The Build Thread Of My Garrett

Bill Barnwell

Bill Barnwell

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Ormond Beach, Fl
Very neat
 
a98087

a98087

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Wiltshire
Here’s a few more picture showing the latest progress,

It’s usally a case of 2 steps forward 1 step back as I make progress and then remove it as I don’t like the look of it!

Here’s the pivot I built

6207C311-137C-4C50-8601-A0ADFA50BA7C.jpeg

It’s just an m4 bolt and washer, and some plasticard and lots of superglue to hold it together

These 2 show the cradle I’ve built for the boiler and cab to sit on, this has brought the overall loco height down and keeps the roof at the same height as a standard stainz

AD71B8F7-CF64-40C5-B04B-2A8F899225D8.jpeg

538E75E8-2ABE-4F1A-A0D8-8832B82D45AF.jpeg

It’s had some wiring fitted, and when the weather in nicer, I will start testing the loco, before I do any more

Dan
 
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Bill Barnwell

Bill Barnwell

Registered
30 Sep 2017
744
540
76
Ormond Beach, Fl
Here’s a few more picture showing the latest progress,

It’s usally a case of 2 steps forward 1 step back as I make progress and then remove it as I don’t like the look of it!

Here’s the pivot I built

View attachment 234409

It’s just an m4 bolt and washer, and some plasticard and lots of superglue to hold it together

These 2 show the cradle I’ve built for the boiler and cab to sit on, this has brought the overall loco height down and keeps the roof at the same height as a standard stainz

View attachment 234410

View attachment 234411

It’s had some wiring fitted, and when the weather in nicer, I will start testing the loco, before I do any more

Dan
Good thing you have the newer style motor blocks that service from the bottom, all the ones I have are old split case. It looks like you are well on your way to a very good looking engine, keep us posted, Bill
 
a98087

a98087

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Wiltshire
So to bring this thread update,

its been sat untouched for a long while, so I decided to try and finish it.

recent work has been

Throw some paint on it
Fit radio control
Cast some custom lead weights

it now looks a lot better, and has even had a short run.
However the weight distribution isn’t very good, as it has the original factory boiler weight, and some weight in the rear tank only.

there were quite a few derailments, so I need to get on, and remake the front tank, and get some weight in it.

the painting makes thing look lots better, and will hopefully encourage me to finish sooner rather than later!

here’s the photos,



Dan 27E35893-A0DB-4A6B-ABA2-51B6B78C9EC5.jpeg 0AE45528-E48E-428D-9D04-056D12DB7F8B.jpeg
 
F

Flying15

Registered
12 May 2015
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209
London
So to bring this thread update,

its been sat untouched for a long while, so I decided to try and finish it.

recent work has been

Throw some paint on it
Fit radio control
Cast some custom lead weights

it now looks a lot better, and has even had a short run.
However the weight distribution isn’t very good, as it has the original factory boiler weight, and some weight in the rear tank only.

there were quite a few derailments, so I need to get on, and remake the front tank, and get some weight in it.

the painting makes thing look lots better, and will hopefully encourage me to finish sooner rather than later!

here’s the photos,



Dan View attachment 272505 View attachment 272506
Something of the Baddesley Colliery Garratt E2E27D6F-C787-4A6F-9334-7C7F515FB1A9.gif
 
dunnyrail

dunnyrail

DOGS, Garden Railways, Steam Trains, Jive Dancing,
25 Oct 2009
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St.Neots Cambridgeshire UK
There has been some talk about Garretts recently in the forum. I think the the general consensus was that the pivots should be quite central. This then should allow you to stuff a goodly amount of weight in the boiler.
 
Zerogee

Zerogee

Clencher's Bogleman
25 Oct 2009
17,122
1,687
North Essex
There has been some talk about Garretts recently in the forum. I think the the general consensus was that the pivots should be quite central. This then should allow you to stuff a goodly amount of weight in the boiler.

Got a link back to those discussions, JonD? I'm trying to catch up with the most interesting stuff I've missed while I've not been here (some would say that I'm never "all here"....). ;)

Are there "rules" about exactly where the pivots should be, in an engineering sense?

Jon.
 
Rhinochugger

Rhinochugger

Retired Oik
27 Oct 2009
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Got a link back to those discussions, JonD? I'm trying to catch up with the most interesting stuff I've missed while I've not been here (some would say that I'm never "all here"....). ;)

Are there "rules" about exactly where the pivots should be, in an engineering sense?

Jon.
The logic suggests that the pivot point should be inside the wheelbase of each set of drivers.

Power is one thing, but traction is key to delivering that power.

To get the traction I'm ridin' the clutch
My pressure plate's burnin' that machine's too much
;);)
 
JimmyB

JimmyB

Semi-Retired; more time for trains.
The logic suggests that the pivot point should be inside the wheelbase of each set of drivers.

Power is one thing, but traction is key to delivering that power.

To get the traction I'm ridin' the clutch
My pressure plate's burnin' that machine's too much
;);)
"Shut Down" by the Beach boys :)
 
dunnyrail

dunnyrail

DOGS, Garden Railways, Steam Trains, Jive Dancing,
25 Oct 2009
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St.Neots Cambridgeshire UK
Got a link back to those discussions, JonD? I'm trying to catch up with the most interesting stuff I've missed while I've not been here (some would say that I'm never "all here"....). ;)

Are there "rules" about exactly where the pivots should be, in an engineering sense?

Jon.
This was a couple that I have found. As for the rules, sorry no knowledge but forward of the wheel or central makes sense as you would want to put the most weight where it will do good. Perhaps someone on here will have the engineering knowledge.




 
musket the dog

musket the dog

Professional engineer, amateur modeler
31 Oct 2009
656
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Leicester
nlrr.webs.com
From a engineering standpoint I would think maybe the position of the pivot is dependent on the relative masses of the weight above the power unit and the boiler cradle.

I would think that the designers would be aiming to have as near as possible, an equal mass acting upon each driving wheel? To achieve that you would need to find the point where the point load of the cradle pivot and the mass have the same effect across the wheels.

Thinking in terms of the front bogie: If the pivot was dead center in between the wheels this would spread it's portion of the boiler mass 50/50 between the front and rear driving wheels. However if you then add the water tank on top of the bogie (which has to sit in front of the pivot) you will be spreading the tank mass over the area between the pivot and the front wheel. This will add a greater proportion of the mass onto the front wheel. To correct this you would need to move the pivot back and use its mass at a point closer to the rear wheels.

So in a roundabout way, somewhere between the center and the rear wheels?

I maybe over complicated things previously in another thread :wondering:

Mass Distribution

Great build too, I'm looking forward to seeing it complete :) I've thought a few times about trying to make a narrow gauge version of the colliery Garratt above.
 
Last edited:
ebay mike

ebay mike

Retired, but still hoarding. (GOF)
6 Dec 2011
3,344
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Norfolk - edge of nowhere.
Got a link back to those discussions, JonD? I'm trying to catch up with the most interesting stuff I've missed while I've not been here (some would say that I'm never "all here"....). ;)

Are there "rules" about exactly where the pivots should be, in an engineering sense?

Jon.
Jon, I have a copy of A E Durrant's Garratt Locomotives of the World. There are a few drawings in it which show the pivot points are normally located between the innermost drivers and the next axle. My effort did not quite match with that so I was prompted to convert from a 4-6-0+0-6-4 to a double pacific format which helped to disguise the fact a little.
P1020234 _2_.JPG
 
Zerogee

Zerogee

Clencher's Bogleman
25 Oct 2009
17,122
1,687
North Essex
Jon, I have a copy of A E Durrant's Garratt Locomotives of the World. There are a few drawings in it which show the pivot points are normally located between the innermost drivers and the next axle. My effort did not quite match with that so I was prompted to convert from a 4-6-0+0-6-4 to a double pacific format which helped to disguise the fact a little.
View attachment 272581


Thanks Mike - yes, it makes perfect sense that the pivots must be within the wheelbase of each power unit; just a question of whether having them at or around the centre of the wheelbase, as Ricky mentioned above, is helpful if it can be done? I guess a lot depends on the relative dimensions of the mainframe/boiler and the power units, much easier to do with a "shorty" like the Stainz-based ones than with the monster you've built....

Jon.
 
Rhinochugger

Rhinochugger

Retired Oik
27 Oct 2009
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North West Norfolk
Rhinochugger

Rhinochugger

Retired Oik
27 Oct 2009
28,505
3,437
North West Norfolk
Thanks Mike - yes, it makes perfect sense that the pivots must be within the wheelbase of each power unit; just a question of whether having them at or around the centre of the wheelbase, as Ricky mentioned above, is helpful if it can be done? I guess a lot depends on the relative dimensions of the mainframe/boiler and the power units, much easier to do with a "shorty" like the Stainz-based ones than with the monster you've built....

Jon.
Ah, that's Rickie's point - you also have to consider the (prototypical - ish) weight of the tanks / coal bunkers over the wheels as well - that will mean that the pivots will tend to be more towards the centre of the entire loco dependent on the wheel arrangement and the size of the tanks / bunkers.

So, and 0-4-0+0-4-0 will tend to have the pivots near the centre of the two driving axles each end, but a 2-6-2+2-6-2 will tend to have the pivots nearer the inner driving axle each end - all this of course on the basis that no generality is wholly true including this one :nerd::nerd::nerd:
 
AusrailQLD

AusrailQLD

Registered
10 Jul 2020
23
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Australia
Thought I'd share my attempt of the Baddesley Colliery Garratt 'William Francis".
I well aware the colour is not correct, but I saw one of these in red and liked it.

Body parts were 3D Printed.
 
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