Building your own PT?

[J_J]

What is the difference between industrial engines and automotive engines? More power/torque at lower rpm? And what are the optimal engine rpm and torque requirements for the PT's hydraulic system?

I still haven't totally given up on the build a PT idea, but from the responses, it sounds like maybe I should.

Bagtic,

What is BMEP?

I looked at your profile, and could not ascertain what your occupation is/was. If you are serious about building a machine similar to the PT, you need to be a mechanical engineer, an expert welding, and have a good knowledge of hydraulics, plus an electrical background. Now, you will have to buy most parts at retail, unless you have a good source for the material that you will need. You also need to be able to cut, shape and weld up things like a built in hydraulic tank, etc. It will not be an easy project, but it can be done, with a lot of money, and friends to help, and your dedication to the project. I believe that if you pay yourself and add up all the cost of the parts, and labor, you will just buy a PT, or something similar and save your self a lot of time and misery if it doesn't work out . Pt, has done a lot of R&D in their effort to build a good machine for the masses. They are not perfect, but they are making good money at what they sell.

 

[KentT]

Ok, so what rpm engine speed do I want for running the PT hydraulics? If you remove fuel consumption from the equation, should I be looking for an automotive, industrial, or diesel to power my custom PT? I personally like the diesel I have in my tractor, but if I were to do this (which judging from the responses, I'd be crazy to do) would any of these do the trick (fuel efficiency aside)?

PT uses air-cooled engines (both gas and diesel) that operate at 3000 RPM. That's what their pumps are "speced out" for -- consequently, the pumps direct connect to the crankshafts without needing any type of "gear reduction" to match engine speed to optimal pump RPM.

Many water-cooled diesels are designed to operate down closer to 2000RPM, with a "red-line" of around 2500 RPM.

 

[ddonnell]

I have to say that for a bunch of tractor jockeys who would weld a lightning rod on top of their ROPS, you guys are definitely throwing some serious negative vibes (and I understand why). Seriously, I am thinking of this as a year long project involving a fair amount of input from you. If money and time were the issues, I'd be heading for Tazewell. But that is not why I'd try this. It just seems like a project that is possible and fun at the same time. It is very probable that it wouldn't look exactly a PT, but at the same time it might end up with some features that are better (and worse).

J.J. As to my occupation, I am a dentist. My dad was a farmer, and I grew up builiding stuff. I'm not sure if I will or can do this, but I tend to try things when people tell me I'm nuts. For the most part, it has worked out pretty well over the last 28 years.

Nuts and bolts: I'm thinking gasoline inline six. Fab the entire engine/hydraulic mess on a 5/8" plate of steel with hooks so the entire unit can be lifted out of the tub for service, etc.. I'd build this from the inside out.

 

[BobRip]

I don't think you are nuts. We would like to help and sometimes that sounds a little too critical. Sorry about that. We are probably a little jelous and would like to do this ourselves.

I think starting from the inside out is a good idea. Try to put the weight in the back and don't get discouraged. I think a 4 cylinder is more than adequate, but what do I know. Go with big tires and lot's of wheel motor torque and it will be better than a PT. Use two speed wheel motors for good low speed torque and high speed.

Good luck.

 

[ddonnell]

BobRip,

I agree that an inline 4 would be more than adequate. Inline, I think, is the key to this, as MR said earlier. Thank you for the positive. I understand where everyone is coming from, but I am looking at this as a project to test my fabrication skills as well as giving me something to do. I already have a nice subcut so it's not like I am in dire straits here. Any advice (other than "don't do it") is welcome. Certainly specs. on pumps, motors, etc., or places where I should be hunting would help.

One other good thing: A project like this gives me the excuse to buy more tools! Might need a bigger shop though. Isn't it funny how things seem to expand. I had a friend who's wife only wanted a bathroom faucet changed. By the end of the day, he had the water turned off out at the street! Been there, done that.

 

[MossRoad]

If you are really serious about building your own machine, you should price everything out first. Just the price of sheet steel alone may sour your stomach. List all of the components that you will need on a spreadsheet and start adding it up.

Also, consider the cost of a welder and consumables.

I would also suggest you join Machine Builders Network and start asking fabrication questions over there, as well. Really see what you are getting yourself into.

As for an articulating machine, make sure you know how it articulates AND oscillates or you will build a machine that will get wheels off the ground real quick.

 

[ddonnell]

Power Trac guys and gals,

This building a PT is a probably stupid idea. But it is an idea. You talk all the time about fabbing this or that and all sorts of hydraulic upgrades to make your PTs better. I don't even own one and I already have ideas (mostly from you people) to improve it. I know that Power Trac can make them for less than what I can. But can they build one in between the 425 and the 1430? Better question is: would they want to and what would it be?

I think that there is an "in between" PT that gives more lift, more power to attachments and wheels without having to be 1430 size. Might be a little bigger in front (steel wise) but with the appropriate sized rear (I'm talking tractor weights - lose the trailer hitch) and the heavier engine, I think this is possible.

Hydraulics, well I'm a novice. But I'm guessing that those issues can be figured out.

Bottom line: I think you could make a PT. Power Trac did. Question is, can you make it better without breaking the bank. As someone a lot smarter than me once said "if it's been done, it's probably possible".

 

[Gravy]

It's going to be really hard to build something smaller than a 1430 using any of the engines mentioned. The air cooled v-twins in the smaller machines are around 15 inches front to back and maybe 18" wide. At a guess, an Iron Duke with fan and radiator is probably over 3 feet long and likely at least as wide as the v-twins. You might consider using one of the Briggs Vanguard big block v-twins that go over 30hp. Someday the Generac 32/38 hp engine may actually be available. According to Terry at PT, that one fit the 425 with no changes to the tub.

Gravy

 

[IrTxRx]

ddonnell,

I'll just start making requests to desing improvements... and I don't have one yet either, LOL

1.) a true emergency break on one wheel. Hydraulic, mechanical, magical... I don't care, but something to keep me from running my new PT (and me) over my cliffs when the hydraulics fail OR something that will force the PT into a sharp turn, so it turns uphill if a catastrophic failure occurs

Thanks

 

[RegL]

ddonnell,

I'll just start making requests to desing improvements... and I don't have one yet either, LOL

1.) a true emergency break on one wheel. Hydraulic, mechanical, magical... I don't care, but something to keep me from running my new PT (and me) over my cliffs when the hydraulics fail OR something that will force the PT into a sharp turn, so it turns uphill if a catastrophic failure occurs

Thanks

Cliffs? I would add a parachute maybe!!

 

[ddonnell]

Does anyone have a picture of the articulating/osscilating connection on the PT. I'm having problems finding any from past posts. Thanks.

 

[Charlie_Iliff]

Does anyone have a picture of the articulating/osscilating connection on the PT. I'm having problems finding any from past posts. Thanks.

Sounds like it's time for you to spend some note taking time with a PT. Where are you located?

 

[ddonnell]

Bowling Green, (northwest) Ohio.

 

[Charlie_Iliff]

Bowling Green, (northwest) Ohio.

Looks like an easy day trip to MossRoad, right MR?

 

[MossRoad]

Looks like 175 miles.

 

[ddonnell]

Is anyone familiar with the Continental inline flathead 6 cyl. industrial engine (F227)? Are parts readily available, and would engine rpm be adequate to run the PT pumps? Looks like a pretty simple engine to work on, etc..

 

[RegL]

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)

 

[ddonnell]

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.

 

[KentT]

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).

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 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...

 

[ddonnell]

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?