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790 Horsepower and 419 loader issue

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deeremd
Join Date: Jul 2003
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2003-11-19          69083

Can anyone explain to me why Deere REDUCED the HP of the 790?? I bought mine on the assumption that it had 30 hp, but as others have mentioned on this board, the specifications of the newer 790s indicate that it has less.

Also, does anyone know of a way to get more lifting capacity out of the 419 loader? It doesn't seem that mine is evem meeting the capacities as specified in the manual.

Any ideas would be appreciated, thanks!


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DRankin
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2003-11-19          69097

I could be wrong, and I am sure someone will correct me if I am...... but I don't think Deere changed engine models on this tractor. I think it was, and remains a 3NTE84.

I think they changed the way they report the numbers. I have brochures that are several years old that give gross HP (30), net HP (27) and pto HP at 25.

After a while they dropped the gross number and just reported the 27 and 25 numbers which morphed to 27/24. When you think about it nobody lists just a 2 HP loss at the PTO. It is always at least 3 HP and sometimes quite a bit more.

The old 30 HP stats said the torque was 54.1 foot pounds at 2600 RPM. What does your owners manual say now?

As far as the wimpy loader the only way to know for sure is to get a baseline. Have the dealer put a gauge on the system to see if it is running up to spec. ....

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F350Lawman
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2003-11-19          69103

The 37/24 hp figure is the figure now. The engine is also a 3NTE82.

I believe I was the one who discovered this "change" when I took delivery and happened to glance at the plaque on the motor. This started a bunch of posts on this and another board. Some of us contacted JD and the JD web site and newer brochures started reflecting the true engine model and power numbers.

I don't think that hydraulic power was changed as the new motor still spins the same pump at the same speed to the same pressure settings before it defaults. As far as lift capacity I don't have numbers. I can say that even before I tweaked it I moved 600lb objects that hung out of the bucket with ease to full height at idle.

It is a great tractor that is a little light in lift capacity, but I don't think the hp reduction cost much if anything in useability. At around 3000lbs with the FEL on this thing will lose traction LONG before it runs out of power. I've pulled huge rocks, 5000lbs trailers, skidded telephone poles 2 at a time all with very litle effort. Like all little tractors if it has grip it's a beast, power has never been it's downfall. I keep a 500lb counterweight on the back and it is very stable and the traction is very much improved.

I don't anticipate much if any decline in lift capacity with age. The tractor's relief valve is what stops you, not the pump running out of power. It seems JD went real safe and conservative with their settings. That is why some of us have tweaked the relief valve settings with about a 20% gain in lift. Tractor now lifts the front end easily without having to curl the bucket and will lift a bucket full of anything I need to lift including wet earth.

Unless someone is going to be lifting huge items all day the 790 is great. If you need that much lift you need a bigger tractor. Even if some other manufacturers tractor can lift more, if it weighs around the same as the 790 it isn't going to be safe to do often. ....

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Art White
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2003-11-19          69112

Many of the tractors basic spec's are the same as smaller tractors. Compare the hitch, loader, it's nothing bad they were just realigning there line up and will probably be introducing a new model shortly. This basic chassis has done them well for many years in this market. ....

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deeremd
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2003-11-19          69117

The newer manual says that the 790 has 50.1 foot pounds of torque. But I guess nobody really knows if these numbers reflect a true change in the later model 790 tractors, or just a change in the way the numbers are reported?

F350Lawman: How did you boost the FEL to get an additional 20% lifting capacity??
....

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Murf
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2003-11-19          69118

The lift capacity of any loader is the result of an equation. That equation is PSI of the hydraulic supply times the surface area of the piston(s) doing the lifting.

If you want to increase th capacity you either increase cyclinder diameter, or increase the PSI powering it, or both. The easiest (read cheapest) way to do that is to raise the pressure at which the relief valve opens. Normally this involves nothing more than loosening a jamb-nut and turning a screw.

A word of CAUTION here. If you boost the hydraulic power to the loader beyond the design capabilities of the loader frame and/or bucket, it could result in a catastrophic failure.

Best of luck. ....

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F350Lawman
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2003-11-19          69119

Here are some posts from older discussions on this topic. I also added a photo . See the link at the bottom the cap is #6 and the shims are #8. Obviously this is at your own risk, but I am confident I am still within safe parameters.

"The part number for the shims is AM875169. I believe the is the number. There is another number on the package (20030213DY4), but I think the first one is the part number. You need to order two of these packages. It is an assorted pack of shims that you can put in to increase the relief pressure."

"OK, I'm going to try and post a picture with this email. Flip up the seat on your tractor and this is what you will see. You will notice there are three caps. The one on the right (looking from the rear, it is the tallest cap) is where you will add the shims. Be careful when removing the cap because there are a couple of parts from inside the cap that can fall down and get lost. The shims get added to the inside of the cap, so as to push all of the other parts down slightly more. I originally said to add two full packages, but don't do this. I put mine on a guage and the PSI was way too high. Get a guage, start with one full package, and then work up from there. Keep in mind that the factory setting is 2050 PSI. I have mine at 2500 now with a modest increase in power. (3500 works really good, but don't ask how I know). When putting the cap back on, if it seems difficult, then reach in the hole and pull out the rubber o-ring and slip it over the threads on the cap. I will thread right in then.
I didn't measure it w/just one pack. I had both packs in when I saw the 3500 (actually a little more...the guage was a 3500 psi guage). My brother, who is a diesel mechanic, said that there was danger of cracking the pump at that pressure. We took out part of one of the packs and came up w/2500. Most of the difference was in the second pack. I would buy two packs (they are very cheap) and add them accordingly. The factory rated 2050 psi is just a safety measure that JD has built into these tractors so that no one turns one over. The frame on the loader as well as the hydraulics are capable of much more than this. I would actually feel comfortable at 3000 PSI....2500 is very well within the safety margin. There is a modest increase in lift capacity w/2500. My tractor would not even pick up a full bucket of sand before."


....

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John Deere Tractors 790 Horsepower and 419 loader issue
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liljoe
Join Date: Sep 2003
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2003-11-19          69143

any chance of getting u to take a dial caliper to the shims u currently have in there. so when i get the shims i can just measure and install them. thanks joe ....

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F350Lawman
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2003-11-20          69144

I installed one full pack of shims.

The pack contains 6 shims of varying thickness. All together they are less than 1/8 of an inch in thickness when combined.

I did not make all those posts so unfortunately I am not the guy with the guage :( I have any means of measuring the shims accurately.

My gains where measured by a big rock that I could only lift several inches high before the modification,I now can lift it to near (I didn't try to go higher due to no ballast at the time)full height. I also could not lift my tractors frontend with the FEL w/o using curl, I now can. Not scientific but all the gain I am really looking for.

when you look st the relief valve you will see it is avery small poppet that is forced into a small 1/4" hole by the spring. the shim pack gives it just a little more downforce into the hole. the spring seems to be alittle mushy for the first bit of movement then it toughens up, the shims probably take away some of that "mush"

I would go find something that has just been slightly too much for your loader, add one pack and try to lift it. Try the FEL lifting the front of your tractor as well. Those tests will let you know if you have achieved any gain. If not add a couple more shims and try again. It only takes 5 minutes and by going in increments it will be safer. Every tractor is probably a little different when we get it from the factory so even if I had measured results yours might be different. Thats probably why they make the shims to bring tractors back to specs.

I probably only gained a couple of hundred pounds of lift but that is the difference between lifting full buckets of dirt as opposed to 3/4 full. Actually I always could lift full buckets but freeing them was sometimes tough and slow if I had to grab mid-pile or lower.

Good luck ....

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mainiak1
Join Date: Jul 2003
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2003-11-20          69146

I installed one pack of shims in mine and it pressure tested at 2400psi. I tested it before and it tested at 2050 psi.
Mainiak1
....

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deeremd
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2003-11-20          69166

So, there is really no way of knowing (without a gauge) whether to add one pack of shims or more?

....

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glalonde
Join Date: Sep 2003
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2003-11-20          69175

Where and how do you connect your gauge ? Is it at one of the 4 hydro lines of the FEL ?

Does JD sell the gauge ?
How do I find out about the correct fittings to connect the gauge to the 790 hydro lines ?

Thanks,
Guillaume ....

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F350Lawman
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2003-11-20          69188

"I installed one pack of shims in mine and it pressure tested at 2400psi. I tested it before and it tested at 2050 psi."
Mainiak1

Uh-oh we've opened Pandora's box!


....

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F350Lawman
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2003-11-20          69190

I pack is a modest increse in power. Several people have done this with no ill effects.

Load that loader up to default, and then try it with one pack. You will lift it with a little power to spare.

....

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Murf
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2003-11-20          69191

Just wait until everybody realizes you can do the same thing to the 3pth capacity.....

And I'm not even going to MENTION the easy ways to get a few extra horsepower .....

Best of luck. ....

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mainiak1
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2003-11-20          69192

Where and how do you connect your gauge ? Is it at one of the 4 hydro lines of the FEL ?

Does JD sell the gauge ?
How do I find out about the correct fittings to connect the gauge to the 790 hydro lines ?


I bought a guage 3000 psi and brought it to my JD dealer.
I got the male fitting that goes onto the quick disconnect.
When you move your loader, one operation will not work but you will get a pressure reading. ....

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Art White
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2003-11-20          69193

The good part of it for the dealer, the bulk of the hoses used are only a 2500 or 2750lb rating and they will be able to sell more parts. Only some manufacturers have higher ratings on there hoses. Bad part is, I hope nobody gets hurt from this. There are things to turn up and it doesn't hurt it and there are things that it will make a difference. ....

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Chief
Join Date: Jul 2003
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2003-11-20          69199

I believe it has already been mentioned once in this thread that whenever you make a modification which exceeds the OEM design limits or capacities; you do this at yours & your equipments peril and risk. I would think that it perhaps might be wiser to consider a large and better suited tractor or piece of equipment rather than making a modification which may at the very least shorten the life of the hyd. pump or lines. Be VERY cautious and careful. Hyd. systems can have disasterous if not fatal consequences should they fail under some circumstances. If you all would like, I can post some pictures of such consequences if Dennis approves. I have worked on and around aircraft and flight line hydraulic systems which readily exceed 3000 psi and have seen first hand what can happen when something goes awry. Use proven and approved procedures and be VERY careful! I will step off of my soap box now and that is the last I will mention of it. ....

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BARNEE
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2003-11-20          69200

I'll second Chief's advice. I work around high pressure/temperature steam systems & it's easy to get complacent with your surroundings. Just because it works now doesn't mean it will continue to do so safely. Just be careful with what you're doing. This is one of those things that could reach out & touch ya when ya least expect it.... ....

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F350Lawman
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2003-11-21          69216

John Deere uses 3000psi hoses in the 790.

According to guys who have tested the pumps with 1 pack of shims I am at 2500lbs at the most. I think I am still safe. The pump is designed to run for years at 2050 or 2100 lbs. I don't think it will grenade at 2500lbs.

I could be wrong but I am the only one who uses my tratcor and I always treated the hydraulics like they might break at any moment anyway. I check the hoses often and make sure I NEVER stand or reach under lifted objects on the FEL or 3pt.

Don't tractor pumps tend to last MANY years? If my pump lasts a few years less, so be it. I think I saw it listed for $375 or $400 dollars. If I get 15 years instead of 20 or 7 instead of 10 it will have been worth it.

I am very good at maintaining my eqiupment so I'll bet I get the average or more out of the pump anyway.

Time will tell. Many of us have diesel trucks, with exhaust systems, air intakes, chips, even propane, it 's just our nature to tinker :)

As far as getting a bigger tractor...I would probably do the same thing to it ;) ....

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Art White
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2003-11-21          69226

I actually think that is just a guy thing! Most all boys like to play with the toys. I do believe that we need to watch what is said here as I would not want to be responsible for someone getting hurt with information from the board. Most hoses from a manufacturer are in the 3000lbs range. I guess I would worry more about a replacement hose needed because of the modification for aggrivation later then the pump wear itself. ....

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Murf
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2003-11-21          69236

From an engineers point of view, gauge readings mean NOTHING. Things don't break, bend, tear or fall down on PAPER. It happens in the real world all the time though.

As Tom noted in a different thread, static loads are one thing, shock loads and inertia are quite another.

If the engineers who designed that device did their job properly, it was designed to operate at optimum performance, with a margin of SAFETY built in. As a rule of thumb, mechanical devices need about a 20% margin for safety. My calculator says that a bump from 2100# to 2500# is a 19% boost, I don't like that idea.

Now I'm not saying that anything WILL go wrong, but if there's NO margin for error, and you were to hit a bump with a front wheel when the bucket was loaded I'm sure that pressure gauge would climb well above the 3,000# point.

In large machines it is common to have scales built into the FEL, they are basically pressure gauges which are calibrated to read pounds on the loader instead of PSI in the system. It would be simple for someone to do the same thing with a CUT by installing a T fitting and screwing a gauge in. Sample 'loads' of known weight, conc. blocks, etc., could then be used to calculate the relationship between system pressure and load on the bucket or forks.

Best of luck. ....

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DRankin
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2003-11-21          69237

I wouldn't worry about the pumps and pressure hoses on the 790. Seems like that engine is used in another model and I would doubt there are two different versions of hydraulic pumps for the same engine.

I believe Deere, being conservative, holds the system hydraulic down in deference to the dated mechanical design of the 790.

My 24 horse 4115 has a system pressure of 2420 psi and I am sure it comes with identical hoses and fittings, probably made in the same plant.

I think if you are going to stress anything by kicking up the pressure, it would be the axles or frame. That would be the place to watch. ....

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TomG
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2003-11-21          69239

I think I'd be more aware of balance and stress to the chassis from working with heavy loads than wear on the hydraulic system. Clutches and HST's would take a greater beating as well.

Almost any gear pump is capable of supporting around 4000 lbs. loads. Newer gear and piston pumps go much higher. But high working pressure over time would reduce the volumetric efficiency prematurely. The system also would run hotter, which also doesn't do components including hoses any good. 3,000 lbs. rated hoses are likely working pressures. SAE standards call for minimum bursting ratings of four times the working pressure, although some designers may not use SAE standards.

Still bursting is an issue and heat, pressure and sun over time deteriorate hoses. Relief valves don't crack instantaneously and spikes well above relief pressures can happen if loads drop etc. That's the reason for conservative burst ratings and it's hard to tell how big of pressure spikes can occur on a particular tractor. What's being talked about here doesn't seem like wholesale compromises of ratings, but just the same the idea that rated working pressures can be increased should also include the notion that there are increased risks to operator and equipment. ....

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F350Lawman
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2003-11-21          69265

"My 24 horse 4115 has a system pressure of 2420 psi and I am sure it comes with identical hoses and fittings, probably made in the same plant.

I think if you are going to stress anything by kicking up the pressure, it would be the axles or frame. That would be the place to watch."

I agree. I was going to do a little search, I would bet even money JD or maybe Yanamr itself uses this pump at 2400-2500 in other applications. The hoses and fittings are a lock to be used in MANY diff. machines at higher pressures.

I think that JD has it low for 2 reasons.

1. They don't want the cheaper tractor lifting as much as their higher priced tractor

2. The tractors a little light and some people need all the help they can get not to hurt themselves. Same reason my lawn tractor has 48 safeties :)

As far as the axles others have posted the specs. they were well more than I can lift. If memory serves me, you would need another 790 in the FEL to surpass them :) The tractor only weighs about 3500 with the FEL and 500lb counterweight. I also have R-4s and the two front tires alone when combined can support 3000 lbs. I should be good there. The rears support over 8000 lbs., no problem there either

Remember this tractor only lifted maybe 800 lbs. before, if it lifts 1000 now we're not talking abotu HUGE loads. I think the 790 frame will compare well to other similar HP, size and weight tractors that are lifting more everyday. If I put this tractor frame next to some of the others I saw when shoping, a first time observer would have thought the 790 was rated higher. Especially that front piece that wraps around and supports the two frame rails, some of them looked like they were 1/4" thick, this one is 1/2" at least. Not scientific but this frame certainly looks pretty good for such a light machine.

In actuality how often will one really be carrying the addtional weight maybe 1-2% of the time??? I am not running a quarry over here :)The only time I would be stressing the frame , axles, etc beyond the original specs. would be when I have between 800-1000lbs in the bucket..that aint' often. When I am anywhere near that much weight I will be driving 2 miles an hour or less on the flattest, smoothest area like I always did for the usual safety reasons.

I would have more concerned with the manufacturers who rate 3000 lbs. tractors to lift 1500lbs when some dummy actually tries it without ballast. The way JD has the 790 setup and rated it's idiot proof......

Well at least it was ;)

I did try to do some checking and spoke with others before I did anything. I usually research things to death before doing them and this was no different.

If I am wrong you'll be the first to know ;) ....

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Murf
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2003-11-21          69270

Unfortunately it's common to 'reverse engineer' things these days.

You start with a destination point and work backwards. Unfortunately there are many pieces that make up the whole system.

I have no doubt that the entire hydraulic system is more than robust enough to handle 3 times that load.

However, Murphy's Law (trust me) says that somewhere in the blend theres a $2 pin, a $0.25 bolt, or a weld that isn't up to the excess load. "That's when it gets expensive." as my former Prof. used to say.

Best of luck. ....

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F350Lawman
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2003-11-21          69271

""However, Murphy's Law (trust me) says that somewhere in the blend theres a $2 pin, a $0.25 bolt, or a weld that isn't up to the excess load

Yeah I'll be the MOST common failure by a 10-1 margin is the owners failure to keep the bolts on the FEL structure, frame etc. tightened causing thing to flex and break. :) ....

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Murf
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2003-11-21          69276

Apparently the Space Shuttle disaster was caused by insulating tiles coming off, maybe they should have used Crazy Glue... Oh well, there's an old adage, "The Devil lives in the details." and I suppose it's true.

Best of luck. ....

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glalonde
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2003-11-21          69291

So far I was able to carry a full load of heavy stuff such as wet clay or sod, etc. without boosting the PSI. However, lifting it up high (for dumping over an existing mound) was not always possible, specially if I had a heaping bucket of the heavy material.

My main problem is more to get that load into the bucket from an existing pile. The lifting capacity of the 790 is sometimes not enough to 'break' the pile.

I will try the additional shims (after I get a gauge first to make sure the extra PSI is not over 2500). Hopefully this will help breaking into the mound of clay/sod I have. I have ~600lbs on the 3pth which so far has kept the tractor very stable. ....

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kwschumm
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2003-11-21          69294

Actually, Murf, the official report on the Columbia disaster was that foam (not tiles) came off the fuel tank and damaged tiles on the wing. Which leads to the question why did the foam break up? They eliminated CFCs from the foam formula to be environmentally correct, and the foam has been breaking up ever since. ....

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F350Lawman
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2003-11-21          69297

"My main problem is more to get that load into the bucket from an existing pile. The lifting capacity of the 790 is sometimes not enough to 'break' the pile."

BINGO!

....

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TomG
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2003-11-22          69331

There are some down-sides to altering factory settings as mentioned. It also might compromise warranty coverage and insurance so I think it'd be something to avoid. I don't know how much operating experience people here have--maybe more than mine. I did learn a few techniques along the way and don't get the bucket stuck much anymore. I'd like to think it's a good idea to make sure that operator technique can't solve problems before thinking about pushing the envelope. However, my bucket is fairly small for the tractor and intended more for aggregates than mulch. I wouldn't expect to be able to break out full buckets of aggregates if I had a large bucket except if I had a bigger tractor to go along with it.

The trouble with envelope pushing is that there's no clear place to stop and there'll always be jobs too heavy for any tractor. It's easy enough to get into a hot-rod syndrome but that's not what I'm hearing here. I agree with the notion that it's frustrating to pay big bucks for equipment to get work done and then find it's been engineered into an idiot-proof vanilla-flavoured lawn ornament. Ultimately it may not be very safe engineering either. Adults are going to insist on being treated as aware and responsible for their own actions. They're likley to take risks to get the job done even if a tractor is hamstrung. ....

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F350Lawman
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2003-11-22          69358

No need to push the envelope any further. The tractor picks up a full bucket of material including wet earth and lifts it to full height. No reason to ask it for anymore.

I just spent the day cutting come horse trails in the woods. The tractor and especially the loader got a real good workout.

That completes the post-modification field trials...all systems go. :) ....

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TomG
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2003-11-23          69378

There's an example of extreme but unintentional envelope pushing over on the antique board. An old Ford farm tractor is blowing a seal in the pump every couple of months. Best guess at the moment is that the relief valve is frozen. If that's the case it's interesting to note in light of this discussion that pump seals rather than the hoses blew--no guarantees though. Good feeling to have a job finished. ....

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Art White
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2003-11-23          69381

Tom many older farm tractors only ran with 1200 to 1500 lbs pressure and 2-3 gallons hydraulic force. Even the 5000-7000 series of the seventies only had a 7 gallon per min pump. Good reason they don't blow hoses. ....

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TomG
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2003-11-23          69388

Real good point Art! No direct comparison intended and my main attitude is to avoid envelope pushing.

I think the example was a front pump on one of the bigger 1,000-series tractors but it probably has similar performance to the main pump. Newer pumps do have higher cut-off pressures and higher working pressures. I read an article from the late '70's that I think said piston type pumps have cut-off pressures around 12,000 lbs. If an SAE 4-times burst to working pressure standard was applied then 3,000 lbs. hose likely would withstand pump cut-off but that would for be new hose and hose does deteriorate so it's not something to depend on.

Most of us have lower pressure rotary type pumps but whatever the case I think that good design wouldn't have cylinder hose as the weakest link. Most systems don't have check valves on the cylinder lines. The concept here is that envelope pushing might push performance beyond the intended weakest link. Systems do have pressure spikes so any envelope pushing should be thought of as running some risks. ....

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F350Lawman
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2003-11-23          69398

"Systems do have pressure spikes so any envelope pushing should be thought of as running some risks."

The biggest risk BY FAR was cutting a horse trail through the woods one week into hunting season. The rest is all just conversation :)

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deeremd2
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2003-11-30          69991

Has anyone confirmed for a fact that the hydro pump on the 790 is the same as on other JD tractors and is operating at a higher pressure? That would be a sure sign there would be no problems with increasing the pressure...

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TomG
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2003-12-01          70019

Hi MD: The hydraulic system likely would withstand higher pressures without much difficulty.

The issues here are whether there's a policy to set relief pressures below spec. If so, is it due to engineering considerations or corporate liability? The subject is more about stability and stress to the chassis from lifting greater weights than about damage to the hydraulic system. Higher pressures would shorten the life of components but most people's tractors are going to outlast them anyway. ....

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deeremd
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2003-12-01          70027

Alright Tom, you've asked the questions...So what are the answers??? :)
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TomG
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2003-12-01          70030

No clear answers and largely a matter of personal choice. For me, I'd leave things alone if I were getting the work I need done without problems. If I had problems I wouldn't think too long about bringing low pressure up to factory specs. If I still had problems I might think a little longer about accepting greater risk and going above spec.

There may be a tendency for factories to turn out vanilla-flavoured tractors that are most suitable for novice owners but it would limit a tractor's capabilities--especially for occasional heavy-duty tasks that might be accomplished just fine by experienced operators. I would have to keep in mind that any problems then would be on my head, but that's the way it should be for adults. I did mostly avoid this issue myself when I bought a 3ph fork lift for my heavy-duty lifting. I may be more risk-adverse then some. ....

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Art White
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2003-12-01          70032

Why would a company mess with something that works? By that I mean that they don't have high warrantee rate! Why would they change it? It could be that they might have some new models coming out, or it could be that they had to many failures or were looking at reliability. Much the same as most parts like a hydraulic pump that would be outsoursed for production. Maybe they were told that do to a change that might save them 50cents per tractor but they had to lower the pumps out put to have them exist for X number of hours. They also lowered the horsepower of the tractor which also tells me they might be at a replacement. If you want more the most dependable way to have it is to buy more! You can change your yugo and install mercedes power train and suspension, the name on the grille is still Yugo! ....

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kubotaguy
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2003-12-01          70043

I am on the side of not making adjustments such as these. Everything has limits and should not be messed with. For example most humans could survive a fall off of an 8 foot high roof, but do you push the envelope and roll off of a 12 foot roof. Making adjustments such as these may work out ok for a while, but when things finally go sour, it may be too late and cost you dearly. I would rather use my compact tractor as intended and take a little longer to get the project accomplished than end up breaking my machine, gettin injured or worse even killed. Those are just my two cents. ....

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TomG
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2003-12-02          70106

Thanks Art for noting that manufacturers may make changes for reasons other than my usual stocking horse of corporate liability for all explanations. I'm also in favour of using more tractor for heavier work.

No matter what you have though, there'll always be jobs too heavy for the tractor that's available and also jobs the tractor is too big for. Almost all operators will face problems sometimes. I think we do a pretty good job around here of bringing out the ideas that can make for fairly realistic ways to approach problem jobs. And well, contractors are sometimes the best solution. ....

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