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Caterpillar 12 grader

  • Swishy
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  • If U don't like my Driving .... well then get off the footpath ...... LOL
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12 years 3 months ago #68358 by Swishy
Replied by Swishy on topic Re: Caterpillar 12 grader

NrMak
gudday M8

Here U go
U decide



Cya
[ch9786]

OF ALL THE THINGS EYE MISS ................. EYE MISS MY MIND THE MOST

There's more WORTH in KENWORTH

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12 years 3 months ago #68359 by Nr Mack
Replied by Nr Mack on topic Re: Caterpillar 12 grader
Me thinks he ha a smaller lighter version 212TD
The has chart was useful

Back to the 12 but what is the difference between a 9k and 7t as there is 5 hp more and weighs 360 lbs more

anyone know why , thi swill help narrow down whether my Cat 12 is the last of the 9 k or a 7T?

thankyou

Chester

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12 years 3 months ago - 12 years 3 months ago #68360 by
Replied by on topic Re: Caterpillar 12 grader
Chester - Thanks for the pics. John Parks is on the ball, but he's still not quite correct. Caterpillar changed their fuel injection pump, injector lines, and governor & governor housing design around 1939/1940 .. not when the 7T model was produced.

In the Caterpillar No. 12 Service Manual , which covers machines 9K1-9K9999 & 7T1-7T3099, there is not even a single reference to the early-style injection pump setup, with the manual only showing the later-style injection pump.

The early design was called the "forged body" pump, the later style was called the "flange mounted" style.

Unfortunately, I can't lay my hand on my Caterpillar fuel injection pump overhaul book right at this moment, to show the differences .. but the basic design of the fuel injection pump didn't change appreciably .. all that changed was the housing designs, and the governor design.
The fuel injection lines were re-routed and the injectors were redesigned to a slightly different shape.

Your tractor is definitely a 9K series equivalent, from around 1940 or 1941, I'd guess. It does have the later design fuel injection pump and governor housing, but this design appeared long before the 7T series commenced production in 1945.
As I stated previously, because your "miscellaneous engines" D4600 engine S/N, is only 55 engines after the start of this S/N number range .. which S/N range was issued specifically for the W&J graders .. then that makes your grader a very early Cat No. 12, when you consider that W&J produced around 600 Cat No. 12's and Auto Patrols between 1936 and 1946.
Approximately 500 of these machines would have been Cat No. 12's (produced 1939-1946), and approximately 100 would have been Auto Patrols (produced 1936-1939).

The "miscellaneous engines" S/N range that started with 2S5501, only commenced upon the production of the new D4600 engine that powered the Cat No. 12, from mid-1938.
It would have been well into 1939, before any of those 2S series engines turned up in Australia, and Cat No. 12 grader production started at W&J's.

Unfortunately, I can find no reference in any Cat literature that I have from the 1930's and 1940's, that details the changes, from the forged body pumps to the flange mounted style.
There are some gaps in my Cat service literature, particularly during WW2. This stuff is hard to acquire.

Your grader has an early W&J design cab, very similar to the Cat No. 10 & No. 11 Auto Patrols. The cab was an extra-cost option during the 1930's and 1940's. The basic grader came with no cab.
The optional, American factory Cat No. 12 cab, pictured below, when the No. 12 was released in 1938, was a totally different and more modern design, than the W&J-produced cab.

In Swishys pics above, the first two pics show a Cat No. 212 (the smallest of the Cat graders, powered by the D2 engine) from the early 1950's .. and the third pic shows a Cat No. 11 Auto Patrol from the mid-to-late-1930's.

The No. 10 & No. 11 Auto Patrols are easily identified by their double section main frame, and the worm gear lift mechanism on the blade lift shafts.

The Cat No. 12 originally came with 7.50 x 24 front tyres, and 12.75 x 24 rear tyres. In May 1941, the tyre producers agreed to standardise on 1.00" tyre width section increases, and eliminate all the old-style, oddball, .25", .5", and .75" tyre width sections.

Thus, after May 1941, the Cat No. 12 came with 7.50 x 24 front tyres, and 13.00 x 24 rear tyres. Later on in the early 1950's, the Cat 12 got 13.00 x 24 tyres as standard, all round.
Your grader has had its front tyres converted to the later 1950's style, with the same tyres all round.
The 212 graders came with 6.50 x 20 front tyres as standard, from 1939.

Swishys chart is from the Caterpillar Performance Handbook, and it is notorious for inaccuracy when it comes to "former models". I refuse to use that chart, because it's riddled with errors.
The Cat No. 12 was 66HP upon its release, and gained a HP increase .. to 70HP, over the life of the 9K/7T series production.
I'd have to dig out my Cat engine performance charts to see if I could find when and where these changes took place.

Here's some scans from a July 1938 sales brochure, produced specifically for the "all-new" Cat No. 12 "Auto Patrol", as it was called upon its release.






Here's the 1938 Cat No. 12 catalog page, showing the engine, and the early style of injection pump and governor, on these early Cat No. 12, D4600 model engines.

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12 years 3 months ago #68361 by
Replied by on topic Re: Caterpillar 12 grader
Here's the page from the May 1941 Service Magazine, that details the changes from the old tyre sizes to the new tyre sizes.

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12 years 3 months ago #68362 by Nr Mack
Replied by Nr Mack on topic Re: Caterpillar 12 grader
Ron thanks for that info , starting to fall into place in the last photo of the 12 there are two drive shafts missing on left and the blade appears back to front unusual way of presenting it

So I need to find some smaller rims if I want to make it original for the front , also where is the 5Hp differnece and 360 lbs weight between a 9K and 7 T to be found

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12 years 3 months ago - 12 years 3 months ago #68363 by
Replied by on topic Re: Caterpillar 12 grader
Chester - I'd say the blade is presented back to front, to better show potential purchasers, the shape and size of the moldboard.
The brochure also shows a picture of how the moldboard can be easily reversed for grading in reverse, when there is little room for turning.

The 360 lbs extra weight is due to modifications and strengthening, that takes place on a continuous basis.
Heavier castings, slightly bigger shafts, and plating where cracking appeared in early models are typical design improvements.
The Cat dozers continually gained weight nearly every year .. even in the same model .. as component design was revised, improved, and usually, strengthened as well.

The HP difference would be due to "tweaking" of the injection pump output (increased lift with an injection pump camshaft that had higher lift) or sometimes, even a slight increase in rated RPM.

EDIT - I have dug out and studied my ancient Cat "rack setting information" book, and have found that there are only two HP settings for the 9K and 7T grader engines.
The early engine has a 2A5573 fuel injection pump camshaft P/N, with a rack setting of .550", and this engine produces 66HP.
The later engine has either a 7B5702 or 3F1672 fuel injection pump camshaft, with a rack setting of .590", and this engine produces 70HP. There is no 75HP setting for these grader engines.

The early forged body injection pump had the governor mounted in the timing gear that is inline with the pump, and this timing-gear-mounted governor actuated the rack via a shaft that went from the centre of the timing gear to the injection pump.
The housing on the rear of the forged body pump contains only a set of governor control linkages and spring.

The flange mounted injection pump has a vertical governor mounted on the rear of the fuel injection pump, and this is driven by a gear on the end of the fuel injection pump camshaft.

I have a parts book for the No. 12 graders from S/N 9K2001 to 9K2853. This book shows that this S/N range of No. 12 graders, used the forged-body injection pump and timing-gear-mounted governor.
I suspect that from 9K2854, the pump and governor design went over to flange mount pump with the vertical governor.

However, I do not have any more parts books on the 9K or 7T graders, so I cannot check on that for sure.
According to my S/N production records, 9K2853 was rolled off the assembly line in early 1941, thus giving us more idea of the actual date-S/N change from forged body to flange mount pump design.

The early fuel injection valves had return lines that were routed into one line, that hung off the side of the block, and which just dripped the by-passed (or "overflow") fuel on the ground.
In mid-1943, the return lines were altered so that they were routed into one line, that went back to the inlet side of the fuel transfer pump .. which sent the by-passed fuel, back into the fuel system.

Cheers - Ron.

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12 years 3 months ago #68364 by Nr Mack
Replied by Nr Mack on topic Re: Caterpillar 12 grader
Ron in Swishy's table above it mentions the 7T having a 75hp engine ??

error?

thankyou

Chester

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12 years 3 months ago - 12 years 3 months ago #68365 by
Replied by on topic Re: Caterpillar 12 grader
Chester - Yes, that Cat Performance Handbook chart is full of errors, there's no 75HP rating for the 7T series in the "bible" .. the rack setting information book.
There's only the two HP settings I mentioned above, 66HP and 70HP. I'd say the 70HP is the rating of the engine with the later injection pump, which is your machine.

As I stated in the earlier post, I refuse to use those CPH "former model" charts, they are full of errors and downright misleading.

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12 years 3 months ago #68366 by ianoz
Replied by ianoz on topic Re: Caterpillar 12 grader
Chester , While your waiting on parts to get the 12 up and running ,you could have a go at something like this .

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12 years 3 months ago #68367 by Nr Mack
Replied by Nr Mack on topic Re: Caterpillar 12 grader
yes that is a great toy , but he has way too much time on his hands when there is a real grader out there that could have done with his skills to preserve it

On th eCat 12 , I may have had a win the previous owner stated He had tried to tow start the grader with the decompression lever set on start , not appreciating that is to be used to get oil around the engin ebefore shiftig to run , sold it out of disgust , he has said it would almost start .... with no compression as it now seems , so will fix the damage to th ecentre pivot ?? and see what happens , she could spring into life !!!

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