Wobbly Bogies is there a cure.........

[3 LINK]

Good morning Guys,

One of my pet hates is watching coaches wobbling down the track, I can live with a prototypical lurch through pointwork but I'm sure you know what I mean when you see these coaches with a mind of their own.

I am still building up my coaching stock so it is a bit meagre to make any comparisons yet, but take my SR/BR bogie luggage van a CRT kit which flows beautifully along the track, then my B set by JLTRT well one is fine but the other . Because they are identical you would think they would react the same but ohhh no, I have tried with various spring rates, checked the B to B you name it still wobbling.

The only other bogie stock I have are 3 GWR Macaws from Connoisseur which ride impeccably, so is there any cures for misbehaving bogies ?

ATB,

Martyn.

 

[Ressaldar]

Hi Martyn,

check the bearing surfaces on the stretchers - quite often the cause of bad running if they are not in good contact with each other.

cheers

Mike

 

[Dog Star]

check the bearing surfaces on the stretchers - quite often the cause of bad running if they are not in good contact with each other.

Or if the bearing surface is not large enough.

GWR carriages have about 9 to 12 inches diameter of bearing surface on the centre of the bolster... with two more supports at the outer edges of the bolster - other companies probably have a similar arrangement.

On our JLTRT Gresley stock we have fixed a 12mm diameter bearing surface to the underneath of the underframe and that has stabilised those carriages.

regards, Graham

 

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Back again, I must of had a senior moment as the screw holding the bogie does not have a spring on it, must be on the CRT kit .

Anyway I have measured the bearing surface on the bolster and it is 12mm dia, and there is a lot of sideways rock and roll.





The main problem is there is a fine tolerance between the wheel flanges and the underneath of the coach body, so much so that if you look at the picture below you will see I had to file down the screw head that fixes the body to the roof.



I will probably try and add a thin piece of plasticard or a thin washer onto the top of the bogie to spread the load, I say thin because at present the ride height is spot on. Also does anyone think I should add a spring onto the screw that mounts the bogie to the body ?

ATB,

Martyn.

 

[iploffy]

could it also have something to do with the wheels

 

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could it also have something to do with the wheels

I don't think so they seem to run ok and I also checked the B to B, the bogies are not sprung but the wheels do slide up and down in there axleboxes between the horn guides quite freely.

I cannot check further at the moment as I'm moving my workshop, and my test track is buried under all the boxes,etc.

ATB,

Martyn.

 

[Dog Star]

Please check that the floor does not have an end-to-end twist on the model which rocks.

 

[3 LINK]

Thanks for the input Guys, the wheels I have used are Slaters and they do seem to run true and I do think the answer lays with the bearing surfaces. The bogies are white metal and the raised circular face of the bearing is 12mm dia, the face plate on the coach body is in resin.

I have noticed that if I nip the supporting screw up tight and then back half a turn it does take a lot of the side play away, but as the bogie turns although very slight each time it actually starts to unscrew the mounting screw .

I will have a look in my spares box and see if I have any springs that will fit up the thread of the screw, so acting like a spring washer.

I have put a steel rule along the sides of the coach and all seems square with no body twist, and also with a set square on plate glass, so touch wood that can be ruled out.

I am off to the Brighton Model World exhibition today ( a great show ) and see if I can find any slim washers which also might do the trick .

ATB,

Martyn.

 

[Dog Star]

I have noticed that if I nip the supporting screw up tight and then back half a turn it does take a lot of the side play away, but as the bogie turns although very slight each time it actually starts to unscrew the mounting screw .

What you describe is going to occur with any retainer for a rotating part where there is no locking of the retainer, eg. split pin/lock tab/"glue". We have replaced the bogie pivot bolts on our JLTRT coaches with a shouldered bolt that can be tightened without pinching the bolster against the underframe (say 15th clearance). The bogie bolster runs on the shouldered portion of the brass bolt so there is no wearing of the pivot hole by the thread of the screw (think round file in hole of white metal bolster). The diameter of the bolt head has been made as large as can fit inside the bolster recess.

I can provide a photo if necessary. The parts were made for us by our good friend Paul Penn-Sayers.

regards, Graham