Working under pressure or under-pressured?

jinman · Sep 13, 2005

There has been a lot of discussion in this forum about hydraulic pressure and how it is set. One member, Spencer, even bought a pressure testing rig and loaned it to other members by shipping it from TBN member-to-member (although it seems to be "lost" at the moment). Lately, I've been digging/collecting/moving some b-i-g rocks with my rock bucket and FEL. These rocks are right at the maximum capability of my 16LA's lift. One of them was so heavy I had to surge the tractor forward just to get the bucket curl cylinders to lift the front of the rock slightly off the ground while I pushed/slid it to where I needed to put it.

All this made me wonder if my pressure was correctly set. I needed all the 2500 psi, and I found myself thinking it would be nice to check and make sure the pressure is correct. I have two liquid filled pressure gages and I rigged one to a quick connect fitting so I could put it on one of my remote adapters.

I installed the pressure gage into one of the rear remotes, then I started the tractor. I let the engine warm up a little and then I raised the rpm up to about 1500. I operated the remote lever and the pressure gage jumped up to 2200 psi. Then I set the engine rpm up to 2200. When I repeated the remote lever, the pressure jumped immediately to exactly 2500 psi and I could watch the exact moment the relief valve lifted to regulate the pressure. It could not have been any closer to perfect. /forums/images/graemlins/cool.gif

Since the pressure is controlled by a pressure relief valve, I suspect the temperature of the fluid will not have much effect on the regulated pressure. I was really impressed with how accurate my pressure is on my 900 hour tractor. It kinda restored my faith in the factory settings. I disconnected my pressure gage and left things exactly as they are. /forums/images/graemlins/grin.gif

have_blue · Sep 13, 2005

Jim,

I used to bemoan my pressure because the FEL wouldn't pick the rear tires up when curling of lifting, like my old tractor would do. Well, I have found out my pressure must be good. I hooked my bucket under a stump and curled, and it bent the lip of the bucket about an inch!

I curled up my bucket all the way and put the bent spot against a tree. I eased forward against the tree in 5th gear, and the bucket bent about 3" too far! My bucket looked like it was ruined. Desperate, I hooked the bent place under the stump again and curled. Guess what? It bent back PERFECTLY STRAIGHT! Whew!

I have been underestimating the pressure all this time or,,, overestimating the steel in the bucket!

I'm a gage guy. I think all tractors should come with hydraulic pressure gages as well as water temp, oil pressure, ammeter, etc. as standard equipment.

jinman · Sep 13, 2005

( I used to bemoan my pressure because the FEL wouldn't pick the rear tires up when curling of lifting, like my old tractor would do. )

Well, Bob, my FEL has put my rear tires in the air more times than I care to admit, but my rear tires are not filled either. Your TC35 is supposed to be set about 2250 psi. I guess that's because they figure the 35 hp can't handle the higher pressure. Honestly, since the pump and all internal components are the same, I'd be tempted to adjust it up to 2500 psi (by removing some shims in the relief valve) and go get an HD bucket with toothbar or cutter bar so the bent cutting edge would not be an issue. I also think a hydraulic pressure gage would be a nice addition, but under working conditions, we might all be surprised at the high pressure spikes we get when the joystick is in neutral and no relief valve is in the circuit. /forums/images/graemlins/smirk.gif

BTW: How did you fair with Katrina? I know you are halfway between Baton Rouge and Lake Charles. I haven't heard you say whether you got beat up or not, however you may have posted to one of the Katrina threads I haven't read.

have_blue · Sep 13, 2005

Jim,

I think my bucket would still be OK at slightly increased pressure, because I don't think it will bend if I can stay away from those stumps. I keep procrastinating about unloading my tires. I really miss the thrill of being hoisted by my own FEL. /forums/images/graemlins/smile.gif

Katrina was no problem here. All we got were gray skies and stiff gusty breezes. We didn't even get a drop of rain from it. I feel guilty because I took advantage of the cool day to do some tractor work. We have about 3500 refugees in our little town of 12000. More than half are staying with friends and relatives. The rest are staying at small shelters. The store shelves get emptied in a hurry, and the gas stations had to adjust their deliveries to the increased usage. Any phone calls out of town are likely to get a "all circuits busy" message. Thanks for asking Jim!

kensfarm · Sep 13, 2005

"I keep procrastinating about unloading my tires. I really miss the thrill of being hoisted by my own FEL."

I have rear wheel weights & loaded tires.. my 17LA will def. make the rears come off the ground.. I was pulling out t-posts from a temp. cow pasture this weekend.. and even w/ my sickle bar mower on the 3pt.. I had to make sure I worked from the bottom - up when working on the slopes pulling out posts. When I'm back scraping dirt.. the fronts come off the ground almost too easily.

What RPM's do you usually operate at.. for heavy FEL work I'll run at 2600 RPMS. Glad Katrina passed by you w/ no damage.

kozak · Sep 13, 2005

Interesting experiment Jim. Very simple to perform....will definitely have to try it some time. What interests me more about your post though is the B-i-g Rock move. I will be getting some rock delivered next year but have no idea what my tractor can handle. Could you do me a big favour & post a picture of a rock your tractor can actually lift & carry. I realize your tractor has a slight advantage over mine but at least it will give me an idea of what I can expect.

In Advance, Many Thanks !!

jinman · Sep 14, 2005

( What interests me more about your post though is the B-i-g Rock move. I will be getting some rock delivered next year but have no idea what my tractor can handle. Could you do me a big favour & post a picture of a rock your tractor can actually lift & carry. )

Do you think I'd do all this and not post some pictures? /forums/images/graemlins/smirk.gif /forums/images/graemlins/wink.gif

Yep! I'll get some posted this coming weekend. I hope to show the rock bucket in action and my "little" rock garden. I also am going to experiment with using some straps to lift the rocks directly under the bucket instead of out on the tip of its tines. That should give me a lot of my power back if I can get the weight centered under the lift arm pivots rather than all in front of them.

have_blue · Sep 14, 2005

Hi Ken,

I know what you mean. My little TC29 with Woods loader would pick the tractor up and wave it around like the tail wagging the dog. /forums/images/graemlins/smile.gif

I only have a 16LA and TC35, both of which are less powerful in the lifting and curling department than you or Jim.

When lifting and curling big loads, I don't find that increasing RPM helps at all. I have a gear tractor, so I usually run at only 1600-1800 RPM doing FEL work. I find that 1600 RPM will activate the bypass valve just as well as 2600 RPM. I may check and find my pressure to be a little low, but as I told Jim, I can bend my bucket with what I have now. So, I'm OK for now. Right now, I have no problems scooping a big load of moist dirt, curling it, and lifting it to any height. If I scoop a big bite of wet clay from a pile, I can't *quite* curl it without wiggling it a bit. Once curled, I can lift it fine. With a max scoop of wet clay, the tractor feels a little light in the rear with a 400# disk harrow on, but has never once lifted a wheel, even while curling.

Some day, I'm going get me a tougher bucket like Jim's setup, and get a gage.

BadDog · Sep 14, 2005

Now that I have my wheel weights along with filled tires... I can pick up rocks that are as big as my bucket. As long as I can get my grapple around them, I can pick them up. Rear end lifts a bit, but tires stay planted. If BH is on, rear end doesn't hardly lift.

As long as they're not black rocks. The black ones weigh a lot more than the white or gray ones. Not sure if the black is obsidian or granite... either way, I can only pick up a black rock about 3/4 the size of a white one.

I definite get the max out of my hydraulic system, so much so that I discovered the next weak link in the chain: the lift links. All four of mine bent pretty badly, I think from tilting the bucket fast with a very heavy load... they shouldn't bend from lifting. No biggie though, only $120 and about 20 minutes to replace them.

kensfarm · Sep 14, 2005

"I don't find that increasing RPM helps at all."

No.. it won't increase your lifting capabilities beyond the relief valve setting.. but what it will give you is faster hydrolic response for FEL work.

"I only have a 16LA and TC35, both of which are less powerful in the lifting and curling "

Mines a TC35D too.. the 17LA is for the SS. Since our rear tires can be lifted off the ground when weighted.. not sure more lifting capabilities would be practical or useable.

"I'm going get me a tougher bucket "

Do you have a toothbar yet?