Back hoe lack of power

Forum Forums Tractor Troubleshooting Back hoe lack of power

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    • #30180
      lenbo
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        I have a Jinma model 354 with a LW7 back hoe – 18″ bucket on a three point hitch and the hydraulic pump came with the BH.  The pump is a small unit bolted on machine just above the PTO spline. I am very dissapointed with the preformance of the BH. The bucket curles very slow, the boom raises slow and neither has much power. When I am able to get a bucket of dirt it is to heavy to lift the boom. I have to run the engine at 1,800 – 2,000 rpm to get it work. However when I move the boom from side to side it really swings with no effort. I  am reall fustrated with this attachment. I have used John Deere equipment in the past and the performance of th JD equipment was superior. I have been told to get a 7gpm Prince pump that attaches to the PTO shaft and it would work better.  I called Afordable Tractor and a tech person (very professional & I believe honest) said that my problem may be with the over pressure valve and to try to turn it in a turn or two to see if I got any more power.  I tried that and the BH still runs solw and I could probably dig faster by hand. 

        Any suggestions?

         

        Thanks

        Len

      • #31358
        mailman55
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          i have a woods back hoe with a simular set up  i was having problems like yours and i borrowed a gage with a whip hose on it and plumed it into the out put side of the pump  and checked the pressure  mine is supposed to operate at 1500 psi, at 540 rpm but it was running at 1000 , keeping an eye on the gage i adjusted the relief valve  until i had the proper psi,  since then it has worked reasonable well,  even though it is still a little weak;  the tech that loaned me the gage  warned against messing with the relief valve with out having the use of a gage, as severe damage can occur if it is set too high;

          leon

        • #31366
          Bob Rooks
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            The pump you have turns at engine speed, that's what the upper PTO does. It sounds to me like there is debris in the pressure relief valve (PRV) and it isn't seating properly. Make sure before you take it apart to clean it to put witness marks on the large screw and valve body so you get the same relative pressure setting when you put it back together.

            Account deleted.

          • #31367
            Affordable
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              I agree with Bob,mailman, the most likely problem is the relief valve,you should also try to get a pressure gauge into the system to confirm your pump pressure,and to set the relief valve once you get it going.

               

              We only sold a few of the backhoes in 2002 ,and we had alot of problems so we quit selling them.hey are less expensive to purchase but can be alot of problems

               

              Tommy

              Affordable Tractor Sales

              “Your Jinma Parts Superstore”

              http://www.affordabletractorsalesco.com

            • #31385
              lenbo
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                Gentelmen:

                Thanks for taking the time to help me out.

                I took the PRV apart and cleaned it, didn't really see and debris when I cleaned it. Turned the screw 1/4 turn less than the orginal mark and it didn't work at all. Put it back to orginal and run real slow, put it 1/4 turn in and seemed to have more power. I just went out to dig a tree stump out and it seemed to work a little better than before, but still weak. Have to run the engine at 2,000 rpm.  I need to get a guage to put on the line to know excatly what the pressure is. Does anyone know where I can get one to fit on my hose and pump or can tell me where to get tge parts to make one?

                 

                Thanks again

                LenBo

              • #31390
                Bob Rooks
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                  Lenbo wrote:

                  Does anyone know where I can get one to fit on my hose and pump or can tell me where to get tge parts to make one?

                  There was several threads on this in the old forums. The metric ORFS to JIC/NPT adapters are available from either Affordable Tractor or Ranch Hand Supply (don't remember which – try both) or over the internet.

                  Account deleted.

                • #31396
                  lenbo
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                    Bob

                    Thanks I give them a call.

                     

                    LenBo

                  • #33355
                    cjimmybond
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                      your pump, you sure it pushes enough lpm

                    • #33445
                      lenbo
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                        I changed to a Prince pump and redesigned the hoses from the sump and to the controls.  BH runs GREAT! See my post on this site “Hydraulic cooling for LW-7 backhoe”

                        Thanks

                        Len

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