Wright writes.....

[APOLLO]

Micro nuclear reactors are the solution.

 

https://www.energy.gov/ne/articles/what-nuclear-microreactor

 

No need for lights, they glow in the dark. !!

 

Brit15

[Chas Levin]

Thanks Chuffer, Tony and Bob, very interesting information which underlines that Tony's technique of turning the drive unit round to have quieter and smoother forward running is a very effective answer to something that's either very difficult or impossible to cure.

I'd forgotten mention of thrust washers in one of Iain's books - have to look that up.

 

1 minute ago, FarrMan said:

Surely whichever direction the wheels are turning, the con rods will be pushing for half a turn, then pulling for the other half turn. When going forwards, it will be pushing going from from in line with wheel centers to the right, over the top of the centers until in line with the left, and pulling for the bottom half of the rotation, for both sides, and vice versa for reversing, or am I going completely gaga?

 

Lloyd

Hello Lloyd, yes, that bothers me too and it makes perfect sense of course, but it still looks to me as if the drive unit has less resistance in reverse, when it's on the forward-travelling one of the two axles, pulling the other, and the behaviour of the rods as observed from the sides seems to bear that out, as they appear to encounter slightly more resistance and to move slightly less smoothly going forwards, though I fully realise it may very well be due to my poor building!

[billbedford]

1 hour ago, FarrMan said:

Surely whichever direction the wheels are turning, the con rods will be pushing for half a turn, then pulling for the other half turn. When going forwards, it will be pushing going from from in line with wheel centers to the right, over the top of the centers until in line with the left, and pulling for the bottom half of the rotation, for both sides, and vice versa for reversing, or am I going completely gaga?

 

 

In reality, for a quarter turn both coupling rods will be pushing forward* and similarly a quarter turn pulling back and for half a turn the rods act in opposition to each other. 

 

* ignoring any slop at the crank pins. 

[Barry Ten]

One thing that can happen if the motor/gearbox isn't firmly restrained, is that the reaction to the torque on the driven axle can cause the whole assembly to want to rotate one way going forward, and the other way in reverse. This in turn can create opportunities for slightly more resistance (hence noise and lack of smoothness) one way than the other - an example, but not the only one, would be the case where the rear spindle hasn't been trimmed back and is free to rub against something inside the body.

[Bucoops]

2 hours ago, Izzy said:

The ‘whine’ in fast running high ratio straight cut spur gear reductions is due to the on/off loading of the pressure on the teeth faces because there is not a smooth continuous transfer of load from one tooth to the next. This actually results in the teeth ‘tapping’ against each other but at higher shaft rpm and with small tooth size is heard by human hearing as this whine. How bad it is depends on the quality of the gears and their meshing. To illustrate this get hold of a small servo motor, the typical 9g type with upwards of 200/300:1 reduction and try turning it by hand backwards via the servo arm. It will almost scream at you, the worst ones. This is the downside of running them at high rpm. Helical cut gears provide smoother transfer so are quieter and the first stage straight cut gear in particular is the prime generator of the whine. This is why the HL design of a worm reduction with slow running spur gear following stages is normally quiet. It’s a shame Portescap didn’t use crossed helicals as a first stage, down to cost probably along with design parameters.

 

Bob

 

 

Agreed, although my knowledge of gearboxes is of the automotive variety rather than teeny tiny model railway ones!

 

Helical cut gears are indeed quieter, but are weaker. Not really a problem in a model but a large part of the reason why motorsport gearboxes make so much noise - straight cut. Many road vehicle reverse gears are straight cut which is why reversing cars whine so much!

 

Having said that, here's the reverse idler of a Saab 900 box I rebuilt a few years back

 

 

 

[Chas Levin]

11 minutes ago, Bucoops said:

 

Agreed, although my knowledge of gearboxes is of the automotive variety rather than teeny tiny model railway ones!

 

Helical cut gears are indeed quieter, but are weaker. Not really a problem in a model but a large part of the reason why motorsport gearboxes make so much noise - straight cut. Many road vehicle reverse gears are straight cut which is why reversing cars whine so much!

 

Having said that, here's the reverse idler of a Saab 900 box I rebuilt a few years back

 

 

 

That's very interesting Rich, I'd occasionally wondered over the years why reversing a car makes such a different noise.

Nice to see a Saab 900 box too - I drove one of these for several years and loved it.

 

It's a pity our model 'boxes don't use different gear types in forward and reverse, or we'd have a ready explanation for the differences...

[Bucoops]

2 hours ago, Chas Levin said:

That's very interesting Rich, I'd occasionally wondered over the years why reversing a car makes such a different noise.

Nice to see a Saab 900 box too - I drove one of these for several years and loved it.

 

It's a pity our model 'boxes don't use different gear types in forward and reverse, or we'd have a ready explanation for the differences...

 

As nice as Saab gearboxes are, some bits may as well be made of cheese - originally designed as a 4 speed with about 60BHP they were modified over the years including squeezing a 5th gear and expected to take 150BHP+ and insane for the time amounts of torque!

 

BL transverse gearboxes (e.g. Mini, Allegro, Metro etc.) are a good one for whiney reverse - parts 11 and 16.

 

 

Also a box that was made from cheese. Stripped a couple of diffs doing burnouts on these! The lower ratio of reverse adds to the noise of course.

 

Edited February 9, 2023 by Bucoops

[Chas Levin]

And now I understand why your signature has a motoring reference, Rich 😉

[Tony Wright]

Well, this new A3 runs particularly-smoothly; in both directions.............

 

 

Thorough layout-testing, even at this early stage, ensures it'll perform on LB exactly like all its siblings.

[46444]

Evening Tony,

 

Today I have received two Isinglass Gresley GE Section 52'6 carriages.

 

One a Corridor Brake 3rd and the other a Corridor Composite.

 

I have had a quick look at one of the kits and I must say I am very impressed particularly with the 3D printing and the over all presentation. 

 

Over the weekend I will have a better look at what is involved in the building process.

 

I think an order with MJT will be  needed shortly. 

 

I must say I am looking forwards to building them both.

 

Thanks for your inspiration on building these kits.

 

Updates when the build commences.

 

Cheers,

 

Mark 

[APOLLO]

Talking of gears - Napier Deltic.

 

 

Or a very small Swiss watch maker !!!!!

 

Brit15

[Chas Levin]

1 hour ago, Tony Wright said:

Well, this new A3 runs particularly-smoothly; in both directions...

(My italics and bold).

 

Bi-directional smoothness noted and admired, Tony!

[Northmoor]

8 hours ago, Bucoops said:

Agreed, although my knowledge of gearboxes is of the automotive variety rather than teeny tiny model railway ones!

 

Helical cut gears are indeed quieter, but are weaker. Not really a problem in a model but a large part of the reason why motorsport gearboxes make so much noise - straight cut. Many road vehicle reverse gears are straight cut which is why reversing cars whine so much!

 

From memory of my days as a marine gearbox lubrication specialist, straight cut (spur) gears aren't stronger, but they are easier to produce; you've only got to align the gear-cutting tool to the axis of the gear centre.  Introducing a helix angle to produce a helical gear, you need to synchronise rotation of the gear with the pass of the cutter, plus consider than in large gearing systems, the helix angles of the mating gears are not exactly the same (this is where is gets really complicated, breathe in) because the slight bending of the teeth under load starts at one end and progressively more of the tooth comes into (lubricated) contact as the load increases.  It's why on marine gear teeth you would see much more severe wear marking at one end of the teeth and an extreme wear pattern like scuffing might only extend part-way along the teeth.

 

I think spur gears are used for motorsport gearboxes because noise, vibration and harshness (that's the NVH the automotive world talks about) aren't a consideration in a car running an unsilenced exhaust and which has had every bit of sound-deadening stripped out!  Racing gears are also ground to a lesser surface finish because again, any increase in noise is irrelevant and gearboxes aren't expected to have a long life.  NVH is extremely important in road cars, so the benefits of helical gears are exploited.

[Tony Wright]

23 minutes ago, Chas Levin said:

(My italics and bold).

 

Bi-directional smoothness noted and admired, Tony!

Thanks Chas,

 

You'll have to take my word for it that's it's a sweet-runner. Until I video her when she's complete.

 

Regards,

 

Tony. 

[PupCam]

2 hours ago, APOLLO said:

Talking of gears - Napier Deltic.

 

 

Or a very small Swiss watch maker !!!!!

 

Brit15

 

Now there is a thing of beauty 😀

 

My little Beeza does it's best to pretend it's a Napier but .... 🤣

 

 

 

 

Edited February 9, 2023 by PupCam
Replaced photograph

[Bucoops]

29 minutes ago, Northmoor said:

From memory of my days as a marine gearbox lubrication specialist, straight cut (spur) gears aren't stronger, but they are easier to produce; you've only got to align the gear-cutting tool to the axis of the gear centre.  Introducing a helix angle to produce a helical gear, you need to synchronise rotation of the gear with the pass of the cutter, plus consider than in large gearing systems, the helix angles of the mating gears are not exactly the same (this is where is gets really complicated, breathe in) because the slight bending of the teeth under load starts at one end and progressively more of the tooth comes into (lubricated) contact as the load increases.  It's why on marine gear teeth you would see much more severe wear marking at one end of the teeth and an extreme wear pattern like scuffing might only extend part-way along the teeth.

 

I think spur gears are used for motorsport gearboxes because noise, vibration and harshness (that's the NVH the automotive world talks about) aren't a consideration in a car running an unsilenced exhaust and which has had every bit of sound-deadening stripped out!  Racing gears are also ground to a lesser surface finish because again, any increase in noise is irrelevant and gearboxes aren't expected to have a long life.  NVH is extremely important in road cars, so the benefits of helical gears are exploited.

 

What you say does make sense, however I would argue against racing gears not being as well finished - lifespan is very important - the last thing you want is an in-service failure. We would frequently send gearsets off to be shot peened to relieve stress in the material. Bearings were regularly replaced, but gearsets were used for a very long time, assuming no catastrophic failure. What tended to let go on the Saab boxes was either the pinion bearing, and as everything hangs off the pinion shaft that usually used to make a big pile of expensive scrap, or the case would flex too much and crack. Similar end result. Straight cut also makes it easier to get some decent meat in the gear - helical needs to be thinner, and also introduces lateral loads meaning side control with thrust washers etc. are needed. These lateral loads probably at least partially explain the wear patterns you witnessed?

[PupCam]

9 minutes ago, Bucoops said:

Straight cut also makes it easier to get some decent meat in the gear - helical needs to be thinner, and also introduces lateral loads meaning side control with thrust washers etc. are needed. These lateral loads probably at least partially explain the wear patterns you witnessed?

 

And the quite considerable side thrust is wasted energy when you are trying to make use of every last bit of it to go faster ......

[polybear]

11 minutes ago, Bucoops said:

 

What you say does make sense, however I would argue against racing gears not being as well finished - lifespan is very important - the last thing you want is an in-service failure. 

 

Poorly finished gears are also a source of power loss; on production motorcycles for example (where the gear finish is very high) the difference between the (higher) power output measured at the crankshaft can be quite significant when compared the the power measured at the rear wheel; some of these losses will be in the gearbox, whilst some will be in the final drive (chain etc.).

[Northmoor]

14 minutes ago, Bucoops said:

 

What you say does make sense, however I would argue against racing gears not being as well finished - lifespan is very important - the last thing you want is an in-service failure. We would frequently send gearsets off to be shot peened to relieve stress in the material. Bearings were regularly replaced, but gearsets were used for a very long time, assuming no catastrophic failure. What tended to let go on the Saab boxes was either the pinion bearing, and as everything hangs off the pinion shaft that usually used to make a big pile of expensive scrap, or the case would flex too much and crack. Similar end result. Straight cut also makes it easier to get some decent meat in the gear - helical needs to be thinner, and also introduces lateral loads meaning side control with thrust washers etc. are needed. These lateral loads probably at least partially explain the wear patterns you witnessed?

You're considering lifespan as up to catastrophic failure, I'm talking about a component being worn up to wear limits.  Remember a racing gearbox might operate well under 100 hours a year (after which it is replaced by the next year's model), a truck gearbox might do several thousand.

Note that I didn't say racing gears weren't well-finished, but that the finish is to a lower grade than for normal family cars.  I remember the Newcastle University Gear Design Unit (probably the best specialists on the subject in the UK) showing me a number of gears for various applications and the Formula One gear was visibly lesser finish than anything else.

[Tony Wright]

4 hours ago, 46444 said:

Evening Tony,

 

Today I have received two Isinglass Gresley GE Section 52'6 carriages.

 

One a Corridor Brake 3rd and the other a Corridor Composite.

 

I have had a quick look at one of the kits and I must say I am very impressed particularly with the 3D printing and the over all presentation. 

 

Over the weekend I will have a better look at what is involved in the building process.

 

I think an order with MJT will be  needed shortly. 

 

I must say I am looking forwards to building them both.

 

Thanks for your inspiration on building these kits.

 

Updates when the build commences.

 

Cheers,

 

Mark 

Good evening Mark,

 

A Gresley GE Section 52' 6" Corridor Brake Third was the first Isinglass 3D-printed carriage I built..........

 

It was ghastly!

 

 

 

I gave it away to a friend, who'll use the cast metal bogies for something else. 

 

It was several years ago; and, things have improved dramatically since then..............

 

 

The second and third vehicles in this train are current Isinglass 3D-printed items - a Gresley TPO and a pigeon van. There is no comparison with that original Isinglass 'shorty', only contrast.

 

They can be made into quite acceptable 'layout carriages' now, as I hope can be seen.

 

I look forward to seeing your progress.

 

Regards,

 

Tony. 

 

 

[46444]

8 hours ago, Tony Wright said:

Good evening Mark,

 

A Gresley GE Section 52' 6" Corridor Brake Third was the first Isinglass 3D-printed carriage I built..........

 

It was ghastly!

 

 

 

I gave it away to a friend, who'll use the cast metal bogies for something else. 

 

It was several years ago; and, things have improved dramatically since then..............

 

 

The second and third vehicles in this train are current Isinglass 3D-printed items - a Gresley TPO and a pigeon van. There is no comparison with that original Isinglass 'shorty', only contrast.

 

They can be made into quite acceptable 'layout carriages' now, as I hope can be seen.

 

I look forward to seeing your progress.

 

Regards,

 

Tony. 

 

 

 

Thankyou Tony,

 

Goodness! Your print of the Gresley 52'6 GE Section Brake Third is I agree a poor print. 

 

Beautifully finished as ever.

 

Thankfully I believe the prints have been refreshed and have recessed windows.

 

Stepping of the print is hardly visible. 

 

I will take some pictures tomorrow.

 

Thanks once again.

 

Mark

[Tony Wright]

1 hour ago, 46444 said:

 

Thankyou Tony,

 

Goodness! Your print of the Gresley 52'6 GE Section Brake Third is I agree a poor print. 

 

Beautifully finished as ever.

 

Thankfully I believe the prints have been refreshed and have recessed windows.

 

Stepping of the print is hardly visible. 

 

I will take some pictures tomorrow.

 

Thanks once again.

 

Mark

Thanks Mark,

 

I'm not sure about 'beautifully finished', however. 

 

 

Not only were the sides (in two halves each) bowed, they looked like a washboard!

 

 

Even after several coats of filler primer. 

 

To be fair, the latest Isinglass prints are far, far superior. 

 

The one above was inferior to...........

 

 

Kirk kits produced over 40 years ago. I still think these stand up as 'layout carriages'. 

 

Regards,

 

Tony. 

 

 

 

 

[billbedford]

I think you are being a bit unfair to John Edison here, in that you are comparing one of his early prints with a "production" Ian Kirk moulding. Though mouldings tend to 'work' or not 'work'. It doesn't take too long for someone who starts doing something innovative, like trying to print long thin coach sides, to realise that they know more about this process than anyone they could possibly ask advice from. 

Edited February 10, 2023 by billbedford

[Tony Wright]

1 hour ago, billbedford said:

I think you are being a bit unfair to John Edison here, in that you are comparing one of his early prints with a "production" Ian Kirk moulding. Though mouldings tend to 'work' or not 'work'. It doesn't take too long for someone who starts doing something innovative, like trying to print long thin coach sides, to realise that they know more about this process than anyone they could possibly ask advice from. 

Good afternoon Bill,

 

It's not the late John Edgson (not Edison) who produces the 3D-printed carriages, it's his son, Andy. 

 

I did acknowledge that the one I've shown was a (very) early print, and that things are much, much better now. I've made three of Andy's 3D-printed kits in recent times, and I'm quite happy with them. I've written two of them up for BRM, and the third will be in the Railway Modeller in April. I hope you'll find my comments fair. 

 

Regards,

 

Tony. 

[Tony Wright]

More on the 3d-printed vehicles I've made of late............

 

 

A closer shot of the Isinglass pigeon van and Gresley TPO in an empty stock train. The former has developed a bit of a bow over time. 

 

All my own work (as is the Mailcoach matchboard Thompson BG). 

 

 

And, the TPO itself.

 

I thought I was being clever (always a stupid thing to do in my case!) by depicting a TPO which had lost its traductor gear and net (this happened to several of the type later in their lives). I should have checked the number! 

 

 

This is the Isinglass Gresley RFO which will feature in the RM in the spring. 

 

Built by me and painted by Geoff Haynes (though I did the lining).

 

Alan Rose's son-in-law has produced some 3D-printed items...........

 

 

Including this 3D-printed ex-GC 'Barnum'. I built/painted it, and Geoff Haynes weathered it.

 

 

Alan gave me a 'scrap' 3D-print for an LNER refrigerated van.

 

Which I sort of made-good (with limitations).