Jinma 284 3 point question

[utahaj]

Hi Gents, I'm new here, just bought a clean one owner 2004 Jinma, seems to run good but, just bought a lands pride RBT 1572 rear blade. Problem is I can't get the 3 point to lower, if the lever is left in the lower position it will bleed down after sitting a few minutes. IT lifts great. Is there adjustments or something in the valve? anyone have any sugestions. Probably something I'm doing wrong. Thanks.

 

[bearcreek paul]

I'm not familiar with jima but there usually an adjustment beneath the drivers seat for the drop rate.Someone will more than likely know for sure.

 

[Diamondpilot]

Hi Gents, I'm new here, just bought a clean one owner 2004 Jinma, seems to run good but, just bought a lands pride RBT 1572 rear blade. Problem is I can't get the 3 point to lower, if the lever is left in the lower position it will bleed down after sitting a few minutes. IT lifts great. Is there adjustments or something in the valve? anyone have any sugestions. Probably something I'm doing wrong. Thanks.

I will have this moved to the Chinese Tractor section.

Good news is I have the very same tractor. Mine is a 2003. What you need to do is get it down. Now with the tractor off move the lever up and down along with the Front End Loader (FEL) valve if installed and the steering wheel to remove any residual pressure in the system.

Now as you sit in the in the operators seat there is a knob between your legs. This is what controls how fast the 3 point drops. Remember, it lifts via pressure and lowers via gravity. On the front side of this knob facing the gear shift there is a set screw. Mine is tough to see and takes a strait blade screwdriver. Remove it. Now take some PB Blaster or other penetrating oil and spray it around the base of the plastic knob. Let is sit and try to turn it. My guess is its never been moved and will be tough to turn. Do not force it.

When you get it out take it fully out and clean both it and the mating surface left on the tractor. Dry it off of hydro fluid and put a film of bearing grease on all surfaces and especially the threads. Put it back together. Fully close it then back it off 1.5 turns and try it. You can either put the set screw back in or just leave it out. If you leave it out put grease in the hole to keep dirt out. If you put it back in put grease on the threads again and just put it in loose.

If you need to fine tune the drop speed its best to do so with the tractor off and the hydro pressure bleed off like I explained earlier.

Hope this helps.

Also, fill out your profile so we know where you live. It helps with fluid recommendations via local climate, parts suppliers in your area, or just guys who could come help you out.

Good luck with it. The Jinma tractor is a work horse. Love mine.

Chris

 

[utahaj]

There is an adjustment under the seat. I will have to check it out. Thanks

 

[Diamondpilot]

There is an adjustment under the seat. I will have to check it out. Thanks

Did you not read what I wrote? It tells you the procedure. Follow it or you can damage the valve.

Chris

 

[utahaj]

Thanks, Chris I'll try it in the Morning. I'm pretty sure the guy I got the tractor from only used the FEL on it. he did say he drug something behind it with the tow bar, but claims he only used the 3 point once. Thanks again for the help I'll let you know what happens.

 

[Diamondpilot]

Very important you take the time to clean up the valve. All it is is a cone and a seat so no part to spring out and loose per say if you take it apart slowly and carefully. Take the time to clean it like I said before and grease it.

Also follow the procedure I gave you. It will prevent you from getting a face full of fluid or damaging the valve itself.

Again, do not force it apart. It is probably stuck from not ever moving so take your time and apply even pressure when taking it apart. I think I had to also use a wrench on mine. I think it had flats under the plastic knob or I used some vise grips, strap wrench, or something.

Chris

 

[utahaj]

Will do thanks again.

 

[Diamondpilot]

No problem. Let us know how it comes out for you.

Chris

 

[RonMar]

Some are just a point that protrudes down into a cone below the threads, on others(newer ones I think), the point is pinned in place and can slide up and down a little. When lifting the 3PH, the fluid comes up from the bottom of the cone and flows around the tip to reach the cylinder. When lowering the fluid must flow down and around the point to exit out the bottom of the cone. On the ones with the sliding tip What will happen is if it is set too far closed, it acts like a check valve, fluid comming into the cylinder when lifting, lifts it up and out of the way, but when you try and lower the 3PH, the fluid flow/pressure forces the tip down into the cone, sealing it. I think they did this so it could lift at full speed, but only lower at a reduced speed to help keep the operator from slamming heavy impliments into the ground accidently.

If that knob is closed to the point where it is acting like a checkvalve, The hydraulic pressure from the cylinder supporting the weight of an impliment will LOCK that knob in place, at least it does on mine. Can't hardly turn it with a wrench if it is too far closed with an impliment in the air. Jack up the impliment, or back it up and onto a dirt bank to completely remove the load from the hitch, and I can then unscrew that valve handle with 2 fingers... The handle should be held onto the square shaft with a drift pin. the handle is pretty fragile... As mentioned, there is a setscrew down in front that must be unscrewed to completely remove the valve for cleaning.

 

[tigers2007]

I too was having the same issue. I just cleaned out the little valve and replaced it.

When I adjust the valve to allow it to raise, it won't lower unless I loosen the valve. Even if I fine tune it to the point where it will barely raise, I can watch it slowly drop. If I tighten the valve a little bit more, it holds its place BUT it is too tight for it to be raised.

Does that indicate that I should replace the seals on the 3-point cylinder with the kit I bought from Affordable?

 

[Diamondpilot]

I too was having the same issue. I just cleaned out the little valve and replaced it.

When I adjust the valve to allow it to raise, it won't lower unless I loosen the valve. Even if I fine tune it to the point where it will barely raise, I can watch it slowly drop. If I tighten the valve a little bit more, it holds its place BUT it is too tight for it to be raised.

Does that indicate that I should replace the seals on the 3-point cylinder with the kit I bought from Affordable?

Do you have a implement on the 3 point? It will not usually drop without a item on the 3 point.

Chris

 

[greg_g]

When I adjust the valve to allow it to raise....

That's not what it's for. The lift raises hydraulically, but is a gravity drop. The valve only controls the rate of fall, not lift

//greg//

 

[tigers2007]

Yes I have a heavy back blade on it now. So Greg, if I adjust the valve to have a reasonable gravity drop time, the whole issue of it dropping on its own is a whole separate problem?

I noticed that if I turn the valve half a turn counter-clockwise (therefore tightening the valve), it prevents the 3 point from slowly dropping down.

 

[greg_g]

the whole issue of it dropping on its own is a whole separate problem?

Yes, and a very common one on the 200 Series Jinma at that. It's typically caused by raising the rear lift too high; either with the lift lever (Jinma claims that's what the thumbscrews are for) or by bouncing down the road with an implement held too high. The higher the lift, the farther the piston travels in an open-ended cylinder. The cylinder isn't long enough to accommodate full piston travel, and - at the extreme - the piston O-ring and wiper(s) extend past the end of the cylinder. The act of lowering the lift retracts the piiston, at which time the O-ring and wiper(s) are damaged. From that point on, leakdown occurs.

On some Jinmas, there's an internal stop bolt that's also supposed to prevent over-extension. The operative word is "some", so there's a chance you don't have one. And it's also been found on some that do, that the stop bolt was adjusted wrong (in that it still didn't stop the over-extension in time).

Knowing how common the problem is, I doubt there's a Jinma dealer in the world that doesn't carry a shelf full of the lift cylinder repair kits. Not an expensive or complicated job, just time-consuming and messy.

//greg//

 

[tigers2007]

Thank you for your insight Greg. I'm glad I purchased the kit from Affordable and I'll fix this up as soon as it gets above freezing.

 

[greg_g]

Since you're dealing with Tommy already, he might be able to shed some more light on the internal stop bolt feature. With luck you'll learn whether or not your tractor has one in the first place. And if it does, whether there's enough adjustment in it to prevent this from happening again.

//greg//

 

[bluechip]

If closing the valve that controls lowering speed prevents it from dropping, it is not the piston seal/rings. The knob will not affect that. It is in the valve that controls lifting and lowering, it is not sealing in the centered position or not centering completely. Closing the knob holds the oil in the cylinder, regardless of the control's position. leaky piston seal will allow the 3 point to drop regardless.

 

[Affordable]

Chip is correct,I would bet on the lift valve bypassing too. There is a stop pin on the rear cover,it's not adjustable that prevents the lift piston from extending out too far and damaging the O-rings and wipers,this would allow your lift to drift down even with the valve closed,

Tommy
Affordable Tractor Sales
"Your Jinma Parts Superstore"
Home of compact Jinma, Foton, and Koyker Tractors and Parts, Wood Chippers, Backhoes - Affordable Tractor Sales Company

 

[tigers2007]

Okay so it appears that it might be the hydraulic lift valve then. Is there a rebuild kit for this? I can't find anything on Tommy's web site except for a new valve assembly.