How do 'running in' and 'warming up' affect locos?

[DK123GWR]

It seems to be a commonly accepted fact that locomotives do not always work to their full potential straight out of the box and that a period of running in (often for around half an hour in each direction) can lead to an improvment in running qualities. I don't wish to challenge this idea as I don't have any evidence to support or contradict it, but what does running in actually do to the locomotive's mechanism in order to cause this improvement?

 

On a related note, I have noticed that some of my locomotives do not work well from a cold start. The best example that I can give is my Lima class 47, which intitially has two speeds: 'off' and 'full speed'. Any attempt to run the loco at a lower (but still very high) speed will inevitably cause the motor to stall. However, following a few laps of the track at full speed it always runs far more smoothly and can get down to reasonable speeds (I would estimate around 10mph) with no risk of stalling - which isn't bad considering the age and costs of production of this particular model. Again, I would like to know what changes this 'warming up' process causes which can improve running (and fairly dramatically in some locos).

 

Thanks in advance for your help here. I have tried a search but as every other thread contains the words 'running in' it brings up a lot of irrelevant content and not a lot of answers.

[Alister_G]

My understanding is, there are two main reasons for running in a new locomotive.

 

Firstly, most locomotives from the usual suspects come with quite heavy lubrication in and around the gear train from the motor, often a thickish grease. This can impede the free running of the model, until it's been warmed up and made thinner. In extreme cases the new owner might have to physically remove some of this grease before the locomotive will perform properly.

 

Secondly, the gear box and drive - whether made of nylon, plastic or metal - will be fresh cut, and may have burrs and sharp edges which can affect their normal operation. A half-hour of running will rub off those rough bits, and allow the gears to mesh more smoothly, which will improve slow running in the future.

 

 

In the case of running in a model that is not necessarily new, but has not been run for some time, then it's normally down to the lubrication having thickened and become stiff. As above, a half-hour of running will warm the lubricant and make it thinner, so the motor doesn't have to work as hard.

 

Al.

Edited October 30, 2020 by Alister_G

[kevinlms]

Another thing to consider is, what sort of controller do you have? Some like the old resistance mat ones are notoriously bad at slow running.

[Captain Kernow]

I would also ask what manufacturers' RTR locos you are considering running-in? Hornby, Bachmann, etc.?

 

Also, are they steam or diesel in outline? In my experience (although perhaps it shouldn't), it does make a considerable difference.

 

There are some things that will improve with running in, such as the grease situation mentioned by others above.

 

However, there are also issues such as cogging motors (they don't run consistently smoothly and exhibit variations in speed, with the controller setting unchanged - talking about DC here, not DCC). I've not found it possible to improve these things, no matter how much running in I've done. Some Heljan diesels have been particularly prone to this, in my experience.

 

Some steam outline models also have issues, which I suspect are to do with slight inaccuracies in the quartering of the driving wheels. No amount of running in can improve that. You shouldn't have to, but one answer is to tweak the quartering by hand - rather a fraught process - until it's right. The other option (which I have done a lot), is to simply return the loco to the supplier and try another one. There have been locos like the Bachmann 64XX pannier, for example, where two locos bought from the same shop and at the same time run completely differently from each other, one nice and smooth, the other with consistent hesitations. It would appear to be a quality control issue as much as anything, with possibly the emphasis being on producing the model to a specific price.

 

Some RTR steam outline models have been so reluctant to improve with running in (and I'm talking of several hours on a circle of track, here, not just half an hour in each direction!), that I have found myself forced to build a replacement etched chassis kit for them, in order to get that particular type of loco running to my satisfaction.

 

In my experience, some of the best 'straight-out-of-the-box' running comes from Bachmann diesels.

 

[Michael Hodgson]

One of the reasons for poor running in steam locos is to do with valve gear, rods slightly out of straight, sticking pivots, rivets which can catch on other parts of the motion etc.  As these are mechanical issues as with quartering, it doesn't matter whether you are DC or DCC, and it won't get any better with warming up.  Handling locos by the motion or derailment damage can cause a good loco to start misbehaving.  I have noticed that pickup wires sometimes work better in one direction than the other.

[NIK]

Hi,

 

Stalling is normally caused by problems getting the power from the rails to the motor.

A loco at that stalls at lower speeds can normally be improved at the very least temporarily by running it at high speed. This seems to clean up the pickups.

 

Regards

 

Nick

[John Tomlinson]

Some good advice here. Re. the factory grease I would add a note of caution that if the loco won't move under power, and has been unused for sometime, then DON'T keep the power on. It is quite possible the whole thing is gummed solid and doing so will burn out the motor. Instead, dismantle, examine and clean, and only apply power again when there is some play in the mechanism.

 

The "Pancake" type motors in Lima locos, and similar ones in older Hornby ones, do display this tendency to loosen up after running for a few seconds. It isn't a defect specific to your loco. I've found that however clean and properly lubricated they are, it just happens after any period of inactivity. Sorry, I can't give you a scientific explanation!

 

John.

[DCB]

The initial roughness of the sliding and revolving surfaces is polished up by running in.   This  will increase side play on axles etc and also polish up wheel tyres and flanges. In my experience a well run in RTR loco will often get around 2nd radius curves when an out of the box one will not.  I usually run locos in for 20 minutes each way around an oval layout, I'm not sure a rolling road does any good for RTR stuff as its all straight line and no curves to polish flanges etc.   Some locos are sluggish from a standing start, Wrenn Ring Fields seem addicted to it, and some overheat and slow down, like Hornby Dublo with 1/2" motors and cast metal kits with K's or X04 motors.

[stewartingram]

Something I learnt from my apprenticeship in the mid-60s.

 

Take one piece of smooth metal and look at it under a microscope - in simple terms it resembles a file!

Now lay it on a second piece of smooth metal (which also looks like a file when magnified), and move one along the other. There will be resistance from the "teeth of the file". That is why you a) do a "running in" session, and b) use lubrication. 

The running in allows the teeth to smooth each other down; the lubrication between the parts by a thin film which slightly separates them.

A very simplified explanation, but makes it easier to understand.

 

[Nearholmer]

On "warming up": I'm always very suspicious of locos that need to warm-up, because it implies that there is something not quite right about the lubrication. In my niche, which includes some quite old stuff, sometimes things that haven't seen much use in decades, its a sign that the loco has old, mineral-oil lubricants that have gone "off" with age, and need to be cleaned-out and replaced with new, synthetic oil and grease.

[DK123GWR]

Thank you all for the interesting replies. It seems that for both situations the answer falls into one of two broad categories: wearing away rough parts which interfere with running and overcoming problems caused by old/poor lubricants. Is that a fair summary?

[FoxUnpopuli]

4 hours ago, John Tomlinson said:

Some good advice here. Re. the factory grease I would add a note of caution that if the loco won't move under power, and has been unused for sometime, then DON'T keep the power on. It is quite possible the whole thing is gummed solid and doing so will burn out the motor. Instead, dismantle, examine and clean, and only apply power again when there is some play in the mechanism.

 

The "Pancake" type motors in Lima locos, and similar ones in older Hornby ones, do display this tendency to loosen up after running for a few seconds. It isn't a defect specific to your loco. I've found that however clean and properly lubricated they are, it just happens after any period of inactivity. Sorry, I can't give you a scientific explanation!

 

I had stored a number of locomotives for ~20 years, and returned them to service last Christmas.

 

Regarding paragraph 1 above: a Replica (Bachmann) 57xx Pannier had set its green factory grease absolutely solid.  The entire loco was stripped, cleaned with IPA, re-lubed and then ran as finely as it ever did.

 

Regarding paragraph 2: Hornby Ringfield pancakes can take a while to get going, but I found this to be lube having set in the (brass?) axletubes in the tender chassis.  I stripped the axles out and soaked the axletubes through with IPA, poking scraps of kitchen towel through until pristine.  These locos ran as well as they ever did after that... not that that was that great!  

 

20 minutes ago, DK123GWR said:

Thank you all for the interesting replies. It seems that for both situations the answer falls into one of two broad categories: wearing away rough parts which interfere with running and overcoming problems caused by old/poor lubricants. Is that a fair summary?

 

Yes, if a little light.  Rough parts in the gear train.

 

If you are buying secondhand or recomissioning, strip them down and clean off all the old goop with IPA.  You'll find anything brittle and/or needing replacement along the way - don't forget to check motor brushes.  Reassemble and relube sparingly with good oil (research what here on RMWeb.) 

 

As for new locos, the number of modern (steam) locos that have trouble out-of-the-box seems startlingly high to me - before zipping new machines around on half-throttle, I'd carefully inspect the motion at very low speed, both ways, both sides.  Ensure all the conrod nuts are wound in and are not catching.  If it's good - time for the run-in.  After a few minutes, inspect the underside of the loco for excessive factory lube spewing out.  If you see any, best strip it and clean out the excess.  You can do this before you start... regardless of manufacturer or loco type, this seems to be highly variable...  but there's some merit in only fixing it if it's broke(n).

 

 

[The Johnster]

The coloured grease lubrication is applied in the factory, and has a 'shelf life' which is variable and unpredictable, and it is not uncommon for one to encounter posts here regarding locos bought from 'Bay or suchlike that are sold as 'brand new in box', truthfully, that have seized solid.  It is my normal procedure when I acquire any locomotive, new or otherwise, to confirm briefly that the thing is alive by running it a short distance in both directions, then take the top off, undo the keeper plate screws, and examine the gubbinses.  I then remove any coloured grease with a rattlecan electronic switch cleaner, leave the model overnight for that to vape off, and relube with my own lube by my own preferred methods; non mineral machine grade oil applied by a hypo syringe, as sparingly as possible. 

 

Avery common mistake, especially with previous owners who were not comfortable taking the body off (and there is no law saying you have to be), is to assume that any stiff running, unusual noise, or such is the result of a need of lubrication, and try to lubricate their way out of the problem.  In fact, a regular regime of about once a year for locos on my small but frequently operated BLT is sufficient.   Excess lube will pick up crud and eventually worsen the problem; I have had very cheap 'spares or repair' stuff off 'Bay which runs perfectly after a cleaning session and re-lube, after the mech has been solidly gunked by the previous owner with the best of intentions!

 

A day later, with the wheels back in place and the keeper plate put back, the chassis goes on the rolling road and is run at medium speed in each direction for half an hour, followed by further running at lower and lower power settings until the best slow running speed is established.  If I am not happy with this, there is as period of checking for binding in the motion or overtighening of keeper plate screws until I am happy with it.  Then the running chassis is tested on the layout, then re-tested with the body on to check than nothing is fouling on the body (splashers can be an issue with this).  My locos are GWR and mostly inside cylinder 6-coupled, so I do not have much problem with Walchearts; only one BR 3MT tank which ran a bit stiff out of the box but loosened up with the running in process.

 

Each loco has it's own individual character and characteristics, and responds differently to my Gaugemaster controller, but all have improved during the running in process and improved further over time in terms of slow running, smooth starting and stopping, and haulage.  They each have a point at which the mech will wear out, mostly the gear train but in the case of older Airfix/Hornby large prairies the plastic slide bars become brittle over time and break, which means a replacement chassis; cheap and easily available on 'Bay.  I then swap out the best components from my exisiting chassis to get the best performance from combining parts from two chassis (I'll replace 'Trigger's Broom' with a new Hornby or maybe Dapol one day). 

 

Some locos seem to be moody, running perfectly one session and reluctantly another.  I have no explanation for this, as the layout is within the heated and ventilated section of the home and climactic/environmental conditions are constant.  Truth is, some locos are just ar*sholes...

 

I am not in agreement with Foxunpopuli about only fixing it when it's broken.  My view is that if it's broken, on most current RTR you can't fix it and have to replace it, and it only broke because you neglected it.  Regular maintanence and instant reaction to any problemm, to solve it completely, preventitive medicine, will keep your locos running smoothly and reliably, and I very strongly recommend cramming as much ballast weight as you can into them as well to improve haulage and pickup.  Another recommendation for RTR locos is to restrict them to a radius a number above the producer's recommended minimum for smooth running and longevity.