D-18 and then D-19 development

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   Looking back, this is how I think things probably went down from 1958 until late 1961 for the AC tractor division. It was determined that a tractor larger than the D-17 was needed. How many $$$$$ that are allotted to the design engineers has a direct effect on what you'll get. A clear direction from the Sales Dept and upper/upper management on what they want is also extremely important. So, the D-18 proto, from the instrument panel forward to the front axle began as a D-17 diesel. Nothing more. Nothing less. The first change was to use the existing 6-cylinder B-series gasoline engine at 262 cubes. The diesel engine, as I understand it, got bulked up on the bore/stroke combo to around 290 cubes, naturally aspirated.  This placed the HP output at far less than they eventually wound up with. So, everything inside the torque tube, including the hydraulic pumps basic design, was pretty much the same as the D-17 tractor. Little $$$ spent so far, The transmission, ring and pinion and differential were also the same as the D-17, inside a new housing. Again, very little $$$$ spent. The rear end housing/casting was indeed all new, and housed the new inboard final drives, so a bar type rear axle could be used. They spent some $$$$ on that, and for the most part, I have no issues with what they did. I've never had any failures of the new design final drives or axles/bearings, etc. The drawbar area was also strengthened and was pretty good. A 3-point hitch wasn't ready when the tractor was first released and that was too bad. Their 3-point was finally as good as anyone else's at the time, just not ready from the beginning. That, is how I feel the D-18 tractor came to be. The hydraulics still weren't "live" or more than 6 GPM's in flow. And, the HP levels were found to be lower than sales demand was going to be.  The 100 HP D-21 was clearly a different and separate project and may have been started the day after the John Deere 4010 was shown to their dealers in August of 1960.

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DrAllis Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Access Joined: 12 Sep 2009 Points: 22310	Post Options Post Reply Quote DrAllis Report Post Thanks(0) Quote Reply Topic: D-18 and then D-19 development Posted: 1 hour 57 minutes ago at 8:09am
	Looking back, this is how I think things probably went down from 1958 until late 1961 for the AC tractor division. It was determined that a tractor larger than the D-17 was needed. How many $$$$$ that are allotted to the design engineers has a direct effect on what you'll get. A clear direction from the Sales Dept and upper/upper management on what they want is also extremely important. So, the D-18 proto, from the instrument panel forward to the front axle began as a D-17 diesel. Nothing more. Nothing less. The first change was to use the existing 6-cylinder B-series gasoline engine at 262 cubes. The diesel engine, as I understand it, got bulked up on the bore/stroke combo to around 290 cubes, naturally aspirated. This placed the HP output at far less than they eventually wound up with. So, everything inside the torque tube, including the hydraulic pumps basic design, was pretty much the same as the D-17 tractor. Little $$$ spent so far, The transmission, ring and pinion and differential were also the same as the D-17, inside a new housing. Again, very little $$$$ spent. The rear end housing/casting was indeed all new, and housed the new inboard final drives, so a bar type rear axle could be used. They spent some $$$$ on that, and for the most part, I have no issues with what they did. I've never had any failures of the new design final drives or axles/bearings, etc. The drawbar area was also strengthened and was pretty good. A 3-point hitch wasn't ready when the tractor was first released and that was too bad. Their 3-point was finally as good as anyone else's at the time, just not ready from the beginning. That, is how I feel the D-18 tractor came to be. The hydraulics still weren't "live" or more than 6 GPM's in flow. And, the HP levels were found to be lower than sales demand was going to be. The 100 HP D-21 was clearly a different and separate project and may have been started the day after the John Deere 4010 was shown to their dealers in August of 1960.

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