Tender drives

[Mrkirtley800]

Way back in 1972, I built a K's kit for a Johnson single driver.

The whole kit was of white metal, even the large driving wheels which I threw away. There were only Romford and Hamblin's wheels then and nowhere near the size required, so I aquired a pair of driving wheels from a Triang G.W. 'Lord of the Isles' which I crudely turned down to reasonable scale proportions and araldited them to a plain axle and to EM gauge, and they have exceeded my expectations

Included in the kit was a made up tender drive unit, using one of the K's mark 1 double ended motors, and driving the front and rear tender axles by worm gear.

It ran and still does after forty years like a Swiss watch, and will pull a bigger train than the original would.

Twenty years later in the 1990's I scratch built a Johnson slim boilered 4-4-0, and following my experience with the single, decided on tender drive. Using a 2/1 set of brass spur gears from the EM Society, plus 20/1 Romford worm gear.

All driven by a DS10 open framed motor.

It pulled well but the noise was terrible, a bit like a coffee grinder on steroids.

I put up with the noise hoping that running the thing would quieten down. But it didn't.

Then in 2009 I had a knee replacement operation which turned out to be a botch job and for two years of pain and problems my interest in model railways was at zero, so my tender driven 4-4-0 languished in a box.

When at last my interest returned I tried to reduce the noise by making sure all the drive shafts were parallel and replaced the DS10 motor by a Mashima 12/24.

Still I had the demented racket. So I wondered if anyone out there has built a tender drive that runs quietly. The second pic is of my modified unit .

Are the spur gears too course I wonder.

[brossard]

That is an impressive looking loco Mr K. My hat is off to you for the innovative approach to traction. I have built a few chassis but I wouldn't call myself an expert. However, my intuition tells me that the source of the noise is likely to be the two brass spur gears. If you were to replace one with nylon (or similar) I suspect the noise would go down. Have you looked at the High level range of gearboxes? There may be something you can use: http://www.highlevelkits.co.uk/

 

Good luck

 

John

[Mrkirtley800]

Thanks John, I never thought of High Level gears. Have rung them without reply so have left a message.

Will let you know if there is any result.

Derek

[N15class]

It could well be the spurs, How is the mesh on the worm and gear wheel? Does it make lots of noise without the body on? It may pay to sound deaden the tender body anyway. As a brass box will magnify the sound.

 

On your lay shaft with the worms on, what are you using to control the thrust from one end to the other as the direction changes?

 

To me I would if you don't already have. I would put a brass washer between the front worm and the mounting block, and one between the spur gear and the motor mount on the same shaft. Set the worm at the front end to remove all the end play but not so tight that the shaft does not spin freely. Oil the washers. This worm shaft if there is end to end movement will make the worms noisy.

 

It is just a thought. It may help.

[Mrkirtley800]

Hello Peter,

Thanks for your ideas.

I put a small brass collar between the two worms and their resective bearings and arranged for a very slight amount of end play. The shaft is set so that the mesh of the worms with their gear wheels allows a minimal amount of movement of the gear wheels when the worm is prevented from moving. With the motor removed the lay shaft spins freely driving the two tender axles without any signs of binding. It is all pretty well lubricated.

I think the source of the noise must be the spur gear combination as it makes no difference whether the tender body is on or not.

The tender is weighted as much as possible by strips of lead stuck in with blue tack which takes up most of the space, however I have tried a bit of insulation with thin pieces of foam.

I am trying to aquire a set of non metallic spur gears, see if that improves things.

 

Derek