Will the CUT let you know you're asking too much?

[WranglerX]

Too heavy and the load will not lift.

Drawbar pull is too much the engine stalls or the tires slip. In some cases the tractor may rotate backwards around the back axles. This happens quickly and may kill you.

Using straight draw bar under axle height prevents this.... The back flip usually occurs when using 3PH drawbar and its above axle height...

 

[jigs_n_fixtures]

Thanks, all. The loader relief valve was the kind of thing I was thinking when I asked the question. If I understand correctly, for straight loading, the system will prevent you from exceeding the max pressure capacity via the pressure relief valve. That's good to know.

A little offshoot from the original question. Did a little reading, and someone please confirm or correct...I think I read that the pressure relief valve serves the entire hydraulic circuit, to include the FEL and the three point hitch. So, if a Kioti NX4510 has a max breakout force at the bucket of 2990 lbs, and the 3ph max is 3177 lbs (TractorData.com Kioti NX4510 tractor attachments information), could I conceivably screw things up trying to lift, say, 3050 lbs with the FEL? That weight would exceed the FEL capacity (at the bucket), but be less than the capacity of the 3ph, so the relief valve would not relieve until after 3177 lbs (otherwise, the tractor couldn't lift that much with the 3ph).

You can’t screw it up by trying to lift more than rated. The relief valive is use a tee on the pressure side with a spring and piston in it. When the pressure gets too high the piston, normally held in place by the print opens a little, and keeps the high side pressure below a limit established by the engineers at the factory, and keeps the hydraulic and mechanical loads from getting high enough to damage things. If a previous owner had increased teh capacity by putting a shim under the spring, you could potentially damage things, becasue the pressure and loads can now get to levels they didn’t design for. You can also get into trouble by increasing cylinder sizes. if you install a 3-inch diameter cylinder where the factory installed a 2-inch diameter, you have increased the load by the difference in the squares of the diameters. 3-sqaures is 9, and 2 squared is 4. Divide 9 by 4, and you have 2.25 times as much force in the cylinder, and it exerts that higher pressure everywhere it connects, and through all of the parts of the frame which support the load. On a FEL it would be the cylinder mounts, teh arms themselves, and all the pivots they attach to.

Simply put, with out the engineer geek stuff: You can’t damage a stock tractor very easily. You would have to make a concerted effort to do it. And, it would involve changing things. That said carry the load high on a cross slope, and tip it over, and you can total it, and injure/kill yourself.

 

[SmallChange]

Others have alluded to this a little bit, but to elaborate on a hazard that may not be obvious until it's too late: if you have too little load on the back wheels, and you're going down hill in 2WD, the back wheels can start to skid and you will go down the hill rapidly, because there are no brakes on the front wheels. Being on a steep downhill also shifts your center of gravity forward. If it does this enough, your rear wheels will have zero load and will come up off the ground, meaning your machine is supported entirely on the pivot of the front axle, an unstable situation that causes tipping, potentially in any direction.

If you are in 4WD, the front wheels are geared to the rear ones, including the rear braking action. So, the skidding problem goes away. However, the balancing problem is still there.

These issues come up when carrying a heavy load in front, in your bucket or other front attachment. If you carry the load very close to the ground, you can't tip very far forward until the load touches the ground and stabilizes things. This will probably fix the tipping problem, but not the skidding problem.

This is scary because it is insidious. On my driveway, as I start down the hill, the slope gets steeper and steeper. I could get into a situation where the tractor seemed ok, and is still upright at the moment, but is running away from me, and I can't stop it, so I'd have to ride along in hyperventilating regret for a second or three before whatever is going to happen does so.

 

[nyone]

The tractor may stall if HST.

Clutch could slip if traditional clutch and gear.

First thing to check: Is the parking brake on or off.......

I would say your more likely to loose traction than any of these.

When you start hitting the relief valve on your hydraulics or lifting the front/rear tires your asking to much. Any machine that's built properly will beable to easily survive this.

 

[CsaUpstateNY]

Particularly nasty issue with overloading a 4x4 tractors front loader is risk of damage to front axle. Tractors typically are designed to push primarily with the rear axle (big tires) front axles are designed to "assist". If your back tires are light most of the push force is directed to the front axle. So as others have said lots of counter weight in the back (bush hog, plow etc.) When your pushing and lifting with your loader.

 

[MHarryE]

In general, you are going to do more damage to things around your place with the tractor than you are going to hurt the tractor. Read through years of TractorByNet and you will find cars, trucks, buildings crunched by hitting with loader, toys left in the yard by the kids backed over, entrances to garages, machine sheds, etc., crunched by ROPS not being folded if low clearance, etc. Loader is protected by relief valve when lifting, but have read of people loading bucket by hand with loader raised a couple feet off the ground - until getting so much weight in the bucket that the rear comes up and then all kinds of bad things happen.

 

[Hermio]

One more thing- you'll sometimes see videos of tractors being operated with the loader up high. Don't do that. It puts a lot of weight up high, especially if there's something in the bucket. That makes it much easier to tip over.

Keep the loader low and learn to look over, around or through the load.

Not only that, but if you lift large objects high without rolling the bucket downward to keep it level, the large objects can roll down the loader frame, right into you! Think round bales, for example.

 

[Hermio]

I have found that when I try to exceed beyond capacities of my SCUT, it simply does not do what I am attempting, generally the hydraulics just refuse to operate and it goes into bypass (pressure relief mode).... At that point I usually back off attempt and look for alternative ... Exception may be trying to lift with FEL and no counter weight ... Only thing I have been really good at doing is in 4WD and low range (HST) I can dig a hole under each wheel and get the silly thing stuck (trying to push heavy objects that refuse to move), and have to use Jeep with winch to rescue it...

Bottom line is just be aware of CUT's capabilities and respect it.... And when using FEL for heavy lifts, use ballast weight...If its a HST transmission and has inboard wet brakes, the less weight on rear tires the less braking power, it can be a rush especially when when going down hill...

True. Most tractors do not have front brakes. That makes it useful to operate in FWD when lifting a heavy object with the loader. In FWD, the front axle is lined to the rear through the transmission, so applying the rear brakes also stops the front wheels.

 

[Zetorboy]

Guys
Watch out not to break the front axel , witch I have done before!!! You have to be back loaded with heavy weight. Add a piece of equipment at the back like a leveler, whinch, etc. Loaded tire with calcium etc is not enough.
Be carefull! Zetorboy

 

[Omega Woods]

@Haldir00

You are very wise to ask these questions before purchasing a tractor. Be aware that you'll be very careful for a period of time when you purchase your machine, then you'll begin to feel comfortable with your tractor and its limitations. That comfort may lull you into a false sense of security that could cause you to make unwise decisions. Like many here, I've been tractor driving for decades and probably have 4000 seat hours under my belt but I almost rolled over my Kubota BX2380 last year when lifting what I considered to be a light load with the front end pointing down hill while turning the wheels. I underestimated the amount of danger that a small tractor could pose to me and I won't make that mistake again.

Tractors are wonderful tools that can multiply your efforts by a factor of 1000 but you have to keep your head when operating in a way that's different than a car or a lawn mower.

Just maintain your questioning attitude and you'll be just fine.