gearbox designs for sprung BO-BO or Co-Co bogies

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junctionmad
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gearbox designs for sprung BO-BO or Co-Co bogies

Postby junctionmad » Wed Aug 31, 2016 4:02 pm

HI can anyone point me to any discussion on ideas around implementing a centre drive scratch built chassis which 2 axle driven bogies ?

thanks

dave

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jim s-w
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Re: gearbox designs for sprung BO-BO or Co-Co bogies

Postby jim s-w » Wed Aug 31, 2016 4:25 pm

Hi Dave

Is it an odd size? If not you may as well just canabailse a RTR one.

HTH

Jim

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Russ Elliott
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Re: gearbox designs for sprung BO-BO or Co-Co bogies

Postby Russ Elliott » Wed Aug 31, 2016 5:01 pm

I reckon Justin Newitt and Ian Perberth have got this area covered:
viewtopic.php?f=99&t=1671
http://www.penbits.co.uk/

junctionmad
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Re: gearbox designs for sprung BO-BO or Co-Co bogies

Postby junctionmad » Wed Aug 31, 2016 5:56 pm

firstly its an odd size and penbits dont have a solution and theres no suitable RTR that Id want to canabalise . its funny we have stacks of discussions on steam engine chassis but little or nothing on diesel bogies and suitable powertrains etc

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jim s-w
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Re: gearbox designs for sprung BO-BO or Co-Co bogies

Postby jim s-w » Wed Aug 31, 2016 6:13 pm

What wheelbase do you need? Anything from the US that would fit? Another option would be a couple of these http://www.hollywoodfoundry.com/bullant%20intro.htm I think they do a version without the motor so you can fit a centre motor.

I think there's not a lot of discussion on diesel bogies because there really doesn't need to be.

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Mike Garwood
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Re: gearbox designs for sprung BO-BO or Co-Co bogies

Postby Mike Garwood » Wed Aug 31, 2016 6:41 pm

If I remember right Bill Bedford did something to aid this sort of build.

http://www.clag.org.uk/demuspine.html

That's if I'm understanding the question properly.

regards

Mike

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Russ Elliott
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Re: gearbox designs for sprung BO-BO or Co-Co bogies

Postby Russ Elliott » Wed Aug 31, 2016 6:52 pm

I'm tempted to agree with Jim (crikes!!) - there's probably not a lot to say about these sorts of drives.

Here's the sketch of what I did nearly 20 years ago to a Dave Alexander BTH. The whole thing was compensated (no, don't ask), but nowadays would be eminently springable, and a lot easier. Only 2 axles were driven, taking 60% of the weight. I didn't have the cardan space to drive all 4 axles. The chassis plate was two layers of 2mm plasticard, iirc. Sorry, have not got any pics. I was pleased with the flyclutch and the cardans, but the rest isn't worth seeing.

BTHchassis-1-general.gif
BTHchassis-1-general.gif (5.51 KiB) Viewed 4756 times
Last edited by Russ Elliott on Wed Aug 31, 2016 8:31 pm, edited 1 time in total.

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Russ Elliott
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Re: gearbox designs for sprung BO-BO or Co-Co bogies

Postby Russ Elliott » Wed Aug 31, 2016 8:10 pm

I'm not sure if I understand the question properly either, but on the DEMU theme (thanks, Mike), here's an underfloor 4-wheel drive arrangement in a Bill Bedford B4 frame modified for a transmission tunnel. (The frame pic has yet to have the endframe bridge piece substituted.) The transmission system, probably from an underfloor 1219 Faulhaber midships, can be dropped without bogie removal. Boxes are 'old-style' BB 14:1. The 2N/mm secondaries are shown in the sketch, but the 0.5N/mm primaries and carriers (standard BB) are not shown, the latter will take 1mm i.d. bushes for parallel 1mm axle ends - I feel slightly uneasy about putting 100g on 4 pinpoints. The bogie was intended to go under the floor of a DC Kits 119 (that was £45 wasted!), but might see the light of day under something else.

4-drive-s4web.gif
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underside.jpg
underside.jpg (15.47 KiB) Viewed 4771 times
Last edited by Russ Elliott on Thu Sep 01, 2016 12:08 pm, edited 1 time in total.

junctionmad
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Re: gearbox designs for sprung BO-BO or Co-Co bogies

Postby junctionmad » Wed Aug 31, 2016 8:21 pm

Thanks for replies

to clarify, Im looking at building a fully sprung CoCo, ( 3 axle) diesel bogie , with at least two of the three axles driven, using a centre driver system

I was interested to see if this has been discussed on the interwebby, but not much it seems,

I had the idea of a floating worm gearbox on each axle,connected by a rigid shaft, then transferring the driver via a reducing spur gear upwards to bring it into line with the motor ( sorry no drawing ) with carden shafts etc . all gearbox self contained and floating .

I can mill the gearboxes, but was wondering if any supplier might have a suitable range of self contained gearboxes , ( capable of handling trust as well of course )

as an alternative , I was thinking that I could just take the drive from the last gearbox and transfer it to the motor , but I think the shaft distances are too short

Ive simply not seen much discussion on this topic
Last edited by junctionmad on Wed Aug 31, 2016 8:35 pm, edited 3 times in total.

junctionmad
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Re: gearbox designs for sprung BO-BO or Co-Co bogies

Postby junctionmad » Wed Aug 31, 2016 8:22 pm

Russ Elliott wrote:I'm tempted to agree with Jim (crikes!!) - there's probably not a lot to say about these sorts of drives.

Here's the sketch of what I did nearly 20 years ago to a Dave Alexander BTH. The whole thing was compensated (no, don't ask), but nowadays would be eminently springable, and a lot easier. Only 2 axles were driven, taking 60% of the weight. I didn't have the cardan space to drive all 4 axles. The chassis plate was two layers of 2mm plasticard, iirc. Sorry, have not got any pics. I was pleased with the flyclutch and the cardans, but the rest isn't worth seeing.

BTHchassis-1-general.gif


this is the closest to my requirements , but I will need the second axle of each bogie driven ( its actually a Co Co bogie )

junctionmad
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Re: gearbox designs for sprung BO-BO or Co-Co bogies

Postby junctionmad » Wed Aug 31, 2016 8:24 pm

jim s-w wrote:What wheelbase do you need? Anything from the US that would fit? Another option would be a couple of these http://www.hollywoodfoundry.com/bullant%20intro.htm I think they do a version without the motor so you can fit a centre motor.

I think there's not a lot of discussion on diesel bogies because there really doesn't need to be.



nothing in the US suits and the hollywood foundry units are not sprung and the compromises for 3 axle in their designs are not great

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Russ Elliott
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Re: gearbox designs for sprung BO-BO or Co-Co bogies

Postby Russ Elliott » Wed Aug 31, 2016 8:47 pm

You might want something like this, then:

junctionmadsketch.png
junctionmadsketch.png (6.17 KiB) Viewed 4750 times

junctionmad
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Re: gearbox designs for sprung BO-BO or Co-Co bogies

Postby junctionmad » Wed Aug 31, 2016 10:03 pm

Russ Elliott wrote:You might want something like this, then:

junctionmadsketch.png



exactly ,

Im not sure I need UJs on the axle hung gearboxes , given they float on the axles and there will be a small degree of lateral movement in the worm, I think even with rigid drive shafts , I think theres enough play to not interfere with the springing but tests will see

by the way, Anyone know a good source of universal joints for small shaft sizes ?

billbedford
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Re: gearbox designs for sprung BO-BO or Co-Co bogies

Postby billbedford » Thu Sep 01, 2016 9:22 am

junctionmad wrote:
Russ Elliott wrote:You might want something like this, then:

junctionmadsketch.png



Im not sure I need UJs on the axle hung gearboxes , given they float on the axles and there will be a small degree of lateral movement in the worm, I think even with rigid drive shafts , I think theres enough play to not interfere with the springing but tests will see

by the way, Anyone know a good source of universal joints for small shaft sizes ?


You will need UJs on the final gear boxes. We have been through this with a RTR Co-Co which didn't have them.

UJ are easily made from silicone tubing (model aircraft fuel line)

You will have to make up your own transfer boxes, I would suggest something between 2:1 and 3:1 ratio depending on how fast you want the loco to go. The gears can be either 0.3 or 0.4 mod depending on the vertical distance between the motor shaft and the bogie lay shaft, but you may have to add an idler to make up this distance.

14:1 gearboxes are available here
Bill Bedford
Mousa Models
http://www.mousa.biz

Alan Turner
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Re: gearbox designs for sprung BO-BO or Co-Co bogies

Postby Alan Turner » Thu Sep 01, 2016 3:27 pm

junctionmad wrote:
Russ Elliott wrote:
by the way, Anyone know a good source of universal joints for small shaft sizes ?


Ultrascale do them: https://www.ultrascale.uk/eshop/product ... CAT028/476

regards

Alan

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PeteT
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Re: gearbox designs for sprung BO-BO or Co-Co bogies

Postby PeteT » Thu Sep 01, 2016 3:49 pm

Alongside the concept Russ has noted above, there is the other option of 1 gear tower and driven out from there, depending on the wheelbase etc, as per this example (this drives the outer axles on each bogie, so 4 of the 6):

http://www.clag.org.uk/class31.html

Edited to note that this is probably the chassis Bill referred to above!

junctionmad
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Re: gearbox designs for sprung BO-BO or Co-Co bogies

Postby junctionmad » Thu Sep 01, 2016 5:38 pm

billbedford wrote:
junctionmad wrote:
Russ Elliott wrote:You might want something like this, then:

junctionmadsketch.png



Im not sure I need UJs on the axle hung gearboxes , given they float on the axles and there will be a small degree of lateral movement in the worm, I think even with rigid drive shafts , I think theres enough play to not interfere with the springing but tests will see

by the way, Anyone know a good source of universal joints for small shaft sizes ?


You will need UJs on the final gear boxes. We have been through this with a RTR Co-Co which didn't have them.

UJ are easily made from silicone tubing (model aircraft fuel line)

You will have to make up your own transfer boxes, I would suggest something between 2:1 and 3:1 ratio depending on how fast you want the loco to go. The gears can be either 0.3 or 0.4 mod depending on the vertical distance between the motor shaft and the bogie lay shaft, but you may have to add an idler to make up this distance.

14:1 gearboxes are available here



Thanks bill , I have good CNC milling so may make a few gearboxes , but by the tine I add ball race trust bearings the costs tend to mount ! Thanks to UJs yes rather then expensive ball joint ones , I could use the silicon tube idea , good point On the central motor , I'll likely need splined shafts as well as UJs , branchlines do suitable ones.


Ps: are the mousa gearboxes able to take trust on the worm axle
Dave

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grovenor-2685
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Re: gearbox designs for sprung BO-BO or Co-Co bogies

Postby grovenor-2685 » Thu Sep 01, 2016 6:08 pm

See http://www.norgrove.me.uk/ajin.htm it might give you some ideas, still in my pending box!
The sleeved D shafts are a particularly simple to make u/j where only a very small angle is needed.
As indicated Bill B does 14:1 gearboxes and last time I looked there were a number of 2:1 spur boxes available, (High Level) Branchlines had some small worm boxes also and u/js.
Exactoscale did both the spur reductions and small 18:1 boxes, have these dropped out with the new owners?

For a bit more variety NWSL in the USA have quite a range.
Regards

junctionmad
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Re: gearbox designs for sprung BO-BO or Co-Co bogies

Postby junctionmad » Thu Sep 01, 2016 7:14 pm

grovenor-2685 wrote:See http://www.norgrove.me.uk/ajin.htm it might give you some ideas, still in my pending box!
The sleeved D shafts are a particularly simple to make u/j where only a very small angle is needed.
As indicated Bill B does 14:1 gearboxes and last time I looked there were a number of 2:1 spur boxes available, (High Level) Branchlines had some small worm boxes also and u/js.
Exactoscale did both the spur reductions and small 18:1 boxes, have these dropped out with the new owners?

For a bit more variety NWSL in the USA have quite a range.
Regards

Thanks Keith

The nwsl boxes I beleive are from New Zealand and are the same as Branchlines

billbedford
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Re: gearbox designs for sprung BO-BO or Co-Co bogies

Postby billbedford » Fri Sep 02, 2016 8:25 am

junctionmad wrote:Ps: are the mousa gearboxes able to take trust on the worm axle


Of course, thrust washers are needed to take up the slack between the worm and the bearings.

WGB14-3 instructions-1.png
Bill Bedford
Mousa Models
http://www.mousa.biz

junctionmad
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Re: gearbox designs for sprung BO-BO or Co-Co bogies

Postby junctionmad » Fri Sep 02, 2016 8:22 pm

PeteT wrote:Alongside the concept Russ has noted above, there is the other option of 1 gear tower and driven out from there, depending on the wheelbase etc, as per this example (this drives the outer axles on each bogie, so 4 of the 6):

http://www.clag.org.uk/class31.html

Edited to note that this is probably the chassis Bill referred to above!


Thanks. It looks like this clag design is interesting as it drives two axles on each bogie but only needs one transfer box. My concern is that the transfer box then is in the middle of the loco and severely limits the motor size
which is opposite to the whole point of a central motor


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Russ Elliott
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Re: gearbox designs for sprung BO-BO or Co-Co bogies

Postby Russ Elliott » Fri Sep 02, 2016 9:31 pm

junctionmad wrote:Thanks. It looks like this clag design is interesting as it drives two axles on each bogie but only needs one transfer box. My concern is that the transfer box then is in the middle of the loco and severely limits the motor size
which is opposite to the whole point of a central motor

The Class 31 only drives two axles on each bogie because that's all that particular prototype (A1A-A1A) did. For Co-Cos, I think it would be near impossible to put silicone UJs between all the boxes if all axles were driven. Putting the transfer box in the middle has a number of advantages over 'integral with the bogie' styles, but it needs a long loco to do it. It comes down to UJ space, again. Motor space is probably the least significant issue.

Maybe six axle-hungs might appeal instead? (But you then might need a bodyfull of electronic control regulation to get the six blighters to behave themselves.)

junctionmad
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Re: gearbox designs for sprung BO-BO or Co-Co bogies

Postby junctionmad » Fri Sep 02, 2016 10:39 pm

Russ Elliott wrote:
junctionmad wrote:Thanks. It looks like this clag design is interesting as it drives two axles on each bogie but only needs one transfer box. My concern is that the transfer box then is in the middle of the loco and severely limits the motor size
which is opposite to the whole point of a central motor

The Class 31 only drives two axles on each bogie because that's all that particular prototype (A1A-A1A) did. For Co-Cos, I think it would be near impossible to put silicone UJs between all the boxes if all axles were driven. Putting the transfer box in the middle has a number of advantages over 'integral with the bogie' styles, but it needs a long loco to do it. It comes down to UJ space, again. Motor space is probably the least significant issue.

Maybe six axle-hungs might appeal instead? (But you then might need a bodyfull of electronic control regulation to get the six blighters to behave themselves.)



Actually my protyoe was A1A, I was using Co Co and Bo Bo as generic examples. As I said in the beginning , in effect , whether the prototype is Co Co or A1A , the model will be A1A, as you said , and I agree is very difficult and not necessariy to drive 3 axles in each bogie on the model

billbedford
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Re: gearbox designs for sprung BO-BO or Co-Co bogies

Postby billbedford » Sat Sep 03, 2016 7:01 am

The centre wheels on a class 31 were smaller than the drivers, so trying to put a drive on them leads to a whole new set of complications.
Bill Bedford
Mousa Models
http://www.mousa.biz


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