Help lowering stalled Grove crane boom

[Faeroth]

Hello all!
I have a 1981 Grove RT630 crane that has a dead engine. I need to lower the boom down in order to have it taken from job site. I'm aware that it has a counterbalance valve and am thinking of releasing it while using another crane to hold the boom and lower it down slowly. I wanted to make sure I am doing the correct thing here and loosen the lone screw on the side of the valve in the first picture in order to release the pressure, or if there's a better way of doing this quickly, as I'm required to do this this week.

Thanks

 

[willie59]

What engine does it have in it?

 

[crane operator]

There's no really "slow" way to release the oil in the cylinder. You have to remove the whole holding valve, and you'll have oil everywhere.

If you don't know what you are doing, its a easy way to get someone hurt.

 

[Faeroth]

What engine does it have in it?

It has a CAT 3208.

 

[Faeroth]

There's no really "slow" way to release the oil in the cylinder. You have to remove the whole holding valve, and you'll have oil everywhere.

If you don't know what you are doing, its a easy way to get someone hurt.

I was under the idea that you could slightly loosen it and it would be somewhat controlled, but I will still have another crane holding the boom up and lowering down slowly. I'm aware that there will be a big oil spill, yet, do you still think it won't have a slow descent?

 

[willie59]

I'm like craneoperator, removing a holding valve to do this, yes, do-able, but you better know what you're doing. I ask "what engine", because, alternative, pull the injectors from the dead engine so it will spin freely, good hot battery and good starter, crank the engine while holding the lever in boom down, may just give you enough pump pressure to make it come down with no risk and no mess, plus I see the front wheels steered slightly to the left, need to correct that to drag it on a trailer anyway.

 

[Faeroth]

I'm like craneoperator, removing a holding valve to do this, yes, do-able, but you better know what you're doing. I ask "what engine", because, alternative, pull the injectors from the dead engine so it will spin freely, good hot battery and good starter, crank the engine while holding the lever in boom down, may just give you enough pump pressure to make it come down with no risk and no mess, plus I see the front wheels steered slightly to the left, need to correct that to drag it on a trailer anyway.

I appreciate the concern. I too am a bit anxious as I haven't done this with a crane boom. I don't have many options though and it needs to be done soon due to where it is at. What do you think could go wrong?

I didn't think about the wheels yet, but you're right. Maybe I will need to try and fix that first. I'm not really a mechanic, and there ain't many machinery mechanics around here but I will contact an engine guy.

Do you think there's any other way to steer the wheels without opening the engine?

 

[crane operator]

Do you think there's any other way to steer the wheels without opening the engine?

You can just hook a chain fall to the frame and pull the wheels straight. You might have to loosen the hyd. lines on the steering cylinders.

I was under the idea that you could slightly loosen it and it would be somewhat controlled, but I will still have another crane holding the boom up and lowering down slowly. I'm aware that there will be a big oil spill, yet, do you still think it won't have a slow descent?

You can loosen the holding valve, but they typically don't run out much oil, until they lose the last thread holding them in the block. Then the holding valve shoots out with evil intent on its mind.

You have to get the holding crane, so it has all the boom weight, and it has to let the whole thing down. So it better be a big enough crane.

The holding valve is right beside the cab, so there's no where to get out of the way on those, when you are working on it, which is why I'm a little hesitant to give much more advice, You can get seriously wedged/ pinched in there, because you just can't get out of the way.

I realize you don't want to spend the money to get people in who know what they are doing. But this is one of those times when its pretty easy to get someone killed.

 

[Faeroth]

You can just hook a chain fall to the frame and pull the wheels straight. You might have to loosen the hyd. lines on the steering cylinders.

Thanks for your reply, I believe that will be my best option for now.

You can loosen the holding valve, but they typically don't run out much oil, until they lose the last thread holding them in the block. Then the holding valve shoots out with evil intent on its mind.

You have to get the holding crane, so it has all the boom weight, and it has to let the whole thing down. So it better be a big enough crane.

The holding valve is right beside the cab, so there's no where to get out of the way on those, when you are working on it, which is why I'm a little hesitant to give much more advice, You can get seriously wedged/ pinched in there, because you just can't get out of the way.

I realize you don't want to spend the money to get people in who know what they are doing. But this is one of those times when its pretty easy to get someone killed.

I understand. Do you think it would be safer to try and remove the piston from the boom with a chain fall while holding the boom with the other crane? The other crane is a Grove RT-745 90000lb.

 

[mekanik]

The oil can come out with enough force to penetrate the skin causing a serious life altering injury.

 

[skyking1]

yes you can lift the weight off the cylinder. it is awkward to pull the pin and handle the weight of the cylinder, but doable.
you need to rig up with come-alongs or a second lifting machine.
Figure at least 500 pounds for that free end on the cylinder and realize that is not even remotely a hand job.
you will have to set up cribbing and cushioning for both the free end of the cylinder and the boom, and be able to secure them to the carbody.
Do all of the above before hooking the crane up to it. no point in picking something and then holding it while you think that next part out.

 

[crane operator]

Thanks for your reply, I believe that will be my best option for now.



I understand. Do you think it would be safer to try and remove the piston from the boom with a chain fall while holding the boom with the other crane? The other crane is a Grove RT-745 90000lb.

View attachment 311889

With a second crane of that size, I wouldn't try to pull the pin and cylinder apart, I would pull the holding valve to let it down.


Attach the other crane to the boom, pull both hoses that come to the block on the cylinder. Raise the boom with the second crane, until there is oil coming out the one hose, and you are lifting the boom up past its current angle. That should remove all the pressure from the lower part of the cylinder, releasing the pressure off the holding valve.

Then when you are sure that the second crane has all the weight of the boom, you can remove the holding valve. With the holding valve removed, you can get clear, and let the boom down slowly. As you do that, the oil will come blowing out of the hole where the holding valve is.

 

[skyking1]

how about pulling that lowering hose and putting it in a bucket? that would save a mess.

 

[crane operator]

how about pulling that lowering hose and putting it in a bucket? that would save a mess.

Can't do that, the oil comes out the holding valve hole.

 

[willie59]

I'm just saying, don't know what you're referring to when you say "dead engine", but if it will turn over, I'd be yanking the injectors out of it, whiz it over with the starter and see if that gives you enough pressure to make the boom come down. It would be slow, but it's worth a try. If it works it's gonna save you a lot of otherwise messy work.

 

[willie59]

And another thing that baffles me about this rig, no fault of yours, but why in the hell did Grove fit a fat a$$ Cat 3208 in that rig??? If you end up re-powering it, I'd go with a 4B or 6B Cummins. Yeah, you'd have to make some changes, but it would be a far better power plant.

 

[skyking1]

And another thing that baffles me about this rig, no fault of yours, but why in the hell did Grove fit a fat a$$ Cat 3208 in that rig??? If you end up re-powering it, I'd go with a 4B or 6B Cummins. Yeah, you'd have to make some changes, but it would be a far better power plant.

I've seen several with the 3208, and also the old Cummins V8 504 .
When you find one with the 6 BT that's the keeper

 

[Vetech63]

Right now, if you took both of the hoses off completely, the cylinder should remain in its position with a small amount of oil loss from what is in the hoses. There should be no danger until you start to unscrew the lock valve from the cylinder base.

That being said, it's very dangerous to unscrew a lock valve from a cylinder because once the oil pressure starts releasing, you can't control anything at that point, and you or someone else is going to be in the way of a very heavy uncontrolled boom dropping fast.

What you can do is take off the hose closest to the rod end and install a TEE fitting then hook the hose back up. At the TEE you can install a hose from a porta power pump and some other controlled fluid power and release the lock hydraulically. That screw is what sets the pressure setting for the valve to shift......so you can back it out to lower the pressure needed. You will need around 400 PSI at a steady pressure, then the boom lever in the cab can be operated to lower the boom. This way no one has to be in danger, and everything can be done safely without risk.

I had to do this a few times in the past. It works providing you have the tools needed.

 

[kshansen]

I've seen several with the 3208, and also the old Cummins V8 504 .
When you find one with the 6 BT that's the keeper

What not a Detroit? Ducking and hiding from Truck Shop!

Just took a look at an old file and see where I worked they had a Grove RT 63S or at least what the records called it. Not sure if it is close to a RT 630. The one the company had had a 6V-53 in it that I was "fortunate" to have had some experience working on. That would be a story all it's own!

 

[Faeroth]

Hello all, quick update.
Could get the boom down by hoisting it with the other crane. Tensed it up, released the two hoses, raised it a bit more and then removed what was sort of a cap from what I believed was the load holding valve. Decided to try and test lowering the boom down slowly and oil started pouring from where the hoses were connected, I will attach a pic I got of it, I don't know if the valve was malfunctioning or if that was supposed to happen. Could redirect the oil to a bucket with minimum mess. Steered the tires with the help of a backhoe as well and pushed it to the lowboy with it and the help of the other crane too. All in all it wasn't much of a problem and am glad it all went well with everyone's help.

Thank you all for your help!