HYDRAULIC CYLINDER REBUILD

Sedgewood · Nov 3, 2003

smartguyz: Guys, what do you think? 

I think the drop is normal - at least on the 1845. I seem to recall someone saying a long time back that it's designed that way. I don't know if that's the case or not, but mine will drop fast enough to see it move (when warm). Always has.

May I add a warning here. I once raised up my roughcut mower and put a piece of one inch conduit pipe under it as a safety prop while I changed blades. Ha, right! Needless to say I hadn't thought this thing through far enough. The arm leaked down leaving the whole 1,000 lbs or so of the mower and arm supported only by the prop. It folded. Instantly - just like I pulled the prop out from under it. The mower gave me a nasty whack on the head as it went by and stopped about a foot off the ground. Fortunately I was smart enough not to have any more valuable body parts under there! /forums/images/graemlins/tongue.gif I decided I'm better off without the false security of a prop.

Sedgewood

MossRoad · Nov 3, 2003

Yep. I notice that when I raise my mower deck up for cleaning, and shut off the engine, it will come down in about a half an hour of so. I always put two 4x4 posts under it to prop it up when I am cleaning, just in case some freak thing happens and the loader joystick gets bumped into float. That would crush you in a heartbeat. And, even with the 4x4 props under it, I NEVER GET UNDER IT!!! I use a garden hoe upside down to scrape the underside of the deck. There is just no reason to get my body under there. Sure, I'll reach in there for the grease zerks, but my body is not under the mower deck. If I need to do some maintenance, like my brush hog repairs in the other thread, I take the implements off, use the pallet forks or tooth bucket to tip it up against a tree or the side of the garage, then chain it up for safety. It only takes a few minutes for safety that could save many hours in the emergency room, or worse /forums/images/graemlins/shocked.gif

OK, Off my safety soap box now /forums/images/graemlins/laugh.gif

Has anyone thought of making sleeves to fit over the hydraulic lift rams when they are extended that would act as a safety in case the joystick was bumped? They have them on many larger units with FELs.

Charlie_Iliff · Nov 3, 2003

I think the drop is normal - at least on the 1845. I seem to recall someone saying a long time back that it's designed that way. I don't know if that's the case or not, but mine will drop fast enough to see it move (when warm). Always has.


When I noticed the speed with which my 1845 dropped its attachment, I called Terry. He told me that there are two kinds of valves, and PT deliberately selected the type which bleeds down slowly. I've not researched the question further, since it doesn't cause a problem as long as you remember.

J_J · Nov 3, 2003

YOU GUYS MAY BE RIGHT ABOUT THE VALVE LEAKING DOWN SLOWLY.
MY PROBLEM IS THAT I DON'T THINK MY 1445 IS LIFTING IT'S RATED LOAD. WITH A FULL LOAD OF DIRT, SOMETIMES IT WILL ONLY RAISE PART WAY. MY PUMP IS PUTTING OUT 13 GPM AT 2700 PSI. I SENT MY RELIEF VALVES BACK TO PT AND THEY CHECKED OUT OK. SOMETHING IS LEAKING SOMEWHERE, AND MY LOGIC IS THAT IF SOMETHING IS LEAKING , THEN THE PUMP CAN'T OVERCOME THE THIS. THE PRESSURE IN THE SYSTEM IS CAUSED BY THE RESISTANCE TO THE AMOUNT OF OIL THAT IS BEING PUMPED AND IF IT IS LEAKING, YOU WILL NEVER BUILD UP THE PRESSURE TOO GET THE JOB DONE.
I HAVE LOOKED THROUGH ALL THE HYD MANUALS THAT I HAVE AND CAN''T FIND A REASON FOR A VALVE TO EVER LEAK DOWN. EVEN NOW, MY 1445 WITH AN EMPTY BUCKET, TAKES ABOUT 14 HRS TO FULLY DROP TO THE GROUND.
HAVE ANY OF YOU DID A LOAD TEST TO SEE IF IT IS CAPABLE OF LIFTING ITS RATED LOAD. I AM SUPPOSED TO BE ABLE TO LIFT 1200 LBS. IT'S NOT HAPPENING.

J.J.

MossRoad · Nov 3, 2003

HAVE ANY OF YOU DID A LOAD TEST TO SEE IF IT IS CAPABLE OF LIFTING ITS RATED LOAD 

Yes and no... Our PT425 will keep lifting until the rear end comes off the groud. I haven't checked the exact weight that is, as I would have to weigh the bucket and the load and I don't have a scale.

Bob999 · Nov 3, 2003

MY PUMP IS PUTTING OUT 13 GPM AT 2700 PSI. This output sounds like the PTO pump. The lift system is powered by a separate auxiliary circuit pump that has a much lower GPM rating. This circuit powers the lift, tilt, steering, and quick attach. Have you checked the pressure in the auxiliary circuit?
 I AM SUPPOSED TO BE ABLE TO LIFT 1200 LBS. IT'S NOT HAPPENING.
 According to the PT website the lift capacity of the 1445 is 1800 lbs, rather than 1200 lbs. Typical earth will weight about 100 lbs per cubic foot +/- 20 lbs. How big is the bucket you are using and how full is it?

Sedgewood · Nov 4, 2003

JJ GRAY: HAVE ANY OF YOU DID A LOAD TEST TO SEE IF IT IS CAPABLE OF LIFTING ITS RATED LOAD. 

Well sort of. I had occasion the other day to move the weight bar you see in the bucket of the 484. I've been wondering how much it weighs. There are 16 weights on it. Anyone know what those weights weigh? The forks would just barely lift it at ground level but would raise it ok once it was up a bit. It caused a nice case of PT pucker too, just about the same a fully loaded small bucket of wet dirt! So I'd say whatever that bar weighs plus the weight of the forks is close to the limit of what my 1845 will lift. It's rated at 1200 lbs. Assuming those are 100lb weights, I was lifting close to 2000 lbs, if you include the forks.

Sedgewood

J_J · Nov 4, 2003

With all due respect to everyone, on the subject of leakdown. I talked to several hydraulic technicians at hydraulic supply and repair business. They say that a good hydraulic system should not leak. Pumps should not bypass, valves should not bypass in the raise and lower situation, and cylinders should not bypass. { bypass means leaking internaly} If this situation were to occur in a boom truck, it would cause many accidents, and scare the hell out of a lot of people. The one person that had the implement almost fall on him, definitly has a leak somewhere. I will almost bet that that machine will not lift its rated load. The test they told me to do was to take off the hose near the rod end and raise the bucket or other implement up and see if oil comes out of the open fitting which is on the unpressurised side. you can expect some oil to come out when you first disconnect the hose
They also said that a new system should not leak. If any one has a new pt, would you check your machine and see if it leaks down.
I am goining to rebuild the other lift cylinder to see if that solves my problem. The rebuild kits are about $13.00
Next I will check out the valve.
By the way, I did switch the PTO pump with the lift pump to check the lift and steering to see if the smaller lift pump was bypassing.

J.J.

Charlie_Iliff · Nov 4, 2003

a good hydraulic system should not leak. Pumps should not bypass, valves should not bypass in the raise and lower situation, and cylinders should not bypass. 

JJ: That is certainly what I thought before I got the PT. Sedgewood's experience and mine are the same, however: the system has bled down since new, and Terry advised me that is normal. The test they advised you to try I think requires that you have the cylinder at maximum extension before you remove the hose. If the system creeps down and oil comes out, I think it means that the cylinder is leaking internally. If it creeps down and none comes out, it means that the valve is bleeding the system down. If the cylinder leaks, certainly it will reduce the available lifting force. If it's the valve, it will depend on whether when you open the valve, it sends all of the pump output to the lift cylinder or whether part goes somewhere else. Please keep us posted as you research the issue. I have learned to live with the leakdown, but I must confess I'd be more comfortable if it always just stayed where I left it.
Sedgewood: when you were researching how to restore the hoses, etc. did you come across any valve info which suggests why we get the leakdown? When you have spent time staring at the circuit diagrams, do you see any clues? Any relationship, for instance, to the syndrome where turning the steering to lock, so that a steering cylinder bypasses, it diverts available pressure from the lift cylinder?

Charlie_Iliff · Nov 4, 2003

MY 1445 WITH AN EMPTY BUCKET, TAKES ABOUT 14 HRS TO FULLY DROP TO THE GROUND.
HAVE ANY OF YOU DID A LOAD TEST TO SEE IF IT IS CAPABLE OF LIFTING ITS RATED LOAD. I AM SUPPOSED TO BE ABLE TO LIFT 1200 LBS. IT'S NOT HAPPENING.


Sounds as if your system and mine on the 1845 are different. Mine leaks down in about 10 minutes, max. The lift rating is the same 1200 lb. Mine will lift enough with the forks or bucket that it will almost or just barely lift the back wheels while straight ahead, and pick the outside rear up pretty smartly if the machine is turned. I'm not sure of the weight involved, but it picks an 18 cu ft bucket of dirt if not too wet, which should be a bit over the 1200 lb. rating.
I don't know how the configuration or dimensions of the 1845 compare to your 1445. The new 1445 is bigger than the 1845, with higher lift ratings, etc.