Bachmann Ivatt 4 pulling power....A seven stone weakling

[gordon s]

I have a Bachmann Ivatt 4 2-6-0 which runs fine, but is severely lacking in the pulling department. I've spent several hours on and off over the past three or four days trying to improve matters, but have now run out of ideas. My Bachmann Jinty runs away quite happily with 23 wagons, but this Ivatt 4 starts with wheelspin and whilst it will pull the train, I am aware the wheels are still slipping.

 

I've stripped the loco several times and am now at a loss what to do.

 

This is what I have done.

 

1. Removed motor and checked all wheels and quartering for any sign of tightness. All OK.

 

2. Stood loco on a sheet of glass and placed a sliver of paper under each wheel. When pulling the paper out, the resistance felt the same on every wheel.

 

3. Removed the front pony truck and unhooked the tender. No difference, still won't pull 23 wagons without slipping.

 

4. Added liquid lead into the top of the boiler and smokebox. The loco now weighs 300 gms versus the Jinty at 198gms. The Jinty pulls 23 wagons easily, not so the Ivatt.

 

5. Turned the loco upside down and cleaned all the wheels with lighter fuel to remove any trace of oil.

 

6. There is no more room in the boiler without moving the decoder into the tender. I can do that, but the sums of weight v pulling power still don't stack up.

 

Tomorrow, I may well strip the whole thing again, but to be honest I don't know what more I can do other than move the decoder into the tender and fill that space in the boiler with lead.

 

Even more strange is that I have a second Ivatt four that weighs in at 276gms and that is better, but still not good enough for my own requirements in terms of most locos should be able to pull most trains.

 

I'm now at a loss to know what to do, so welcome any ideas.

Edited April 10, 2020 by gordon s

[Wickham Green too]

Sometimes you just get extra-shiny wheels that just won't grip : I have a Bachmann Lord Nelson that struggles with the rice pudding skin test yet my - relative lightweight - C class had 41 wagons the other day ................................. sorry, that doesn't help you one iota !

[atom3624]

I love my double chimney one for the appearance and detail but to be honest never expected to be a great puller - it isn't, but it's not bad.

 

I would guess on a par with the Jinty, but as you, I've added lead as well.

 

Best out of the box was my Ivatt 2MT 2-6-2 - tank by name and nature.

 

Al.

[gordon s]

I did wonder if there is something in the wheel material that could cause such a problem, but then the Jinty wheels are from the same manufacturer. Of course that doesn’t mean they are the same material, just probable.

 

I know you’re not suggesting it, but roughing up the wheels would be a nightmare and they would pick up dirt all the time.

[gordon s]

The Ivatt 4 is a strange one as there doesn’t appear to be a Service Sheet on the web. I’ve had the loco a few years, but it’s never really run as I’ve not had the layout to run it on.  I’ll see what transpires over the weekend and maybe give Bachmann a call next week.

 

The bit I can’t get my head round is that both the Jinty and Ivatt have six driving wheels, but the Ivatt is over 50% heavier  (300gms v 198gms)  and still can’t match a tank engine for pulling power.

[cessna152towser]

I was very disappointed with the Bachmann Ivatt 4.  Sold mine at a loss on eBay only a few months after buying it brand new.

[Nova Scotian]

Is the tender attachment causing weight transfer off the driving wheels? (additionally checking the running of wheels on the tender to make sure they're free running). 

 

Other forums make reference to overtighting of screws of the body to the chassis causing traction issues - and on older models issues with the keeper plate.

[atom3624]

Had me curious this one!!

 

I've no layout as such, but have a circle of 4th radius 'test track' on which I have a rake of 8 Mk.3's - 7x Oxford, 1x Hornby.

My Ivatt  4 weighs 283g plus tender 110g.

 

It had a 'gear mesh issue' when initially purchased, for which I sent to Bachmann to replace the motor - couldn't get the body off myself without risk of breaking something and they ended up replacing the motor and gears ... another story.

 

Bottom line, it's about as powerful as they'll get ..

 

I lifted out, connected up to the rake, and ... it's off without a problem - slow start or higher power - limited slip and not a problem - forwards and backwards - no difference - brilliant little loco - really like it.

 

Al.

[gordon s]

Thanks for that. I’m somewhat surprised by your tender at 110gms as my standard one is 67gms and my modified one (coal load and additional pickups) is still only 90gms.

 

My standard loco only is 276gms.

 

What is really encouraging is your haulage capacity as that is what I would expect. My layout has no gradients and a minimum of 36” radius curves anywhere. Most of the main running line radii are 60” +, so the loco should romp away.

[gordon s]

17 minutes ago, Nova Scotian said:

Is the tender attachment causing weight transfer off the driving wheels? (additionally checking the running of wheels on the tender to make sure they're free running). 

 

Other forums make reference to overtighting of screws of the body to the chassis causing traction issues - and on older models issues with the keeper plate.

I wondered if that was the case particularly as I have it close coupled. The tender roof is still not fouling the loco roof even though they are overlapped.

 

I tried running the loco with the pony truck removed and the tender uncoupled so that only the driving wheels were on the track and still had the same result.

 

Maybe I’ll take a couple of videos to show the extent of the problem.

[atom3624]

The tender will have extra weight as well.

I try to keep the tender weights representative as well - which may take away from traction, but that's what I do.

 

I hate featherweight locos, but also dislike overlight tenders.

 

Mine was connected at the close coupling setting, 'though I doubt it would have made any difference.

 

Al.

[atom3624]

To answer the next question, I tried lifting the rear end of the locomotive with the tender coupled and before affecting the tender I could lift the rear drivers perhaps just less than 1mm, so I doubt there's any effect from the tender weight.

 

Al.

[The Johnster]

1 hour ago, AlexHolt said:

I've had similar problems with different Bachmann locos and I eventually found that the wheels looked more shiny and worn on the loco that was struggling. Could just be that the wheels have worn down a bit too much? Is it second hand, new or have you had it a while?

 

One possibility could be to get a new wheel set from Bachmann Spares if this is the problem. 

The standard issue on Bachmann locos is the opposite, that the wheels are too highly polished when they are new and prone to slipping, but that when run in, the surface plating becomes worn and grip improves.  I had this with a 57xx, and because the layout is a small BLT it was a good while before she developed her full haulage potential. 
 

Gordon, is the loco slipping, with the wheels spinning at high speed, when loaded?  If so this is possibly your problem and will improve in time.  Or is she simply stalling because she’s overloaded and can’t pull?  This is a different issue and if the loco is new she should be returned under warranty for one with a motor up to spec, or if not you need a new motor.   But before you do this there is a process of elimination fault finding exercise to go through.  You’ve already done some of it, but in addition, check the smoothness of your starts and stops, and the slow running; she should be fully controllable down to about a driving wheel revolution every 6 seconds at least.  
 

If she can manage this or better, then you can be sure nothing is binding or sticking, and the problem is lack of tractive weight or a weak motor.  Otherwise you have something rubbing where it shouldn’t (stop that giggling at the back, there, yes, you, that boy) and need to find it.  Loosening the body fixing screws has already been suggested, and the same thing with the keeper plate retaining screws can prove effective. Too slack and they’ll allow the gears to run out of mesh, but too tight can bind on the bottom of the axles.  Also, check that the body is not fouling on anything that rotates or reciprocates, and that the slide bars are parallel, vertically in line, and the correct distance apart to fit the crosshead.  Ensure that all crankpins and other motion pins are not overtightened and lubricated to run freely. 
 

Try and get as much ballast weight above the driving wheels as you can even it it means moving some of the electronics to the tender.  Also check the back-to-backs, as they may be out enough to affect grip if wheels are not sitting squarely on the rails but not out enough to cause turnout issues. 
 

Let us know how you get on.  
 

Stay safe!

[gordon s]

It’s very much the former. Once on the move, the loco will move round at a pace, but when pulling away from a standing start, it is a mix of wheelspin and forward movement. As a kid I stood on the end of platform 10 and saw even large Pacific’s spin their wheels as they tried to get grip with a heavy train.

 

With the diminutive Jinty on the front, it just moves smoothly away, but too much throttle on the Ivatt and you can hear and see the wheels spin. I’m actually wondering if the gearing is too high and the possible lower gearing on the Jinty as a tank engine means it moves away slowly. My J50 from Hornby is outstanding in that respect and can pull anything I throw at it.

 

It’s the weight issue that is confusing me. At over 100gms heavier the pulling power of the Ivatt should leave the Jinty standing and yet it’s the reverse. I’ll have another go tomorrow when I’m fresh and enthusiastic........

[truffy]

14 minutes ago, AlexHolt said:

Could depend on where the weight inside the Ivatt is, if its not over the driving wheels it won't have as much of an effect on the power. 

 

That's what's always puzzled me. If you add weight to the tender, doesn't that just add to the haulage load, and not to tractive power?

[adb968008]

Could the balance off ?

 

what is it like, if you remove the tender, and have it pull a load smokebox first ?

[The Johnster]

If there is wheelslip then the motor is powerful enough, and if the loco can be controlled at low speed and srarts from rest smoothly, then it must be down to ballasting.  

[PMP]

@gordon s

Check the back to back measurements, and whilst you have pony trick and tender off look along the lengthwise axis at rail level. As this is one of the Bachmann models that has the older almost pizza cutter style wheels, it could be a combination of the back to back and wheels profile. 

 

My my thoughts are on your hand made track, the tyre tread coning and b2b might be lifting the core of the tread off the top of the rails with a much reduced contact patch only in evidence at the inside shoulder of the rail head. If so a b2b adjustment may work, or it could mean replacing the driving wheels with Gibson’s. Obviously the old school wheel profile if the b2b is adjusted might give issues with check rail clearance too. Those I’ve seen converted to EM/P4 don’t appear to suffer this problem. On that particular model a lack of ballast isn’t the issue it’s adequately weighted for typical RTR use.

Edited April 11, 2020 by PMP

[RonnieS]

Bachmann Locos are a bit variable! As new my "Flying Pig" was Front heavy and had a very strong spring on the front bogie. Balancing a loco seems to improve performance so I added 40 grams of lead to the cab by plating the cab floor and roof.  (its almost invisible because of the tender cab) Playing about you can reduce the pressure on the spring. It's OK now on 33 wagons (my longest train)

[RonnieS]

The test to see if the front pony spring is part of the problem is to run the loco tender first on the load. With no tender; try putting coins in the cab or on the cab roof (with blu tac) to see if  weight helps?

[34theletterbetweenB&D]

16 hours ago, gordon s said:

... I’ve had the loco a few years, but it’s never really run as I’ve not had the layout to run it on...

 

...The bit I can’t get my head round is that both the Jinty and Ivatt have six driving wheels, but the Ivatt is over 50% heavier  (300gms v 198gms)  and still can’t match a tank engine for pulling power.

I would suggest most of the problem is in that first sentence I have quoted. Give it a few hours of running to polish up the driving wheel tyres. My worst from Bachmann was a MR 3F, well over three hours before it began to pull as it should.

 

Bottom line in this is that there are two principal physical factors for traction, if the driven chassis alone is assessed. Mass carried on the driving wheels, and the coefficient of friction between the tyre material and the rail material. Many Bachmann locos start out weaker for traction than the weight on the driving wheels would suggest, but to date every one I have worked on has 'come around' to the expected performance given enough running time. But it is very variable, some are good from the box, most very quickly become so, a few  need hours of running.

[gordon s]

Thanks for all your suggestions, guys. much appreciated. Checked the back to backs and all OK. Best pic I could  get of the front drivers on the rails and that looks OK.

 

 

 

...but following your suggestions about weight balance, I tried to weigh the load on both the back and front drivers. Not totally scientific but certainly something worth pursuing.

 

The overall weight was 300gms without the tender. Lifting the back slightly gave a figure on the front drivers of 225gms, but a similar test on the back drivers was only 175gms, so that would suggest the centre of gravity is too far forward and that means with less weight towards the back, the drivers are losing adhesion and starting to spin.

 

The decoder is in the smoke box and moving it into the tender would be pointless as the last thing it needs is weight forward. There isn't much room  above the motor, so it may have to go in the cab as suggested.

 

Interesting.....

[The Johnster]

On 11/04/2020 at 10:08, RonnieS said:

Bachmann Locos are a bit variable! As new my "Flying Pig" was Front heavy and had a very strong spring on the front bogie. Balancing a loco seems to improve performance so I added 40 grams of lead to the cab by plating the cab floor and roof.  (its almost invisible because of the tender cab) Playing about you can reduce the pressure on the spring. It's OK now on 33 wagons (my longest train)

You can also increase the spring pressure by stretching it, or reduce it by trimming the end (if you do this do it increments  and go over the end burr with emery cloth).  This is actually recommended in the Hornby owner's service sheet for the 2721 and J83, and presumably Jinties of a particular vintage.

 

On 11/04/2020 at 10:51, 34theletterbetweenB&D said:

 

Bottom line in this is that there are two principal physical factors for traction

I would add a third, mechanical friction from the drive train, which will affect smooth stops and starts and slow running but also increase the drag and reduce the loco's haulage capacity.  It is not unusual for new locos never taken out of the box to have spent some time in storage or on dealers' shelves, and the coloured grease lubricant can a) go off, becoming 'lubrican't, and won't, or b) get into areas it shouldn't (having been over-enthusiastically slapped on by a tired and exploited Chinese assembly plant worker at the end of a long shift), like wheel treads, and cause wheelslip, and then transfer itself to the railheads causing problems everywhere.  The manufacturers use it because they have to meet fire regulation and insurance requirements in packing and shipping.

 

My third action after acquiring any loco, new or otherwise, after taking it out of the box, giving it a good looking over, and seeing it it will run by putting on the track and running it, is to strip it down and clean any and all lubricant with a rattlecan switch cleaner, backed up by tissue cleaning of any crud left.  This is left to gas off overnight, and I re-assemble and relube, as sparingly as possible using a non-mineral machine oil recommended by a model shop who understand what you are going to be doing with it, applied by a hypodermic syringe.  It then has a running in session of 20 minutes each direction with the chassis upside down (I don't have a roller or continuous circuit test track) starting at 6 on the controller and progressively reducing speed, closely observing for smooth running and any clicks or squeals.  You should be able to get the motor to run slowly enough to manage a driving wheel revolution in no less than 30 seconds; your mech is now run in, as is the rolling chassis.

 

If you have problems running when you test drive the loco, you have already eliminated any cause other that the re-attached body or the keeper plate fouling somewhere, and once any such problem is tracked down and eliminated, the loco is giving it's best performance.  Now you can work on the haulage, bearing in mind that Bachmann locos need time to 'bed' in even after running in.  The key is distribution of ballast and getting as much of it as you can in the right place, and you may improve the loco's haulage by moving DCC stuff out of the way and using lead ballast which is not permitted in items classed as toys for retail legislative purposes.  The loco, complete with any detailing you have added, should balance as far as possible on the centre driving wheels (between them for 4- or 8-coupled locos.  Place the loco on a level surface with the centre axle over a wooden bar, and try to get it so that it won't tip in either direction held only by the centre drivers.  You can spend eternity seeking perfection with this; close enough for jazz is fine!

 

It may take several months of trial and error before you bring the loco's full potential to bear, during which you will unwittingly absorb the best driving technique for this individual loco.

[34theletterbetweenB&D]

1 hour ago, The Johnster said:

...I would add a third, mechanical friction from the drive train, which will affect smooth stops and starts and slow running but also increase the drag and reduce the loco's haulage capacity.

Not in my experience provided the motor and gear train* combination enables the wheels to slip when  the model is held back at the slowest speed it can sustain: the proof test is easy to undertake: remove the wipers and power via flying leads, compare the performance with and without wiper drag.

 

*Multistage gear trains truly score in this respect.  There is some effect with direct worm drive on axle, but nobody would seriously entertain using this method now. 

 

[Combe Martin]

I'm a Somerset & Dorset modeller, and when Hornby re- introduced their improved ex-Mainline (and everybody else) 2P but with a new loco drive chassis, I bought one. Now on the S&D, the usual load for an un-assisted 2P was 3 or 4 coaches, but I'd heard of one service (down I think) where more were added along the way, so it ended up being 8 (on the southern part of the line). 

 

I therefore decided to test it's haulage capacity.  First I tried the usual 4 coaches, it romped away. then I added the extra 4, again it romped away. I added 2 more, same.  2 more, same. 1 more, same, so it's up to 13 now (this was the maximum my best loco, a Hornby rebuilt West Country could manage easily without slipping).  After that I kept on adding 1 more until it reached 18, same !!.  At this point I gave up !.

 

This was a completely standard loco, not big and heavy, just a 4-4-0 and with big driving wheels too and no extra weight added.  The difference was it had traction tyres on the rear driving wheels.

 

Now I'm not advocating that you fit traction tyres, but because of them this loco has GRIP, so if you've exhausted all the other checks and the mechanism is free running with nothing causing drag in it, unless it has a weak motor, this must be where the problem lies.

 

 

  

Edited May 2, 2020 by Combe Martin