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rob D2

Hornby 31 shorting out bullhead points

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Hi,

as has been mentioned before, the superdetail 31 doesn’t have the narrowest and nicest wheel profile.

 

I have one that constantly shorts on the points - quite annoying and also irritating as if it’s a big short it wipes the addresses from all ten cobalts and I have to dig around under the baseboard to reprogramme them.

 

As I understand it my options are 

 

- check back to back and maybe adjust ( not sure how easy this is )

- tried taking out the frog feed and making it “ unifrog “ isolated - didn’t help and caused the 08 to start stalling,

- stick some nail varnish across the frog to make the gap bigger 

 

 

anybody got any advice or opinion ? Alarmingly I hope the new 31102 has better wheels as mine is being delivered today !

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I don't think its the wheels that are the issue rob, i think its more to do with the way Hornby collect the power on the 31 and indeed the 50....as you know instead of using wipers....like every other manufacturer in the UK...(Hornby decided probably at the same time they came up with chassis mounted couplers.)... that they would collect power from the axle ends....in short (pun intended) the wheels have a far more generous amount of side-play than their bachman/Heljan counterparts!!!

 

if you have one try a 50.... and see if this has the same issue? (uses the same method of pickup) then if you can try a 56...(uses the old method of wipers) 

 

another problem could be a loose bogie side-frame (exasperating the problem) or worse...as i have found on several of my SD 31s....the side frame nibs have snapped off....

 

you could try narrower profile wheels....and the back to back issue, hopefully that will resolve things but it may not :(

 

Hornby....wipers worked perfectly well for the last.....30+years........why re-invent the wheel.....

 

 

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Are your frogs switched or powered by a frog juicer type device?

 

Andi

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Oh no - do we have a whole new set of issues to resolve? Am struggling to see where a short can be on unifrog style point unless the BTB is so bad that the back of a wheel is contacting the opposite stock rail before it gets to the frog...

 

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Posted (edited)

Problems with certain wheelsets causing shorts on Bullhead points have come up before, I'm afraid.

 

Near the common crossing the closure rails are quite close together and since they have "opposite polarities" wheels that are outside the tolerance expected by Peco can cause shorts (one reason being that some bogie/pony designs cause the wheels to crab across the track when turning).

 

I guess the first thing to try is to check and adjust the wheels if possible but some people have taken to modifying Bullhead points to overcome this. For example: 

 

 

It's rather sad because these turnouts were designed to overcome some of the problems of electrofrog turnouts, to make them easier for people to understand and to not need modification...

 

P.S. Fingers crossed for 31102! That might show another potential answer to problem: Just condemn models that short out Bullhead turnouts as being "too coarse for modern standards" and replace them with more modern examples... ?

 

Edited by Harlequin
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Correct Track and wheels standards are the foundation of reliable running. Mess with them without thinking through the engineering and you end up with permanent problems. The trend of 00 to stray from the original normal 00/HO standard in regard to the width and back to back of wheels has it's price. Mixing up dimensions from the NMRA, BRMSB, EM and miracle claiming universal panacea gauge bodging is a recipe for continual issues.

 

My latest Hornby Gresley coaches have a non-standard ( wrong ) 2.5mm wheel width and a narrow BB.  Where they got the dimensions from, I have no idea.

 

Andy

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1 hour ago, pheaton said:

I don't think its the wheels that are the issue rob, i think its more to do with the way Hornby collect the power on the 31 and indeed the 50....that they collect power from the axle ends....in short (pun intended) the wheels have a far more generous amount of side-play than their bachman/Heljan counterparts!!!

...another problem could be a loose bogie side-frame ...

Yes, and when I first acquired a couple of Mazak rotted mechanisms, they were happily shorting out Peco live crossing points, modified with the closure rails bonded to the stock rails and the crossing with a switched feed, all well before we had Peco's BH product. The trouble I found was the brass strips in the bogie frames were splaying outwards, allowing the wheelsets to drop.

 

Straightened the strips, also put washers on the axles to near eliminate sideways movement appropriate for a 30" minimum radius layout, and all has been well since. What I also saw once the bogies were apart, and didn't like, was the way the axle to axle gear train could practically lose mesh between axle gears and idlers.

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Thanks for the responses,

the frogs as powered by supplies off the cobalt motors.

 

31118 is ok, slight “ pffttt” on some of the points

 

31304 is the real culprit , causing issues over several points in several directions .

 

31102 is out of the box....and it’s still 2005, however an important upgrade for £157 is the removal of the fan belt....

as they still insist on 8 pin sockets, I don’t currently have anything to run it with, but will report back once it’s got a chip 

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You have two issues that need fixing. 

1 the Class 31 wheel problem. 

2 The defaulting of your point decoders,  that should not be happening,  that needs to be resolved.  I'm no expert but perhaps you should ask the modes to move this thread to the DCC question section. 

Report you original post, along with a request. 

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32 minutes ago, kevinlms said:

You have two issues that need fixing. 

1 the Class 31 wheel problem. 

2 The defaulting of your point decoders,  that should not be happening,  that needs to be resolved.  I'm no expert but perhaps you should ask the modes to move this thread to the DCC question section. 

Report you original post, along with a request. 

Thanks but I’ll leave it here, the decoders take 5 mins to sort, I’m more concerned but he expensive loco issue TBH 

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Posted (edited)
1 hour ago, kevinlms said:

You have two issues that need fixing. 

1 the Class 31 wheel problem. 

2 The defaulting of your point decoders,  that should not be happening,  that needs to be resolved.  I'm no expert but perhaps you should ask the modes to move this thread to the DCC question section. 

Report you original post, along with a request. 

The response from dcc concepts is to use a suppressor but not really convinced if im honest..... I occasionally get the same issue with rob with my 4 cobalts, but strangely my 16 other tortoises with their hare decoders are completely unaffected..... 

Edited by pheaton
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Posted (edited)
11 hours ago, rob D2 said:

I have one that constantly shorts on the points - quite annoying and also irritating as if it’s a big short it wipes the addresses from all ten cobalts and I have to dig around under the baseboard to reprogramme them.

 

 

 

5 hours ago, pheaton said:

The response from dcc concepts is to use a suppressor but not really convinced if im honest..... I occasionally get the same issue with rob with my 4 cobalts, but strangely my 16 other tortoises with their hare decoders are completely unaffected..... 

 

If you don't have a circuit breaker on your main track bus I would install one. A CB will pick up any track shorts and prevent the problem reaching the command station. For the Cobalt points, you can install a separate pair of bus wires that are connected directly to the command station (ie bypass the circuit breaker). In this way the Cobalts will be protected from the shorts that are causing this problem. And an added benefit is that when you do get a track short, you are still able to operate the turnouts.

 

Of course, it goes without saying that it seems poor electronic design for the Cobalt to lose its address in this way …..

Edited by RFS
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Guest MM1991
On 03/01/2020 at 11:44, rob D2 said:

Hi,

as has been mentioned before, the superdetail 31 doesn’t have the narrowest and nicest wheel profile.

 

I have one that constantly shorts on the points - quite annoying and also irritating as if it’s a big short it wipes the addresses from all ten cobalts and I have to dig around under the baseboard to reprogramme them.

 

As I understand it my options are 

 

- check back to back and maybe adjust ( not sure how easy this is )

- tried taking out the frog feed and making it “ unifrog “ isolated - didn’t help and caused the 08 to start stalling,

- stick some nail varnish across the frog to make the gap bigger 

 

 

anybody got any advice or opinion ? Alarmingly I hope the new 31102 has better wheels as mine is being delivered today !

As well the checking the Bullhead Points thread, it may be best to check your back to backs.  I do it as a matter of routine these days with every item of stock and every replacement wheelset I buy.  If nothing else it results in smoother running

 

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A long shot:

 

Hornby 31s have very little clearance above the wheels and the cast chassis frame.

If wheels of both sides contact the chassis as the same time, then there will be a short.

This can happen if there is an excess of vertical movement in the bogie.

 

 

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35 minutes ago, newbryford said:

A long shot:

 

Hornby 31s have very little clearance above the wheels and the cast chassis frame.

If wheels of both sides contact the chassis as the same time, then there will be a short.

This can happen if there is an excess of vertical movement in the bogie.

 

 

I do t think it’s that TBH, seems to be running pretty flat .

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So, I’ve chucked a journeyman decoder in this to get it going, no problem with the points TBH, one slight pfft but runs across the complex ones no issue.

 

for those that are interested, see the new lighting feeds below that are plugs, annoyingly one of which is hidden by the mounting for the non existent fan belt, so had to unscrew that first.

 

main screws still foul on bogies,,

 

nothing much has changed in 13 years other than the price. 
 

 

oh, and there are no headcode discs in the accessory packet, but there are holes. Checking with supplier to see if they should be there .
 

 

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4316622A-1A79-4B44-A1CF-657E97AD1160.jpeg

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Ok, I reckon this end is the culprit ,there is so much play in this wheel, it literally needed .25mm of the side frame moved out and the end fell out. It moves up down and back and forth far too easily.

 

 

anyone know how to get the bogie side frames off to try and tighten things up a tad ?

3AFA0395-C4EE-4D34-9993-92E13249B210.jpeg

E81D271B-6ADD-4313-A4BE-EF75D7E33D35.jpeg

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The side frames are a push-fit to the main bogie block.  They push into the lugs to the right of the axle in your pic.

I once had a 31 that had a similar bow in the frames - the end cure was a stretcher bar across the two ends between the outer frames to hold them inwards

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On 03/01/2020 at 16:23, Andy Reichert said:

Correct Track and wheels standards are the foundation of reliable running. Mess with them without thinking through the engineering and you end up with permanent problems. The trend of 00 to stray from the original normal 00/HO standard in regard to the width and back to back of wheels has it's price. Mixing up dimensions from the NMRA, BRMSB, EM and miracle claiming universal panacea gauge bodging is a recipe for continual issues.

 

My latest Hornby Gresley coaches have a non-standard ( wrong ) 2.5mm wheel width and a narrow BB.  Where they got the dimensions from, I have no idea.

 

Andy

 

Very true!

 

Hornby wheels are (or at least were - I understand they've changed recently) to BRMSB standards and should be 2.5mm wide with a 0.5mm thick flange with a back to back of 14.5mm. Reducing the last dimension will give trouble and I believe it did tend to vary during production. Most of mine got reset to 16.5mm B2B for EM gauge, so the original setting is unknown.

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