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Arm in, stop and go

Hydraumind

Well-Known Member
Joined
Apr 7, 2011
Messages
134
Location
LB
When using arm in starting from fully extended position, the arm stops for 2 seconds when it reaches vertical position (kind of a float), then it kicks suddenly and continues its way in. The engine is at high idle and the arm in joystick is at full stroke. The machine is a komatsu PC340-7. Any idea?
 

lantraxco

Senior Member
Joined
Jan 1, 2009
Messages
7,704
Location
Elsewhen
That's very common on excavators, unless it has suddenly started doing it and it did not before, I wouldn't worry about it.
 

GregD1

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Joined
Oct 6, 2013
Messages
221
Location
Tonopah, Az.
Occupation
Equipment for a paving contractor
That's very common on excavators, unless it has suddenly started doing it and it did not before, I wouldn't worry about it.

That would be the correct answer to your question. It isn`t unusual for the bucket circuit to also to act the same way as gravity/weight of the arm or the bucket is playing the big reason it acts that way.
 

JBGASH

Senior Member
Joined
Jan 1, 2011
Messages
758
Location
Missouri
Occupation
Plumbing & Excavation Contractor / farmer
I have several excavators 3- are Komatsu and none stop or pause for a couple seconds when working, I would think something has to be wrong with your machine, unless I am misunderstanding what you are saying.
 

Hydraumind

Well-Known Member
Joined
Apr 7, 2011
Messages
134
Location
LB
I think I have to check the arm cylinder seal and if it is clean I gonna consider it as a normal behavior
 

lantraxco

Senior Member
Joined
Jan 1, 2009
Messages
7,704
Location
Elsewhen
No machine should do this under load, it only happens when gravity lets the arm or bucket get ahead of the oil flow. The makeup checks in the control valve are supposed to let enough oil through to keep up, and some machines have regeneration valves which should keep the backside of the piston pressurized, but nothing's perfect. If it's something that has developed over time or just started recently I would look at piston seals first.
 
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