Building your own PT?
- Thread starter ddonnell
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Charlie_Iliff
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- Jun 13, 2001
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- Arnold, MD
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- Power Trac PT1845, John Deere 2240, John Deere 950, John Deere 755, Jacobsen Turf Cat II
ddonnell said:
Sounds like it's time for you to spend some note taking time with a PT. Where are you located?
Charlie_Iliff
Veteran Member
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- Jun 13, 2001
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- Arnold, MD
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- Power Trac PT1845, John Deere 2240, John Deere 950, John Deere 755, Jacobsen Turf Cat II
ddonnell said:
Looks like an easy day trip to MossRoad, right MR?
MossRoad
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- Power Trac PT425 2001 Model Year
Looks like 175 miles.
RegL
Platinum Member
Here's a good start to a 425.
eBay: WISCONSIN AIR COOLED ENGINE VF4D w/hydraulics RUNS GOOD (item 130098283348 end time Apr-13-07 03:55:06 PDT)
eBay: WISCONSIN AIR COOLED ENGINE VF4D w/hydraulics RUNS GOOD (item 130098283348 end time Apr-13-07 03:55:06 PDT)
I've been reading the posts about the hydraulic wheel motors with interest and have a question regarding my "custom PT".
What size wheel motors would be ideal in my in-between 425/1430? What is the size in the 1430? I would want built in brakes. Obviously, if I am building this, I don't have to worry about retrofits and specific shaft/hub sizes. Top speed is less important than power to the ground. The engine I would use would have no less than 35-40hp (probably gas automotive or industrial).
Someone is selling used Char-lynn 4000 series motors that came off of skid steers on Ebay. They are 24.6 cu/in. with 1 5/8" tapered shafts. No more info given. Starting bid was $40 apiece. Too big? Used a bad idea?
Haven't given up on this idea yet, but I do need to get a handle on some of the big ticket items before pulling the trigger.
What size wheel motors would be ideal in my in-between 425/1430? What is the size in the 1430? I would want built in brakes. Obviously, if I am building this, I don't have to worry about retrofits and specific shaft/hub sizes. Top speed is less important than power to the ground. The engine I would use would have no less than 35-40hp (probably gas automotive or industrial).
Someone is selling used Char-lynn 4000 series motors that came off of skid steers on Ebay. They are 24.6 cu/in. with 1 5/8" tapered shafts. No more info given. Starting bid was $40 apiece. Too big? Used a bad idea?
Haven't given up on this idea yet, but I do need to get a handle on some of the big ticket items before pulling the trigger.
Last edited:
KentT
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ddonnell said:
What size wheels/tires do you plan to use? How fast do you want it to go? I'd make those decisions first, then work backwards from there. The Eaton application guide I've linked below is a great reference for working through the sizing process.
http://hydraulics.eaton.com/products/pdfs/E-MOLO-MC001-E2_Intro.pdf
Once you have nailed down the engine you're using, you'll need to size the pumps (variable speed drive pump, PTO pump, plus any pumps used for steering, the loader functions, etc.) to take full advantage of the engine at its operating RPM.
In a nutshell, I'd recommend getting the highest displacement wheel motors you can get that will give you the speed you want. Then, you'll have the max torque you can get out of your pump/wheel motor setup. Note that there is NO direct relationship between the HP of your gas/diesel engine and the HP available at each wheel -- until you should happen to reach the engine's limits. At all the interim points, the output of the hydraulic pump (in gpm x PSI) is the real limiter -- not the HP out of the gas/diesel engine.
I'm guessing that even the newer PT-425s have never had a wheel motor larger than 15ci or so (15.3 or 15.4 or something like that). The 15.3 ci ones with brakes currently listed Surplus Center were tempting for me, but just didn't offer enough "boost" to make it worthwhile for me to invest the money and take that gamble on them performing well enough to satisfy me. I'm going larger still -- then if I find out that I've "geared it too low" I can always use taller tires to speed it back up somewhat...
On the engine rpm: If I were to get an engine that has a peak horsepower/torque output at a lower rpm than 3600 (which most industrials and diesels have), say 2000 to 2500 rpm, is that a problem with running hydraulic pumps to power my custom PT? Could the whole hydraulic system be based on a variable volume pump and piggyback pumps that optimally run at a lower engine rpm? It seems to me that you should be able to mate hydraulic pumps etc., to the engine that powers the system, and based on KentT's recent posts, finding the right wheel motors shouldn't be a problem. Remember, I'd build this thing from the inside out.
I have a line on several 30-40 hp engines with peak rated outputs lower than 3600 rpm (which to my understanding is what the PT's pumps run at) but could run all day without skipping a beat at 2500 rpm or less. Is this a matter of gearing up or finding pumps that work best at lower rpms?
Suggestions?
I have a line on several 30-40 hp engines with peak rated outputs lower than 3600 rpm (which to my understanding is what the PT's pumps run at) but could run all day without skipping a beat at 2500 rpm or less. Is this a matter of gearing up or finding pumps that work best at lower rpms?
Suggestions?
