Hello all. I am new to working on this excavator and have an issue that I have not seen addressed. When I have my breaker (Bobcat 680) attached the return hydraulic line leaks from the hose attachment of the breaker. At first I thought I had developed a leak in the return line hose or fitting, but I had a new line made up and pressure tested at the hydraulic shop and the same thing occurs. I swap hoses to the breaker and the problem switches fittings, i.e. the problem stays with the return line (top line on the boom). I have no issues when using the aux for my thumb, but the breaker fitting just drips fluid, even when the aux system is turned off! I also thought the breaker may be low or out of Nitrogen, and I just had it checked and pressurized to 470psi, so I feel the breaker is not the culprit. I'm deep in the service manual, but I'm not seeing anything obvious. Any guidance would be helpful. I need this breaker to function. it's all lava rock here.
Maybe try and send pictures of your complete breaker set up on the machine and also pictures of the where the leak is occurring. Try and also give additional details such as machine serial number and the breaker model and serial number. With this information someone on this forum should be able to assist you with the issue. Best regards
Is it possible the breaker could be causing pressure spikes in the return line? I don't know if there is such a thing as a hydraulic damper to limit pressure spikes.
When running an aux attachment like a breaker that requires continuous loop flow the return should be routed directly to filter returning to tank instead of back through the control valve. Does yours have a valve to change that or loop flow switch or setting change in monitor? If not it can cause out flow restriction and higher return pressure. Just something to check.
Thanks folks for the replies. The breaker had been functioning correctly but then started to leak at the return line, whether attached to the upper or lower port. 8V71 that fits with what is happening and with what welder dave has suggested, I get that I need an unrestricted flow, and perhaps something has been switched to restrict that. I wonder whether trying to run the breaker the opposite way (switching the line and running the aux button the other way), at some point may have damaged something. I will investigate more. Thanks again all! Really helpful to get some perspective.
I thought I'd complete here so maybe it would help another person with this problem. I discovered that some of these excavators are equipt with a high volume return valve that allows the high volume of fluid used by the breaker to return to the reservoir. My excavator does not have this valve so there is a lot of back pressure in the return line, which seems to have been the reason for the line to develop a leak. However this does not explain why the breaker worked with the excavator for some time while I was digging and building here. The only reason I can think of at this time is the breaker I purchased was not used for some time and the flow in it was restricted until I put some hours on it and freed it up a bit. Don't know