Hi all , Just started working on a new to me EW140B wheeled .. Main Boom lifting fine, if push servo forward to lower it drops like a stone!!no power if tried to raise machine either. Lever feels normal. Haven't done any investigation yet but I'm presuming a broken spring in spool valve, or faulty boom check safety valve. Any hydraulic guys any opinions or advice???? TIA
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Volvo EW140B
- Thread starter volvoeire
- Start date
BigWrench55
Senior Member
Tee into the servo/ pilot line with a suitable gauge for the offending spool. slowly engage the control and watch your pressure. if you don't immediately see pressure when engaging that function then the control has failed. likely trash stuck in the spool on the control. I have seen it before on a 480E and it was contamination from a catastrophic pump failure. Praying that yours is just a faulty spool inside the controller..
Thanks Paul, all other functions seem to be working good so fingers crossed its just inside the boom spool. Really hate that word catastrophic!! an expensive word!
BigWrench55
Senior Member
I'm thinking that the problem is going to be in the controller. The other problem I was referring to , the failure happened first. And after cleaning the hydraulic system, some contaminants made it into the controller valve. Try as you might but once it's contaminated it will never be factory clea .
Sorry paul i read your reply wrong. When you say the control you mean the servo joystick in cab?? Will have to pressure test the servo line. Just thinking today I just noticed an old height limiter system teed into the boom also.. maybe il disconnect it or could it have anything to do with it you think??
BigWrench55
Senior Member
Yes the joystick in the cab. I find it easy to plumb a gauge into the servo line at the main control valve. Not familiar with a height limiter don't see it around my part of the world. Check your servo pressure at the main control valve for the boom down valve.
funwithfuel
Senior Member
Do you have boom hose rupture valves fitted to the boom cylinders?
Yes rupture valves on both boom cylinders.. if I do drop the boom fast they catch it after a short delay but it usually has hit the ground before they get a chance!
uffex
Senior Member
Good day Folks
It may be that the floating selection has been switched on please see attached.
Kind regards
Uffex
It may be that the floating selection has been switched on please see attached.
Kind regards
Uffex
funwithfuel
Senior Member
While the float function may be causing grief, it would be an inability to push down, but I don't think it would cause an uncontrollable free fall.
The reason I asked about the rupture valves. If the logic valve inside the block "hangs up" you have to apply more down force to unlock the spool, when this happens, you've already got a lot of force trying to push down along with gravity. I first experienced this on an EC700. Talk about scary.
My suggestion, remove and inspect both valves, they're very simple. Check for any debris, packing material etc. Here's where it gets fun. When you resecure the valves to the base of the boom cylinders, only tighten the screws in a crisscross pattern enough to not leak. Do not tighten like you would instinctively want to. Try it out gently, tighten them up a little more. If there is any difference in torque or clamping force, it will bind that spool.
Please give this a try, it costs nothing but time and maybe a couple o-rings.
Good luck
The reason I asked about the rupture valves. If the logic valve inside the block "hangs up" you have to apply more down force to unlock the spool, when this happens, you've already got a lot of force trying to push down along with gravity. I first experienced this on an EC700. Talk about scary.
My suggestion, remove and inspect both valves, they're very simple. Check for any debris, packing material etc. Here's where it gets fun. When you resecure the valves to the base of the boom cylinders, only tighten the screws in a crisscross pattern enough to not leak. Do not tighten like you would instinctively want to. Try it out gently, tighten them up a little more. If there is any difference in torque or clamping force, it will bind that spool.
Please give this a try, it costs nothing but time and maybe a couple o-rings.
Good luck