KRModels announce a GT3 Model

[JSpencer]

1 hour ago, adb968008 said:

Interesting design, if the “white” is the metal chassis, then the lumpof weight is over the front pony's... wouldnt that be tipping the centre of gravity forwards ?

 

I wonder if using a shaft, having the motor over the ponys, running the shaft to the centre driving wheel and having the weight either side of the other two would have been more balanced ?

 

i dont know if its possible, but if the motor did sit forwards, but lower, over the ponys, it could have a shaft to operate the fan too, and maybe eliminate 1 gear from the tower, or even have 3 gears on a long shaft going straight to each of the axles eliminating the intermediate gears between them ? Though the risk is making the weight above the chassis top heavy, but it could be a monster for haulage.

 

 

Either way its nice to see progress, should the footplate steps sit so far out..way beyond bufferbeam width, they look somewhat out of gauge ?

 

Yep, you definately need the weight of gravity centred over the drivers, otherwise the extra weight serves no purpose. Take the Hornby H class 0-4-4 vs the DJM O2 0-4-4. The Hornby is heavier, bigger with a bigger motor but sadly not balanced over the drivers, while the lighter smaller DJM is and will perfectly out pull the Hornby (a rare case of DJM superiority - a shame the14XX and J94 were not similary balanced).

[adb968008]

I notice the green colour outline around the drive chain, I wonder if it is plastic ? (The motor housing is also green and often these are plastic).

 

if it were, in that sense maybe this design could be based on a “co” 6 wheel diesel bogie, upsized and slotted in.. for instance the drive chain does look to me, a lot like the Dapol class 52 motor bogie..

 

https://www.dccsupplies.com/item-p-107043/gear-type-1-Dapol-oo-class-52.htm

 

If I was correct it could be a plastic cradle slotting into the metal weight block that holds the motor and thus avoids a split chassis (though the plastic cradle would be two halves).

 

that would pose another question though.. wheels would need a metal axlebox, to not wear out the plastic cradle, where would the pickups be ? - would it be like piko in the tender ?

 

 

 

Edited June 18, 2019 by adb968008

[Pre Grouping fan]

A small update posted over on facebook tonight regarding the chassis design:

 

Quote:

"Following the cut-away photo of the GT3, we have gone back the drawing board a little.  Apparently, the reasoning behind the gearing is to take the strain from the connecting rod on the drive wheels, to keep good traction.  they have used this arrangement before without issue.  That being said I have asked him to look at producing a set up with just one set of drive wheels connected to the 5 pole motor and prop shaft and using the connecting rods to keep the 6 drive wheels.  It's a full cast metal chassis, not a split chassis."

[brianCAD]

The mechanism appears to be the same design as used by for Heljan (O scale A3 and assorted diesels), so experience there, good or bad (split gears), should provide some pointers.   I would prefer to see an old fashioned X04 or can motor powering one axle directly.

[black and decker boy]

1 hour ago, JSpencer said:

 

If true, as we know DJM fell out with said factory over a year ago, then that would then be proof that DJM is not at all involved here.

Im surprised DJM hasn’t popped up to pre-claim the GT3 as a secret project he had started and bemoan someone else stealing his idea again and then laying claim to the IP for horribly complicated all gear driven rod coupled drive wheels which he could more easily claim to be his unique design cues

[PMP]

6 minutes ago, Pre Grouping fan said:

That being said I have asked him to look at producing a set up with just one set of drive wheels connected to the 5 pole motor and prop shaft and using the connecting rods to keep the 6 drive wheels.  It's a full cast metal chassis, not a split chassis."

 

Its good to know that with less than six weeks (assuming tooling starts end July), that a major redesign can potentially take place, hopefully with no cost burden on any crowdfunders.

The drawing isn’t telling us much, if it’s a cast metal chassis then perhaps the driving wheel section (in green)is inserted from below the chassis block as a separate power unit, like a diesel bogie in effect. This unit could be plastic getting round the electrical issues with the cast chassis. That could then be connected with the prop shaft to the motor.

That still leaves the weight distribution issues. If the drive section (current configuration), is plastic that’s even less weight over the drivers compounding a potential nose heavy weight distribution.

 

I’m somewhat surprised the commissioner hadn’t addressed these potential issues earlier in the design specifications.

[JSpencer]

13 minutes ago, PMP said:

 

 

I’m somewhat surprised the commissioner hadn’t addressed these potential issues earlier in the design specifications.

 

The factory is supposed to be full of engineers. Not easy to question unless you have some user hard facts to come back with. 

[PMP]

^^ The factory presumably designed to a submitted specification/list of minimum requirements. That’s why I’m surprised at this late point, that the fundamental chassis design is possibly subject to a significant re-design. Having said that, it’s obviously better to get a design the commissioner is happy with, prior to cutting metal.

[K14]

5 hours ago, adb968008 said:

... should the footplate steps sit so far out..way beyond bufferbeam width, they look somewhat out of gauge ?

 

Photos suggest they ought to be flush with the cab door & therefore inset from the body sides:—

 

https://vintagetrains2.wordpress.com/2017/07/01/gt3-in-vulcan-works-yard-newton-ie-willows-superb-shot-963/

 

https://railway-photography.smugmug.com/1/Pre-TOPS-Locomotives/Prototype-Diesel-Locos/GT3/i-7cMhGns

 

 

[Hilux5972]

49 minutes ago, K14 said:

 

Photos suggest they ought to be flush with the cab door & therefore inset from the body sides:—

 

https://vintagetrains2.wordpress.com/2017/07/01/gt3-in-vulcan-works-yard-newton-ie-willows-superb-shot-963/

 

https://railway-photography.smugmug.com/1/Pre-TOPS-Locomotives/Prototype-Diesel-Locos/GT3/i-7cMhGns

 

 

I passed this on via the Facebook CAD images. 

[RedgateModels]

Bit of idle speculation here - Maybe IF this is the same factory/designer that DJ used for the J94 it may be that Dave is not the one to blame for the fully geared chassis etc. It could be that this is an in-house standard and Dave as well as KRModels just went with it .....

 

My joking comment on FB about Dave Jones designing the chassis might have been entirely the wrong way round LOL

[truffy]

6 hours ago, Hilux5972 said:

I passed this on via the Facebook CAD images. 

Crowddesigned, as well as crowdfunded!

 

Actually, nothing wrong in the design being improved by positive feedback. I'm looking forward to the Rails/Dapol Terrier also having benefitted from open review at the EP stage.

Edited June 19, 2019 by truffy

[Pre Grouping fan]

This is now the benefit of using forums like this and social media to allow customers to interact and assist manufacturers/commissioners to improve models. Which has been proved on many occasions to work.

[DavidH]

10 hours ago, Pre Grouping fan said:

they have used this arrangement before without issue.

 

This could be true, because their standard of engineering is better than that on certain other recent 00 models, or it could be that they never had to stand the cost of all those reported 14XX returns.

[No Decorum]

The DJM O2 had gear drive with coupling rods. It was awful – the rods flail around at odd angles and look terrible. The 14XX exhibited the same tendency, so I avoided it. I decided to go for the J94 Austerity because I thought the one-piece coupling rods and six coupled wheels would overcome the problem. It did but at the price of articulated coupling rods, which would have been an advantage. The J94 exhibited other problems, though. On the other hand, Bachmann drove two axles of its 9F through gears and the arrangement seems to work well enough, although the Hornby Railroad version runs, if anything, better with the gear train in the firebox and using coupling rods to drive the other eight wheels. All in all, I think the best solution is to use the coupling rods to transmit drive. After all, they have to be present. Just make sure they are beefy enough to take the strain. We have lots of steam models using coupling rod drive and they work perfectly well.

[RedgateModels]

Now this is better! maybe if we all concentrate on giving positive feedback on the cads then a good GT3 model will be produced.

[Pre Grouping fan]

Indeed although I think the chassis/drive train is the only issue aside from the cab steps.

 

One thing that I don't think has been picked up on is is the rather empty tender body. Assuming finer details like DCC sockets, speaker mounts, pickups etc come later down the line in the CAD as we only seem to have the motor modelled in the loco.

[cctransuk]

11 hours ago, Pre Grouping fan said:

"Following the cut-away photo of the GT3, we have gone back the drawing board a little.

 

Perhaps this might help - it runs superbly.

 

 

Regards,

John Isherwood.

Edited June 19, 2019 by cctransuk

[Pre Grouping fan]

If you dont mind ill pass that on to Keith for use?

[cctransuk]

3 minutes ago, Pre Grouping fan said:

If you dont mind ill pass that on to Keith for use?

 

By all means - I will waive the IP charge.

 

Regards,

John Isherwood.

[gary_lner]

11 minutes ago, Pre Grouping fan said:

Indeed although I think the chassis/drive train is the only issue aside from the cab steps.

 

One thing that I don't think has been picked up on is is the rather empty tender body. Assuming finer details like DCC sockets, speaker mounts, pickups etc come later down the line in the CAD as we only seem to have the motor modelled in the loco.

I asked Keith about the location of such items a few weeks ago as I'm on the fence about dcc sound. And the plan was for the dcc socket to be installed in the tender and speakers to be fitted in the area behind the fan. So hopefully that's all in hand in the design.

 

Regards Gary.

[Pre Grouping fan]

35 minutes ago, gary_lner said:

I asked Keith about the location of such items a few weeks ago as I'm on the fence about dcc sound. And the plan was for the dcc socket to be installed in the tender and speakers to be fitted in the area behind the fan. So hopefully that's all in hand in the design.

 

Regards Gary.

I will mention that in an email to Keith. And will suggest the speaker position. Hopefully he can confirm the few details that seems to be lacking currently. Especially as theres no apparent NEM sockets shown.

[polybear]

2 hours ago, cctransuk said:

 

By all means - I will waive the IP charge.

 

Regards,

John Isherwood.

 

Of course if Keith adopts your suggestion and it runs like poo then everyone's gonna blame you.....

[cctransuk]

7 minutes ago, polybear said:

 

Of course if Keith adopts your suggestion and it runs like poo then everyone's gonna blame you.....

 

No chance - I can demonstrate that mine runs like a Swiss watch.

 

The skill is in converting a design into a successful product; I have no control over that process.

 

Regards,

John Isherwood.

[Pre Grouping fan]

That's now in the hands of Keith and the design engineers to come up with the goods.