William Whitelaw A4 rubbish on R2 curves

[ukpooky]

Just converted my WW A4 to HM7000 with the Next 18 chip and am now struggling with performance on curves.

It was always a bit rubbish on the curves anyway but was fine at any kind of speed. The acceleration rate is so slow (even when on max) on HM7000 that it's still not at sufficient speed on the curves to keep going so basically keeps grinding to a halt/slipping. It's nigh on useless at slow speeds on a curve with carriages.

I know it seems to be the one of the most problematic of the TT locos from all the forum posts but is this just what I have to live with or are there any fixes? Or back to Hornby?

Have had it since Feb but only did the HM7000 conversion the other day as was waiting for Android release.

[Skelton Junction]

I hear you pooky.

[D9020 Nimbus]

On DCC systems you can control the acceleration rate by altering the values of certain CVs (configuration variables). Is this not possible with HM7000?

[david_watts1]

Send it back, the more Hornby can see issues the quicker they will get resolved. When you're forking out 200 quid for a loco it should be perfect. They might even get a QC dept.

[Moccasin]

Send it back, the more Hornby can see issues the quicker they will get resolved.

Agree that it’s best to send it back. I had the same issue with my Flying Scotsman and it was returned fixed within 10 days.

[Fishmanoz]

Take a look at this, the thread itself and the linked post: https://uk.hornby.com/community/forum/tt120-flying-scotsman-bogies-358535?ccm_paging_p=1#end-of-replies

[Paul K]

One of the noteworthy YTers (Simon's Shed, maybe?) also had poor performance with his TT Pacific once converted to DCC/HM7000. Turned out not to be an issue with the loco or decoder at all, but with using the analog track power connector included with the set.

Switching to the digital power track (or direct hard-wiring the track) solved the issues. YMMV, and I don't know what your setup is, but something to consider, and not necessarily obvious as a source of problems for something marketed as "DCC-ready".

[ukpooky]

I thought it might be power supply related so now have it running on a P9300 power supply. That fixed Trigo but not the A4. Will send it back and report back

[Fishmanoz]

Turned out not to be an issue with the loco or decoder at all, but with using the analog track power connector included with the set.

Switching to the digital power track (or direct hard-wiring the track) solved the issues.

 

 

This will only be an issue if you are using a DCC controller. It matters not when operating HM7000 decoders with the app as all that is going through the power track is DC.

[My name is Bond]

Maybe that’s the reason all the sets and bundles have R3 curves.

I have observed that pacific locos when pulling coaches run at the regular speed on R3 curves but do slow on R2 curves.

I have a R2 return loop at one end of a long straight shelf section which by its nature curves right before looping left through a 240 degree arc and on this section I do sometimes wonder if the loco pulling 4 coaches will make it.

It needs a certain entry speed to ensure that it does. Too slow and it struggles.

Try the same with R3 and fine but that increases baseboard width at the loop end which is “off scene” so to speak.

This is using HM7000 with a 4amp power supply.

To be honest this phenomenon does occur with OO and all scales with smaller radius curves. It’s the laws of physics as the tighter the curve the greater the leverage effect of the rolling stock on the hauling loco. So it’s not really an issue just something to be aware of when designing a layout.

The wheel sets of the locos have a factory tolerance also I guess and those locos with wheels at the extreme width of what is acceptable to QC will suffer this effect greater as a result of increased friction on curves.

So I would suggest using no more than a 180 degree arc for R2 curves to enable a straight entry and exit to minimise the effect described above. If creating a return loop R3 is recommended by me anyway.

I remember the days of steel rails and magnatraction. Maybe Hornby should reintroduce this for tt:120! grinning

[StuLarge]

Just got my DCC Eastener set. Running it around on the Table Top. And can now see the camber on the curves everyone has spoken of. Just running in at the moment but:

Front bogie wheels lift and do not turn while going around the corners. Found a small bit of electrical tape covering a screw above the bogie, once removed the wheels infrequently turn. Is this normal resulting from the track or something else?

[Silver Fox 17]

My WW goes around Tri-ang small radius curves without issue and they are tighter than Hornby R1 curves.

[Rallymatt]

Things to check and adjust have been covered quite a few times previously, if you take a look through related threads and you should find a wealth of information that hopefully will help. 👍

[StuLarge]

Thanks Rallymatt. As noted in one of the posts I eventually found the search function of the forum is a bit rubbish!

I found: isolation tape, bent mounting arm, spring washer, casting clash, and checking the gauging. All as possible causes, 1down 4to go! (Might have the gauging issue on the tender as running backwards over the power track is like putting your finger in the way, loco stops, wheels spin!)

Then perhaps I'll try the Triang A type track test laughing

[Rallymatt]

Gauging on the tender could do that as well as the hook on the coupling fouling the centre of the power track, then it’s case of making sure NEM socket it correctly clipped into the guide.

[ukpooky]

I sent it back and got it returned the other day. The note said something in the tender had been repaired/adjusted but I know it's a brand new loco because I had fitted the accessories kit and the loco I got back didn't have any of them on the tender or the engine!