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Fiat 702 Tractor

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Brian in OZ12/12/2012 19:47:10
63 forum posts

Hi Graham, what an amazing little machine, what scale are you planning.
Some interesting machineing/fabrication, especially the back wheels, please keep "us" in the loop.
Regards
Brian

JasonB12/12/2012 20:58:30
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Yes it does look an interesting project though looking at Grays drawing it may not get done with the spuds/cleats just plain strakes like a traction engine, a quick look at google images shows a lot of these tractors with plain strakes.

J

Jeff Dayman12/12/2012 21:45:50
2176 forum posts
45 photos

Hi Graham,

Unless I'm mistaken the dims you give calculate out to 9.906 cc. Small, but with sufficient ratios in the transmission it should move itself.

You do know what FIAT stands for? (Fix It Again Tony!)

just kidding....had friends growing up with FIAT 128 and X1/9 cars. Lots of wrench action on those, but great fun and very cheap, used.

Looking forward to the trattore agricolo build.

JD

Les Jones 112/12/2012 22:06:23
2234 forum posts
153 photos

Hi Jeff,
I came up with a different result. 15.5 mm dia. is 0.775 cm. 0.775 * 0.775 = 0.600625
0.600625 * 3.142 = 1.88716375 (sq cm) 1.88716375 * 2.625 = 4.9538 (cu cm) This is for one cylinder so the total capacity would be 19.8 cc

Les.

dcosta12/12/2012 22:10:07
496 forum posts
207 photos

Hello Jeff. Good evening.

Fabbrica Italiana Automobili Torino (meaning Italian Automobile Factory of Turin).
See ***LINK*** please for more complete information.

Regards
Dias Costa

Jeff Dayman12/12/2012 22:27:41
2176 forum posts
45 photos

Hi Les,

My calc is as follows:

Area of piston x stroke = vol of 1 cylinder

(pi x 15.5 squared)/4  x stroke = vol of 1 cylinder

188.69 x 26.25=4953.16 cubic mm volume of one cylinder

2 x 4953.16=9906.32 cubic mm volume of two cylinders

9906.32 x .001 = 9.906 cubic centimetres (cu mm x .001=cc)

Hi Dias, thanks for the real words matching the initials.

Cheers JD

Edited By Jeff Dayman on 12/12/2012 22:30:49

Les Jones 112/12/2012 22:37:35
2234 forum posts
153 photos

Hi Jeff,
The discrepency is in the number of cylinders. The picture looks like four cylinders to me.

Les.

Jeff Dayman12/12/2012 22:53:34
2176 forum posts
45 photos

Hi Les,

You are quite right, it does look like a 4 banger in the pic, not only that, but Graham mentioned cyls 2 and 3 in his text so there are at least 3, anyway! I am sure it is a 4 cyl, and at 19.8 cc per your calculation (and 2 x my calculation) I am sure it will have lots of power to move itself.

Cheers JD

JasonB13/12/2012 08:05:53
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Its a pity all the photos on the net have it with a bonnet, shame to cover that engine up.

Gray have you not considered rolling the rims and soldering/welding in the web of the tee? standard traction engine model method

Edited By JasonB on 13/12/2012 08:07:13

John Stevenson13/12/2012 09:19:56
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Posted by Les Jones 1 on 12/12/2012 22:06:23:

Hi Jeff,
I came up with a different result. 15.5 mm dia. is 0.775 cm.

Les.

.

15.5mm was 1.55cm when I was at skool.

John S.

JasonB13/12/2012 10:20:28
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Yes the all steel wheels do make things a bit easier than having to buy or cast rubber. Being as I like hit & miss engines I did take a look atteh IHC Titan drawings that Reeves sell but they leave quite a bit to be desired. Galloway also made a small tractor that used their engines and that is a slight possibility for the 1/3rd scale engine castings that I have but more likely a saw rig.

MEB has featured a couple of nice US style tractors which may offer some inspiration like this John Deere.

I'm sure the engine will give enough power to turn the wheels with the model up on blocks which is likely to be the best way to display it rather than trying to ride behind.

Keep us posted of progress.

J

JasonB13/12/2012 13:19:38
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The article in MEB mag says it uses coil and points hidden away somewhere in the engine as the Magnito would have been about 1/4" square. It has a lower compression ratio than scale and the crankshaft is meatier to help with the flywheel effect

And all built on Emco machinesthumbs up

Jeff Dayman20/12/2012 13:43:53
2176 forum posts
45 photos

Hi Graham,

What about building a wagon for use with the tractor, with a box or barrel load to hide coils, battery, maybe CDI unit etc for the ignition? That way the scale appearance of the tractor would not be compromised, and you would get the reliability of full size ignition components.

A set of points or a timing sensor can probably be hidden in the engine somewhere, and shielded wires from these components to the wagon would not be too obtrusive. Two low voltage wires from the engine (ground and ignition timing pulse wires) and one high tension lead from wagon to a scale distributor on the engine would do the job I think. If CDI was used you may need one more low voltage wire. Is Jan Ridders cooker igniter a continuous sparking unit? you could also use a buzz / trembler coil continuous sparking unit in the wagon and run a high tension lead to the distributor. That way there is one wire from wagon to engine and no points are used. Cattle prods and some Model T cars use buzz coil style continuous sparking units.

Just my $0.02.

JD

JasonB20/12/2012 14:31:16
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21431 forum posts
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With a CDI being the size of a match box and able to be run off 3No AAA batteries I'm sure a partition in the fuel tank would do the job of hiding the parts.

You can also make a buzz coil with an automotive relay rather than the usual sprung contacts and coil which will get the size down a bit and run that off a small sealed 12V battery but that would need a separte compartment off the engine.

J

Jeff Dayman21/12/2012 16:45:42
2176 forum posts
45 photos

Is it just me, or does the clutch look a little undersize?

In many USA built tractors (the ones I am much more familiar with) a heavily built large diameter clutch is a main selling point for durability in hard service with unskilled operators and high torque engines.

Thanks for the pic - very interesting!

Looking forward to watching the build.

JD

JasonB28/12/2012 07:51:26
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Gray, you may find these videos interesting, the link was posted on SmokStak and show a 1/5 Fiat crawlersmile

**LINK**

Stub Mandrel29/12/2012 20:52:14
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4311 forum posts
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Hi Gray,

A fascinating prototype. You rear axle section is an interestingcontrast with how the Fordson was arranged.

Neil

Stub Mandrel30/12/2012 18:03:05
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Hi Gray,

So the drawing is your 'solution' rather than the original. A horizontally split axle seem challenging, even in full size. Good luck with machining that big thread.

I still haven't figuresd out every subtlety of the Fordson yet, it isn't obvious what stops the axles sliding out of the differential gears!

Stub Mandrel30/12/2012 21:27:25
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Hi again,

The Fordson bevel was splined to the shaft, but its hemispherical back appears to have been 'cupped' by the differential housing (a dome-shaped casting on each side of the worm wheel that held the four pinions. A split ring stops the shaft pulling out of the bevel, but I can see nothing that keeps the bevel in mesh with the pinions .

Ah confound it! The cross section is very poor but now I see a spacer (that I thought was a space) between the bevel and the inner bearing.

Neil

Jeff Dayman07/02/2013 16:40:12
2176 forum posts
45 photos

How's the FIAT tractor coming along Graham? Haven't heard from you on it for awhile.

JD

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