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