Hello, My first post here. I have an EX45 on which I replaced the floating seal assembly in one of the final drives. When re-assembled, it is still inclined to leak. I have disassembled again, however not sure if there is something I have missed. When assembling, the entire front housing and motor assembly have to be compressed in order to get the cir-clip back on, so I would have thought the seal assembly would be in enough compression to seal. Any advice appreciated. Disappointed if the job isn't going to be a success, after going to the trouble of dismantling Thanks.
First question. Did you use any form of lubricant to install the replacement seal.?
I may have had some on the rubber O ring, yes.
Ok, so potentially that is a problem. The silicone rubber Toric Rings in that type of seal are supposed to be installed dry after first being cleaned with isopropyl alcohol. Also the ramps where they install are supposed to be cleaned and dried the same way. The operating method of the seal is that the rubber ring grips on the ramp and rotates as pressure is put on the steel rings when the component is assembled. Strictly speaking the two halves of the seal should be fitted using an installer tool, but experienced mechanics can install them without. The other critical factor is that the height of the metal face above the housing is supposed to be within very close run-out tolerances over the complete circumference of the ring, probably less than 0.5mm if it was a Cat seal, I have no idea what Hitachi's standards are. Too much up/down "wobble" and it's not going to seal adequately. Here is a LINK to a guide produced by @willie59 regarding the installation of this type of seal when you don't have the tooling.
Thanks, Will have a go at this again in the evening. Will let you know how it goes.
Had a chance to get back at this. I have installed the seal and o-ring, it appears to have gone into position evenly (the cable above the o-ring was a big help) The following picture is one I had from the first time. You can see that the seal wasnt installed evenlym gap not even the whole way round. Hopefully this time it will be successful. It appears to be functioning correctly, in that when i press in on the sealing ring, the o-ring is in torsion.
Only now, when I look at the image where the bearing is installed. Is the fact that the bearing is pushing against the steel ring some of the problem? If pushing it back it may be stopping the other sealing surface from shutting out tightly enough?
What condition are the two bearings in ? Is there any wobble or axial play at the hub after the snap ring is installed ?
The bearing shouldn't ever touch the toric (duocone) seal, IIRC.
The outer bearing is ok, the inner bearing fell apart when I was dismantling so I have a new bearing. None that I can see, when the snap ring is installed, the whole assembly is tight.
I will need to look at that so, when i have the seal in position, the outer race of the bearing comes in contact with the seal before the inner race seats/ stops. This may be a large part of the problem. The inner race and outer race are offset from each other. If its touching the seal, should I look at making a spacer up to keep the bearing away from the seal? (the outer housing may not allow for this) or else maybe i have overlooked something, incorrect assembly, incorrect parts maybe? Where did you get the exploded diagram from? Is there a manual available? Id be interested in getting one if there is. Thanks
Hi Have the drive back together, however it is still leaking. I'm not sure what to do now with it, When assembling, the O-ring and seal function as expected, when not compressed it rolls out to the position as per the photos above. Checking the components and measuring bearings, etc. The total stack height in compression from inner bearing to outer bearing are correct. I was thinking of just putting it back and seeing if it would bed in over time. Unless you can offer any other suggestions.
Those seal types wont "bed" in. If it leaks on assembly........it will just get worse and fail altogether.
Referencing @heymccall parts explosion, oring #12 and spacer #26 are in correct position ? the hub is not scarred where the oring sits ?
Do you still have the old seal? Can you post pics of it.........especially the metal sealing surface?.
I dont think i have that o-ring 26, is 12 not the second half of the seal? Dont fully follow your question on the hub?
I will get some pictures
I have dismantled the hub again, Its easy done now that I have it apart numerous times The old seal, different to the new one, one part locates in the other. The new seal upon disassembly, it has returned to the position it was in when installed, so functioning correctly The outer housing, A is the new sealing ring/face, B is the ring in which the outer race of the inner bearing locates, outer race shuts out against red shaded surface
Inner bearing pulled out Sketch of the assembly (excluding inner bearing)
Maybe an incorrect seal?
I’m questioning whether you have the correct seal at this point. Where did you get your new replacement?
Seal was brought from a local plant spares supplier, not sure if its genuine hitachi, doubt it though
Is this a 45-1 or 45-2?
A Hitachi EX45 serial number prefix starts with 1BD A Hitachi EX45-2 serial number prefix starts 1BEP . Your Hokuetsu Airman AX45 mini excavator, not sure if there is a clear cross to a Hitachi model.
It does looks to be incorrect seal comparing your hand made sketch and the exploded diagram. But sometimes due to space constraint these seals are designed with one side O-ring with metal ring and other side metal ring interference fitted in housing with a lapped face something like below image Nevertheless, it is important to follow assembly instructions. You may consider designing a tool which ensures proper pushing of duo cone seal. Here is an image: There is a good animation here in this link: Hope this is useful.
Thanks Yes, maybe incorrect seal. From what I have done, the installed seal appears to be installed square, I will check measurement as shown in video at 3 points around circumference and see how they compare. Other than this, i may have to bring the drive to someone that specializes in them Thanks for all the advice. I will update the thread if I find a solution. Good video by the way.
Hello all, I have found the problem with this. The "flat" ring turns out wasnt flat. No amount of pressure/pre-load was going to have it seal. I got this ground flat/ both sides parallel. Assembled it last night and its working as intended now. Thanks for the advice and help on this.
How, exactly, did you get that ground flat?
Yes, enquiring minds want to know
A surface grinder and an experienced toolmaker (work for a precision engineering company). He blued one face of the seal and assembled, it wasn't making contact around its entire circumference. Taking the seal half out and leaving on a surface table, it wasn't flat, some points in contact/some not. Delighted to have it sorted.
In cross section too, both faces weren't parallel either.