Bachmann Class 158 Derailing

[burtos]

Not sure if this is the correct place for this topic. 

 

I have recently purchased a Class 158 dmu, when doing some testing the heavier coach seems to push the light 2nd coach of the rails mainly at points.  Going forward when the heavier coach is in front its all fine, only when I reverse the train it does the derailment. 

 

Would adding weights to the 2nd coach help, so the 2nd coach has a bit more force against the heavier 1st coach. 

Or remove weight from the 1st coach if possible, to try and balance the weight distribution more.   I haven't locked to see if there are any weights in the 1st coach to take out. 

 

Any other suggestions would be helpful. 

[Red Fox]

Are the wheels correctly aligned on the non-powered bogie. It seems they have a habit of popping out of the bogie frames on the new 158/159 causing derailments.

Edited March 30, 2023 by Red Fox
spelling

[DCB]

What

39 minutes ago, burtos said:

Not sure if this is the correct place for this topic. 

 

I have recently purchased a Class 158 dmu, when doing some testing the heavier coach seems to push the light 2nd coach of the rails mainly at points. 

 What radius curves.  Is it Set track?    Does the leading or trailing bogie derail?    I have had problems with Lima Sprinters derailing the unpowered coach on sharp 3rd radius ish curves which needed quite drastic modifications including changing from powered leading bogie to powered trailing bogie.  Making sure all 4 wheels of each bogie are on the rails at the same time (see above) is a good starting point.  Nice bit of thick glass is a handy tool for checking that the axles are correctly engaged.

[burtos]

2 hours ago, DCB said:

What

 What radius curves.  Is it Set track?    Does the leading or trailing bogie derail?    I have had problems with Lima Sprinters derailing the unpowered coach on sharp 3rd radius ish curves which needed quite drastic modifications including changing from powered leading bogie to powered trailing bogie.  Making sure all 4 wheels of each bogie are on the rails at the same time (see above) is a good starting point.  Nice bit of thick glass is a handy tool for checking that the axles are correctly engaged.

 

Track is peco code 75, the derailment happens on the y point. Done a quick test and if I go slow enough the train travels over the points fine with no derailment.  

 

I shall check the wheels on each bogie to make sure they are sitting correctly. Let you know tomorrow.

[Geep7]

12 hours ago, burtos said:

 

Track is peco code 75, the derailment happens on the y point.

I'm presuming that this is the small radius Y point, which has a nominal radius of 610mm or 2ft in old money. Whilst 2ft radius should be ok for your 158, it depends your track formation.... if it's part of a switchback curve, it could cause issues at speed. However, might be an idea to check the wheel back-to-backs, just in case one of the wheelsets on the unpowered car is slightly out....

[burtos]

On 31/03/2023 at 09:33, Geep7 said:

I'm presuming that this is the small radius Y point, which has a nominal radius of 610mm or 2ft in old money. Whilst 2ft radius should be ok for your 158, it depends your track formation.... if it's part of a switchback curve, it could cause issues at speed. However, might be an idea to check the wheel back-to-backs, just in case one of the wheelsets on the unpowered car is slightly out....

Track formation is just straight track coming from single track than splitting into 2 straights ethier side of a platform

[Geep7]

18 minutes ago, burtos said:

Track formation is just straight track coming from single track than splitting into 2 straights ethier side of a platform

Ok, so nothing that should cause any issues really.....

 

One suggestion, split the set, and run the unpowered car through the point by hand slowly, and see if it jumps anywhere. It could be a small bit of debris between the catch rails or frog that the powered car is heavy enough to just ride over....

[andyman7]

On 30/03/2023 at 17:27, Red Fox said:

Are the wheels correctly aligned on the non-powered bogie. It seems they have a habit of popping out of the bogie frames on the new 158/159 causing derailments.

I'm assuming that this is in fact the old Class 158 as both coaches are powered and the same weight on the new one. The old one has a heavy powered vehicle and a much lighter non-powered vehicle.

[Il Grifone]

As already stated, I'd check the wheel back to back dimensions and that the bogies can turn freely. A bit of weight would probably help. Vehicles of different weights is a likely cause of problems. I try for about 15 gm. per axle, though the NMRA advises rather more.

[ISW]

On 30/03/2023 at 16:53, burtos said:

Any other suggestions would be helpful. 

If you've not checked already I'd check that the track is 'level' and that there is no 'twist' at the derailment location. It doesn't take much of either (especially twist) to unload a wheel leading to a derailment.

 

Ian

[Gwiwer]

21 hours ago, andyman7 said:

I'm assuming that this is in fact the old Class 158 as both coaches are powered and the same weight on the new one. The old one has a heavy powered vehicle and a much lighter non-powered vehicle.

My assumption also when I read the first post.  

 

I have two of the earlier design.  Both have occasionally exhibited the same tendency namely to derail when the unpowered coach is leading and being pushed by the much heavier motor coach.  There is significant drag on the axles on this design as they seem to run through the bogie frames.  When the unpowered coach is pushed along straight level track it does not continue to roll freely as it perhaps should.  Compared with a Mk1 it stops itself in a very short distance; the Mk1 rolls on until something else stops it.  

 

I suspect friction of axles through bogies is the issue here.  Mine have correct back-to-backs and the pointwork is free of any stray objects such as a gain of ballast which might foul free running.  There seems to be no particular reason for derailments otherwise but they do seem to occur through reverse-curves.  Such as was mentioned above as the Y-point feeds two platform roads and so probably takes both tracks through reverse-curves.  

 

I have not been able to find a satisfactory "fix" and have to remember which way round the unit goes on the track to avoid embarrassment.  

[burtos]

I've tightened and checked everything.  If I go slow enough, it's fine so just have to remember to do that.

 

Bought the new released class 158 today so will see how they compare