Bachmann GWR 64xx Issue?

[thx712517]

I've got a Bachmann GWR 64xx pannier tank, DC only, running on Kato track with a Kato power supply. It hesitates over my two #6 turnouts, which I assume is a wheelbase issue/size of dead frog and thus not something I can fix. The other problem I have is when reaching the end of a siding if I throttle down and then switch direction on the control pack, the engine won't respond as I open up the throttle again. Sometimes tapping the track (it's snapped together and resting on a table) will get it moving again. I'm not sure why it works up until the point I throttle down prior to switching direction. I don't have these issues with an Atlas GE B23-7 diesel locomotive though, which makes me wonder if it's a locomotive issue or track issue. 

[Gordon A]

I have problems with the pickups on a Bachman 64xx that runs on a track in a pub.

I find the Bachman pickups too flimsy so I have fitted additional pickups using phosphor bronze wire on the middle and trailing axles that bare on the treads of the wheels.

 

Gordon A

[The Johnster]

The Baccy 64xx picks up on all 6 wheels, and should not have trouble with dead frogs. so long as...

 

.all pickups are properly adjusted

.all pickups and the wheel backs are clean

.the wheel treads are clean, 

.the track is clean

.the track is level, and

.the track is laid smoothly with the adjoining pieces providing a smooth run across the join.

 

 

Dead frogs will stall your loco if they are the same distance apart as two of the pickup wheelsets and the third is dirty.  Laying track on the table and not fixing it permanently is probably not helping.  Your GE diesel runs on 6 wheel bogies and has twice the chance of picking up current successfully over dead frogs and coping with any uneven-ness.  I had no trouble with my 64xx but have well laid permanently fixed track and gentle curves.  

 

My feeling is that the problem is more likely to be the track than the loco, but that extra pickups will do no harm.

[34theletterbetweenB&D]

21 hours ago, thx712517 said:

... Sometimes tapping the track (it's snapped together and resting on a table) will get it moving again...

That's the clearest evidence that pick up reliability needs work on your model. Remainder of para. not applicable to N gauge. I would start with the pick up wipers. Bachmann's design is good, but often needs adjustment. Release the keeper plate, and set all the wipers at forty-five degrees from the chassis sides. Then they will make positive contact with the wheelbacks, and after fifteen minutes continuous running to polish up the contact tracks, then retry for those aspects where performance is currently poor.

 

The other major aspects are cleanliness of track and wheel tyres, and reliability of set track rail joints. Have a go at these too. Using a heavy twin bogie all wheel drive model as a benchmark is a good plan. It needs 'everything' right on a light shorter rigid wheelbase loco to match the performance these easily attain.

Edited July 10, 2019 by 34theletterbetweenB&D
clarification relating to model scale

[TheSignalEngineer]

Besides checking the pick-ups are contact correctly especially on curves, clean the inside surface of the wheel tyres. I've had a couple which have been dirty from the factory. Lubricant can also get on them by accident and pick up dirt.

Edited July 10, 2019 by TheSignalEngineer
Auto speller interfering again. I know what word i want to use. The machine thinks it knows better.

[D9020 Nimbus]

Is this OO or N? Just asking because Kato track is more commonly used with N than OO—I know you said Bachmann rather than Farish, but there doesn't seem to be a #6 point in the OO/HO Kato range, while there is in N?  As far as I'm aware, the #6 points in N are live frog (or the frogs can be set to be live). You shouldn't have problems with stalling with this combination in N, let alone OO.

[thx712517]

To clarify a few things, 

 

Yes, the locomotive is OO. It's a Bachmann Branchline 64xx, not Graham Farish. 

 

The track is HO scale Kato track, with #6 manual points. I live in the United States, but I would assume the product would be available globally. The frogs, from my understanding of the package info, are dead. There are no wires to the points, they just clip into the regular track, and when the switch is thrown (say, to the left) I have a live track in the direction of travel to the left and dead track on the right. 

 

My diesel locomotive is a bo-bo/4 axle unit rather than a 6 axle, but it is longer by a few inches and substantially heavier than the pannier. I assume it's just heavy and long enough it can't be bothered with any track problems. 

 

The current setup is an Inglenook layout. Perhaps when I get better at laying track I'll switch to Peco and pinning things down permanently. 

[Pinehill]

Got 2 of them & they run fine on my DC cameo shunting layout. I use Peco 75 track & points with DCC Concepts motors. All live frogs with extra feeds wired in as DCC Concepts instructions. 

Any Insulfrog points should consigned to the bin in my opinion.

[34theletterbetweenB&D]

3 hours ago, thx712517 said:

My diesel locomotive is a bo-bo/4 axle unit rather than a 6 axle, but it is longer by a few inches and substantially heavier than the pannier. I assume it's just heavy and long enough it can't be bothered with any track problems. 

It's not just the weight and length that are advantageous: the greatest asset is all wheel pick up over two subchassis - the bogies - that have some movement independence from each other. A rigid chassis steamer can only be guaranteed to have three of the rigid chassis wheel tyres in contact with the track at any moment in time. The twin bogie machine, provided there is sufficient independence between the bogies (and there typically is) will have three wheel tyres in each bogie in contact with the rail: twice the effective pick up points.

 

Enough of the advantages of twin bogie all wheel pick up, now the steamer. Dead frog points are unfortunate devices. Because of hysteresis in the formed curved rails, the typical RTR point is bowed upward very slightly. The dead frog too is often marginally taller than the rail. Between these two effects, a wheel in a rigid chassis on the dead frog will often lift all the wheels that side off the rail: no pick up, no movement. And this effect is most likely when moving slowly, at speed the loco skids through and resumes current collection.

 

Sighting along the rails will reveal if the bowing effect is present, and a steel straightedge will enable you to try for the plastic frog standing higher than the rail. A little judicious bending and securing to the track base to ciorrect the first, taking down the plastic moulding with very fine grit wet and dry - don't abrade the rails - very gradually until you have a continuous rail top for the second.

 

And as above, live crossing is much to be preferred for realistic operation. If prepared to re-equip, go live crossing.

[The Johnster]

This is the major advantage of any chassis that employs even the most basic compensation; it gets over the 'only 3 points of contact guaranteed' issue.  

[Barry Ten]

There's a general perception that the 64xx chassis is not as well engineered as the 57/87xx panniers.

 

Here's one fix:

 

 

I did a less sophisticated bodge on mine which involved increasing the float on the rear axle, to give

it a bit of vertical play.

[The Johnster]

I wouldn't say the 64xx chassis is not as well engineered as the 57xx, but it is a different design and benefits from such modification.  My 64xx has moved on as it is out of period for my layout, but I have 4x 57xx chassis in operation, all of which are better than my 64xx was at very low speeds, an important aspect to me.  It was adequate for auto work, but a bit stiff for shunting.  

 

But stiffness is not the same as a pickup problem; it occurs because the friction inherent in the chassis that the motor needs to overcome at very low power outputs and speeds for good slow running and smooth starts and stops is too great.

 

My 57xx chassis are individualists in this respect, each performing differently.  My conclusion is that there is an inherent variation in these chassis, none of which perform badly by the way.  This is presumably down to assembly and tolerance of components as cleaning/lubrication does not seem to make a difference.  By contrast, both my 56xx chassis perform identically and excellently.  

 

All my locos have as much extra ballast as can be got in ('Liquid Lead') and this helps keep the wheels firmly on the rails as well as giving the locos a pleasing 'heft'.

 

I find Bachmann pickups to be very effective once they are properly adjusted, but of course like any pickup they must be kept clean.  Pickup performance is achieved by the pressure with which the strip bears on the back of the wheel, and whilst this is pretty basic engineering, it needs to be right.  Too little pressure will compromise pickup, too much will act as a brake on the mech and compromise slow running, and the pickups must be flexible enough to cope with sideplay on curves.  

 

This is why I prefer the simplicity of a split chassis, which dispenses with the need for such pickups, and, were I scratchbuilding a chassis, I would adopt this system.  A well built split chassis with a coreless, i.e. brushless, motor, is capable of running with effectively no friction at all, and I was very influenced by Chris Pemberton's locos in the 80s that were built this way using Portescap motors.  But they are not the easiest of of things to produce in volume RTR, as Mainline found out the hard way!  Modern RTR chassis have mostly reverted to traditional pickups and worm/cog drive, and are able to achieve very good performance, by which I mean controllable slow running with smooth starts and stops and reliable pickup, despite this, which shows that it is much easier to volume produce and assemble models at a competitive market price level by this method.  

 

Any chassis, whatever type or general quality, will be helped in it's performance by good level, rigid, baseboards and careful tracklaying.  I use Peco insulfrog 'medium' points and have no pickup issues on my layout, mostly with steam outline 6-coupled chassis from Bachmann and Hornby.  

Edited July 12, 2019 by The Johnster

[tomparryharry]

Being a DC Luddite, I've always found that electrical continuity to any low-voltage circuit is key to happy operation. On my old shunting puzzle, each & every rail joint had a electrical joint to the next rail, running on a busbar circuit under the base board. If you can avail yourself of some feeler gauges, try running a straight edge over the rail joints. After a little while, you'll find that you have some pretty 'spot-on' joints, and some joints where you can a park a bus underneath. 

 

oil & grease has some interesting properties, and knowing what is what helps enormously. Some promote connectivity, and some effectively insulate. I did have a problem with one joint on my shunting plank. No matter what I did,  nothing. I cured the problem by putting in a electrical bridge through the joints. Upon dismantling the joint years later, I discovered that a hair had got in between fishplate & rail joint, enough in this case to provide a break in the circuit. 

 

 

[melmerby]

49 minutes ago, The Johnster said:

  A well built split chassis with a coreless, i.e. brushless, motor, is capable of running with effectively no friction at all, and I was very influenced by Chris Pemberton's locos in the 80s that were built this way using Portescap motors.

No such thing.

Coreless motors are normal brushed motors but with the windings formed into a cage without a metal (i.e. iron) former, this means the rotor has extremely low mass compared to a similar iron core moto, because of the lack of iron core they also overheat and fail easier if overloaded.

They were designed for usage where rapid acceleration and deceleration were needed e.g. X-Y plotters and such like.

As they were designed for such use the construction was usually of the highest quality, which was not matched by typically similar size iron core motors at the time.

Model locos ideally require a motor with some inertia which coreless motors do not have due to low mass.

IMHO this worshipping of Portescaps is smoke and mirrors stuff. There is no mechanical reason why they should be better than a well designed iron cored motor.

[melmerby]

One advantage of coreless motors these days as they can be more compact than iron cored ones meaning they can be fitted into the boilers of the smaller steam classes.

Personally I would still prefer a traditional motor as the current typical coreless motors are IMHO rather cheaply made.

 

As regard the 64XX, I have two and they run fine but I use Code 75 Electrofrog points.

[The Johnster]

2 hours ago, melmerby said:

No such thing.

Coreless motors are normal brushed motors but with the windings formed into a cage without a metal (i.e. iron) former, this means the rotor has extremely low mass compared to a similar iron core moto, because of the lack of iron core they also overheat and fail easier if overloaded.

They were designed for usage where rapid acceleration and deceleration were needed e.g. X-Y plotters and such like.

As they were designed for such use the construction was usually of the highest quality, which was not matched by typically similar size iron core motors at the time.

Model locos ideally require a motor with some inertia which coreless motors do not have due to low mass.

IMHO this worshipping of Portescaps is smoke and mirrors stuff. There is no mechanical reason why they should be better than a well designed iron cored motor.

I’d agree that Portescaps were , in retrospect, overrated and arguably too delicate for model railway work, but stand by my view that a properly built split chassis with no wiper pickups can be made almost frictionless.  It introduces a new set of problems of it’s own, though, notably the issue of maintaining electrical contact through the lubricated bearing/axle interface.  

 

A large tender loco can overcome this by picking up through the bogie, pony, and tender wheels, but a small tank engine is vulnerable. 

 

The matter is a little academic as my RTR locos all run well enough for my purposes, even at very low speeds and voltages. 

[tomparryharry]

A Romford Insulated Axle would serve this purpose admirably.... It would solve the problems of old Mainline chassis at a stroke as well.

 

having just posted this, I've just thought of Delrin rod, 1/8" diameter, or 3.2mm in new money..... Plastruct sell a round bar in this size....

 

Ian.

Edited July 12, 2019 by tomparryharry
Ideas time.

[melmerby]

2 hours ago, tomparryharry said:

A Romford Insulated Axle would serve this purpose admirably.... It would solve the problems of old Mainline chassis at a stroke as well.

 

having just posted this, I've just thought of Delrin rod, 1/8" diameter, or 3.2mm in new money..... Plastruct sell a round bar in this size....

 

Ian.

Unfortunately the Mainline/Bachmann split chassis locos use a larger diameter (4mm?) axle, so some bushing would be necessary.

[melmerby]

2 hours ago, The Johnster said:

I’d agree that Portescaps were , in retrospect, overrated and arguably too delicate for model railway work,

 

I'd agree that they were the quality motor of their time, better than most else available.

That was then. These days I see little point in them, unless you need to replace one in a loco that already has one.

 

As regarding split chassis, they are not dead as a few new models have them, e.g. Hattons's/DJM 48XX, which is let down by it's over complex gear train. I'm one of the fortunate ones as mine runs reasonable well, (as do both original Airfix ones!)

 

Many Bachmann models aren't totally rigid as they have a vertically floating middle axle (which in days of yore had a light spring to keep the wheels on the track) in an attempt to get more wheels in contact with the rails. I havent't checked the 64XX though.

[tomparryharry]

3 hours ago, melmerby said:

Unfortunately the Mainline/Bachmann split chassis locos use a larger diameter (4mm?) axle, so some bushing would be necessary.

 I'd assume that you're correct, but I don't have a vernier to hand. If we are  (hypothetically )  trying to create a Mainline-type arrangement, I'd be thinking about a Romford uninsulated wheel, with a Romford axle spacer (3/16"?) straight behind that, for electrical continuity. The axle will require squaring off to receive the Romford wheel, and then tapped to take a securing screw. Markits & 24/7 have the correct etched rods for sale. The original Mainline gear wheel is glued in place with the new axle.

 

If you are going to go down this route, you're getting real close to choosing something like an High Level chassis. The amount of work I've just outlined would require a small lathe with an index mill capability. On a cost basis ,it wouldn't add up.

 

However, if the lathe & mill are set up, then.....

[34theletterbetweenB&D]

10 hours ago, tomparryharry said:

A Romford Insulated Axle would serve this purpose admirably.... It would solve the problems of old Mainline chassis at a stroke as well...

If 'someone' wanted to produce a better steam loco driving wheel for split chassis, the way to do it is very simple.

Normal steel axle. This is proven, robust, trouble free for gear mounting.

Turned all metal wheel form, with an integral hub on the inside to run in the chassis half bearing.

Plastic bushes in both wheels, and press fitted onto axles. This is proven, robust, trouble free.

Job done. Much more expensive than two plated castings held together on an insulating muff, but better technique will cost more.

 

Both Bachmann and Hornby have very successful plastic insulating muff split axle construction in their d&e product, where it is adequate because these wheelsets do not have to tolerate the drive forces transmitted through the crankpins and rods, awkwardly ubiquitously present on steam locos.

[tomparryharry]

11 hours ago, 34theletterbetweenB&D said:

If 'someone' wanted to produce a better steam loco driving wheel for split chassis, the way to do it is very simple.

Normal steel axle. This is proven, robust, trouble free for gear mounting.

Turned all metal wheel form, with an integral hub on the inside to run in the chassis half bearing.

Plastic bushes in both wheels, and press fitted onto axles. This is proven, robust, trouble free.

Job done. Much more expensive than two plated castings held together on an insulating muff, but better technique will cost more.

 

Both Bachmann and Hornby have very successful plastic insulating muff split axle construction in their d&e product, where it is adequate because these wheelsets do not have to tolerate the drive forces transmitted through the crankpins and rods, awkwardly ubiquitously present on steam locos.

 Hmm, I see what you mean. However, I don't really model D&E, although some of the modelling appeals to me. Each & every model I possess carries a set of crankpins & rods, which are there to make the machine work, both in model form & real life.  Some models I do possess need working upon at some time or other. Perhaps we need a new section on the forum to delve into this more fully, as I don't own a 64xx pannier at the moment, apart from a discarded body donated to me by The Johnster about a year ago. 

[34theletterbetweenB&D]

3 hours ago, tomparryharry said:

... Perhaps we need a new section on the forum to delve into this more fully, as I don't own a 64xx pannier at the moment, apart from a discarded body donated to me by The Johnster about a year ago. 

So I have posted the suggestion in 'Modelling Musings and Miscellany' to avoid clogging up this thread.

 

22 hours ago, melmerby said:

Many Bachmann models aren't totally rigid as they have a vertically floating middle axle (which in days of yore had a light spring to keep the wheels on the track) in an attempt to get more wheels in contact with the rails. I havent't checked the 64XX though.

Sadly a feature that has steadily fallen out of favour. The last Bachmann steam model introduction with a sprung driven axle the Peppercorn A2 I believe. It is a shame as it is much superior to alternatives such as wiper tender pick ups. Especially valuable on tank locos with only the driven wheels available: the smooth running of their Jinty, 57xx and class 08 all benefit greatly from this feature's contribution to pick up reliability.

[DCB]

On 09/07/2019 at 23:26, thx712517 said:

I've got a Bachmann GWR 64xx pannier tank, DC only, running on Kato track with a Kato power supply. It hesitates over my two #6 turnouts, which I assume is a wheelbase issue/size of dead frog and thus not something I can fix. The other problem I have is when reaching the end of a siding if I throttle down and then switch direction on the control pack, the engine won't respond as I open up the throttle again. Sometimes tapping the track (it's snapped together and resting on a table) will get it moving again. I'm not sure why it works up until the point I throttle down prior to switching direction. I don't have these issues with an Atlas GE B23-7 diesel locomotive though, which makes me wonder if it's a locomotive issue or track issue. 

Sounds like mainly a track issue. Track snapped together often has big clearances and or wear in the rail joiners which doesn't conduct too well. It's fine when the loco runs at speed but breaks down when the loco tries to overcome inertia. I have this on my outside branch for a different reason. 

On dirty track a loco with lots of weight on its pick up axles picks up better than on with less weight.  A heavy metal body on an old Triang chassis with Romford wheels only 4 of which are on the track, will run happily where lightweight locos will barely move.  Our early Bachmann split chassis 57XX is much better than the later Bachmann 8751 version DCC ready version as it is much heavier, adding weight is always a good idea.

 The Bachmann pickups don't always make contact with the wheel backs especially if run round very tight curves, ours is not happy on 2nd Radius.   This can result in only one wheel pick up on one side, which will stop it on dead frogs.  

Well worth running a continuity tester over the wheels and check they make contact when pulled away from the chassis as well as pressed in. 

[thx712517]

I took the time today to play around with the little pannier. Off with the keeper plate and, yes, the contacts weren't angled out very far. So I gave them a gentle tweak outwards to increase pressure on the wheels. I wiped down the wheel backs with an alcohol wipe, and I gave the gears a tiny little droplet of lubricant since it looked dry. 

 

With everything back together I gave it a few runs to see how it did and low speed performance does seem to have picked up a bit. Not night and day mind you, but a little better. So I went over the track to make sure it was butted together and tried again. Again, a little better but still occasional stalls on my surplus #4 switches. I ran my hands over them and the frog does seem to be a little higher than the associated rail. 

 

So, grand test. Put my #6 switches back in, wiped down the track carefully with more alcohol wipes. Pannier runs to the buffers now and reverses without needing a poke. Still the occasional stall in a #6 switch, but not nearly as frequent as before. I think whenever I get the money to try permanently fixed Peco track the stalls will finally be sorted.