Want to move from 425 to 1430 or 1845

[duane]

The HI-Lo transmission uses a gear set to increase the wheel torque. You will see many Kubota posts where owners have problems climbing hills, but then realize that they need to shift to the low range. Climbing hills is all about wheel torque. You can increase wheel torque by reducing the wheel diameter, going with different wheel motors or increasing hydraulic pressure. Increasing the pressure in your current set-up reduces the life expectancy of your wheel motors and variable volume pump, and you could start to find your limits of engine power.

I ran some rough numbers, a PT425 with operator pushing a 60" mower deck up a 20 degree incline is right at the rated capacity of the wheel motors. The 1400 series will produce more wheel torque, but then is heavier, so will it have the same problem as you have now?

The 18" tire option is the cheapest means to increase your wheel torque. As mentioned, it should increase your wheel torque by 25%. Would this be enough, would the reduction in ground speed by acceptable (8 mph - 6 mph), would the reduction in ground clearance cause any problems, and would the theoretical increase in torque translate into real life? Of course the best way to answer these questions is to try it? See if you can find some second hand 18" rims/tires that fit the PT. We love to hear the results of PT experimentation.

I'm sure the PT designer struggled with speed vs. wheel torque. The answer as always was a compromise. The best answer would be a hi-lo range, but that would not fit economically into the PT design.

Good luck. This is fun.

Duane

 

[Schultz]

Well, I'll post my 2cents of experience with hydraulic drive systems. I had the same problem with my Ingersoll, which as many know is hydraulically driven through a 2 speed trans. When I first got it, hi range was too fast and touchy for mowing 0-8.8mph and had little power up hills. Low range was too slow 0-4mph but had all the power. My solution was to change the gear in high range to a better compromise. I slowed it down to 6.5mph and now it has a constant speed up hills, doesn't bog down... it's just right...for my yard anyway.

You have to be careful with adjusting pressure of your drive system. I would first find out the operating specifications of the motors. I'm not familiar with the PT system but it looks like the drive system has it's own pump that is separate from everything else. If it does, then you have more room to work with. You could do some experimentation by trying the following. Back the tractor up to an immovable object then slowly try to push the immovable. As long as no tires are spinning you should hear the pressure relief valve crack or go full open before the engine stalls @ full throttle (it will sound like an open faucet). Maybe your system has a place were a gauge can be mounted in the system, if it does then you can find the cracking pressure and full open pressure. If it doesn't then one can be made by making a "T" type splice with gauge on the dead end of the T. The T splice could be inserted on the high-pressure side of one of the wheel motors, before or after the valve. PT should provide you with the cracking and full open pressure specs that they set for full and or low rpm.

Another thing that could be happening is your oil may become too hot which makes the whole system less efficient. The only way I can think of testing this is to stick a thermometer or thermocouple in your reservoir tank and see what it runs at. Does it make a difference how it climbs in the winter? Also the replaced/changed Hydraulic oil should have an anti-foaming agent in it, there, are many brands, the one that comes to mind is Shell Rotella.

If all else fails and you really love this size machine and don’t mind, spending likely a $1000 or more you could replace all the wheel motors to provide more torque. This still might be the less expensive route because you wouldn’t loose all the money on depreciation of your machine.

 

[Charlie_Iliff]

<font color=red>another note - the machine does climb straight up the hill and does not stall
- it just whines stains more than usual and I think the wheel motors shutter a little while cresting it</font color=red>

Ed: If the machine will climb the hill straight up, with the mower running, and the engine rpms still up, I'd be very leery of changing anything. Despite a little hydraulic groaning, it might be that the hydraulics are properly keeping the engine in a decent torque range, and what you are hearing is the relief valve opening.
That being said, of course, the analysis you are doing is a lot of fun, and certainly worthwhile. If you ever get to the Maryland area, I'd be happy to demonstrate the 1845. Closer might be John Coxon, in East Chatham,New York. With 45 hp, and the 72" rough cut mower, you can drag the engine down seriously in heavy growth, particularly if you are going uphill. Sometimes you have to creep to keep the revs up on the mower. That is rare, but I think the mowers draw a lot of power, and 20 degree hills are seriously steep and require even more. I doubt any machine will scoot around them as if it were level. I also don't think the 72" mower can do as nice a job as the 60". If it can take it, however, that 60" deck with 15 GPM flow should sure get some blade tip speed, at least for a short time. /w3tcompact/icons/grin.gif
I begin to think that Power Trac keeps us all interested by withholding the information we ask for. That way we have to chase around and learn all sorts of things on our own. I'd get mad at them if I didn't like my 1845 so much.

 

[Anonymous Poster]

Charlie,
"the warranty is void if anyone messes with pressure settings" This is understandable, but one ought to be able to ensure that it is at factory "spec"...Has PT revealed that spec to anyone that has asked...

"there seem to be some variations in experience with the 400 series that suggest varying relief settings"...I'm wondering,
then, if this variability is due to differences in component supplier for a given function...this in turn might require
different relief settings for peak performance & reliability.

Sure wish PT would be more forthright w/ info to end my speculation...

Ahh, the questions are adding up for that first visit...

 

[Anonymous Poster]

EDM,
"I don't think it is engine protection - The engine has power in reserve "

What I meant by "protection" was that the hydraulics were designed to "give up" before the engines design angle was exceeded on a slope and the motor lost ability to maintain oil pressure.

"does not stall
- it just whines stains more than usual " Based on previous ownership of a Case 446 and a failing pump(not yours) I'd check oil temp and relief valve settings. Oil temp would be easiest but I'm not sure what the magic number is(below 200 deg.f., for sure)...Current owners have brought up the temperature issue before (engine and hydraulics,I think)

This has to be a tough call for you...whether to adjust (relief settings)and void the warranty which would depreciate the tractor further before a sale if it didn't work (and you might not know if it's going to work till next summer when heat conditions are a worst case test) or act on the "gut" feeling that this model is "not enough" for your needs regardless of "adjustments" you might make. This is that "place" that everyone trys to avoid.

 

[Anonymous Poster]

Hi Schultz,

Reminding me of my Case experience (mostly pleasant)...As a test for my "squealing" hydraulics,my dealer told me in a similar fashion to put the tractor against the wall and with high engine speed move the lever forward...he said that I should get wheelspin on pavement before the "squeal" begins. As this was a just purchased used machine a month earlier in cool weather,my problem surfaced later in the "heat"...He sent me a new pump and all was well.

One issue I tired of was a "speeding up" when heading down slope and was told that later models had a "flow control valve" ,whatever that is, to help maintain a steadier speed...

This brings up a ? I have for PTer's on slopes...Does downhill speed seem controlled or do you have to compensate with
exaggerated pedal movement between uphill/downhill?

"Another thing that could be happening is your oil may become too hot which makes the whole system less efficient. The only way I can think of testing this is to stick a thermometer or thermocouple in your reservoir tank and see what it runs at."...Great Advice. My crystal ball sees this as a dash mounted guage with a yellow/red zone...yet another project/mod to add to the list...I can't wait.

"Hydraulic oil should have an anti-foaming agent in it"...
This is another point I'm trying to come to grips with before I buy...which oil to use ,i.e.,which is more shear stable and which holds viscosity better under heat...etc.,etc.

 

[Anonymous Poster]

Reply to how does the unit handle downhill

I can tell you that I am very satified with the unit
downhill - I IS VERY STABLE and also seems to maintain
a constant speed -

You guys know more than I RE pressure settings relief
valves - etc - I have to go read up - thanks for the ideas

EDM

 

[Anonymous Poster]

Sorry about all the typos - I do know how to spell

 

[MossRoad]

Very stable down hill. If you let off the treadle, it stops itself.

For everyone's information: I saw a combination hydraulic pressure/temperature guage at northern but it was over $200.00.

 

[Anonymous Poster]

Some great suggestions - and yes the problem is worse during the hot weather -

what I am trying to find out first is the specs of the system and how it is set up (ie trans pump and wheel motors) - I would think that they would have to provide this info otherwise you can't service the unit unless you drive it to Tazewell - but first I need the model numbers - which PT won't provide -

Today I provided Eaton as well as an Eaton distributor with the number on the top of my 425 pump - they are researching it - I am not sure if it is a PT # or an Eaton number - the number is 7090079 - but I could not match that up to anything on the Eaton website - based on looks it appears to be in their "medium duty line"

No one as of yet has posted model numbers for pump and wheel motors for the 425, 1430 and 1845 - probably because
no one knows -

But I am sure that I will find out soon enough either through my research or someone will post it -

When I find out I will post it

I love the Power Trac units - so much so that I will still probably buy the larger one even though the Company is really bad at providing customers the critical information they need especially given that there are no dealers to turn to for information.

But before I move forward with my next unit - I am going to know exactly what the specs are so I am sure that it will handle my situation - I am not going to go off what they say
- that for example the 1430 is rated for 30 degrees - because that does not necessarily mean climb - it means cross ways without turning over

Anyway - any info available out there would be great help

edm