p2 "Cock of the North" go slow

[Friendly Fryer]

Hi,

As I have mentioned elsewhere I have a new P2 (R3246TTS) and while it looks the business and occasionally derails this topic just relates to its jerky motion at slow speed, whihc is my other complaint about her.  I have read that this is due to the quality of the motor fitted, so my question is can that be easily changed, corrected with the adition of a heavy flywheel,  or are their experts out there who can do this for me?

 

[96RAF]

As it is TTS try changing CV150 to value 1. If that helps but does not fully cure it then fiddle with CVs 153/154.

If staying on value 0 at CV then you can similarly fiddle with CVs 151/152.

 

A flywheel can make a difference as can turning off BEMF but remember that is how the chuff rate is controlled. No BEMF = no chuff control.

 

Finding a suitable replacement motor can be hit and miss due to Hornby constantly changing the part numbers whilst often reusing a previous inventory item. Its a case of getting out the tape measure. Changing a motor physically is usually a simple job, body off,  unsolder the brush wires, release the motor mounts, lift out the motor. If using a replacement bare motor swap the worm gear over and install a flywheel if desired, drop the motor in, refit the motor mounts, resolder the brush wires and test.

[ColinB]

I have one of these and I must admit it never struck me as going slow, but there again they made a few different versions. I had a lot of issues with the front bogie derailing, but there is a separate post curing it. I retro fitted a TTS decoder and again I don't remember any issues. It might be worth inspecting the drive train, worm drive, crown wheel, driving wheel to check that they are running freely and of course the valve gear, it might be catching on certain curves. As to changing the motor, I bought some of those cheap Chinese motors that "Sams Trains" tested and yes they work perfectly, I am sure they are the same as the Hornby ones. The big issue is they do not come with the worm drive, so you have the issue of either obtaining one (not very easy as no part number) or pulling the one off your existing motor (again not always that easy).

Oh, I forgot, if the motor has a suppression capacitor across it, remove it, they seem to cause no end of issues. If you are running DCC you don't need it and they fail.

[Friendly Fryer]

Hi both,

just be clear it does move at slow speeds, but rather jerkily possibly because of the motor design.  I know I can fiddle with CVs whihc I guess will ultimately supply less current to the actual motor but what I am after is a smoother action at that low speed. So I am sorry my original post did not make that clear

[ColinB]

I will check mine again, but I am pretty sure it is quite good at slow speed. I am sure it uses the standard Hornby motor which generally is really good at slow speeds. I must admit most of my locos with jerky movement  I have put down to the DCC decoder, but the TTS one is usually good. When the weather here cools down a bit I will try mine out in the loft (hot weather has a habit of killing Hornby TTS decoders). I must admit the only issue I have ever had with mine is the front bogie derailing. With a TTS decoder you get PWM control of the motor, so unless there is something wrong with yours it should be ok.

[ColinB]

I have just checked mine on a length of track in the kitchen at incredibly slow speeds (no bar on the Elite) it is a little jerky but nowhere near as bad as other locos and to me perfectly acceptable, most of my other locos wouldn't move on that setting. Perhaps you just have a bad motor or bad TTS decoder. It is definitely a lot better than the Bachmann G2A that had a serious issue at low speeds (later traced to a bad Bachmann decoder).

[Yelrow]

hi, Mine has been fine from day of purchase. I only bought it, following release of video, showing its pulling power. It pulls for england,  and runs at all speeds, fast, or slow. I am also very content with its sounds.

[Going Spare]

Are your rail surface, wheel treads, wheel rims and pick-up faces (loco & tender) all scrupulously clean?  Do the geartrain and motor turn smoothly by hand?  Any hesitation would be noticeable at slow speeds but would be overcome by the flywheel at higher speeds.  

[Howbi]

Change CV150 to a value of 1...........this has resolved the jerky movement at low speed with TTS in dozens of cases on this Forum.......no point in discussing the quality of the motor if you haven't changed this CV first and reported the result...........changing CV150 to the alternative algorithm will not reduce the current to the motor.......HB

[Fishmanoz]

FF, HB has now emphasised for you that the first reply you have from Rob under your original post is the tried and tested solution to TTS jerky running. A forum search will find you heaps of threads going back to early TTS days.  You will even find one thread where someone has posted exactly how you go about fiddling as you put it with CVs 151/152 or 153/154 to get the best results fine tuning after you've selected the best algorithm with CV 150. 

I have nothing to add, Rob and HB have given you the answer. 

[Friendly Fryer]

Friends

I have dome testing today as part of running in Cock o' the North (and because it's raining wohoo!) as I do try and follow the excellent advice on here. 

My main line route on my layout is only about 12m in length or about 0.61 scale miles.  The P2 takes about 235 secs to complete the course and maths makes that a speed of 8mph . However the speed I set on Rail Master was 14mph so she's on a bit of go slow.  At the sime time I was running on Channel Packet which is fitted with the rigth MN TTS decoder.  She was also set to run at 14mph and got round in under 2 minutes so an actual speed of 18 mph.

So what's interesting here is that I have right TTS decoders in the right locos, with no chnages to any CV's apart from setting their ID's and one goes roughly twice as fast as the other.

I'd appreciate any thoughts on this feel free to cirrect my maths too. However what I am really after is a good guide to gettnig the best out of these lovely looking models. @RAF96 you mentioned some CV stuff ealrier in this thread, so is there a guide, blog post or even dare I say it Hornby documentation to help me understand what to fix as well as actually fixing it

Thanks as always

[Friendly Fryer]

OK forgoet about the CV stuff. Note to self don't search in here use the search engine in your browser.  Found loads of good stuff thanks @Chrissaf to the link to Tony's trains.  It would be nice ot have a delete post button for idiots like me 

[96RAF]

Just point to the offending post FF and a Mod will hide it for you.

[96RAF]

The basic information about changing motor PID values i.e. CV150 and subsequent can be found in the TTS user ‘manual’. The science behind motor PID and how to adjust for best perfromance can be found using Google.

 

It was intended to provide a motor self calibration for decoders but few have the facility to date. Essentially you place the loco on a good length of track, set a certain CV to a certain value and the loco legs it down the track then stops - motor is automatically set to optimum settings. All very clever and should be mandatory in my opinion on all decoders, so they can be matched  to any loco they are installed in.