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Re: class T9 chassis rot

Posted: Sat Jun 03, 2017 11:26 pm
by GWR_fan
Bachmann have a long history of splitting gears and disintegrating plastic gearboxes from "h.o." through to 'G' scale. Some issues were evident right from release with others not showing until several years later. Part of the problem was attributed to the use of recycled plastic. It seems anything that looked like plastic was substituted for the designed material. What is in the specs is not necessarily what makes it to production. The Chinese are masters of substitution. They will look at the requirements and then find a cheap alternative to the manufacturer's design specifications.

When LGB production first moved to Hungary from Germany, there were many quality control defects reported. One in particular amused me. A particular locomotive had a drive block at each end, each with a cover plate secured by six screws. Customers reported issues with gears stripping. On investigation it was found that only the centre two screws and not the required six screws were being fitted. This allowed the axle driven gear to separate from the motor worm gear causing slipping and gear teeth stripping. The assembly line workers were questioned and their response was why fit six screws when only two were needed to hold the cover on and they could easily accomplish the task in the allowed timeframe. They had no idea of the specification requirement to fit the six screws. The cover not only retained the large motor but also held the worm in contact with the axle driven gear.

With poor manufacturer control over both metal and plastic production then enjoy your models while you have them as it seems they will not last forever.

Re: class T9 chassis rot

Posted: Sun Jun 04, 2017 9:34 am
by Bigmet
D605Eagle wrote:
Bufferstop wrote:It is absolutely incredible that we should be discussing MAZAK rot three quarters of a century after the cause and solution were discovered by Meccano Ltd assisted by the wartime Ministry of Supply. Particularly as the current purveyors of this rot bought the the physical and intellectual property of Meccano Ltd over 50 years ago. Just shows how the quick buck so easily overules good practise.

Cheap Chinese c**p. they don't care for the sort of quality control you need to ensure Mazak lasts. I have several triang chassis from the early 60s that are as good as the day they were cast. Can you imagine any of the fragile models made in China being any good when they are 55 odd years old? Its not just the Mazak that's poor, I've noticed and increasing number of early Chinese Hornby models suffering from plastic failure too. And we all know about the Bachmann axle muff and keeper plate issues.......

Rather selective comparison there: take a look at the 1950 productions of what became Triang. Acetate bodies on locos and coaches bent like bananas and totally unusable, likewise the 1930s OO Hornby-Dublo, mazak rotting here there and everywhere. It seems to me a common start up problem in model railway production.

I am pretty confident of the chinese productions that haven't shown mazak rot after half a dozen years from the factory, and are of better design than the Mainline/Bachmann split chassis steam loco mechanisms. My oldest N2 0-6-2T at 40 years, Mainline coaches and wagons ditto: at 23 years now, the class 46 with centre motor drive that Bach brought out in the early 1990s. Still as good as ever. Ditto the WD 2-8-0, A1 pacific, BR Std 5MT 4-6-0 BR mk1 coaches and 16T minerals bought 15 to 17 years ago. Having got this far, my guess is these will outlive me!

Re: class T9 chassis rot

Posted: Sun Jun 04, 2017 10:42 am
by b308
GWR_fan wrote:Bachmann have a long history of splitting gears and disintegrating plastic gearboxes from "h.o." through to 'G' scale.


Correction... "N" through to "G"!!

The "white box" American Bachmann stuff is well known to NG modellers all over the world for their dreaded plastic gear splitting antics...

Re: class T9 chassis rot

Posted: Mon Jun 12, 2017 12:32 pm
by GWR_fan
I notice that Hattons have an NRM T9 #120 and surprise, surprise it is a poor runner. It would appear to be suffering early stages of the dreaded lurgy.

Re: class T9 chassis rot

Posted: Mon Jun 12, 2017 5:28 pm
by mahoganydog
b308 wrote:The "white box" American Bachmann stuff is well known to NG modellers all over the world for their dreaded plastic gear splitting antics...


Ah yes and how can we forget Graham Farish Diesels doing the exact same thing years ago. The cause? Nylon gears. Why? Because Nylon is the wrong material with two properties that you don't want which are; absorbing water causing it to swell up. The other is that it doesn't age at all well with a tendency to fall apart eventually especially when exposed to sunlight. Incompatible oils and greases don't help either.

Jim

Re: class T9 chassis rot

Posted: Mon Jun 12, 2017 7:14 pm
by Bufferstop
Just like MAZAK nylon needs careful quality control to avoid deterioration in service. A peice of kit which frequently gave me trouble had a nylon gear moulded integrally with its shaft. They would frequently seize up because the shaft had cracked and swollen, jamming it in the bearings. No ammount of washing, scraping sanding and lubricating them would get them to rotate reliably again. Hearts sank when a new machine had an almost identical device, but our fears were misplaced, totally reliable. Talking about it to one of the development engineers he claimed the difference was the pretty pink plastic it was made from. The old white nylon had a mixing tolerance of 1%, the exorbitantly priced pink stuff 0.1%. You pays your money...........

Re: class T9 chassis rot

Posted: Tue Jun 13, 2017 2:45 pm
by D605Eagle
To wander off T9 topic but staying on plastic. Volvo D5 Diesel throttle bodies are driven via a nylon gear, which unsurprisingly disintegrates over time. Price for a new one? That will be £555 plus fitting I thank you :shock:

Re: class T9 chassis rot

Posted: Tue Jun 13, 2017 11:11 pm
by GWR_fan
I seem to recall the Mitsubishi Magna 2.6 litre four cylinder camshaft driven distributor had a nylon drive gear. When that went to God the car would suddenly stop and definitely not restart until repaired.

Re: class T9 chassis rot

Posted: Tue Jun 13, 2017 11:22 pm
by Peterm
GWR_fan wrote:I seem to recall the Mitsubishi Magna 2.6 litre four cylinder camshaft driven distributor had a nylon drive gear. When that went to God the car would suddenly stop and definitely not restart until repaired.

That engine was a disaster. The water jacket would crack between two core (welch) plugs, the timing chain, being so long would rattle around, the counter balance chain would do the same. They were heavy on juice and sluggish.

Having covered their good points....

Re: class T9 chassis rot

Posted: Wed Jun 14, 2017 11:50 pm
by Peterm
Talking of nylon gears, I wonder how much extra it would cost to have brass gears and worms like we used to.

Re: class T9 chassis rot

Posted: Thu Jun 15, 2017 8:46 am
by Bigmet
And also the likes of five pole motors and sprung driven axles. These are pennies at the factory, but with all the intermediate profit and tax takes before they reach the customer are probably each £5 increments on the price. I'd pay it, but there's a lot of price resistance in the UK: most won't pay the price despite wanting the better mechanism quality.

Actually I'd not want brass gears! The right grade of polymer is what I want, and they do exist but cost a little more. The big thing with plastic gears is how they contribute to quietness despite a fairly crude straight tooth form = cheap. It needs considerable advances in all of design and precision of cut and the surface finish to get the same quietness from all metal: all of it proven technique, but = expensive.

Re: class T9 chassis rot

Posted: Thu Jun 15, 2017 2:03 pm
by D605Eagle
When Triang changed from brass to plastic drive gear on the axles, in the majority of cases they lasted the life of the model, so as Bigmet says, the right grade plastic shouldn't be an issue.

Re: class T9 chassis rot

Posted: Thu Jun 15, 2017 3:48 pm
by RAFHAAA96
Do not get me started on Volvo cars and their dodgy plastic bits or mechanics or paint or rusty tin or their warranty swerving dealers...
...and moving on to a newer Nissan Qashqai, everything is held together with disintegrating expanding plastic studs (clips) at £2 apiece from a dealer or the same price per hundred from China.
e.g. The front fog light brackets are secured by 2 of these clips and you have to take the front bumper off to get at them. Bumper is held on by ... yes even more of these clips.

Re: class T9 chassis rot

Posted: Mon Oct 23, 2017 3:36 pm
by Ken Shabby
My T9 died today, It's only been run twice this year and was fine 4 months ago. I've been keeping an eye on it and this morning I got it out to run with my new Birdcage set and found It was noisy and juddery.
I'm guessing the worm is not longer meshing as there is a lot of grinding noises.
Any idea how to get the body off ?

Thanks, Ken

Re: class T9 chassis rot

Posted: Mon Oct 23, 2017 3:55 pm
by Ken Shabby
It's off , and the chassis came away with the motor and fragments the the metal housing that sits over the worm still wedged inside the body.
There is NO point contacting Hornby, I'll attempt to repair it myself.
Ken.