New Holland Boomer CVT benefits over hydrostatic in High RPM/heat

[NewHollandTN75]

Hello,

I've been looking at New Holland Boomer CVTs with the thought that the CVT transmission may have some benefits. Specifically, I have been using a rototiller on a Deere 3720 and a Kubota L4630. Both machines tend to heat up after a while as the hydrostatic fluid gets hot, and the engine temperatures climb. This phenomenon also occurs when pulling a 6 foot mower. It does not relate to clogged radiators etc.

Does the CVT transmission allow one to run a rototiller/similar attachment at high RPMs in high heat for prolonged periods where a hydrostatic transmission would otherwise start to get hot?

Thanks so much.

 

[TSO]

What do you mean by "prolonged" ?

I've run my Massey HST PTO for hours at a time, during brush-hogging, stump grinding, chipping, tilling, etc. She's never gotten hot.

As far as PTO benefits, CVT is still a hydraulic system, like HST. It still equates to about the same PTO HP loss, from numbers I've seen anyways... and it still heats up hydraulic fluid.

Are you referring to the large compact tractors (40-50 HP) or are you talking about large farm tractors? I took your question to refer to the compacts, but just making sure...

 

[NewHollandTN75]

What do you mean by "prolonged" ?

I've run my Massey HST PTO for hours at a time, during brush-hogging, stump grinding, chipping, tilling, etc. She's never gotten hot.

As far as PTO benefits, CVT is still a hydraulic system, like HST. It still equates to about the same PTO HP loss, from numbers I've seen anyways... and it still heats up hydraulic fluid.

Are you referring to the large compact tractors (40-50 HP) or are you talking about large farm tractors? I took your question to refer to the compacts, but just making sure...

My question is really, take a Boomer 3050, and a comparable hydrostatic machine (i.e. Deere 4720, Kubota L4760), and run it flat out with a rototiller on a hot day. Which is more likely to get hot? The machine with mechanical power transfer (Boomer CVT), or the machines with the hydro pump? I'd assume the boomer CVT given my experiences with hydro machines but never having run a boomer CVT. Am I off base?

 

[s219]

I don't think there is a fear of the HST running hot -- they are designed with appropriate cooling so that both the HST system and engine should never get hotter than is safe.

In general, I have found the engines in diesel tractors run cool. I have worked my HST Kubotas very hard doing a full day's grading work with a box blade, to the point where I could feel the heat coming off the engine very noticeably and the hydraulic lines were warm to the touch. The engine temp gauge still never moved past middle, and I detected no loss in hydraulic performance.

Bottom line to me is that as long as the tractor is properly designed with required cooling capacity for the HST and engine, you don't even need to worry about it.

CVTs are a good design with a lot of benefits. Don't see cooling as one of them though.

 

[Grandad4]

Perchance, has a tractor salesman been whispering in your ear lately? Kidding aside, you probably know that it's normal for an HST to warm up with use and that doesn't itself indicate a problem or shorten its operating life. HST drives are widely used in all kinds of equipment worldwide, they all heat up and are very reliable with good maintenance.

That said, CVT does seem to offer advantages for ground engagement work. If that's the primary use of your equipment, it would be something to look at. Check in the New Holland sections regarding owner experiences with CVT's. Lot's of stories, both good and bad.

 

[RDrancher]

Have they worked out the kinks in the CVT and electrical issues for the smaller tractors? The problems that my NH dealer had with them played a big part in their decision to drop the entire line of CUT's and go with Mahindra. They're still a NH dealer for everything else, but my service manager advised me to stay away from them for the work I do and keep my TC going for as long as possible.

I've worked the heck out of my tractor for a lot of years performing tasks that it was never designed to do. Overheating the hydro has never been a problem, even in Texas 100+ degree heat. I did blow a radiator at the seam once, but it was my fault.

 

[oldpilgrim]

there are a very few cars out there with CVT and from what I've heard, the mfgrs are still working out the kinks. If they were perfected and as reliable, and as economical to make and maintain as a hydro, there would be a lot of them in use.

There aren't a lot of them in use.

Both machines tend to heat up after a while as the hydrostatic fluid gets hot, and the engine temperatures climb. This phenomenon also occurs when pulling a 6 foot mower.

All machines get hotter as they are worked harder. It's a law of physics...not a phenomenon.

I don't know which gets hotter first, the engine or the tranny, but one is not heating the other. Each has it's own cooling system.

 

[NewHollandTN75]

there are a very few cars out there with CVT and from what I've heard, the mfgrs are still working out the kinks. If they were perfected and as reliable, and as economical to make and maintain as a hydro, there would be a lot of them in use.

There aren't a lot of them in use.



All machines get hotter as they are worked harder. It's a law of physics...not a phenomenon.

I don't know which gets hotter first, the engine or the tranny, but one is not heating the other. Each has it's own cooling system.

Don't gear drive machines stay cooler than hydrostatic machines in the same application? Wouldn't the benefits of a gear drive machine apply to the CVT transmission with respect to running cooler? I'm speaking from experience where hydro machines heat up a lot more than similarly sized gear drive machines in the same application and am just curious if the CVT transmission is closer to a gear or a hydro in this respect in a high RPM PTO application such as running a rototiller.

 

[TSO]

From what I understand about the NH CVT system in the Boomer tractors, and someone please correct me if I'm wrong, they are still fully operated by hydraulics. The fluid pushes open a swash plate to drive the gears, and the opening is controlled by throttle position. So, the more throttle, the more fluid pushing the swash plate open. That's a very rudimentary description from what I remember reading. Anyhow, PTO operation is still run off the engine, same as HST. The power loss from HST is that the engine also drives the hydraulic pump, so the engine must run both the direct drive system (PTO) plus the pump.

Under "no driving" conditions, when stationary, using little or no hydraulics, I'd assume that PTO power would be nearly identical between gear and HST systems (ie, stationary tractor running PTO, like my wood chipper, etc).

So anyhow, being that the Boomer CVT and traditional HST systems are still hydraulically driven, I don't see any benefit in PTO operation or operating temps

 

[oldpilgrim]

From what I understand about the NH CVT system in the Boomer tractors, and someone please correct me if I'm wrong, they are still fully operated by hydraulics. The fluid pushes open a swash plate to drive the gears, and the opening is controlled by throttle position. So, the more throttle, the more fluid pushing the swash plate open. That's a very rudimentary description from what I remember reading. Anyhow, PTO operation is still run off the engine, same as HST. The power loss from HST is that the engine also drives the hydraulic pump, so the engine must run both the direct drive system (PTO) plus the pump.

Under "no driving" conditions, when stationary, using little or no hydraulics, I'd assume that PTO power would be nearly identical between gear and HST systems (ie, stationary tractor running PTO, like my wood chipper, etc).

So anyhow, being that the Boomer CVT and traditional HST systems are still hydraulically driven, I don't see any benefit in PTO operation or operating temps

that's how I understand it too.

Don't gear drive machines stay cooler than hydrostatic machines in the same application?

yes because the oil is only being used as a lubricant and not under pressure as a driving force, like the HST and CVT.


added:
It appears there are many kinds of CVT's. I guess we need to know what form the tractor you are referring to uses.

https://en.wikipedia.org/wiki/Continuously_variable_transmission#Hydrostatic_CVTs

 

[NewHollandTN75]

Is the Boomer 3050 using hydraulic fluid in this way? I thought it was using a chain to transmit power.

 

[arrow]

that's how I understand it too.



yes because the oil is only being used as a lubricant and not under pressure as a driving force, like the HST and CVT.


added:
It appears there are many kinds of CVT's. I guess we need to know what form the tractor you are referring to uses.

https://en.wikipedia.org/wiki/Continuously_variable_transmission#Hydrostatic_CVTs

The wife's 2014 Forester has a CVT tranny. I never looked to find out which type it has. It improves mpg by 5 to 7 points over the 2013's and earlier Suby's. When they don't dick around with seasonal "gas blends", it gets 35 mpg which in my mind is pretty good for an AWD car.

 

[bigdeano]

Here's a video that shows how the New Holland CVT works.

https://www.youtube.com/watch?v=inMtx6X3rY0

Looks to me it would be more efficient and generate less heat than pure hydrostatic. At some speeds the power goes 100% gear drive.

 

[TSO]

Here's a video that shows how the New Holland CVT works.

https://www.youtube.com/watch?v=inMtx6X3rY0

Looks to me it would be more efficient and generate less heat than pure hydrostatic. At some speeds the power goes 100% gear drive.

Is that the big equipment, or the compact Boomer CVT?

 

[arrow]

Here's a video that shows how the New Holland CVT works.

https://www.youtube.com/watch?v=inMtx6X3rY0

Looks to me it would be more efficient and generate less heat than pure hydrostatic. At some speeds the power goes 100% gear drive.

Apparently it is more efficient as it increases mpg. Less slippage or transfer loss than a regular automatic. How it equates to agricultural use as far as efficiencies could be the same: getting more work out of a determined amount of fuel.

 

[MinnesotaEric]

Hello,

I've been looking at New Holland Boomer CVTs with the thought that the CVT transmission may have some benefits. Specifically, I have been using a rototiller on a Deere 3720 and a Kubota L4630. Both machines tend to heat up after a while as the hydrostatic fluid gets hot, and the engine temperatures climb. This phenomenon also occurs when pulling a 6 foot mower. It does not relate to clogged radiators etc.

Does the CVT transmission allow one to run a rototiller/similar attachment at high RPMs in high heat for prolonged periods where a hydrostatic transmission would otherwise start to get hot?

Thanks so much.

Too hot?

I've yet to overheat my HST Kioti NX6010 running a BB720X cutting through heavy brush and 4" trees and I've added remote valves that add an extra 10 degrees to my transmission/hydro fluid which my machine easily dissipates through the oil coolers.

At any-rate, my experience with CVT transmissions in cars is that they rock and all of the crop row tractors seem to be heading toward CVT transmissions for the increased economy they offer. Always giving max power or maximum efficiency to the speed and load. Hard to beat when combined with Tier 4 tech for efficiency.

At any-rate, all things the same, a CVT should run cooler than an HST transmission because the HST is effectively a heat pump turning hydraulic pressure into mechanical force with the oil carrying that heat away, while CVTs function similar to industrial versions of snow machine transmissions with two centrifugal clutches (although there are variants in various 3rd and 4th generation CVTs).

 

[Dillier23]

New Holland CVT's use hydraulic pressure to move the clutches in and out to increase or decrease gearing in relation to load or conditions. There is not a significant loss in PTO or engine power as in a HST because of the mechanical nature of the transmission. CVT shouldn't run any hotter than a HST, likely cooler if anything because of the mechanical drive system. Early versions had an electrical problem now and again, but the biggest issue was getting the operators trained to use the system correctly. There are safety mechanisms built into the transmission to prevent stalling and operator errors.

 

[MHarryE]

The CVT on the Boomer is completely different than large ag tractor CVT or IVT (IVT is John Deere's terminology). Boomer CVT uses the chain drive on variable diameter pulleys like automobile CVTs while the large ag tractor CVTs (and IVT) use hydrostatics. The hydrostatic is not a complete hydro like CUTs. Rather the hydraulic motor(s) is/are turning ring gear(s) on planetary gearsets. Turn it one way and speed through the gear set is increased, turn it the opposite direction and speed is decreased. Turn it fast enough and there rotation of the ring gear completely negates the drive through the sun and planets and the machine stops.

https://www.youtube.com/watch?v=dgtIKMAjvFI

https://www.youtube.com/watch?v=xhmN_CwB9B8

https://www.youtube.com/watch?v=b_-LL0sCT-k

The first link is the AGCO CVT. The second link is the CNH CVT which illustrates how it depends on the ring gear rotation to vary speeds. The last one is AGCO's Fendt transmission which better shows how the AGCO CVT is a combination hydrostatic/mechanical. Both designs completely different from the Boomer CVT somebody posted earlier.

I see where the Boomer type CVT has captured about 10% of the automobile transmission market as of the beginning of 2014.

 

[MinnesotaEric]

Is that the big equipment, or the compact Boomer CVT?

That looks like a 3rd or 4th gen CVT used on heavier equipment. As I pointed out and Harry unpacked, the smaller CVT is much like a car using a chain between two pulleys that infinitely vary the gearing depending on speed and load. The fundamental design is claw-hammer reliable as the chain lives in oil or an oil bath. The only downside is that it isn't tough enough for super high torque loads like crop row tractors. AGCO and others solution for high torque, high-load applications is a hydro-gear CVT which is a much heavier way to do that same thing the lighter car-style transmissions do.

New Holland explains their Boomer CVT here: http://agriculture.newholland.com/a...omer-Compact-Tractors2/Pages/CVT_details.aspx

FWIW, if I was car or tractor shopping, I'd jump at any car I like that offers a CVT. They are super efficient. The only pushback is that people think they need "gears" and oftentimes, software is developed for CVTs to make them "act like" they are rowing up and down through gears.

 

[bigdeano]

I don't see any provision for reverse on the variable pulley type. Does the same foot pedal put it in reverse?