OO Gauge class 71 Electric Locomotive

[Budgie]

Quick question, is anyone else having an issue with the front bogie wheel (small vent end) derailing when the loco transitions from curve to straight when going a fair speed?

 

Mine keeps doing it, also only when under load, like the wheels are being pulled off??

Yes, on third and fourth radii. I wondered if it has to do with the track being twisted (as it has to be when going uphill/downhill). Is it possible the bogies can't swivel fully in all directions.

Edited June 11, 2017 by Budgie

[JSpencer]

What radius curve do you have? When I ran mine in on a 2nd radius circle test track the bogies at one end seemed to be at their limit of travel.

 

Roy

 

Yes, on third and fourth radii. I wondered if it has to do with the track being twisted (as it has to be when going uphill/downhill). Is it possible the bogies can't swivel fully in all directions.

 

On my big ageing layout, it does not like transition points were the curve switches from flat to super elevated (admittedly that is my fault in perhaps making the transition a little too sharp plus a little water damage and its age causing minor distortion of the boards, but no other model has a problem here).

 

I put this down to the limited up/down play of the bogie (between 1 and 2 mm), which is restricted to the outer wheels only. The pivot points sit almost above the inner wheels of each bogie (like a Dapol class 22 or class 73, but these have 2 to 4mm of up/down play). I also find that due to these pivot points not being in the centre that I cannot fit the lifting hooks (which need to be fitted in the centre of the bogie) as the centre of the bogie can swing out rather unnaturally to foul them even on 26inch curves. Hornby's chassis is much more flexible in this area, a 2mm up down play on both pair of wheels on each bogie, the pivots being centered which helps to prevent fouling of the lifting hooks (though the bogie itself is also about 1/2mm narrower/underscale width than the DJM).

[Bernard Lamb]

Yup that's me - I still use a H&M Powermaster complete with all the hummimg, slight tingling from the case corners and delicious smell of brutalised AC to DC rectification ..............................

What do you mean by "still"?

Mine powers my oval test track and has seen off several more modern controllers on various layouts.

Nothing quite like it and for certain it will never be equalled let alone bettered.

A short on a coach that had lighting the other day did make it growl a bit but usually it works fine with all types of motors, including those used in DJH locomotives.

Bernard

[Budgie]

Quick question, is anyone else having an issue with the front bogie wheel (small vent end) derailing when the loco transitions from curve to straight when going a fair speed?

 

Mine keeps doing it, also only when under load, like the wheels are being pulled off??

 

 

Yes, on third and fourth radii. I wondered if it has to do with the track being twisted (as it has to be when going uphill/downhill). Is it possible the bogies can't swivel fully in all directions.

 

 

On my big ageing layout, it does not like transition points were the curve switches from flat to super elevated (admittedly that is my fault in perhaps making the transition a little too sharp plus a little water damage and its age causing minor distortion of the boards, but no other model has a problem here).

 

I put this down to the limited up/down play of the bogie (between 1 and 2 mm), which is restricted to the outer wheels only. The pivot points sit almost above the inner wheels of each bogie (like a Dapol class 22 or class 73, but these have 2 to 4mm of up/down play). I also find that due to these pivot points not being in the centre that I cannot fit the lifting hooks (which need to be fitted in the centre of the bogie) as the centre of the bogie can swing out rather unnaturally to foul them even on 26inch curves. Hornby's chassis is much more flexible in this area, a 2mm up down play on both pair of wheels on each bogie, the pivots being centered which helps to prevent fouling of the lifting hooks (though the bogie itself is also about 1/2mm narrower/underscale width than the DJM).

I've just been to the layout, and studied what happens with my class 71 when hauling 6 Bachmann Bulleids.

 

First of all, we have a new proverb: A watched locomotive never derails.

 

The part of my layout that was giving me trouble was the oval double-track helix, which is just like an ordinary helix except it is extended by straight tracks so it looks a bit like a train-set oval when viewed from above. All of this helix is supposed to be at the same inclination, which is impossible because the outer track is at a different inclination than the inner on the curves, so I tried to minimise the differences by ensuring the centre-line has the same gradient all the way up. However, this is practically impossible due to my inability to measure things to the nearest half-millimetre, let alone the two decimal places that I've calculated. I thought I had got it better than I did when I built the helix, but I have since bought an inclinometer, and I obviously hadn't.

 

What I discovered is that the loco derails when both of the following happen at the same place

• There is a change of gradient from gentle to steeper going down or steeper to gentle going up
• There is a change of curvature (i.e. curve becomes straight or vice-versa)

I found the solution to be to try to make both sides of the change of curvature the same gradient (or as near as possible) and ensure that any change of gradient occurs on the straight. I am not going to try to figure out how to make the gradient the same all the way up the centre line, because as far as I am concerned the track is OK if nothing derails, and if the class 71 doesn't derail then it is unlikely that anything else will. Edited June 12, 2017 by Budgie

[mikesndbs]

On my big ageing layout, it does not like transition points were the curve switches from flat to super elevated (admittedly that is my fault in perhaps making the transition a little too sharp plus a little water damage and its age causing minor distortion of the boards, but no other model has a problem here).

 

I put this down to the limited up/down play of the bogie (between 1 and 2 mm), which is restricted to the outer wheels only. The pivot points sit almost above the inner wheels of each bogie (like a Dapol class 22 or class 73, but these have 2 to 4mm of up/down play). I also find that due to these pivot points not being in the centre that I cannot fit the lifting hooks (which need to be fitted in the centre of the bogie) as the centre of the bogie can swing out rather unnaturally to foul them even on 26inch curves. Hornby's chassis is much more flexible in this area, a 2mm up down play on both pair of wheels on each bogie, the pivots being centered which helps to prevent fouling of the lifting hooks (though the bogie itself is also about 1/2mm narrower/underscale width than the DJM).

 

Thanks for the replies, 2nd radi, you can see the outer line in my video review of the 71, oddly she does not derail on the inner circuit which is tighter in places???

I noticed the weight seems to be over the inner wheel sets.

 

I was wondering if it was anything to do with the NEM socket that slides about, I don't use it.

[JSpencer]

Thanks for the replies, 2nd radi, you can see the outer line in my video review of the 71, oddly she does not derail on the inner circuit which is tighter in places???

I noticed the weight seems to be over the inner wheel sets.

 

I was wondering if it was anything to do with the NEM socket that slides about, I don't use it.

The unused NEM sockets move with the bogie, so not really issue (it is not like a Heljan 33 socket that catches on the pipe work sometimes).

 

Mine copes with 2nd radius but not 22 and 24 inch super elevated track.

 

Looking closely at the bogie play, is has just over 1mm up play on the outer edges of the bogie and zero down play (maybe fifth of a mm at best). Weight concentration is mostly over the inner wheels where the pivot points are almost located. This is a very stiff model compared with anything else I have so track work needs to be perfect.

[luke_stevens]

I had the same at the club last week. A few swipes with a needle file to remove a slight tight spot at the place of transition from curve-to-straight and all was fine.

 

Luke

[mikesndbs]

D J Dave, can you comment on the comments being posted on my video regarding the model not being 100% crowd funded.

I know its daft and I have tried to explain but it would be good to get a good explanation.

I have to share the video here so you and others who might be able to answer can get to the comments.

[DJM Dave]

D J Dave, can you comment on the comments being posted on my video regarding the model not being 100% crowd funded.

I know its daft and I have tried to explain but it would be good to get a good explanation.

I have to share the video here so you and others who might be able to answer can get to the comments.

https://www.youtube.com/watch?v=CFYKMAO_2A8

Hi Mike,

 

The model was 100% crowdfunded,

Extra models were made for clients to deal with the importation and transportation costs and rising costs in China during the gestation of the model.

 

Cheers

Dave

[mikesndbs]

Hi Mike,

 

The model was 100% crowdfunded,

Extra models were made for clients to deal with the importation and transportation costs and rising costs in China during the gestation of the model.

 

Cheers

Dave

 

 

Thanks Dave, can I share that?

[Wigan Wallgate OO Gauge]

So guys, after parting ways with my half a packet of crisps, a can of warm coke, and a date expired sausage roll, I believe I'm the new MD of DJ models!

 

Only joking of course, I say keep all the pics flowing of the 71s!

[hurri67]

Evening gents,

 

 

I have now have a Cl 71.To run on my fathers layout.

 

I purchased a Bachmann chip today, and programmed it.It seemed to work ok on chip the test bed.

 

When it is in the loco, it runs lumpy, then ok for about 2ft then lumpy.Also the marker lights flicker when it is running.

 

Could the problem be the chip. 

 

Dave told me about turning "off" the back EMF. Any other tips in case this done solve this.

 

Thanks

 

Andy

[RFS]

The Bachmann chip is not really a good choice for this loco.  It was originally designed for locos with flywheels and the Back EMF defaults to values suitable for such locos.  The DJ 71's coreless motor has very different characteristics so you could first try turning Back EMF off. Further, you need a 5-function decoder which the Bachmann isn't, I believe, hence the head-code lights do not work. 

 

I would recommend reading back through this thread as there have been a lot of posts regarding the most suitable decoder for this loco. 

[Aldwych]

Hello hobby colleagues,

 

I have fitted the loco with a Uhlenbrock 75330 Decoder (6 functions).

The function key for the headcode light does not work, the CV has set the function to f4 and also there nothing works.

Who can help me?

 

Thanks and Greetings

 

Dennis

[RFS]

The head code lights need function #5 and this needs to be a logic function and not a normal function, so I would suggest first checking the spec of the decoder you have fitted.

[Scottish-Exile]

Update today from Hattons:

 

http://www.hattons.co.uk/NewsDetail.aspx?id=171

[Module00]

Hi at all !    

 

Here are some photos of the 71008 class DJ MODELS  in situation on the network, leading a train of minerals. Aesthetically this locomotive is perfect  realy a great and beautiful model. For operation I expect to see how the locomotive run (work ?) with the sound decoder (an ESU Loksound programmed by Legomanbiffo). In the meantime, the locomotive is equipped with an ESU Lokpilot, but this one does not seem perfectly adapted to the engine of the locomotive.  

 

The start-up is not progressive. The locomotive run with not normaly with leaps forward ... 

 

Sorry for my english... 

 

 

 

 

 

 

 

 

 

 

 

Have a good day. 

Edited July 23, 2017 by Module00

[Module00]

I also made a video, waiting for the ESU loksound.

 

Here it is.

 

Or on my Youtube channel.

 

https://youtu.be/Q7CpmYI_Ewo

 

Have good day. 

I also made a video, waiting for the ESU loksound.

[SRman]

The LokSound decoder should be already tuned to suit your locomotive when it arrives, but in the meantime, you could try turning off the BEMF on the decoder you have used. That was the answer with the Lenz decoder I used on my non-sound-fitted example.

[Module00]

Thank you very much for these explanations. Can you tell me what the BEMF is?

[leopardml2341]

Back EMF, it's the way the decoder senses how the loco motor is running. It is a CV value and can be changed by the user on a programming track providing that the user's DCC system allows CV programming.

 

I know coreless motors, like the one in the DJM class 71, don't work well with the chip's BEMF sensing enabled.

 

Can't remember what CV it is, but it's been discussed earlier in the topic, a search should find it.

Edited July 23, 2017 by leopardml2341

[Oldddudders]

Back Electro-Motive Force. Adjusting this to the needs of the specific locomotive (even locos from the same batch may vary slightly) really helps maximise the harmony between decoder and motor, which can otherwise 'fight' each other. ESU provides a clever automatic way to set this up in a decoder, but I can't put my hand to the CV details. It involves CV54. You may be able to find it on the ESU website.

[jprp]

I have jumped straight to the end of this thread so apologies if this has come up already- i have just received the blue Golden Arrow 71, should it have alternative headcodes or just the one that is fitted?

[SRman]

Back Electro-Motive Force (BEMF) is the electrical "back-pressure" that builds up as an electric motor spins. It results in the motor "fighting" speed increases or increasing loadings, or surging as it tries to balance the feedback, with sometimes erratic behaviour as a result.

The DJM class 71 has a coreless motor which doesn't generate much BEMF, whereas most decoders are set up to balance out BEMF by default. In the case of the DJM model, this setting is not really needed, hence you can reduce the effect or turn it off. Just how you do that depends on the decoder, with each manufacturer having their own CVs and settings.

 

Some decoders have an auto-sensing adjustment - the LokSound has something like this - but even with that, you may have to override the settings manually. In my case, the LokSound with Legomanbiffo sounds and settings was already set up perfectly to control my sound fitted E5004. The Lenz Silver+ 21 in my E5003 needed the setting turned off. Before doing that, E5003 was chattering and surging at low speeds, but was fine at higher speeds.

Edited July 23, 2017 by SRman

[luke_stevens]

I have jumped straight to the end of this thread so apologies if this has come up already- i have just received the blue Golden Arrow 71, should it have alternative headcodes or just the one that is fitted?

I would think that if it is the Golden Arrow version then it will only have the headcodes appropriate for the Golden Arrow. Any other headcode would be wrong

 

Luke