grease makes no difference.
I have a re-motored Ixion C32 (similar mech to Wombat C30T) and it is quite noisy, particularly in reverse, but otherwise runs well since fitting a Mashima motor.
If there is a significant difference in noise between forward and reverse then one must suspect the helical gear that meshes with the worm, this will be thrust either left or right depending upon the direction of travel.
NSWRcars
Sugestion only
  Oscar Train Controller

Regarding brass gears a6et, I haven't had any experience there but must admit I used to think brass must be better only based on a general view of anything metal must be better than plastic. Not always the case I suppose.  For example, a number of years ago my son and I dabbled with RC planes and there was a perception and some marketing that metal geared servos were superior.  I can't quote the article I read but I became convinced otherwise.  They were all noisy to be honest but plastic suited our needs and budget particularly as every plane crashed out of service before a servo failed.

Similarly during my search for greases to use on the wombat and assuming the gears were nylon, I read on an engineering site about the preference for metal worms on plastic gears. There was something about nylon on nylon create heat and wear prematurely. As for metal on metal, or rather brass on brass, I really can't speak to why that isn't used except that moulded gears are easier and cheaper to make than machined metal ones and generally speaking nylon and delrin too perhaps are proven and do the job for our purposes.  On many newer gearboxes I looked at online most were brass worm on plastic.  But there were always exceptions.  As to whether all brass would be quieter I wish I could test it but one would think metal would dissipate that heat from contact surfaces more easily.

About that third pic and the large gear - I'm pretty confident that the large final drive gear doesn't touch anything.  The axle sideplay is minimal and I just can't see where the gear could touch anything. On the other hand that lateral movement of the idler between the first two pics above has had me curious as to whether there's contact with the side of the helical and reduction gear combo.  Check the old pic below of 3004's gears which has received the most abuse. I'm sure I oiled this mech with Labelle 102 during the many motor swaps and the black is due to the brass/nylon contact.  But what's obvious in this higher res version below is the idler is picking up some of the blackened oil off the side of the helical gear, perhaps contacting it.  

Which brings me to your really good point NSWRcars. I never really thought about side thrust on this helical gear moving laterally.  Well I've just gone out to the shed to look at 3004 that's partially stripped at the moment and can confirm the helical gear does have lateral movement and in that loco moves quite easily. It seems pretty obvious now that the sides of the gears are touching. I'm not looking forward taking the gears out again or saying this'll cure the gear noise but if I can shim the helical and idler we may be onto something.  Wont be able to test till the weekend or early next week but perhaps we can tackle why slow motion point motors are so loud....

https://flic.kr/p/2kXNcMK
  NSWRcars Assistant Commissioner

Notice that the OP comments his Wombat is weighted. My Ixion C32 is weighted, as well as having the motor changed, and it has significantly increased tractive effort. It stands to reason that a loco weighted like this will be seeing higher forces in the driveline - including lateral thrust on the gears. I always assumed the noise of my C32 was related to the motor change, but now I wonder. Oscar, I look forward to your further work and investigations on the Wombat. As for my C32, I've had enough of fettling these locos, it can just growl around the layout for a while...

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