Ground speed

[GT2]

Hi all, noob here.
I'm researching building my own compact tractor.
What is an exceptable ground speed in MPH for low gear and high?

 

[BTDT]

What will this tractor be doing? If it is just mowing yards, I would go with a higher speed gearing, if plowing, dozing, etc, may need to gear toward lower speed. Need more info. Where are you located?

 

[GT2]

What will this tractor be doing? If it is just mowing yards, I would go with a higher speed gearing, if plowing, dozing, etc, may need to gear toward lower speed. Need more info. Where are you located?

Mostly light digging, pulling on some stumps, moving rocks.

 

[BTDT]

Sounds interesting. Where are all the parts for this tractor coming from, did you inherit a junkyard?

 

[Bird]

Welcome to Tractorbynet, Tim. I don't know what materials you plan to use to build a tractor, but you can go to some of the manufacturers' websites and look at the specs on different models. They do vary a bit, but just as an example: I used to have a Kubota B7100 that had a top speed of about 9 mph, then a B2710 that had a top speed of almost 12 mph (11.9 I believe, to be exact). They both had hydrostatic transmissions so it was infinite speed up to those limits. For a geared tractor, I'd say you want one mph or less for things such as running a tiller; maybe a little more would be OK for some other jobs.

 

[GT2]

Welcome to Tractorbynet, Tim. I don't know what materials you plan to use to build a tractor, but you can go to some of the manufacturers' websites and look at the specs on different models. They do vary a bit, but just as an example: I used to have a Kubota B7100 that had a top speed of about 9 mph, then a B2710 that had a top speed of almost 12 mph (11.9 I believe, to be exact). They both had hydrostatic transmissions so it was infinite speed up to those limits. For a geared tractor, I'd say you want one mph or less for things such as running a tiller; maybe a little more would be OK for some other jobs.

Thanks.
What I'm looking at right now is using a VW rabbit 4 cyl diesel with front wheel drive 5 speed trans axle. Turn it sideways, lock the diff., run drive shafts to front and rear shortened axles.
With 34" rear and 24" front tires its looking like about 1.3 MPH @ 1000 RPM in 1st gear and about 7 MPH in 5th gear, higher with more RPM.

What do you think about using an automatic trans? (weighs more)
Tim

 

[Bird]

What do you think about using an automatic trans? (weighs more)

I have no idea, Tim. You're way out of my area of knowledge.

 

[johnk]

GT2,
I think you'll smoke the tranny......

 

[GT2]

So I looked around and the only manufacture to list low speed is NH (that I could find). Theirs is 1.75 MPH.
Does this sound about right?

 

[Bird]

You'll find that some tractors have their regular lowest speed that high, but offer an optional "creeper" gear. 1.75 mph would be just fine for a lot of tractor work, but I think it would be a little fast for a tiller.

 

[Soundguy]

I agree w/ bird.. you want your lowest gear to be good for a tiller.. if you plan on using a tiller. 1.75 mph is almost max ground speed for a tiller, assuming that also is the speed that your pto reaches operating speed.. etc. You want plenty of hp available to the pto if you are using a high ground speed.

For instance.. old ford 5 speeds were just barely capable of running a tiller. The 4 speeds were just too tall, even on the 8xx seiers that had the extra hp...

Soundguy

 

[schmism]

i got a HST.... i go as slow as i want

 

[Soundguy]

But can ya get off a roadway or RR crossing (with a blown hyd line) using your starter?

Mine will. (grin)

Soundguy

 

[schmism]

But can ya get off a roadway or RR crossing (with a blown hyd line) using your starter?

Mine will. (grin)

Soundguy

huh..... dude just leave it parked and collect the check

 

[bx23barry]

I don't know if/how you plan on a pto so tiller work may be a non-issue. I think the gearing will be fine for bucket, box/back blade, plow/disc, or other dirt work. You might look at some jeep/samurai axles that you wouldn't have to shorten and have ratios in the 5/1 range. A good belt drive Hyd pump and system wouldn’t be much of a problem. The only real problem I see would be turning radius on nontractor axles is way wider so maneuverability is less but not a real big deal. It may not do everything a 50/60 hp tractor can do but would run circles around most subs/compacts for a lot less. Of course it might not look like much depending how good a paint/body guy ya are or if ya care (I wouldn’t). Sounds like fun.

 

[GT2]

I don't know if/how you plan on a pto so tiller work may be a non-issue. I think the gearing will be fine for bucket, box/back blade, plow/disc, or other dirt work. You might look at some jeep/samurai axles that you wouldn't have to shorten and have ratios in the 5/1 range. A good belt drive Hyd pump and system wouldn’t be much of a problem. The only real problem I see would be turning radius on nontractor axles is way wider so maneuverability is less but not a real big deal. It may not do everything a 50/60 hp tractor can do but would run circles around most subs/compacts for a lot less. Of course it might not look like much depending how good a paint/body guy ya are or if ya care (I wouldn’t). Sounds like fun.

Thanks for the input.
Yes I'm looking at Suzuki axles. Stock they are offset so I am planing on shortening the "long" side so I can use short axles on both sides of the diff.
I am thinking of using wheels with a lot of back space to help narrow it up a bit.
Also I would try to hook up steering brakes.

I can buy ring and pinions, so I'm thinking a 34" rear tire with a 5.24 R&P. And a 24" front tire with the stock 3.73 R&P. This would probably look better than using the same size tire front and rear?

I am thinking of using a 6 gpm or so pump on a gilmer belt drive to initally run the loader and 3 pt. I was thinking of using a hyd motor for the pto drive.

I also would like to build a BH for it.

Any other ideas?

 

[john_bud]

Thanks.
What I'm looking at right now is using a VW rabbit 4 cyl diesel with front wheel drive 5 speed trans axle. Turn it sideways, lock the diff., run drive shafts to front and rear shortened axles.
With 34" rear and 24" front tires its looking like about 1.3 MPH @ 1000 RPM in 1st gear and about 7 MPH in 5th gear, higher with more RPM.

What do you think about using an automatic trans? (weighs more)
Tim

Tim,

Interesting. I think you need to gear down the low so that where the peak torque for the engine is you are doing 1 mph or a little less. For loader work, you want the option of creaping into a pile.

Have you thought about just hard mounting the engine and putting a 40 - 50 gpm hydraulic pump on it? Then you can mount hydraulic motors on all 4 corners and still have enough volume for the loader, 3pt and a possible BH. You can also make the frame much stronger and totally custom it.

jb

 

[GT2]

Tim,

Interesting. I think you need to gear down the low so that where the peak torque for the engine is you are doing 1 mph or a little less. For loader work, you want the option of creaping into a pile.

Have you thought about just hard mounting the engine and putting a 40 - 50 gpm hydraulic pump on it? Then you can mount hydraulic motors on all 4 corners and still have enough volume for the loader, 3pt and a possible BH. You can also make the frame much stronger and totally custom it.

jb

I'm still trying to figure out how to get the speed lower mechanicaly, I might have to run a smaller diam tire. Not sure if thats a good idea or not?

I had thought about hard mounting a pump on the engine and run two motors, one each on each front and rear axle ( dident realy want to articulate), but I think it will be too expensive.

 

[Ifixcars]

How 'bout 2 manual four speeds stacked, like a twin stick Mack? Sweet!

 

[bx23barry]

You could mount a transfer case to the transaxle output (weld the diff and run a short drivshaft) and run the driveshfts off the transfer case for some more gear choices (or just runan auto trans with a good cooler). Personally I'd run the biggest tire I could on both ends because traction is always an issue not power so much. The hyd pump/pto is a good way to go but it will need some volume and make some heat (you'll need to do some math for what ever ya want to run). Sounds like you're on your way.