Posted by NCWayne on December 23, 2012 at 21:13:56 from (69.40.232.132):
Spent most of last week working on a 345B Series 2 CAT excavator. Machine had a bit under 10,000 hours on it and had been experiencing a few strange hydraulic problems lately. With me being busy as heck and not having a manual for the machine, and the customer being 100 plus miles from me, he had called the local dealership to look at it. It had dropped the boom a few times, and the swing break had been setting unexpectedly. Their guy went out to look at it, checked pressures, and while 'troubleshooting' it the hydraulics died. Basically the pilot pressure went to nothing, so absolutely nothing worked.
At that point the 'technician' told the guy that they needed to take the machine back to the dealership to work on it. In this case it would have meant using 'special' equipment to get the boom lifted and positioned on a trailer. Too it would have required a beam trailer and either dropping the couterweight or a special 'super load' permit and all the cost and requirements associated with that. In other words it would have cost the guy a ton of money just to get his dead machine moved to their shop. Knowing all of this the guy (a long time customer of mine anyway)called me to see if I thought all of that expense was necessary. Based on past experience I told him no and offered to take a look at it, manual or not if he wanted me to.
I made the first trip up and after a few checks I pulled the main pump to check the pilot pump. Seems CAT's engineers felt it necessary to put a pump, that used to be external and easily accessable on many machines, on the front of the main pump. So, now, its now located inside the flywheel housing and requires pulling the main pump to access it. I had everything apart in less than a day and based on what I found suggested getting the main pump rebuilt. Turns out it was just worn out due to the large number of hours on it, and piece of a worn part had come off and had gotten into the pilot pump locking it up and causing the input shaft to get twisted off.
Fast forward and I went back this past week to put the rebuilt pump back on the machine. Getting it all back together, and doing a few other minor repairs took me a little over two days.
The remainder of the third day, and the forth day, consisted of figuring out why it was still having problems and dropping the boom. Based on experience I made an educated guess that it had to be a bad relief valve. Problem was I wasn't that familiar with the machine as far as the layout of the hydraulics since it had two boom circuits for both low and high speed operation. The manuals had been ordered over two weeks prior to me going up but the dealerships printer had dropped the ball and hadn't printed or shipped us nearly $800 worth of service and parts manuals yet. So, in their favor, the dealership was nice enough to print me off the necessary parts of the manuals from the computer.
This is where the real fun started. The manual stated that oil was put to the head end of the cylinder to make the boom rise. In all the years I've worked on equipment the rod end of a cylinder is the head end and the two names are interchangable. The other end of the cylinder is the barrel, or the butt end. This being the case the oil actually raised the boom by going in the barrel end. Figured this was just a typo but found out later 'I was wrong' as other parts associated with that side of the cylinder were also designated as being for the 'head' end. At the same time there were identintical parts being designated as being for te rod end. Nothing anywhere said anything about the barrel, or butt end. Basically it made it look like they were using different nomenclature for the same part, not two different parts, since both the up and down sides of the system had basically the same parts .
Ok, I moved onto the schematics to help troubleshoot the problem. One print showed a valve connected to the line going to the cylinder, one showed it not connected, and a third showed it connected too. This valve, I thought was, the relief valve I figured was bad, but the legentd said it was the boom anti-drift valve. TWhat turned out to be the actual boom anti-drift valve, in turn, was simply labled as a valve. Since there were two different valve spools in the actual anti-drift housing I figured they were both part of the same assembly (which was not available without buying a complete valve section), and that there was no relief valve. I had already talked to one long time CAT tech I know well and he said he didn't think that circuit had a relief so I didn't think anything more of the discrepencys. So, after checking everything I knew to check on Thursday afternoon, and feeling like an idiot because what I knew from past experience, knew from seeing, had been told, and what the manual was saying simply didn't jive. Confused as heck by now, I finally called it a day. Went back to the dealership on Friday morning and talked to the tech services guy who had printed me off the manual parts the day before. He, unlike me, knew that CAT's manuals were now calling the barrel/butt end of the cylinder the "head" end. This made some of what I had read make a bit more sense, but still didn't explain the differing info given by the manual and schematics, or make it all make any real sense. Basically there were still three different different schematics, and additional pics of what was supposed to be there, and all were different. Between me and the tech guy both looking at the schematics, and several other pics, legends, and the text, we finally figured out what all had been screwed up. Best of all we figured out where the relief valve, that the schematics said didn't exist, was actually located. I ordered a new relief valve, which thankfully they had in stock. Within 30 minutes of getting back to the machine, and changing out the port relief on the "head" end of the cylinder(actually it was on what was called the barrel or butt end for many,many years) the old girl was working like a new top.
In the end I have to say the dealerships tech services and parts operation was great, other than their printers falling down on the job. What I can't understand is why their service department felt they couldn't do such a simple job in the field. Heck the guy they sent out said if they did something as simple as pulling a cylinder they couldn't even haul it back to the shop in their service truck and would have to call something like a roll back to do it for them. This, to me, is just plain ridicilous. As far as the manuals, this machine that isn't even ten years old. How can a factory manual possibly have so many screw ups in it. I mean between the strange, new nomenclature for things that have been called the same thing, for years, in their other manuals, schematics that show different things, drawings/legends that call of one part by the name of the other, and the right part something generic, even the dealerships guys (especially the new ones that have little to no practical experience) are going to have problems working on the machines.
In the end all I can say is in the past I've seen problems with other manuals, etc on the older machines but it was usually things like typos, etc. Never have I seen anything as screwed up as this, on something as important to troubleshooting a hydraulically operated machine as the hydraulic schematics....Just doesn't make good sense........
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