This was a great explanation. I have a Hitachi ex230lc and i was curious about why the swing does not feel very accurate. My swing motor probably doesn't have the valve to stop the back and forth after i stop swinging. I read that checking the swing relief valves for contamination may help as well. Thank you again.
I just discovered your channel today , and the subjects are all clearly and in depth explained. This is realy helpfull and also enjoyable to watch , thanks !
Nice video, thanks for posting...I have a Hitachi EX120-3 with the same swing drive shown in your video with the anti-reaction spool option. Oil literally sprays out from under the front anti-reaction spool cover and bolt holes when swinging left. I replaced the O-ring under the front spool cover with an OEM JDeere O-ring and lapped the cover flat but it still leaks terribly. I'm thinking there might be a problem with the front swing relief valve after watching your video. Can swing relief valves be serviced/cleaned or just replaced?
Thankee, Think I'm ready to rebuild mine now... and figure out why its never really stopped swinging, it would slow down, but never stop, unless engine was off, then it stopped hard, so its either a secondary solenoid, or the pilot pressure is remaining on.
Okay, well my mate has a 3t Bobcat Excavator, I think from their now discontinued series (machine's at least 8, not more than 15 years). I work on it for him, it has a good bit of rock to and fro on the swing bearing and almost every pin/bush is wore out on the boom, most concerning for me is it has free slew/swing movement at least to a degree (I haven't tested in depth), could this be related to the wet brake on the drive? Or maybe just that swing bearing again allowing all that free play between teeth? I also operate & work on a Komatsu LC605 Crawler Crane, which seems to be based on a 8.8t Komatsu PC80LC, the slew function is very slow, does seem to lock, but may have the free lift function you mentioned. I assume this is all by design - But what would be the cause of the slow slew/swing speed? Just a lower flow rate or maybe a greater gear reduction? It also seems to pull to the left when tracking, I figure this might be a tensioning issue, but it is a pain to check as it obviously lacks a standard boom with which to lift a track off the ground, is there another way to check or could it be something else?
Awesome instructional video, thnx! Ques- On a mini (hitachi 35), is there oil in the reduction drive? Wondering if that is something to change (not clear from the documentation) ~
Is it possible to manually release the swing break? We are working on a bobcat e26 and have it halfway apart and meet to swing it a little bit to get bolts out.
Greta video. I have a ? Komatsu Pc 60. When u push left or right to swing sometimes the brake activates n abruptly stops. If I push a little coward adding the crowd cylinder it swings nice. So it seems the swing function is not always activating that pressure valve u talked about. Where would u start ur diagnosis? Thanks
How do the track drive motor's fluids get through the slewing mechanism? I presume there are no limits on how many rotations in one direction are allowed?
Can you help please. My Cat 311C swing motor, just serviced with new seals broke the two bolts holding it and bent the plate holding shaping it like a bowl. The left track motor has no movement. Both track motors were replaced recently. Where would such high pressure be coming from to bend the 10mm steel plate and lift up the whole swing motor. Your reply would be highly appreciated as the mechanic can't work it out. Just replaced the main hydraulic pump as well. It did the same thing , broke the bolts and bent the plate an don movement in the left track motor? Jason
I could come up with 50 reasons for any particular excavator. Multiply that by the hundreds of models with different systems from 2 dozen manufacturers... probably a thousand things could be listed. I'd have to run the machine, do some visual and basic tests, then hit the schematic and start looking for what's common to the swing and blade functions if I thought the symptoms were connected. I have 35 years experience working on heavy equipment and I wouldn't even begin to guess over the internet- waste of everyone's time.
Im running a 308 cat im geting a slight grinding noisewhen im swinging back as long as i swing slow it doesn't do it but when i dig fast it does it im not sure what it is it just started a couple days ago
working on a 425 bobcat mini excavator .If the seals were bad on the swing motor would that cause low system pressure throughout the entire hydraulic system.We have checked everything filters ,pump filters.main reliefs cannot figure whats going on.Buddy of mine told me if seals were bad in swing motor it could cause low pressure through the hydraulic system
@@hydraulics yes we did cut open old filter just pretty much a normal dirty filterFlow tested the hydraulic pump all up to spec.We tested main relief at main relief port on the excavator. by deadheading all functions.When we first start machine pressure reads over 3000 psi after 5 minutes drops to 2400 after 30 minutes drops to under 2000 psi.Main relief on control valve is the only thing we have not swapped over.Is it possible its bad ?Is a way to bench test a main relief valve?
I've got a question I hope you can help with. I have 2001 Cat 313B cr, if I'm on a slope my swing brake locks after 5 seconds and releases if I bump and hydraulics bucket, boom ect BUT my cab starts to swing towards gravity (downhill). Is this normal? I figured it would hold after the swing (park) brake is released. Thank you!!!
Loss off brake release pressure will cause swing to lock . Check for blown orings in pilot brake circut . Friction discs worn out also. Pilot Hydraulic pressure release discs. Rare for discs to wear out since they only hold machine not stop swing .
Hi! I have a Hitachi Zaxis 120 leaking Hydraulic oil from gear oil filler and dipstick on the swing motor. Any help or advice would be much appreciated.
The main seal at the bottom of the shaft of rotary group has probably done its work. Cause of it can be a high case drain pressure, so it’s probably necessary to also replace the rotary group. Also check if the case drain hose isn’t clogged so the pressure doesn’t build up in the hydraulic motor, because that could be the cause of the blown seal.
@@zanpetric4008 Thanks for the reply. it wasn't clogged. Rotary manifold rebuild didn't solve issue. (i didn't think it would but boss told me to do it.) We ended up replacing swing motor which solved our issue. Suspected valve plate or axial piston failure.
@@_maxstockwell rotary manifold has no connection to the swing motor, except the case drain in some cases from the final drives. By rotary group I mean the swing motor cylinder block pistons and valve plate (not rotary manifold). Your analysis could be correct. It’s good that you fixed the problem, but I still think the motor could be rebuilt. I just fixed mine (slew drift and low slewing power) and changed the main seal, rotary group and bearings (altogether about 700-800$/€ but nit the oem parts). Machine is tak 1140 which I believe has the same motor as yours-hms072?