Leon, the mech says there is an individual relief valve for that function; so (according to him) it only affects that piston and none of the others. Will def operate it when they bring it. I'll chime in here once I know, thanks for the input.
Mike
Uh huh;
What they have done and what they should have done............
If it had been me I would have run a pair of hydraulic lines to another tractor and used that tractors fluid power to verify the "Problem" and narrow the number the usual suspects or at least had a hydraulic power pack to feed it and test it for the issues by blocking the booms up the operate the bucket cylinder.
Ok
On to the dance................................
backhoe fluid flow
open center hydraulic system
Using the three point hitch hoist circuit for pressure side of valve body
one pressure line........ used for the hoist function used to feed the
pressure side of the valve body fluid flow for all circuits
one return line ............
IS the backhoe- the type with the individual valve spool for each
function?, or is it the type that uses the gimbaled control valves
simular to the Kubota's front end loaders?
OK so if we have a standard valve body with 6 spools-
left outrigger one spring centered double acting valve spool
right outrigger " " " " " " "
boom swing cylinder " " " " " " "
some use roller
chains and a double
rod cylinder or
paired cylinders
upper boom arm " " " " " " "
lower boom arm " " " " " " "
bucket cylinder " " " " " " "
the valve body may or may not have a relief cartridge for each BOOM
function being the upper boom, lower boom, boom swing, and
the bucket cylinder and or thumb.
the oil flow would be from left or right outrigger to the boom functions
to the opposite outrigger back to tank.
A gimballed system is open center with spring centered gimbal spools with two gimbals.
one example:
left outrigger spool valve
extend
retract
left gimbal
upper boom extend
upper boom retract
lower boom extend
lower boom retract
right gimbal
bucket extend
bucket rectract
boom swing left
boom swing right
right outrigger spool valve
extend outrigger
retract outrigger
The dipper cylinder should have been pulled and tested to see if it is intact.
The dipper cylinder hoses should have been removed and tested; the issue with the single function not working leads one to think it is the cylinder or the hoses.
1. internal hose casing failure- the rubber inner hose collapsing and closing off flow.
2. floating debris such as hose rubber wedging in the fitting or fittings or piston packing.
3. piston separated from cylinder rod and piston nut free to move in the barrel side of the cylinder possibly breaking off metal and being stuck in hose end.
Piston O ring is blown refer to (a) below
a. oil flows freely with no restrictions and not capable of doing work.
b. cylinder has become egg shaped and bypasses oil BUT is not leaking oil-not likely
c. broken spring in gimbal for digging cylinder function and the spool becomes useless under resistance-any resistance.
c1. the spring could still work at times to center the gimbal and then not work when the bucket encounter resistance.
I can see a bad relief valve "Only" if all the boom functions had a relief valve and could bypass back to tank or the valve bank had a main relief valve that reacted to system over pressures at the specific function used.
(I would hope that the valve body can be photographed and posted here or an example valve body posted for reference).
I dont know why the punctuation marks do not line up under the first row of words like they should as the first line is the same for all the sentences.
