Siroma 204E (Jinma?) hydraulics questions

[J_J]

You don't need to do that using a DA valve.

One side of lever movement allows fluid into the cyl as a pressure port, and lever the other way, lets the fluid out the same port if there is sufficient weight to accomplish this.

You can even plug the A work port and only use the B work port for SA cyl work.

 

[Jimmy965]

You are correct JJ however assuming the trailer is plugged into port A:
Lever one way to pressurize port A the trailer will lift.
Lever the other way will release the pressure to port A and pressurize port B.
If there's nothing plugged into port B there is no where for the oil to go and the pump will dead head. The whole system will be pressurized up to and including the valve, the same valve that is trying to allow oil to return back to the tank.

Some valves, John Deere for one have a switch to allow the use of single acting cylinders, Jinma do not. If fitted, use the single remote that is operated by the 3PL lever otherwise shut down the engine when lowering to avoid pump damage.

 

[J_J]

The pump will not dead head as there is a relief in the valve that you using for the dump trailer.

The short time the valve is in relief is better than shutting down the tractor.

If using this DA valve a lot, just run the unused work port to tank.

 

[RonMar]

If using this DA valve a lot, just run the unused work port to tank.

Pressure on the supply shouldn't make a difference on A NORMAL da valve installation, but this is a chinese system we are talking about here. Not sure where the OP's rear remote valve is tied in, but I am guessing it is probably like the loaders are tied in, right in the middle of the system without a dedicated return. It's return is probably feeding the diverter, steering and 3PH valves. When trying to lower the dump trailer and the DA valve relieving into these restrictions could indeed be causing the dump trailer lowering pressure to not be enough to overcome the pressure already in the line...

JJ, that is a fantastic idea. A QC fitting to tie into the unused rear remote port, of course the hard part is tying this back into the reservoir. It is easy if you put a new vent into the reservoir, then the filler can be put to use as a return. This is what I did to mine, for two reasons. One i wanted a return on the reservoir. Two, I work on hills/banks quite a bit and the vent in the filler would occasionally burp fluid down the back of the tractor. I drilled and tapped a new vent location up near the middle of the top of the reservoir housing. This fixed the burping reservoir vent. I welded an elbow on top of the filler and added a QC fitting to that so I have an easilly accessed return port which still unscrews and serves as the filler port.

 

[Jimmy965]

Wow ok. In my opinion any operation that causes the massive restriction of oil which in turn causes heat generation at the pump is dead heading. We both know the horsepower required to open a relief valve that is set to give strength at the cylinders. If I had $100 for every pump or transition drive I've replaced under warranty due to continuous operation on relief I could almost visit USA lol. Tractors with draft control mostly. Besides like I said, the trailer will not lower unless the pressure in the system is released. You have pressurized oil flowing from the relief at the same time oil is trying to escape from the cylinder. How do I know? I have the exact same setup, too lazy to fabricate a return to tank for myself but I did fabricate one for a customer. A return to the tank... now why didn't I think of that. Ah maybe I did in my first reply.

A third option:
Adjust the relief valve to the minimum and maybe you won't have to shut the tractor down. Then.....

 

[Jimmy965]

Hi Ron.

I like the way you explain your thoughts with clarity... I'll be taking notes of your style lol. Yes you are correct, the DA valve is in the middle of the system.

Jinma hydraulics:
Pump >> Loader >> Steering priority valve >> DA (if fitted) >> 3PL (and single remote) >> Tank. No dedicated return on any except 3PL.

Doesn't your Jinma 284 have a blanking plug on the left hand side of the reservior to fit a return? When I order Jinma's I specify how many standard QA remotes (not DA remotes). One (pressure only), two (pressure and return) or none. I also sell the return remote with banjo fitting as a spare part. Raising the breather is a very good idea though.

 

[RonMar]

My 284 does have a return on the left side of the reservoir probably where that blanking plug you mentioned is located. But that location already has a return pipe with banjo fitting attached to it, that is the return from the hydraulic steering. I have seen an option that adds a QC on a pipe out the back that is stacked onto the steering return banjo.

ANother option for the OP's dump trailer issue would be a T attached to a QC and plugged into one of the rear remotes. TO the oter two ports on the T, one would go to the dump trailer, and the other would go to a ball valve and back to a return port. Use the DA valve to raise/dump the trailer and use the ball valve to lower the trailer. But again, you still need the point to return to.

I think the OP is probably on the best track, tapping into that port on the right side of the speed reg valve where the OEM single acting port connects to, for using the 3PH controls to operate a dump trailer... The port is already there, so he just needs to plumb to it, vis having to "create" a return port...

 

[EE_Bota]

I have seen plenty of DA valves that won't work right with a SA cylinder. Some, as mentioned, do have a "Switch" that can be turned to do SA, but I doubt that the Chinese stuff does. One example in the tractors I deal with is the remotes on a MF 175.

The real reason I am writing is to say that the 304 has a bolt on the side of the lift body that is most likely that dual triangle shaped valve. If I screw that in, the lift is denied fluid, and the lift control works the quick-connect for a dump trailer instead.

I take it that the 200 series didn't have such a lift shutoff valve? I know some of you fellows know about the "bolt" on the 304, since you guys are the ones that clued me in about it.

I'd probably take the advice about turning the tractor off to lower the trailer since I wouldn't want to dead head the system even for an instant, and it seems like such a small penalty.

 

[RonMar]

The real reason I am writing is to say that the 304 has a bolt on the side of the lift body that is most likely that dual triangle shaped valve. If I screw that in, the lift is denied fluid, and the lift control works the quick-connect for a dump trailer instead.

I take it that the 200 series didn't have such a lift shutoff valve? I know some of you fellows know about the "bolt" on the 304, since you guys are the ones that clued me in about it.

On the 200 series you screw the 3PH lowering speed knob/valve all the way in. That blocks off the fluid to the 3PH lift cylinder and forces it to the SA port.

A system with a relief properly set is NOT dead heading... Ever lift a loader till it reaches the end of the cylinder and stops with the lever still pushed? Ever try to lift something too heavy for the loader and it dosn't move when the lever is pushed? Happens every time I use a loader or any piece of hydraulic equipmet for that matter It is a perfectly normal function to open the relief valve on a hydraulic system, it is also why it is vitally important that the relief gets set/callibrated properly. The relief pressure is set to the maximum system working pressure that the system can maintain. Does it work the pump and load the engine? Yes. Does it generate heat? yes. Is it overly harmfull to the system? No... This is how closed center systems operate all day long. They come on and go right to full working pressure regulated by the relief. The main difference(besides the plumbing) is that closed center systems have large oil coolers to dissipate the heat. Open center systems only casually used do not need the added complexity of oil coolers. and don't consume as much fuel when not performing actual work, so that is what is typically found on tractors and small equipment

"Dead Heading" is when NO relief pathway is provided, such as opening the quick connections on the chinese tractors where the loader is connected, while the engine is running. Since maximum system pressure is regulated by controlling that relief opening, no relief pathway equals the pump tring to build as much pressure as it is capable of(well above the maximum working pressure that the relief is set to), untill something breaks...

 

[EE_Bota]

On the 200 series you screw the 3PH lowering speed knob/valve all the way in. That blocks off the fluid to the 3PH lift cylinder and forces it to the SA port.

The OP is looking for answers, not questions, and you guys are providing answers, so I should just wonder off.

Per the schematic, closing any of the valves, including the variable flow control valve is just a nicety to keep from cycling the lift every time you dump the trailer. The lift will go up, but should not come down, or will come down slowly. That will have the effect of making the trailer dump without delay, but it should dump regardless of what you do with the valves.