Hydro/CVT ??
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Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=180191
Printed Date: 02 May 2025 at 9:09pm
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Topic: Hydro/CVT ??
Posted By: FREEDGUY
Subject: Hydro/CVT ??
Date Posted: 28 Apr 2021 at 7:41pm
| Are the 2 at all related in their mechanical sense, or completely different yet do the same thing ? Thanks |
Replies:
Posted By: steve(ill)
Date Posted: 28 Apr 2021 at 8:13pm
|
a hydro is normally a hydraulic motor connected to the gearbox / drive wheel... basically a hydraulic pump pushes oil thru a hydraulic motor ( basically a pump running backward) to get power.. CVT is continuous variable transmission... I can be as simple as a spring loaded pulley on the end of the motor that changes diameter as the engine speeds up ( more RPM) and there by changing the gearing to the rear axle or drive wheel.
------------- Like them all, but love the "B"s. |
Posted By: steve(ill)
Date Posted: 28 Apr 2021 at 8:20pm
------------- Like them all, but love the "B"s. |
Posted By: steve(ill)
Date Posted: 28 Apr 2021 at 8:26pm
------------- Like them all, but love the "B"s. |
Posted By: tbran
Date Posted: 28 Apr 2021 at 9:22pm
|
Fendt has patents on a lot of the CVT internals as used in their and Agco tractors. The principle is simple and results with the flywheel being directly connected to the ring gear and pinion w/o a clutch and variations accomplished via planetary gear pinion. Imagine this - the planetary on the final drive of a 7040 - the input turns the planetary/sun gears and the reduction effect spins the axle. NOW, lets unbolt the outside planetary gear and float it on brgs. Now when the input turns the planetary the axle has resistance and the now unbolted out side gear spins and the axle stands still. Again now lets put teeth on the outside of the gear we unbolted and connect a couple of hyd pumps. The pumps are pumping oil so we start throttling them and SLOWING the ring gear and this starts spinning the axle or in the CVT case the pinon shaft. The pumps/motors are variable displacement piston type with patented high angle strokes. The more the outside ring is slowed down the faster the axle turns. NOW again suppose we REVERSE the gear instead of slowing or stopping and we can now OVER DRIVE the pinion. Now we can run down the road at 45 KPH at say 1400 engine rpm on an engine that turns 2200 rpm in the field. Tremendous fuel savings on road travel. REVERSE ? This is hydrostatic as the the pumps that slow the outer gear now reverse the gear and it spins backward. All gear in forward - hydro in reverse. You ask about wasted hp in braking the ring gear?. Neat idea - they tee into the two pumps or motors and use that pressure to help drive a motor that helps the engine drive the power train... like perpetual motion ha . Anyway the Fendt tranny used in Fendt, MF , the Agco HHP units and Challenger has proven to be the best tranny on the market and defiantly the most efficient on the market. It is sold to others as well - JCB... imagine that tranny in a semi !!!! all gear , no clutch. https://www.youtube.com/watch?v=dgtIKMAjvFI" rel="nofollow - https://www.youtube.com/watch?v=dgtIKMAjvFI ------------- When told "it's not the money,it's the principle", remember, it's always the money.. |
Posted By: SteveM C/IL
Date Posted: 28 Apr 2021 at 11:56pm
| They were thinking outside the box when they came up with that! |
Posted By: Gary
Date Posted: 29 Apr 2021 at 10:18am
|
Steve In your hydraulic schematic, what is the difference between the 'Motor' and the 'Hydrostatic motor' above it ? Old Snowmobiles are a good example of Variable Speed Belt Drive. G |
Posted By: Tbone95
Date Posted: 29 Apr 2021 at 10:37am
Thinking "motor" is engine.
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Gary wrote:Posted By: jaybmiller
Date Posted: 29 Apr 2021 at 10:48am
|
'hydro' has 2 meanings to me.. usually #2 is what is meant though.. #1 . Hydraulic. Hydraulic pump connected to hydraulic motor, old CASE garden tractors used this.... #2 Hydrostatic. pump/motor/gearbox,diff all in one 'package', typically found in 99% of the riding 'mowers' and now in CUT,SCUT and bigger tractors. ------------- 3 D-14s,A-C forklift, B-112 Kubota BX23S lil' TOOT( The Other Orange Tractor) Never burn your bridges, unless you can walk on water |
Posted By: Gary
Date Posted: 29 Apr 2021 at 11:27am
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Hydr. is the abbr. for Hydraulic. There is no 'o' in the word Hydraulic. Hydro. is abbrev. for Hydrostatic. G |
Posted By: jaybmiller
Date Posted: 29 Apr 2021 at 11:37am
|
some smartphones 'spellchecks' ain't so smart, and a lot of people think Case tractors were 'hydrostatic'....... ------------- 3 D-14s,A-C forklift, B-112 Kubota BX23S lil' TOOT( The Other Orange Tractor) Never burn your bridges, unless you can walk on water |
Posted By: steve(ill)
Date Posted: 29 Apr 2021 at 12:31pm
|
Gary, i think you caught on to something... The GAS or ELECTRIC motor should drive a HYDRAULIC PUMP ( the picture is miss marked)... the PUMP should send high pressure oil to a HYDRAULIC MOTOR which might look something like the HYDRAULIC PUMP, but a motor is different that you put HIGH PRESSURE OIL INTO IT, and get Mechanical Drive Power out of it to the wheels.. The diagram paragraph explanation is correct, but the MISS MARKED the Hydra motor and hydra pump.  ------------- Like them all, but love the "B"s. |
Posted By: Gary
Date Posted: 29 Apr 2021 at 4:28pm
|
Ya Steve, I'd agree. Some kind of Motor drives a Hydraulic Pump. The pressured oil then drives the Hydrostatic Transmission. G |
Posted By: FREEDGUY
Date Posted: 29 Apr 2021 at 7:13pm
The only reason I brought this up is I was at a job site late in the afternoon and watched a NEWER model MF ( ) tractor pulling an older White 12 row planter and noticed that the engine RPM's NEVER deviated ( I think they already put a "get-around" on the exhaust as it was VERY throaty ) as they pulled into corners/reversed and continued forward in VERY smooth motion, almost like I recall riding in the cab of a neighbors M2 Gleaner 
|
Posted By: DrAllis
Date Posted: 30 Apr 2021 at 5:52pm
| In 1967, International Harvester came out with the first "hydrostatic" transmission in a farm tractor. It was in the model 656. As a young teen, I was fairly easily impressed with all the color cut-aways showing the innards of this new concept driveline. The last paragraph of the advertising said this, and I quote: " Someday every farm tractor will be equipped with a transmission like this !!" Well, it took about 30 years and Fendt had a working CVT transmission, which includes some of the "hydrostatic transmission" parts to make it work, but no one other than Farmall ever used hydrostatic transmissions for farm tractors, and the majority of them never did any plowing or discing. |
Posted By: FREEDGUY
Date Posted: 30 Apr 2021 at 6:47pm
Thanks DR.  !
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Posted By: jaybmiller
Date Posted: 30 Apr 2021 at 7:04pm
|
It could be 'numbers' as to why no big hydrostatic farm tractors, or marke share. Someone must know the 'total sales' of 'big' tractors per year. Let's say 1,000,000 ? ,for sake of argument. OK, let's say you hope to get 30% of the market, 30,000 tractors. Now, you have to figure out how HUGE an investment into R&D to final prouct you have to cough up for the sales. BTW, 1st years sales MIGHT be 1/3rd of your goal, so only 10,000 tractors get sold. If 10% have problems, you've lost 1,000 units(recalled or returned for $$). Bad press( 1 out of 10 isd a lemon.....) KILLS your market share....... One thing I'd like to know, is how many of you ,have bought more than 1 NEW tractor(say 100HP+) during your farming career ? and why ( did you buy more land ??) ------------- 3 D-14s,A-C forklift, B-112 Kubota BX23S lil' TOOT( The Other Orange Tractor) Never burn your bridges, unless you can walk on water |
Posted By: DrAllis
Date Posted: 30 Apr 2021 at 8:38pm
| The only reason for no big hydrostatic farm tractors (under hydrostatic technology like IH used) was the performance was terrible for heavy draft work that required high drawbar HP. That is the only reason. It would NOT match the performance of a gear drive or power shift transmission of the day. |
Posted By: tbran
Date Posted: 30 Apr 2021 at 9:01pm
|
one interesting note, in 1968 Fendt's CVY was mechanical - there was a lever one pushed which mechanically stroked the pump or pumps that sped up or slowed the tranny. The first units of AGCO and MF had a lever that could still be attached to the stroke control and mechanically drive the tractor if the electronics failed... ------------- When told "it's not the money,it's the principle", remember, it's always the money.. |
Posted By: SteveM C/IL
Date Posted: 30 Apr 2021 at 11:29pm
| Neighbors had 2 new gas 656's with hydrostats when they first came out. Traded off for diesel gear drives a couple years later. Mostly cultivator tractors but couldn't afford to feed em. They still have one of the diesels. |
Posted By: victoryallis
Date Posted: 01 May 2021 at 4:55am
Any gas tractor is expensive to fuel compared to a diesel. ------------- 8030 and 8050MFWD, 7580, 3 6080's, 160, 7060, 175, heirloom D17, Deere 8760 |
Posted By: DrAllis
Date Posted: 01 May 2021 at 6:54am
| So, in 1968 Fendt had a prototype ?? or a marketable tractor ?? The first one I drove was in 1997 or 98 when AGCO just bought Fendt. |
Posted By: farmtoybuilder
Date Posted: 01 May 2021 at 9:17am
|
I love our Hydrostat 4wd compacts! Wish we could get bigger one in 75 hp. range with 30'' rear wheels. We have a green 65hp. with hydraulic shuttle 16 speed but it still not as smooth or convenient as hydro for mowing and loader work. ------------- 5 different TT-10's,5 TT-18's Terra Tigers,B-10,2 B-207's,B-110,2 B-112's,HB-112,B-210,B-212,HB212,2 Scamp's & Homilite T-10. Still hunting NICE HB-112 & anything Terra Tiger & Trailers for them. |
Posted By: Les Kerf
Date Posted: 01 May 2021 at 10:02am
Yup. I worked for two neighbors 40+ years ago, one had a diesel IHC Hydro and the other had the same model in gas. I loved driving those Hydros, the farmer with the diesel version used his for chores (feeding dairy cows) and also for baling hay; you could keep the PTO speed constant and vary the ground speed to match the needs of the baler. The fellow with the gas version told me that he tried plowing with it when he first bought it brand new but it burned over 6 gallons of gas per hour! Never plowed with it again, but he used his for feeding dairy cows for many years. The last I saw of those tractors they were both running fine a few years ago. The gentleman with the gas model said that the diesel version cost several thousand dollars more than the gas model when new which is why he chose the gasoline one. |