M4700 transmission ratios/speeds

[rv7charlie]

I suppose this might be considered a rant in the form of a question, but here goes:
Any thoughts from you 'pro' users on why the M4700 has such a big speed jump from high 2nd to 3rd? Mine gets about 95% of its hours running a 7' cut finish mower. (Mowing ~3 acres of my land, and 20+ acres of a grass airstrip six to eight times a year whenever my turn rolls around.) 2nd gear & 2600 rpm gives a pretty cut, but takes a generation to mow 20 acres. 3rd gear & 2600 rpm gets it done in about 2.5 hours, but gives a ragged cut and the mower tends to deflect the grass at its edges instead of cutting it. (This is with freshly sharpened blades.) Going any slower in 3rd results in the mower turning too slow, making the cut look even worse. When you look at the speed range chart, the speed jumps from about 8 mph to around 12 mph when going from 2nd to 3rd.

Anyone have any idea on why Kubota would have built such a wide gap into their system? I realize that most jobs don't get done in 3rd or 4th, but mowing really does need either a slightly slower 3rd, or a 'variable ratio' PTO rpm. Shelling out the money to replace the tractor with a hydrostatic drive model just isn't in the budget.

 

[newbury]

Your getting into "highway" speed for the tractor. Mine spends it life with me between 1R and 4L. But then all my time seems to be spent in the woods.

 

[TripleS]

Put a shorter tire on it.

 

[Farmer495]

I suppose this might be considered a rant in the form of a question, but here goes:
Any thoughts from you 'pro' users on why the M4700 has such a big speed jump from high 2nd to 3rd? Mine gets about 95% of its hours running a 7' cut finish mower. (Mowing ~3 acres of my land, and 20+ acres of a grass airstrip six to eight times a year whenever my turn rolls around.) 2nd gear & 2600 rpm gives a pretty cut, but takes a generation to mow 20 acres. 3rd gear & 2600 rpm gets it done in about 2.5 hours, but gives a ragged cut and the mower tends to deflect the grass at its edges instead of cutting it. (This is with freshly sharpened blades.) Going any slower in 3rd results in the mower turning too slow, making the cut look even worse. When you look at the speed range chart, the speed jumps from about 8 mph to around 12 mph when going from 2nd to 3rd.

Anyone have any idea on why Kubota would have built such a wide gap into their system? I realize that most jobs don't get done in 3rd or 4th, but mowing really does need either a slightly slower 3rd, or a 'variable ratio' PTO rpm. Shelling out the money to replace the tractor with a hydrostatic drive model just isn't in the budget.

You are into road gear territory, that is why. The gears space nice for upshifting to top speed.

The ratios don't change low range 2 to low range 3, but the multiplier factor of the range transmission spaces them out further speed wise. If 2 and 3 were closer together, they would be almost the same speed in low range. Low range gears might be 1 MPH apart, high range 4 MPH apart.

Most, if not all, tractors with straight 8 speed transmissions have the same set up. Under 5 MPH for low range, 5 to 8 MPH High 1 and High 2, with High 3 and high 4 are highway use. You would need to get into a tractor with another splitter (12, 16, 24 speed etc) to get a better selection in the 5-10 MPH range.

The comment on getting a shorter/smaller rear tire size has merit. Turf special models of utility tractors had short, fat turf tires and the same 8 speed transmission, the smaller rear wheel meant the top speed was considerably lower, and also meant that the high range gears were spaced closer together speed wise.

 

[ptsg]

Turn it into a low rider.

 

[sixdogs]

The others are correct in that the higher gears you're using are preludes to a road gear for highway driving. I have an MX5100, which is mostly the same tractor aqs yours, and would not be able to mow in those high gears.

Most ag equipment is designed to operate at 5mph and that's where tractor makers put their gear ratios. My rear Woods mower--now sold--called for a 5mph max speed. I also got ragged cuts at higher speeds.

I felt the same pain mowing hay in a 3/4 mile long field but when I went faster it left a ragged cut or machinery damage issues. I just slowed down. I also mowed at a higher level and that left the grass softer and that cut a little better at a slightly higher speed.


Smaller tires are an expensive option with not much resale value and a hydro transmission will kind of leave you in the same situation of wanting a higher ground speed.

 

[rv7charlie]

Thank you all for the replies. The smaller tire idea might be worth pursuing, if I ever wear out the existing back tires (or they dry rot ;-) ).

I guess I'm back in rant mode, but it seems nonsensical for tractor mfgrs to devote two top gears for highway use, when (at least with this tractor) it's quite capable of getting under way in high 4th. It would seem logical that high 3rd has no use at all, if it's not for something like mowing. I wonder what the mfgrs think people are using to run 7' & 8' finish mowers, and where those mowers would actually be used.

Again, thanks for the smaller tire idea; that sounds like a potentially workable solution, when I really didn't even expect to hear one.

 

[5030]

Again, thanks for the smaller tire idea; that sounds like a potentially workable solution, when I really didn't even expect to hear one.

If you do that and the unit is front wheel assist, you'll have to change the front's as well to maintain the proper lead-lag ratio or you will destroy the front differential

 

[rv7charlie]

Fortunately (I suppose), it's straight 2WD. It'll likely never happen anyway; I'll probably age out of grass mowing before the tires do.

 

[LouNY]

Thank you all for the replies. The smaller tire idea might be worth pursuing, if I ever wear out the existing back tires (or they dry rot ;-) ).

I guess I'm back in rant mode, but it seems nonsensical for tractor mfgrs to devote two top gears for highway use, when (at least with this tractor) it's quite capable of getting under way in high 4th. It would seem logical that high 3rd has no use at all, if it's not for something like mowing. I wonder what the mfgrs think people are using to run 7' & 8' finish mowers, and where those mowers would actually be used.

Again, thanks for the smaller tire idea; that sounds like a potentially workable solution, when I really didn't even expect to hear one.

If you had a towed load behind it or starting up a hill you'd find a good reason for that 3rd gear.

 

[Jchonline]

You dont really have a tractor built for field work. My M7060 has 12 forward and reverse gears..so its really easy to find the right speed for mowing, haying, seeding, spraying, etc. Machines like my L6060 or your M4700 are a compromise at best....these arent "field" tractors. Just dont have the fine tuned gearing. Sooo you can either buy the correct tractor or you can suffer with the rest of us! I have mowed 20 acres with a brush hog a few times....no fun at all. I also cant imagine going across the field in high gear...talk about a bumpy ride. I guess the airfield is a bit smoother.

 

[Farmer495]

but it seems nonsensical for tractor mfgrs to devote two top gears for highway use, when (at least with this tractor) it's quite capable of getting under way in high 4th. It would seem logical that high 3rd has no use at all, if it's not for something like mowing.

I do a lot of road travel. I use every gear in high range pulling wagons and implements etc on the road. My travel includes upgrades where I have to downshift to keep moving. I'd use high 3rd plenty on an M4700 if I farmed with one.

 

[Farmer495]

You dont really have a tractor built for field work. My M7060 has 12 forward and reverse gears..so its really easy to find the right speed for mowing, haying, seeding, spraying, etc. Machines like my L6060 or your M4700 are a compromise at best....these arent "field" tractors. Just dont have the fine tuned gearing. Sooo you can either buy the correct tractor or you can suffer with the rest of us! I have mowed 20 acres with a brush hog a few times....no fun at all. I also cant imagine going across the field in high gear...talk about a bumpy ride. I guess the airfield is a bit smoother.

M4700 is really the same premise as almost every farm tractor in that HP class built in the 60/70/80/90s. I farm only with 8-speed tractors at the moment, work gets done fine, more gears are better though.

 

[rv7charlie]

The ride isn't an issue. If it's smooth enough for 13" tall aircraft tires and 7" tailwheels on 1500 lb gross aircraft at 70+ mph, a tractor in 3rd gear handles it pretty well. ;-)

There are seven or eight tractors on the field now, and two are Kubota hydrostat drive & the rest are similar (another M4700, a larger Kubota manual trans, a ~40-50 hp JD, a big MF). There have been up to 9 or 10 in the past (pilots all like having their own toys), and I don't think any of them have ever been anything other than 6 or 8 speed or hydros. The ones that haven't gone to 5' zero turns are using 6' or 7' cut 3ph mowers. A couple seem to enjoy sitting in the sun for most of a day and mow in 2nd or use zero turns; the rest of us mow in 3rd.

 

[Jchonline]

M4700 is really the same premise as almost every farm tractor in that HP class built in the 60/70/80/90s. I farm only with 8-speed tractors at the moment, work gets done fine, more gears are better though.

I looked you could actually have purchased the M4700 with a 12 speed creeper (if tractordata is correct)!

TractorData.com Kubota M4700 tractor information

www.tractordata.com

 

[rv7charlie]

I wish; it had around 700 hrs when I bought it. New is playing in another universe for me. ;-)