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Hydraulic problem with pilots
Got a shout the other day with the report that the digger was throwing out the dipper arm as soon as the operator started it up. Fearing the worst I was ready to strip out the valve block 
.. anyway always keep an open mind 
Went to pick the machine up and knew what it was straight away .. the control lever was really slappy, and the pilot valve 'A' had stuck down for the dipper out service, and its caused by the brass barrel picking up on the stainless pilot bullet that slides in and out of it, see pic below
parts.jpgIMG_0885.jpg
Once you unscrew the control lever 'C' .. the whole assembly falls down and the four pilots & pilot body drop below the plate you see, all you need to do then is lever out the offending brass collars 'B' with a screw driver as they are just a push fit into the body .
Then up end it and force the pilot 'A' out of the brass collar the other way.. it will be stiff, thats why the valve was sticking after all, get some fine emery and polish up the brass bore, watching that it contains an 'o' ring near the top.
Refit the stainless pilot and make sure its running easy, best to clean out the brass barel first to remove any filings and lightly oil.
Stick it back to gether and bobs yer aunty ! .. This is the second one Ive had in a couple of years, dunno why the brass starts to bind like that ? .. but it sure beats pulling slices out of a valve block
..........
.. anyway always keep an open mind Went to pick the machine up and knew what it was straight away .. the control lever was really slappy, and the pilot valve 'A' had stuck down for the dipper out service, and its caused by the brass barrel picking up on the stainless pilot bullet that slides in and out of it, see pic below
parts.jpgIMG_0885.jpg
Once you unscrew the control lever 'C' .. the whole assembly falls down and the four pilots & pilot body drop below the plate you see, all you need to do then is lever out the offending brass collars 'B' with a screw driver as they are just a push fit into the body .
Then up end it and force the pilot 'A' out of the brass collar the other way.. it will be stiff, thats why the valve was sticking after all, get some fine emery and polish up the brass bore, watching that it contains an 'o' ring near the top.
Refit the stainless pilot and make sure its running easy, best to clean out the brass barel first to remove any filings and lightly oil.
Stick it back to gether and bobs yer aunty ! .. This is the second one Ive had in a couple of years, dunno why the brass starts to bind like that ? .. but it sure beats pulling slices out of a valve block
..........
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