My Tractor Forum banner

1 - 15 of 15 Posts

·
Treefarm
Joined
·
69 Posts
Discussion Starter #1
I was hoping people could tell me the proper RPM to run a diesel tractor or a gas garden tractor for that matter.

I just purchased a Ventrac 3200 with a 23 horse Vanquard Diesel. I will use it primarily for mowing and moving mulch and dirt. This is my first diesel tractor and admittedly I have little experience with oil burners.

It is hydrostatic.

I have tended to run low RPM's in all my equipment except when needed but my dealer told me this unit should be run flat out. Do you all really feel this is correct?

Thanks for any feedback.
 

·
Tech Nerd Tractor Convert
Joined
·
1,388 Posts
My tractor (gas, not diesel) has hydros (2 of them) and I was told the same thing.. run at "max RPM". Kohler courage v-twin 25 hp engine.

The interesting thing is my dealer and the manufacturer (MTD) don't agree on what "max" is. MTD says 3600 RPM, and my dealer says they set all Cubs to 3200. So I split the difference and run at 3400.

Also MTD says the reason to run at 3600 is that the mowing deck won't produce as good of a result at lower RPMs. They didn't even mention hydro cooling, which I know is the main reason (mow cut quality would be secondary for me).

So maybe take what you get from the mfg with a grain of salt. I'd go with consensus of the board on this one.
 

·
9K+ Poster
Joined
·
12,160 Posts
toro,

PTO hp with the diesel will be slightly below full throttle. I don't know if you have any markings on your tachometer, but on the Deere tractors, there is a little yellow PTO mark. The PTO rpm will be the best combination of power, economy and longetivity. :)
 

·
Tech Nerd Tractor Convert
Joined
·
1,388 Posts
Spec sheet for the Ventrac 3200 indicates "operating RPM" to be a range: 1600-3200 RPM. That would seem to suggest it's ok to run at lower than max, but you should check the owner's manual to be sure. OM is on same website but requires a valid serial number, which you would have but I don't.
 

·
Registered
Joined
·
2,034 Posts
JDFanatic is right on the money. But it depends on what you're doing, if you're just pulling a light trailer or something of that nature, then no, 1/3-1/2 throttle would be plenty.
 

·
Treefarm
Joined
·
69 Posts
Discussion Starter #8
Thanks for the info. I had heard flat out was the best for the hydro but wanted to check with you all.
 

·
Registered
Joined
·
150 Posts
I agree w/JDfanatic
 

·
AKA Moses Lawnagan
Joined
·
4,642 Posts
I had heard flat out was the best for the hydro .
This is true. If you have a manual trans, use whatever throttle setting gives you adequate power without the engine lugging. With my old Yanmar, I pretty much left the hand throttle at idle and used the foot throttle like you would the accelerator in a car. With a HST, though, the pump must develop sufficient pressure to operate the trans properly, and the operating PSI of the pump depends on enough rpm from the engine. This is why the mfg recommends full throttle for most, if not all, of the tasks the tractor performs. Max pressure is usually developed by 2/3 throttle, but varies with the size of the pump in the tranny. Once max pressure is reached, more engine speed doesn't mean more pressure in the tranny, there are relief valves and bypasses that prevent that. Running the engine at WOT ensures that the proper operating pressure in the HST is always met with a reserve for full loading during heavy work.
 

·
Super Duper Member
Joined
·
1,471 Posts
I avoid running a max RPM while mowing normal height grass. I've been doing it this way for almost 30 years and have never had a problem. I WILL run her full out when it comes time to collect leaves, or while mowing higher than normal grass.
 

·
Just passing through
Joined
·
8,419 Posts
I was hoping people could tell me the proper RPM to run a diesel tractor or a gas garden tractor for that matter.

I just purchased a Ventrac 3200 with a 23 horse Vanquard Diesel. I will use it primarily for mowing and moving mulch and dirt. This is my first diesel tractor and admittedly I have little experience with oil burners.

It is hydrostatic.

I have tended to run low RPM's in all my equipment except when needed but my dealer told me this unit should be run flat out. Do you all really feel this is correct?

Thanks for any feedback.

So...did you get the RED TAG SPECIAL?
http://www.ventrac.com/promo.php
 

·
Treefarm
Joined
·
69 Posts
Discussion Starter #13
I did get the red tag special but swapped the mower for the diesel upgrade. I must admit this is way more tractor than I need right now but it has been great. The slip scoop has really come in handy for moving dirt and logs.

I hope to buy 5 or more acres this year with plans of starting a christmas tree farm at some point.

I am a true novice at this stuff but after sitting behind a desk all day I love it.

I have learned a lot from reading all the posts. What a great website.
 

·
Moderator
Joined
·
22,088 Posts
This is true. If you have a manual trans, use whatever throttle setting gives you adequate power without the engine lugging. With my old Yanmar, I pretty much left the hand throttle at idle and used the foot throttle like you would the accelerator in a car. With a HST, though, the pump must develop sufficient pressure to operate the trans properly, and the operating PSI of the pump depends on enough rpm from the engine. This is why the mfg recommends full throttle for most, if not all, of the tasks the tractor performs. Max pressure is usually developed by 2/3 throttle, but varies with the size of the pump in the tranny. Once max pressure is reached, more engine speed doesn't mean more pressure in the tranny, there are relief valves and bypasses that prevent that. Running the engine at WOT ensures that the proper operating pressure in the HST is always met with a reserve for full loading during heavy work.
All any hydraulic pump, including a hydrostatic transmission, does is move oil, NOT create pressure. Pressure is created by the resistance to flow when work is being done. At idle or full throttle when the tractor is sitting still, a hydro makes only sufficient pressure to overcome internal flow losses from resistance to flow, usually under 150 psi. and this is created by the charge pump, not the hydro pump proper which should be moving no oil when in the centered position. There is no loss until you start doing work. The harder the tractor works, the higher the pressure. Lawn mowing is not hard work on level ground, but gets progressively harder as the hill gets steeper. It doesn't take much pressure to keep a tractor moving, but it does to overcome inertia to get it to move or climb a hill. It takes lots of horsepower to run the mower and that requires RPM.

Screw a 5000 psi guage into the forward port on your tranny and check it out. Acceleration valves on my Sunstrand are set at 4500 psi. I have no idea where other manufacturers set theirs.

:sorry1: for the lecture, I trained too many millwright helpers over the years. Just wanted to give some understanding.


Bob
 

·
Registered
Joined
·
79 Posts
The 23 hp diesel Vanguard engine was made for Briggs by Daihatsu. Daihatsu also makes small outboard engines for Mercury Marine.

For mowing, many manufacturers specify RPM imput to the deck to achieve the best cut. I believe the DEERE 2305 for example has a mark on the tach for mowing.
 
1 - 15 of 15 Posts
Top