Goaty Posted May 5, 2015 Report Share Posted May 5, 2015 Im in the process of changing tractors. From an open center hydraulic system to the closed center modern type. Thought I would post for my reassurance and everyones interest. When I purchased the Bryce` post knocker, I vaguely remember reading that the valve block on the knocker needed alterations. I have been in touch with Jock and received the needed parts. I understand the basic difference with the pumps is the open center is always circulating oil under pressure, which returns to the supply. Whereas closed center, the pump is moving all the time but only supplies fluid when it senses a need for it. This means sometimes because the post knocker is pumping through the spool valve but actually idling because the machine is not being used. The tractor can fail to supply fluid at pressure when needed. I might be wrong but this is the theory I believe. Anyway here is my valve bank as configured in the open center configuration. Then we did the following. Does anybody elses look similar? Link to comment Share on other sites More sharing options...
ffencing Posted May 9, 2015 Report Share Posted May 9, 2015 I've run my Bryce a 2011 model on both Open centre and closed centre tractors with no modification. I was under the impression you only needed to make the modification if using an older JD type CCLS system. Or are you using power beyond and need a 'sensing' line? Link to comment Share on other sites More sharing options...
Goaty Posted May 9, 2015 Author Report Share Posted May 9, 2015 Mine is a 2011 model too. I tried the knocker briefly on the new tractor a while back without altering it. It worked fine. I think there is two issues with closed center pumps depending on manufacturer. Either the system fails to supply the pressure when needed or it stresses the valve bank on the Machine causing leaks. I did enquire with Bryce before doing this and followed the instructions they supplied. I asked my mechanic about this. To sum up what he said. The closed center systems are weird and don't all work the same. Will see how it goes. I think more pressure is now in the return line from the hammer as the return oil is going back by a different route. Power beyond and sensing line is Beyond my hydraulic knowledge at this time. Thanks for being informative ffencing. Link to comment Share on other sites More sharing options...
ffencing Posted May 10, 2015 Report Share Posted May 10, 2015 It's important that the return is genuine free flow and through a 3/4" coupling. If there is back pressure on the return, one problem caused will be the back pressure can damage the seals in the valve block, particularly when the hammer is dropped and there is a small spike in return flow. What tractor have you changed to? Link to comment Share on other sites More sharing options...
Goaty Posted May 10, 2015 Author Report Share Posted May 10, 2015 John Deere 6620. I did have the proper free flow wider spec coupling and pipe returned in to the transmission plug below the axle on the case, the JD goes into the transmission block housing without a pipe. It was fitted for a diet feeder wagon. Link to comment Share on other sites More sharing options...
Ben Fencin Posted September 13, 2015 Report Share Posted September 13, 2015 I operate my new Bryce on a John Deere 6310. The post driver seemed to work fine without the kit, but I would have to cut the flow to use my draft/link arms or loader. After installing the kit I was then able to operate other functions with oil flowing to the driver. I did have a problem with the pressure relief valve in the valve block after installing the kit, I started another post about the solution to this. Link to comment Share on other sites More sharing options...
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