Hornby Pullman wheel sets

[jonnyuk]

hi all, i have the Hornby devon bell train pack and having issues with the pullman coaches. Out of all my rolling stock (i have Hornby mk3 coaches, maunsell coaches, Bachmann, Hornby and Dapol wagos)  the 3 coaches from this pack are having issues on certain parts of the layout, it happens 1 in 5 times on certain sections of track, speed does seem to play a part. it looks like the wheels are riding up the rails and causing derailments, one section is a small straight section. the track appears flat and straight, even my Dapol wagons roll over it fine which is usually my benchmark for well laid track.

 

i don't know if its drag caused by the metals wipes over the axle or something that's causing tension on the bogies, before i go and rip up track and ballast are there deeper flanged wheels i could try?

thanks

[ozzyo]

Check the wheel sets before you do anything else. B2B and back to flange.

[jonnyuk]

i have never really understood b2b and back to flange, i don't have a gauge. support taking the wheels off and just checking the distance between each wheel is the same would suffice?

[ozzyo]

B2B is the distance between the backs of the wheels on one axle, this is IIRC for OO is 14.5mm.

 

Back to flange root, is the distance from the back of one wheel to the base of the flange root of the other wheel on the same axle IIRC for OO 15mm?

 

You do not have to have a gauge to check all of this out you can make one of your own, all you knead is some 40 or 60 thou plasticard and a bit of time.

 

What are the rad. of the curves that you have the problem with?

 

OzzyO.

[Andrew F]

This derailing problem could be to do with the top of the bogie side frames catching on the chassis or the close coupling mechanism jamming. The tension lock couplings on Hornby Pullmans are better replaced with the Roco or Hornby equivalent close coupler for reliable running.

[DCB]

The B to B, distance between the backs of the wheels is quite important, It should be about 14.5 mm so I use a home made gauge 14.25mm thick with a slot for the axle (And Bush)  to ensure the wheels are not too close together and one 14.65mm wide with a similar slot which if the wheels fit show they are too wide.  Using an internal micrometer or Digital vernier caliper is tedious, it is much easier to make a gauge or three out of a bit of wood carefully filed to size.

The wheels should also be evenly spaced within the bogie so there is an equal gap to the outside bearings.

I find wheels wide to gauge are common with Hornby as Streamline points are tight to gauge in places while Streamline track tends to be wide to gauge while set track straights are generally spot on 16.5mm. The wider tyres of Hornby Dublo and Lima are much more tolerant than current Hornby and the Jackson etc fine scale wheels of yesteryear.

The drag of pickups is stupid, my lit coaches pick up through pin point bearings and /or wipers on the axles, poor design to require wheel back wipers.

Draggy wheels can cause derailments but anything which stops the bogies returning to straight ahead is a much more likely cause of derailments on plain track.

[jonnyuk]

I have had a play tonight, I put kadee no 19 on all couplings and it's behaving allot better, details now and again still not nearly as much, I'm starting to think it's the tension on the exit and entrance to curves, for info I think they are 3rd and 2nd radius.

[34theletterbetweenB&D]

Swap out the Kadees temporarily between the cars for the R8220 couplers that Hornby include with the Pullmans (or with your Maunsell coaches, if they don't include these in train packs). Should do better yet, as in no derailments.

 

The close coupling mechanism needs a coupler design which recentres the mechanism positively as the cars come off curves. Kadees are better than tension lock, but not designed to operate close coupling mechanisms optimally.

[jonnyuk]

out of my 3 maunsells only 1 had the close coupler, i fitted this between two coaches that where derailing and its fixed the issue. interestingly i removed my devon observation car and all the coaches stayed on track. i do think its the tension on the coupling and specifically the concertina effect of slowing on the entrance and exit of curves because of the drag.

going to order a pack of teh r8220 today.