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

[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?