R2420A Class 31 - Flywheel fitted?

[Jim49]

As it says, should the R2420A D5511 version of the Class 31 have flywheels? I recently bought a new (old stock) R2420A a few weeks ago and while it looks and runs marvellously, when I turn the power off the loco stops immediately unlike my Bachmann diesels which glide smoothly to a stand. I haven't taken the body off yet but if I get some encouragement, I will have a go.

 

Jim

[stewartingram]

I suspect that the rubber band drive to the fan will also have an effect on this, any momentum that the flywheel can produce is absobed here. I'm sure that flywheels are still fitted. I don't have a R2420A but did buy a D5657 earlier this year and think that had one. My 31's have had the fandrive and lights removed, but don't keep rolling on when the power is removed as much as Bachmann do anyway.

 

Stewart

[34theletterbetweenB&D]

Exactly what I recall when this model came out, it wouldn't coast like the Bachmann, Heljan and Atlas centre motor chassis I was used to. Just as Stewart's post, first the fan, then the lights. The rubber band driving the fan may be unhooked and parked out of the way if the fan assembly is temporarily detached and part disassembled, if you want to leave the parts on board. The lights do absorb some power, mine are disconnected because you couldn't see BR diesel lights....

 

The final refinement is to make the smaller centre wheels undriven, and that helps the freedom coasting a little too. Very lightly ream out the geared axle centre of these wheelsets and grease. My pair of 30s have been running in this form for over ten years now without mishap, so I think it is OK as a mod. Access is fun. Unclip bogie from chassis by removing clip on cover over the worm. (Yes, really!) Unclip bogie baseplate from gear tower sides. That releases the sideframes, and it all falls to pieces. Straighten the brass current collectors if necessary. Add washers on axle ends to reduce axle aideplay and help keep gears better meshed; this also stops the loco skewing across the track.

[bigherb]

Mine has never coasted, but it is probably the smoothest running mechanism I have, only Heljan comes close.

[Jim49]

Thanks for the comments folks. I have taken the body off and can see that flywheels are fitted but don't seem to be doing much. I can see the arrangement for driving the fan but can't figure out how to remove the rubber band apart from either cutting it or stripping the whole drive train down to separate the cardan shaft on that end and easing if off there. I can slip it off the top roller and leave it loose but it just jams between the roller and the side support. 

I definitely do not fancy 34C's idea of converting the centre wheels to idlers, even if it is prototypical. That is too much like skilled work for me.

 

There is really no problem if the flywheels don't work as I have plenty other locos not fitted with them and I can generally get those to start & stop smoothly despite this. The 31 is having another  spell of extended running-in and hopefully this might make a little improvement.

 

Thanks again

 

Jim

[43179]

Good evening, 

 

The Hornby class 31 bogies  share the same gear train as the Hornby 50 - I've found Hornby have a habit of filling this with a very thick sticky horrible assembly grease that adds an awful lot of resistance to the whole gear train.

(If you separate the complete bogie from the loco and remove the worm gear then try and roll the bogie down a slope you'll see what I mean - it'll just stop dead )

 

I don't have any 31s myself , but on all my Hornby 50s I unscrew and completely strip down the bogies to individual parts and remove all the grease from the gears and their little axles- (being made of slippery engineering plastic those gears shouldn't need tons of grease on them) - the locos run much more 'freely' as a result and the flywheels can do their job - I just put a little light oil on the brass worm gears and their bushings - but that's all.

I run all my 50s 'dry' and they work beautifully  

 

If a fully degreased bogie wont roll down a slope easily , then obviously there may be a fault with the gear train , which wouldn't be an impossibility - I've had a few where the gears are too tight on the axles/not formed correctly - Its a good way of checking.

 

HTH 

 

 

Jon 

[Jim49]

Thanks for the information Jon. It may explain why the engine is sluggish for the first dozen laps or so until the factory applied grease warms up.

 

I may have to read 34C's instructions again on how to remove the bogies but it may be a week or so before I get around to it.

 

Thanks again

 

Jim

[34theletterbetweenB&D]

May be some variation in the appled lubrication? The chassis I have were early production of the type, and had what I would regard as a sensible amount of a fairly light grease in the gear train as supplied. Not bought any further specimens of Hornby's centre motor drive (no other appropriate prototypes for me), but have several varieties of Bachmann's and the greasing has been variable from sparing to jammed full. Presumably down to the instructions the assembly worker of the day has received.