The Build Thread Of My Garrett
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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
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
It’s had some wiring fitted, and when the weather in nicer, I will start testing the loco, before I do any more
Dan
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
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
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
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
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
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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.
The logic suggests that the pivot point should be inside the wheelbase of each set of drivers.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.
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 boysThe 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
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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.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.
What to do with a Newquida loco
Bit of progress on making a Garret (yes I finally made up my mind) the Newquida body has been hacked to pieces as have an aristocraft slope back tender and an LGB "Shorty" tender. A new boiler bottom was fashioned out of a piece of 60mm PVC plumbing pipe. Below are some pictures of the cut and...
www.gscalecentral.net
Baby Garrett
Okay this one's been on the back burner for while now so I finally got my finger out to finish it......................:)
www.gscalecentral.net
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
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.
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
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.
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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.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.
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.
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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
hey this cool kinda looks like what i was gonna build (yes i am aware this thread is a bit old)
It's a pity I didn't have two of the Anniversary chassis' with full metal valve gear as that would have looked much better. Good luck with your project.