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Atlas AK125.1 A2 swing and overheating problem!!

ROAMER_AUS

Well-Known Member
Joined
Sep 6, 2018
Messages
246
Location
Croatia
Hi everyone.

I have truck mounted crane as per title. I have a problem where crane swings normaly to one side, but barely moves to the other side. On top of that, after about 7-10 full range swings left - right and back, oil becames so hot that you can't keep your hand on the tank. Swing cylinders get quite warm too. I have checked all the usual things, enought oil present, filter is new. I have tried swinging the crane by hand with cylinder hoses taken off, and it moves smoothly.
Does anybody know what would heat up the oil so quickly? About 70 litres is in whole system.
Now my taught was that one cylinder is passing. But, also there are either pressure regulating or overpressure protection valves for both sides of swing, I don't know what they are for exactly, no marking on them. Rreturn pipe from this valve gets hot, which means that valves are opening and sending oil back to the tank. Cylinder passing and overpressure valves opening is a bit contradictoy to me.
Can anyone help me to diagnose this problem a bit better? My first concern is that oil gets so hot so quickly. And second obviously swing problem. But they are same root cause I guess.

Thank you!
 

ROAMER_AUS

Well-Known Member
Joined
Sep 6, 2018
Messages
246
Location
Croatia
Update.
Swapped over cylinder hoses, now slow side is opposite thsn before. So it's not the cylinders. Valve or overpressure regulator then.
Still puzzled with oil getting hot.
 

SoCoHyd

Member
Joined
Oct 29, 2020
Messages
6
Location
Houston
Sounds like there’s a bypass somewhere. Heat is created when high pressure oil moves to low pressure without work being done. Do all the other functions work normally ? Does it only get hot when using the swing cylinders ? If it only gets hot when the swing cylinders are being actuated then it’s probably the valve bypassing
 

ROAMER_AUS

Well-Known Member
Joined
Sep 6, 2018
Messages
246
Location
Croatia
Everything else works fine. I suspect actuating valve passing. Now when it is cold i will turn on the pump and just let it idle and see how temparature goes. When there is no work, it should be passing from the pump straight to the tank. If it heats up then, something is blocked. That's what I think anyway.
I took return hose fron that regulating or overpressure valve. When crane swings at normal speed there is more flow from this hose then when it swings to problematic side going slow or no at all. This makes me think that this is regulating valve rather than overpressure. And actuating valve is not opening fully and passing back to the tank. What I've never seen before is how quickly it heats up the oil. 70 litres to more than 70 celsius in matter of minutes.
 
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