I'm not sure where to post this...Attachments, or here in the Compact Excavator Forum. I am the original owner of an '06 Bobcat 435ZHS. The machine currently has around 6,400 hrs on it. Though it is showing it's age some, it still works fairly well. The issue is the performance of a particular attachment...a PCF34 vibratory compactor. The compactor is a Bobcat brand compactor and was purchased from my local dealership. They also installed the required manual diverter to switch the auxiliary circuit to mono-directional when this particular attachment is being used. The attachment performed well for many years but started to develop a leak from the eccentric housing last summer. To be clear, there was no issue with how the attachment performed....it was simply leaking oil. To remedy this we removed the hydraulic motor from the attachment and found the leak to be coming from the motor. We then sent it off to a local hydraulic shop for repair. They repaired it and we re-installed it. This is where the issue has prompted this query here on HEF. The ho-pac no longer performs well since the re-install. It does not seem to reach the same RPMs as before and thus does not exert the same amount of compaction energy to the work. We noticed this right away and thought that maybe there was some sort of mix up with hose routing. This is not possible as the hoses are not interchangeable unless one swaps the couplers on the machine end. We sent the motor back to the hydraulic shop and they claim to have taken it apart and found nothing wrong with it. They claim that it has been repaired correctly and they have "bench tested" it. They returned it to us and we re-installed it (again) yet it still does not perform as it did before the repair. I have had a mechanic out and he states that the auxiliary pressures are good. I requested the he check pressures and flow but he did not bring a flow meter (Once at the job, he told me that he doesn't even own one but failed to mention this on the phone when I specifically requested it). So, I don't know what pressure is at any given flow rate. The machine does not have any other performance issues. The thumb works fine (uses same circuit but in bi-directional setting of manual diverter). This has been going on for months now (dealing with hydraulic shop, trying to get a mechanic out to work on stuff, etc.) and I am frustrated because I am not sure which way to go on this. Right now I am thinking about dropping the $800 to buy a new hydraulic motor from Boobcat (that was a typo but I left it like that intentionally as it seems appropriate upon my reflection of my experience with the brand over-all -but not relative to this issue ). The only other way I currently have to check the circuit is anecdotal. I could drag my Bobcat breaker up to the job and see if it performs as it used to. I'm not sure how much this will tell me unless it performs poorly. If it works like it should I still don't know if it requires anything similar to the ho-pac as far as pressure, and/or flow. Oddly enough, the breaker does not require the manual diverter to be set to mono-directional. It works returning oil through the valve, not directly back to tank (unlike all the attachments for my larger machines). Does anybody know if this machine employs a separate hydraulic pump for the auxiliary circuit? If not, wouldn't I see other performance issues while operating the machine? Any other suggestions or ideas as to what might be going on here? Should I be looking at the machine, or the attachment? I am sure that it could be coincidental that the ho-pac started performing poorly at the same time as the re-build but, looking at all the anecdotal evidence, it seems much more likely that the issue lies in the repair since this is the only thing that has been changed.
Vibrators are checked on BPM’s “beats per minute”. A set pump flow, set temp, set engine rpm and there should be a manufacturers spec for it. Has this been checked at all? It would be nice to know how far out of spec it is. A few rpm’s on a vibratory system can make a huge difference. Is this a single amplitude system?
Hearing less "BPMs" is what I was describing when I said that the plate does not reach full RPMs. The BPMs have not been checked and I wouldn't even know how to test that. What type of device can check how many impulses a compactor has per minute? As far as how much out of spec it is I can only speculate. It is enough that it can be noticed by the operator. I suppose one could control the amplitude by changing the engine RPMs but we always run the engine at full RPMs when using vibratory compactors. Short answer is that it only has one amplitude.
A pro shop rebuilt this motor? Did they reseal the entire motor or just a shaft seal replacement? Is this a gear motor? Do you have a manufacturers tag on the motor that you could take a pic of and post here?
I thought that I had a picture of it but can't find it. I'll see if I can get one and upload it.
Did the hydraulic shop replace the bearing in the motor. I had one rebuilt and there wasn't any end play on the shaft and was bound up so tight it couldn't be turned by hand. I had to disassemble and remove the shims the idiots had fitted to get the required end play. It worked great after that.
Well, here is the way I see it at this point. 1. It's unknown that the pump rebuild accomplished anything. I question whether it was "checked". How did they do that? By sight? .........so your f%^&d here. 2. You have had a mechanic out, that didn't have the proper troubleshooting equipment or knowledge, which has accomplished nothing............f$%^&d again. At this point what do you have to lose by replacing the motor? The down time alone has cost more than $800. I don't see any other options. 3. There is a possibility that the motor is OEM proprietary. That means......guess what...........F%#^&d again. Post your motor tag and I will see if there is any other option.
I don't think that it's proprietary. The hydraulic shop was able to get parts for it. Here are some pictures. Not sure what good they'll be as the tag is roached. The repair invoice states that it is a Permco, S/N JJ41270DB, PT#22061. They charged me $247.50 for the work, $110 for the seal kit and $58.41 for seal kit freight. Total for the repair is $409. 91. I just called Bobcat and they told me that this pump is over $1,700 today....and don't yet know what the lead time is. Hopefully I can source it elsewhere for less.
Could the diverter plate(s) be installed with the crescent on the wrong port side?