Morning folks, I have no books on this rig and actually retired but trying to help a guy that’s about to pull whatever hair he has left out. Chokes out when using the boom only under load. Push or pull . Swings / travels fine individually or in combination. Lift circuit lines get hotter than I’d call normal. All filters are good and were changed just to eliminate that possibility. As I said, I don’t have any books on this thing to go chasing stuff down. I may have the wrong machine in mind but doesn’t they use electro over hydraulic power shift valve that function like a swash plate type deal? Any direction would be great Thanks…
Hi, Yes, as you said cat 320B excavators uses proportional reducing valve which operates via controller electronically to reduce the out put of the pump. Controller monitors the rpm via speed sensor. if the rpm drops down to a certain level ( that means engine starts to feel the load ) then controller sends a voltage signal to proportional reducing valve. And this valve direct the power shift pressure to the pump regulators to destroke the pump. If this function doesn't happen correctly due to faliure of some components or system then engine will stall under load. But as you said "Chokes out when using the boom only under load" it is good to check line relief pressure setting of the boom cylinder to see whether it has increased by someone. It should be around 36800 kpa. Also it is worth of checking whether "boom rais pressure switch" works as intended which is located on the main control valve. Because sometimes this pressure switch also may have some impact on this issue as i think .To check it disconnect the pressure switch at the main control valve and check the continuity by using DMM. Move the boom up lever to its full stroke and hold it there, now continuity should exist if it works properly. if it is not working you can short circuit two terminals of the pressure switch at the machine end and operate the machine and see whether problem goes away.
If you want to get hold of manuals then a Serial Number is necessary. There are over 30 different models of 320B and not all use the same manual. S/N determines the Publication Reference for the correct manual for a particular machine.
Thanks for the reply… Finding out he has other problems that probably related… I stopped by and they were installing a new alternator saying the old one went out.. and they also been having intermittent display and throttle issues.. They Installed new alternator while I was there and still not charging thus my thinking erratic voltage supply could very well be a root cause of the other problems.
A Serial Number would get you the electrical schematic if that’s any use.
320BL 6CR03317
OK, so the manuals for your machine (with new prices in brackets) are:- Complete Service Manual. Paper version includes Hyd/Elec schematics plus an Operation & Maintenance Manual - SENR9240 ($390 on CD, $600 in paper form) Parts Manual - XEBP7645 ($230 CD or download, $275 paper) Operation & Maintenance Manual - SEBU6975 ($49 CD or download, $57 paper) The publication Reference numbers will allow you to search for them in places like eBay but be warned a lot of sellers are extremely proud of their used manuals and often ask higher than new prices. I will send you the Electrical Schematic.