HIAB Legs stuck ...... why? & how do we fix

[Will Hinchliffe]

Before I start I apologise for the any incorrect terminology I use bellow. Il try to be clear so you understand.

 

We have a forwarding trailer with a 1970s HIAB 550 mounted on it. We have been recently trying to get it to work.

 

The legs are simply big rams with feet. They are not piped to the spool valve block and each leg has its own control lever.

 

When we first tried to operate the crane the leavers on the legs appeared to do nothing but the legs extended and retracted eraticly when the crane was operated.

 

John took the block on top of the leg rams apart and replaced the O rings on the leaver and blanking bolts. He also examined the ball bearings, pistons and spring that are part of the leaver/valve assembly.

 

Both legs are now stuck out but are holding. This has lifted the whole trailer way up in the air.

 

Turning the levers now does nothing.

 

Our thoughts are that either the ball bearing that blocks the return is not being moved by the leaver or due to the excessive extension of the rams they are kinking slightly so wont go back in.

 

I think we will try to lift the trailer with a loader and see if they go back in with the weight off tomorrow.

 

Any advice greatly appreciated. All of this is outside of our area of expertise and we are a bit stuck.

 

We also have 4 spare legs 2 the same and 2 that are piped to spool valve blocks.

 

Thanks

 

Will

[twistedhicap]

where does the flow come from on board pump or from the tractor ?

 

if from the tractor it may be that the flow is the wrong way either try the pipes the other way round or put the spool leaver in other direction ?

[arbwork]

Non Forestry cranes I’v used have a separate divert valve for the legs, possibly to stop you from accidentally moving the leg/ s whilst operating loaded crane, there will/? be a divert lever on the supply which will lock the legs at the same time as enabling the crane to be used

[Will Hinchliffe]

Thanks for your reply

 

Turning the lever does nothing.

 

The trailer has a pto pump and its own hydraulic system.

[Will Hinchliffe]

Non Forestry cranes I’v used have a separate divert valve for the legs, possibly to stop you from accidentally moving the leg/ s whilst operating loaded crane, there will/? be a divert lever on the supply which will lock the legs at the same time as enabling the crane to be used

 

This makes sense to me but there seems to be no divert lever. The pipe that supplies the spool valve block also supplies the legs we traced it back and cant find a lever.

[ben lightfoot]

might need to upload some photos if possible

[Will Hinchliffe]

:001_tt2:Im on it ben

[Will Hinchliffe]

The cranked pipe is attached to the return, the other is pipped to the pump.

[ben lightfoot]

only because its confusiing me trying to imagine what im looking at if that makes sense although thats not hard hahaha hope your well anyway Will

[Will Hinchliffe]

Im good thanks Ben. Il drop you a pm when I get some time and find out what you've been up to. I gather from some of your other posts you've now gone self employed. Hope its going well for you.

 

It confuses me when I look at it in front of me. Your right pictures are necessary.

 

Another picture of the lever on top of the leg.

 

And one of the trailer before it got stuck up in the air.