my new tractor- manual vs hydro

[Trev]

Re: my new tractor manual vs hydro

Hey Rat,

<font color=blue>Bob, I respectfully disagree about the emergency situation but perhaps it's because you are not familiar with HST, particularly that on the Kubota. </font color=blue>

From what you say, it does sound like the HST on the Kubota wouldn't cause any of the problems I had on my little JD235. And I do see the advantages you point out. Wish we had a Kubota dealer nearby to go and play with one. But then I might be tempted and my wife would behead me. /w3tcompact/icons/smile.gif

Here is the quote from a guy who also had trouble.. note that he is also talking about a JD ... and note that he came to love it eventually. So, at least as far as the Kubota system goes, I stand corrected.

Best,
Bob

<font color=green>Yes I have got myself in trouble with hydro peddles. I had a Simplicity for years (gear) and went to a JD 235 last spring. One side of property in blackberry bushes and on Simplicity I would ride the clutch in case I got tangled. Well went along with hydro and got caught up, hit the peddle, and result was lots of blood.Another time I almost put it in the creek. Now I am used to the hydro and wouldn't give it up for nothing.</font color=green>

 

[MossRoad]

Re: my new tractor manual vs hydro

Rat,
I didn't agree with this comment in your first post:

<font color=blue>While HST is super especially with lots of loader work, it certainly is not for everyone. You do loose power to the wheels and PTO</font color=blue>

But you won me over in your second post when you clarified with:

<font color=blue>The HST tractor will require more HP to do the same amount of "push/pull" work.</font color=blue>

The first way of putting it sounds like you lose power to the rear wheels. You do not ever lose power to the rear wheels. The second way you put it is corrrect. Less engine power is transferred to the rear wheels in a HST vs a GEAR. You overcome it by using a bigger engine.

Also, I asked earlier, on a CUT with an HST, is there less PTO HP than the same CUT with a gear transmission?

Looking at the specs for, say, a NHTC21 and 21D the 21 has one more PTO HP but the 21D has .2 more KW. (kind of confusing). The JD4110 shows no difference that I can see.

Can anyone please explain to me how the PTO gets power from the engine on the same tractor equipped with gear vs HST? Thanks /w3tcompact/icons/smile.gif

 

[BWS]

Re: my new tractor manual vs hydro

seems like a gst might be a happy median.havnt driven one yet.anybody purchased a second[4] set of ag tires/rims say from less swabb or a discount tire store?how much was the pkg?tires/rims/mounting ect?thinking of taking the r4's and just buying a second set of r1's.drove the n.h.tc35d hydro last night its kinda jerky the way it stops so fast kinda uncomfortable is this adjustable?

 

[hazmat]

Re: my new tractor manual vs hydro

<font color=blue>Also, I asked earlier, on a CUT with an HST, is there less PTO HP than the same CUT with a gear transmission?</font color=blue>

Where does the power go?

Gross engine HP this is how much the motor will put out. Then you need to subract for accessories:
Alternator
Fan
Hydraulic Pump (Biggie)

Now you've got Net HP into the transmission.

Then you subract for the transmission losses to get PTO HP

A Hydrostatic Trans is a big oil pump, it is pumping oil even when in "nuetral". So it robs more power, thus less available to the PTO or the wheels.

A gear trans does have some power loss (friciton of bearings & it moves the oil lubricating the gears around)

A TC21 vs. 21D is not a good comparision as the 21D has a bigger hydraulic pump. The class III boomers have the same size hydraulic pumps (brochure is right in front of me)

TC35
Gross HP 35
PTO HP Hydro 29.1
PTO HP gear 29.6
% difference 1.6%

TC40
Gross HP 40
PTO HP Hydro 33.2
PTO HP Gear 35
% difference 5.1%

TC45
Gross HP 45
PTO Hydro 37.8
PTO Gear 39.6
% difference 4.5%

For the hobby farmer / estate user (Most of us here on TBN) you aren't going to miss the 5% HP. A full time farmer would care about the 5% power loss due to fuel costs.

A hydrostatic transmission has the potential to overheat if it is used for high load pulling situation for a long time. (Not a problem if the manufacturer put a big enough oil cooler on the tractor).

A gear tractor gets better fuel economy for a given PTO HP, but the main advantage is the ability to go a known constant speed.

 

[markie61]

Re: my new tractor manual vs hydro

"<font color=red>But then I might be tempted and my wife would behead me</font color=red>"

I thought your wife ALREADY beheaded you for something else - all I see under the name "Trev" is a floating head!/w3tcompact/icons/grin.gif

Mark

 

[Trev]

Re: my new tractor manual vs hydro

<font color=blue>I thought your wife ALREADY beheaded you for something else - all I see under the name "Trev" is a floating head!/w3tcompact/icons/grin.gif</font color=blue>

No, actually she cut off all the other body parts and left only the head. If she beheads me I'll be gone completely. /w3tcompact/icons/smile.gif

 

[MossRoad]

Re: my new tractor manual vs hydro

Thank you. /w3tcompact/icons/smile.gif

 

[JATO_RaT]

Re: my new tractor manual vs hydro

Moss, yeah, you know its a problem with me, fat fingers, slow typing, a laptop with a tiny keyboard and a brain going 100 miles an hour. Then I have to come back and fix all the typo's and loose my train of thought. I know what I mean but dang if I can get it right sometimes.

 

[JATO_RaT]

Re: my new tractor manual vs hydro

Bob, I could see that happening especially when ones not familiar with the controls, Rat.

 

[Kodiak]

Re: my new tractor manual vs hydro

Lets see if I have this right. And please any of you tractor mechanics out jump in and correct me if I'm wrong.

On a hydrostatic transmission tractor the engines primary purpose is to drive a large hydraulic pump that only powers the Hydrostatic motor. Secondary purposes are the secondary hydraulic pump for 3pt and loader or other aux. hydraulics. and finally to power the alternator and power steering, the latter of which is really your third hydraulic pump.

So the back of engine is basicly hooked directly to primary drive pump. Which in turn supplies hydraulic fluid through a control valve (foot pedal) to a large hydraulic motor. That motor is then direct coupled to a secondary or auxillary transmission that contains your gear ranges, high , medium and low or whatever your tractor is equipped with. This aux. trans is then direct coupled the differential which supplies power to the axles and finally the wheels. The pto is yet another gear driven shaft that is comes off the auxillary transmission, and is either shifted manually or electricly. And the front drive shaft for the 4x4 is yet another manually shifted gear driven shaft also coming off the auxillary transmission.

You then set your rpm to a set engine speed. This provides a set hydraulic flow rate through a open loop system. You then determine how much of that set hydraulic flow rate is diverted through the hydraulic motor by the control valve (foot pedal). and that determines how much power is delivered to the auxillary transmission. Ground speed/power is then adjusted using the varius ranges. But the hydrostatic drive doesn't actually have gears itself, unlike a regular automatic transmission.

Several of the post here have stated using the engine on hst tractors for braking. But as I see it you can't actually use the engine for braking. In reality your simply restricting the hydraulic fluid supplied to the drive motor.