COM--101

Hey Guys,
Thanks for the contributions over on TT about the 800's
BUT, the fact is that the 800B was not a 16 speed. It was an 8 speed with a Torque converter backup. In Direct drive the converter input turbine and output turbines are locked together with a hyd clutch pack. In converter drive the input turbine, connected to the engine flywheel, drives the output turbine with oil, so the output rpms of the converter are always changing in relation to the resistance from the transmission. As the difference in input rpm related to output rpm ramp up so does the output torque, until the converter can no longer turn the tranny input shaft. The Case converter was capable of multiplying max engine torque under converter max load by 3.14 times. For an example, lets say the engine has been pulled down to 1800rpms, and is delivering 300lbs.ft of torque which is spinning the unput turbine at 1800rpms. The output shaft from the converter has stalled, (tractor is no longer moving in the selected gear) at that point the tranny input shaft is being supplied with 942 lbs. ft. of torque with zero revs., thus ground speed is infinate betewwn 0 and max per gear selected. When in direct drive max engine torque is all that can be delivered to the trans. input shaft.
The PTO is a solid drive link from the engine flywheel to the PTO clutch pack, When engaged the pto can consume all the power it needs, and as it sifons off that power the engine rpms drop, as does the engine torque, and thus converter output drops slowing output rpm and torque, thus adjusting speed to the PTO load automatically. The only downfall of the COM was heat buildup when under continuous load in converter drive, Dropping to a lower gear and using Direct Drive, droping down to converter drive, only in tough spots, would eliminate the heat buildup. To sum up this design, it was an 8spd with infinate speeds and torque from about 17mph., down to 0mph.
Loren

like dad always said, case didn't explain to dealers how to use it. then most dealers didn't tell farmer how to run it. got a bad rap right from the start. he always liked them. once you get use to it you like it. i never got to plow with one, will some day.

golly you make me feel lucky ,, Dads 800 diesel pulled 3/16s in 4th gear easy enuf ,, trouble was i had to constantly work the hydro lever because the plows did not have a tail wheel ..my brother tinkerd with the pump , and hitched the 800 to a 6 shank chizlplow ,strait piped her too,!!we weighted the nose and filled the rear tires with fluid ,, 3rd and 4th gear ,depending on the soil ,turn off the lites and the pipe was glowing red ,,. done that for a ccouple years and then the sleeves and heads cracked ,, tranny held up fine thru it all ..

Bro I agree that while in COM the speed could vary I was going by how the lit describes them direct one gear COM one I had thought of the varying speed but did not know how to explain thanks for the wording

If only Case had set it up to be direct drive as soon as you release the foot pedal and then slip it into COM when needed, maybe it would have had quicker acceptance. Might have helped gear grind when shifting too. Yes I know there's no clutch, just saying had it been designed different.....

Yery concise explanation of one of the best drives anyone ever used.

mEl

I think the bigest flaw in design, if you want to call it that was the design of the inching spool. (It was in or out) if the spool was made to feather the converter pressure when manovering to hook up to implements it would have been better accepted. Back when it came out customers were used to having the hand throttle set and slipped the clutch to manouver in close quarters. They wern't use to foot throtles or automatic trannys in cars for that matter. Any time Dad and I took out a COM tractor for a demonstration, the first thing we did was to spend some time showing the customer how we could hold the breaks and ease the tractor back to hook to an implement. This was very critical. Many Case dealers didn't understand the tractor themselves, so they lacked the experties to overcome customer objections. Once the tractor was out in the field it spoak for itself. When we demoed any tractor we always spent at least a half day with the customer, and made very sure he understood it before we left him. We tried also to get back the next day to gather his thoughts, and adress any isues he had while trying the tractor out. At this point we could also make a decision on weather the customer was serious about the tractor or just trying to get some free use of a tractor. Beware of a new customer who wanted you to bring a demo tractor out on a Friday afternoon!
We were fortunate that we also had the farm operation, so we could pre adjust a tractor and plow, prior to ariving on the perspective customers farm. We sold about 80% of the tractors with COM trannys.
Loren

I just want to comment what a good explanation of the COM. !!

Loren, thanks for that explanation on the COM.We have 3 Coms,a 410,a 800,and the ever reliable 830.Have put a lot of hours on the 830,Ilove the shift on it,no trouble.I try to keep the oil in good shape,I think that makes a huge diffreence with all Case power shift type of trannys!

Your right on target Loren.
And like others have said here,alot of the customers didnt understand COM,and got them hot,my Dad would stop anything he was doing if a customer asked questions,he really understood them.

I inherited a 611B that my Dad had used and abused for many years as his chore and loader tractor. The COM worked great as far as drawbar work went, I always thought it was superior to the IH TA or MMs AT. It would start an incredable load with out spinning out. But by the time it was handed down to me while doing pto work the live power feature couldn't be used. If you stopped the forward motion of the tractor you had to idle the engine, let the "clutch" petal out, open the throttle starting out on the torque converter. If you just let the petal out as you would on a Dual Range you would get whiplash while popping a wheelie.I thought this was because the linkage to the petal as worn out and the valve seemed to stick, have been told this is the nature of the beast. I find it hard to beleive that live pto was sacrificed for COM. I would certainly like to a have a small case with COM if live PTO could be used.

I understand what you are saying, BUT what is the problem with idling down and then rethrottling. If the pto powered equipment won't handle the input or the tractor is dieing down select a lower gear. You don't hop in your PU and rev it up and then pull it in D do you? Like your PU if you do that, apply the brakes when engageing the inching spool and the lurch will be minimized. (part of the learning curve)
Loren

I really don't understand your assertion that there was no livePTO, the PTO driveshaft drove from a spline in the COM front cover that was engaged to the flywheel. Every PTO in a COM tractor had a multiple disc, on the go engage and disengage fully live PTO. those are the facts, to my knowledge the tractors were not available without live pto unless there was no PTO at all.

mEl

Sorry that my reply was so confusing, I didn't mean that I had no live PTO, It was just so unhandy. Now I realize a 611B was just not designed to run a finish mower in tight quarters where lots of stops and starts are required. It was the wrong tool for the job. I stand corrected.

You have said this before on slowing the engine down,but there were-are some PTO machines that have to be running at set speed when starting to move on non draft loads.If they could have feathered it somehow,like a normal clutch then all would have been fine.The brakes were almost useless in the bottom 3 gears.The 600s were OK,but the 800s were-could be treacherous on full RPM clutching.

333 I'm not understanding you. On my 800 even at full throttle if I let the pedal out there's no lurch unless I force the tranny to stay in direct. It's a much more gentle start as I recall. I guess I'm confused. I find the COM to be a fantastic system.