Fitting additional pick ups to steam locos

[philsandy]

After fitting additional pick ups to the front pony wheels of a Bachmann 3MT, it now runs superbly at very slow speeds through all pointwork, and it now never stalls. 

 

I have a couple of 0-6-0 tanks that very occasionally stall, (always on points) and would like to fit additional pick ups to these also to achieve perfect running.

Obviously there are no pony/bogie wheels to fit more pick ups to,  but I have read on here advising to have 2 pick ups per wheel for 0-6-0 's 

Electrics is not something I'm well up on, but I assumed that when locos stalled most of the time it was usually down to loss of wheel /rail contact. 

 

When this is the case how would the extra pick up on the wheel improve running if that wheel is not in contact with the rail?

Would connecting the 3 exsisting  wheel wipers, on each side, by soldering  a length of phosphor bronze strip to them improve the running? 

[Spitfire2865]

It sounds like either the pickups arent touching the wheels, the wheels or track is dirty, or your tracklaying needs work.

The double pickups in theory is to allow a couple pickups to waver slightly and lose contact with the wheels, which is normally the case.

 

As long as all pickups reach the motor, connecting them together will do nothing,

[34theletterbetweenB&D]

After fitting additional pick ups to the front pony wheels of a Bachmann 3MT, it now runs superbly at very slow speeds through all pointwork, and it now never stalls...

 The learning point there is that it is a wheelset largely independent of the typically rigid coupled wheelbase that has made a big difference.

 

On 0-6-0T and any other all wheels driven tank loco, what you really want is at least one sprung or compensated axle to confer some movement independent of the remainder of the axles. One wiper per wheelback is more than sufficient.

 

What are the 0-6-0T in question. You may just be lucky, if it's any from the Bachmann Fowler 3F 'Jinty' or 57xx, or the Hornby J94, (possibly others too, haven't sampled every 0-6-0T on the market) there is sprung movement available on the centre axle, but typically prevented from effective action. 15 minutes work to enable the sprung movement to take effect, and the improved pick up that results can be yours.

[philsandy]

 The learning point there is that it is a wheelset largely independent of the typically rigid coupled wheelbase that has made a big difference.

 

On 0-6-0T and any other all wheels driven tank loco, what you really want is at least one sprung or compensated axle to confer some movement independent of the remainder of the axles. One wiper per wheelback is more than sufficient.

 

What are the 0-6-0T in question. You may just be lucky, if it's any from the Bachmann Fowler 3F 'Jinty' or 57xx, or the Hornby J94, (possibly others too, haven't sampled every 0-6-0T on the market) there is sprung movement available on the centre axle, but typically prevented from effective action. 15 minutes work to enable the sprung movement to take effect, and the improved pick up that results can be yours.

 

Hi 34C, thanks for your reply.

 

Yes, the two 0-6-0 's are a Jinty and a 57XX with sprung centre axles, and they do only very occasionally stall.

What do you mean re. typically prevented from effective action, and what work is required to enable the sprung movement to take effect?

[34theletterbetweenB&D]

Oh you lucky fellow! See how much vertical movement there is in the sprung axle. All the examples I have looked at the axle has very limited vertical movement; it doesn't rise appreciably above the plane of the other axles, and barely falls. What I would suggest is a total of about 1mm movement of the sprung axle centre above and below the plane of the fixed axles, 0.5mm above, 0,5 mm below. 

 

With the mechanism out of the body, remove the keeper plate, and the wheelset, and the plunger and spring from the centre axle. Make a mark on the chassis block and slightly deepen the recess for the centre axle, likewise on the keeper plate side in the same way make shallow recesses for the axle to drop into; and clean up. Stretch the plunger spring about 20% for a more positive action, and adjust the pick up wipers to stand well out from the keeper plate side. Reassemble the mechanism, and assess: you have enough spring tension if one of the end wheelsets is slightly lifted off the rail. With the body on, the more than adequate total weight will have all wheels firmly on the rails, then give it a run for half an hour to polish up the wiper tracks. You will easily observe the centre wheelset lying slightly lower than the other two wheelsets before you place the loco on the rails; and once it has had this running go to 'dead slow' and you will see the vertical movement of the centre wheelset occurring on point crossings and any rough track joints.

[philsandy]

Thanks for that, That does sound like it would do the job, and improve wheel/rail contact.

 

There is plenty of movement in the centre sprung axle, but as you say it's all upward, the centre wheels do not drop below the 2 other wheel sets.

Would it just not need to be the keeper plate that needs to be modified to allow downward movement, if there is already enough upward movement?

[34theletterbetweenB&D]

That's right, if there is upward movement already present, just cut very shallow recesses in the keeper plate sides. Stretch the spring acting on the plunger, if the chassis alone doesn't float slightly at one end, to ensure positive action.

[HLT 0109]

I followed 34C's advice successfully on my Bachmann Jinty - but I would add a note of caution: the pickups on each side are joined along the keeper plate and, if you overdo the deepening of the recess in the keeper plate, it seems to me there is a danger of the axle of the centre wheelset shorting the two sides in the event of both wheels droping simultaneously.  Perhaps it would never happen but I think it worth keeping an eye on the amount of recess you create - 34C does say "slightly deepen".

 

Harold

[34theletterbetweenB&D]

'Slightly deepen' : it only needs a 0.5mm maximum depth recess below the axle in the keeper plate sides, still well clear of the pick up strips. (Most models there is a shallower interior rib between the pick up strips, you'd need to cut most of that away before the axle could bridge the pick up strips.)

[Sam Moss]

Try tweeking the existing pick ups. Bachmann steam loco's are notorious in all the ones I've seen for having poorly adjusted pick up wipers.

 

The same goes for Heljan diesels!

[31A]

That's right, if there is upward movement already present, just cut very shallow recesses in the keeper plate sides. Stretch the spring acting on the plunger, if the chassis alone doesn't float slightly at one end, to ensure positive action.

 

 

The Bachmann Class 08 is also an 0-6-0 with a sprung centre axle and to allow the sprung axle to drop slightly more than the design allows, I put 10BA washers over the fixing screws between the keeper plate and the chassis block.  This allows just enough extra movement for the locos to traverse the Peco Code 75 insul frog double slips in the station throat without stalling.  It probably allows the fixed axles a bit more play too, but this doesn't seem to do any harm, and if you don't like it you can just take the washers off again.  I think I had to open out the holes in the washers slightly with a round file, to allow the fixing screws to pass through.  Another way of achieving the same end.

 

I have used the method of reducing the keeper plate slightly with a file under the centre axle on my Hornby N2s, which are much cruder animals, and this worked worked just as well.

[34theletterbetweenB&D]

So there's several of us know that this is the way to get good reliable pick up.

 

[Rant] Not the total waste of space drag inducing wipers on tender wheels, but one or more sprung driven wheels which incur no drag penalty as the motor overcomes all friction directly through the gear train; and most importantly is a technique applicable to all wheels driven tank locos which were a very large proportion of the UK steam loco stock, and which modellers typically want to have running slowly over pointwork. Why is it that lame old tender pick up is preferred by purchasers and manufacturers? What would it take to change this poor approach? [/Rant]