The following is the email I received from Jim R:
I have just purchased a Jinma 180, and other than one item, I am very pleased with this tractor.
The one item that I "changed", was the fact that it did not have any protection for the hydraulic pump in case that the quick coupler was inadvertently separated while the engine is running. A quick trip to your local farm supply store will allow you to buy and install a hyd relief valve after the pump, and before the quick coupler. The relieving port (tank line) will have to be dumped on the ground (not really recommended) or hosed back into the hyd reservoir. This was done on my tractor by removing the oil from the tank and drilling and tapping a standard pipe thread in the upper left side of the case, but below the normal oil level (to avoid foaming), and running a line from the relief port on the new valve, to this extra tank return port. The initial relieving pressure setting was 1000 psi, but I had to take the pressure up to about 1100 psi, after I tried to lift my 5' (500+pound) tiller. But I now feel better, knowing that my $35! 0+ hyd pump is protected in case something "unforeseen" happens!
I do have one other comment about your installation of a hyd filter in the hyd pump suction line. The suction filter that came with the tractor is just about all the filter that you should really be installing in front of the pump. That very nice spin on filter would be much better, if installed in the return line somewhere just before the oil enters the tank again. From twenty five years of hyd experience, I will tell you that one of the fastest ways to shorten the life of a hyd pump, is to have a restriction (of the oil flow) ahead of the pump. I work with some hydraulic systems that filter oil down to 2.5 micron size (new oil is filtered to about 40 micron) , but we put the really good filtration after the pump, to prevent any sort of cavitation. Protect the pump with the filter that came with the tractor, and protect "everything" (without cavitation) with a good filter in the low pressure return line (just before the storage tank).
If you would have any interest in viewing just how I installed the relief valve in my Jinma, I would be very happy to send a digital photo, if you desire.
yes, please send pictures and parts list, if possible. Thanks.
The relief valve that I purchased was from our local Fleet Farm store, but it has no special markings, other than it was a 3/4" valve, rated 2500 psi max. A 1/2" valve would be more applicable, but with pipe bushings, this one works well. The valve has basically a straight through flow design, with the relieving port (to tank) on the side of the valve, and the relief adjustment screw on the top (on my installation).
The relief valve mounting bracket was attached (welded) to the factory bracket that holds the splitter valve, and hopefully, out of the way of my future loader mounts.
The factory female coupler will thread on to a standard 1/2" (American) pipe thread, but the hose coming out of the pump, in my opinion needed to be changed. What I did, was cut the hose away from the end that threads into the outlet of the pump, and welded half of a female 1/2"pipe coupling to this now separated threaded end. What this does, is allow you to use American 1/2" pipe fittings and hose, all the way through the relief valve installation, and then put the metric female (factory) coupler back on, utilizing the existing (factory) hose that feeds the oil splitter valve. My system is set to relieve at about 1100 psi, which will lift my 500+ pound tiller, and not over pressure the pump itself, but if someone knows the correct maximum pressure for these Jinma pumps, I would very much appreciate receiving that information.
Hope this information is what you wanted.