Todays Project - What did you do today?

[Pete O]

I posted a bit of my tractor refurb last year; there's been one major ongoing problem in the form of a hydraulic oil leak from the diverter valve. With a heavy implement on the 3PL, hydraulic oil leaks out between the diverter valve and it's mounting surface on the transmission top cover. I bought a 6' slasher this year that weighs a bomb, also been moving some heavy logs around with a 3PL forklift attachment and the oil leak was a real pain, especially after all the work I did on the tractor.
This is the culprit- the valve mounts to the top of the transmission in front of the operator seat, it's used to divert hydraulic power from the 3PL to the front-end loader.
   
I put the tractor back in the shed last week and pulled the top cover off and stripped it down.  I knew the mounting surface for the diverter valve was not flat so I introduced it to the surface grinder. A bit tricky to set up.
   
I swapped to a 3 1/2" diameter wheel to overcome this problem but that only led to other problems so I ground the surface with the part hanging off the front of the mag chuck.
   
   

I ground the mating face of the valve as well. Two mating faces that actually mate should be a reasonable place to start.
   

I did a bit of research into O-ring applications and it seems that the ideal 'squeeze' is about 30% so I borrowed a boring head from a friend (haven't got one in R8 yet) and ground a D-bit with a suitable end profile to re-cut the seats. Took them all down to a depth of 70% of the thickness of the O-ring. Also enlarged the diameter of a couple of them to suit O-rings from my assortment kit rather than the original oddball sizes.
   

I made a tool to hone the seats with lapping compound; a slug of aluminium bar turned to 20mm on one end so I could use collets to take the pain out of swapping it back and forth from the lathe to the mill, then turned the other end down to the diameter of the largest O-ring seat, used some lapping paste and light pressure from the quill to lap the seat. Back to the lathe and turn the tool down to the next largest diameter, back to the mill and lap that seat, back to the lathe.....got a reasonable finish on the o-ring seats- at least the scratches are all circular and not radial.
   
   

Got it all reassembled last night. I won't know if it's a success until I get a chance to put something heavy on the 3PL again. I think I'm going to have to get the blue paint out again too- had to grind the top surface of the valve to mount it to the mill table. Tried a HSS flycutter but that thing is hard as rock, wore the HSS down like butter.