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This problem was probably posted before, but I can't seem to find it in the archives. And basically being lazy, I thought I'd ask the question again.
I had bought a Jinma 284 a year or so ago. Got a chance to use a little before I had to go overseas. I tried using the Backhoe but noticed it was way too quick in it's reaction when I barely pulled/pushed the controls. I can't even move them 1/4″ before it goes to full power. It is a frame mount with a separate pump. I tried varying the RPM, but this resulted in loss of power, duh… naturally.
The question is this…. is there an adjustment on the spool valves, pressure at the control body, an adjustment on a pressure regulator, or maybe inserting a flow regulator in it to allow greater control? It has plenty of power to do what I want, I just need a “less sensitive” response at the handles. Thanx in advance for any input.
Jack
People are hilarious...
I'm supposed to choose and be in one of the 2 parties. And NEITHER is worth a damn! -
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I've heard of others who have installed flow restrictors in the lines to slow down the response. I believe Bob Rooks has done this and may have some guidance to offer. My recollection is that a copper disc with a 1/16″ hole was used on the swing cylinder fittings to slow them down, but I could be mistaken.
You can buy adjustable flow restrictors at hydraulic supply places, but finding them to mate up to a Chinese hydraulic fitting could get iffy.
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When I bought my dozer I did not even know what an open centered valve was but thanks to RONJ on another site I believe I know a little more with emphasis on little. I have to yield to Bob, Leon, Rich et. al. for their vast knowledge.
I look at the open centered valve as a variable restrictor. When you open the valve you divert oil to the cylinder circuit. The more you open the valve, the more oil is diverted. I installed copper disks with 1/16″ holes in my blade tilt cylinder. This gave me the control I wanted but when I open the tilt cylinder valve you can hear the engine coming under load and I am sure the relief valve is working. This and the fact that the copper disk may rupture because of the pressure caused me some concern but the tilt cylinder is rarely used so I am happy with the copper disk restrictor. For a cylinder that is used all the time, I would focus on installing a new control valve. That is only my opinion.
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Jackpine wrote:
The question is this…. is there an adjustment on the spool valves, pressure at the control body, an adjustment on a pressure regulator, It has plenty of power to do what I want, I just need a “less sensitive” response at the handles.
Answer: No.
Here is a primer on hydraulic flow (speed) control.
http://www.hydraulicspneumatic…..ulicValves
The flow restrictor that Phil is using in his tilt cylinder is made of copper so the potential for wire-drawing damage (to the restrictor) isn't known. A flow restrictor will economically solve your problem of “jerkyness” without loss of power. If these are to be used with the ORFS fittings then I would have them made from steel with O-ring captures on both sides.
Account deleted.
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Hal,
It's a JW3. Maybe not a great choice, but hey… it was already on it. For what I got to do… it works okay.
Phil,
Sounds to me that that's the easiest/cheapest route. Thanx
Bob,
Interesting link. Thanx. Some of it I knew but there was info there that is current and I wasn't aware of due to not keeping up with techno advancement. See? you can teach an old dog new tricks.
I also agree that steel would be better as maybe copper is too soft a material due to pressure and wear factors. I don't suppose you would have offhand at the top of your head the outside dimensions of the orifice and a starting point for the size of the hole. I then could enlarge it gradually till I get the desired handle response.
I guess the biggest problem I'm facing gentlemen, is the side swing and also trying to do finishing touches where I'm only wanting to remove/smooth material at the end of the dig. As it stands now, you literally have to “tap” the handle to get the B/H to move only a little. NOT what I'm used to… VERY frustrating.
Thanx all.
People are hilarious...
I'm supposed to choose and be in one of the 2 parties. And NEITHER is worth a damn! -
Also check your pressure @ the backhoe valve. When I retrofited mine with a hydraulic thumb I installed a pressure gauge on the discharge of the PTO pump
(should have also installed a relief valve before the quick connect, but that is another story) . I found that I was operating at 3200 psi. Dropped it back to 2200 psi. Much less banging around, power was still good.
You can take the chineese hoses in and have them cut (mine are one wire), they have fittings that will fit the ID & OD of the hose and install what ever type of fitting you want. The problem will come when the OEM hose fails and you have to find a fitting to connect to a pump, valve block or cylinder. They do exist and can be purchased, usually through special order from an industrial hydraulic supply shop.
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