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Class 50, uprated cardan shaft why, how


Rallymatt

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Two points from watching the tutorial. 
1. Does it matter which way round the uprated shafts are inserted? Thin end in bogie or motor? 
2. It seemed incredibly easy to slot the shafts in place which contradicts my experience. 
 

Diolch yn fawr 

Edited by Skelton Junction
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Normally a part will be made thinner at one end.  The length of the shaft will experience ‘twist’ so the thinner section would need to be even thinner to achieve the same performance if it was in the centre. Twist is built into shafts, both elastic and non elastic. Elastic being that once the torque is no longer applied, the material will revert to its original. Non elastic being that the elastic limit has been exceeded so the twist remains when the torque is no longer applied. Different materials can remain serviceable with different levels of twist. A line is painted or etched along length or strain gauges applied. Through mathematical modelling and dynamic testing you can determine how much ‘twist’ is acceptable before replacement is required. Stiffer, ie better power transfer is generally more brittle (there are some trick alloys that almost defy science!) but a more flexible material can result in a smoother power delivery and more predictable failure. 
The coupling nearest the motor or power take off will experience the greatest amount of torque.
If it was for reasons of protecting the motor, thin end at motor end. It would also protect the gearbox at the other end as the shaft wouldn’t still be flailing around at motor speed in the case of a failure. In a more extreme scenario to increase the instant load the shaft could endure using the same component, put the thin end into the gearbox. 

After all that, it really doesn’t matter, ABS plastic is a nice balance of flex and effective power transfer. Please feel free to paint a line along the shaft to measure twist, free fishplate to first entry 🤣

For this purpose the extra diameter is more useful at the bogie end as there is no chance of the shaft getting caught in the drive cup slots as these are deeper than at the motor end. 


 

Edited by Rallymatt
Typo
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1 hour ago, Skelton Junction said:

Two points from watching the tutorial. 
1. Does it matter which way round the uprated shafts are inserted? Thin end in bogie or motor? 
2. It seemed incredibly easy to slot the shafts in place which contradicts my experience. 
 

Diolch yn fawr 

1. See my previous post. 
2. it was easier without filming it! Practice. 
 

and 

mae croeso i chi 

or in Apple English 

maestro crossover I Chinese 

👍

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@Rallymattgreat vid well explained don't  have a  class 50 yet but i have got a class 43 which left it's camdan shaft in the middle of my track has i picked it up when it was making a loud noise  and was  not going any where   so i turned it off first  .   richard should get a very large order off hornby and send them to the factory in china asap to retrofit the class 66 before they get sent to hornby .

don't  they test these things i want to thank richard  youself and people like peachy and all the rest that try to fix all  the thing that are wrong with  hornbys  TT120 whats the point of all  the bells and whistles if they don't run it's ok under warranty .

how about a survey i will start 1 dodgy motors A1 to A4 =£30 to fix  2 camdan shaft various class 43 class 50  class 66 ? class 37 ? £15 plus .

I love TT120 🥰but before 2022 there were piko tilig and the rest Hornby don't prove people  like sam and the and the people who  don't like  TT120 and hornby  to be right 😊

Edited by happy tt
TT120
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12 minutes ago, Rallymatt said:

Thanks, worth remembering not all 43s and 50s have thrown a shaft. Ironically, I feel they may have used a longer collar on the drive cup to combat the issue other manufacturers have had. 

I have 2 HST's and 4 class 50's and not had a shaft pop out. Two of the 50's have had a fair bit of grinding on the chassis to fit the Deltic bodies but the work never affected them.  Admittedly they may not run as often as other modellers may do but certainly not had an issue when they have run.

Edited by Silver Fox 17
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@RallymattI know that it's not all of them i have had my class 43 for six mouth  from the 3rd of march it's been on my layout from day one .

I have run  it a few times ln the past one or two laps around my layout it's  6ft 3ft it's been keep it in a sideing  i have been very happy with it but i  decided give it  a good run last week after 4  laps  then it stop and made the loud noise    so it  could happen  anytime . 

I don't want it to affect hornby going forward that  is all  .people are moaning about the price of all model trains if you buy a loco say an A1 or A4 +a new motor to make it work ok is more money to  fork out thats all 😊   them camden shafts look good fix worth £15 

I still think hornby should give richard a call lol😃

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An Update,

having seen the Video close ups done by Richard on the Class 43 and spoken, it’s worth when swapping out the shafts for the updated ones just checking what’s happening with the bogies at limit of their travel.
Watch the video Richard made and see how the drive ball is almost coming out.

It’s a bit harder to see when I did the video on the 50 (blame the camera and lighting crew!) but it wasn’t doing the same thing. There was sufficient plunge, ie it was engaged enough to not come out without serious effort enough to break something. I never thought to measure the length drive cups but they look longer on the 50, that could be helping. 
There are two options for adjusting the space between the motor and the bogie drive cups. 
1/ de solder the motor, use a suitable puller to move the combined flywheel and drive cup assembly along the motor shaft 1mm. Re solder the motor wires.
2/Richard’s nifty hack shown in his video, remove the clip on cap that retains the worm drive, carefully withdraw it taking car not to lose the end bushes, remove the cup from the shaft by hand, it’s simply a push fit on a splined end. Use one of the isolator washers from underside of PCB to act as a spacer (or source some suitable 1mm washers, brass would be ideal) push the drive cup back on, making sure the inner brass bush is free running. Drop back into the gear tower and clip the retaining cap back on. 
Either way will do the trick but the 2nd doesn’t need anywhere near the same work/tools to achieve the same result. 
I am also going to revise my advice on uprated shaft orientation. Seeing the close up of 43 phenomenon, for both 50 and 43 install the uprated shafts thicker end into motor, thinner end into bogie end. It might not be critical but it is a more belt and braces approach. Richard’s experience with N gauge models is way ahead of mine.
It’s an instance where model railway engineering with plastic differs from high performance steel applications. (No one mention Aircraft carriers and shaft issues 😉
@Richard-358946 I’ll ask mods to put up a ‘revision in title’ and see if I can tweak my video. 

Link to show the video Richard did with 43 and the hack on closing up spacing easily. 
https://youtu.be/2Hozv1vc58w?si=rwFwSc01PbMVwuTX

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M1.4 brass washers are readily available and are usually a good sliding fit on 1.5mm shafts (often sold as Pocher car upgrades) - other sources include the various  material and thickness washers to be found in N20 motors.

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That will be the 'Pocher Premium'- got to keep the riff raff away. Cheaper sources are available if you do a wider search.

FWIW EBay items with included postage will often not discount for multiples so one ends up paying way over the going postage rate. Try going direct to the sellers own web site where far better rates may be found.

Edited by Les-345151
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The main thing for me is knowing that there is a fix, and one even I can cope with fitting. It gave me the confidence to buy a 50 so Hornby benefits too.

I will not rush into making the change. With 4th radius curves on my main oval I will see how the Hornby setup fares.

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Hi everyone, You've all been great 👍Hope this "breakdown" list helps... 

*Install propshafts wasted end towards bogie

*The shafts for sale at the moment are injection molded and only fit the Class 50. I only have a finite ammount of these, working on a solution in the background...

*The HST ones are shorter, i dont have any of these yet and a solution to this is also happening in the background.

*Try your new propshafts and see how much play there is, if its just over a washer thickness of wiggle then do the washer hack 👍

 

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