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Crawlers I photo'd recently.

OzDozer

OzDozer

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Perth, Western Australia.
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Semi-Retired ..
It's a late-model D7 3T with the D8800 engine. The "new" model D7, 7M series, was released in 1940 and was replaced by the slightly upgraded 3T series in 1945, and the 3T was built until 1955, when the 17A appeared with the "new" D339 engine. Over 28,000 3T tractors were manufactured, making it one of Caterpillars most-produced models.

Along with the 8R and 1H series D8's, these models of D7 and D8 were the tractors that helped win WW2. The Engineers with their D7's and D8's were at the front lines with the infantry during WW2, landing on beachheads and pushing aside rubble and flattening obstructions, so troops and vehicles could get through.
In the WW2 landing in Sicily, the D7's and D8's and Carryalls built and finished a new airstrip capable of taking B-17's, within 3 days of landing.
 
Oxbow

Oxbow

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Nov 22, 2012
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Idaho
OzDozer said:
It's a late-model D7 3T with the D8800 engine. The "new" model D7, 7M series, was released in 1940 and was replaced by the slightly upgraded 3T series in 1945, and the 3T was built until 1955, when the 17A appeared with the "new" D339 engine. Over 28,000 3T tractors were manufactured, making it one of Caterpillars most-produced models.

Along with the 8R and 1H series D8's, these models of D7 and D8 were the tractors that helped win WW2. The Engineers with their D7's and D8's were at the front lines with the infantry during WW2, landing on beachheads and pushing aside rubble and flattening obstructions, so troops and vehicles could get through.
In the WW2 landing in Sicily, the D7's and D8's and Carryalls built and finished a new airstrip capable of taking B-17's, within 3 days of landing.
Click to expand...
I thought all the 3Ts had spoke idlers. It's been a long time, but I ran a 17A quite a bit in the early 80s.
 
OzDozer

OzDozer

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Perth, Western Australia.
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Semi-Retired ..
It was the original design, and I would hazard a WAG that the design was a follow-on from cart wheels and other heavy wheel designs, which were all spoked from the earliest days.
I would expect the disc design was a design aimed at easier and cheaper manufacturing processes. Casting was the standard procedure for many parts and components up until WW2, when faster and cheaper methods had to be found - and I think Caterpillar dragged their feet on design changes, because other manufacturers such as Allis-Chalmers and IH led the way on these new, improved and cheaper manufacturing methods, that reduced the amount of castings needed.
There was also the problem that spokes cracked under heavy operating conditions, whereas disc designs were less prone to cracking, and the disc gave better support to the rim.
Vastly improved and heavier presses also led the way to enable much thicker metals to be pressed.

FYI, and a little off-thread - Did you know, that the largest percentage of the worlds heavy manufacturing presses are made by Komatsu?
 
Truck Shop

Truck Shop

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Dec 7, 2015
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WWW.
The wheel tractor is a Oliver-Hart Parr. The JD combine is a model 45. And the AC Buggy tractor
was popular around here for use in asparagus fields. And the green AC with blade was a U.S. Forrest
service crawler. McKinney's son started it for me-ran like a top, the under carriage was in perfect shape
built in 1945.
 
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J

JaredV

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Jan 22, 2022
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349
Location
SW WA
I'd love to have that little green grain cart in front of the Hart-Parr. Probably sounds pretty random with all those great crawlers and combines around it but they are almost non existent on the west side of the state and I've been looking for a few years.
 
Truck Shop

Truck Shop

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WWW.
Tugger2 said:
Thats sure nice country where you are T.S. Looks like that land could feed the nation.
Click to expand...

True--right in that area because it follows the edge of the Blue Mountains average bushel for
dry land wheat is 115 plus, the top soil there around 50'. It's also unfortunately a beautiful area
that the rich would just love to buy to put mc mansions on. McKinney and his son have zero
intention of that happening as long as they are alive.
 
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