Hydraulic failure on 7 ton Hi-Ab

[jackpreacher]

Our trusty wood pellet supplier came with 3 pallets today but we had to handball them off because his crane wouldn't work. There's nowt wrong with the hydraulics, pump or hoses but it was the complicated electro/pneumatic solenoid device that slots his vehicle's engine into PTO mode - he's had issues with it in the past and it has cost him £2000 in breakdown fees and workshop repairs.

To cut to the chase, could a relatively compact 24V hydraulic power pack handle a small Hi-Ab? Here is one on EBay that I thought could do the trick:


View item:
HYDRAULIC POWER PACK 24 volt ( MOTOR + PUMP + TANK )


any opinions welcome.
Thanks.

[Stock]

What the hiab/crane on jack?? I don't think there would be sufficient oil reserve even for a small crane on the one you linked to.

[jackpreacher]

It's on the back end of a small 7.5 tonner flat bed wagon. It's not huge and is rated to lift 1 to 1.5 tons at full reach. I'll get more details of the flow rate and oil capacity of the hydraulics already installed.

[Muz]

Yea I think you would need about 6 gallons of a reservoir for a crane like that plus the flow needs to be good since you can pull on mor than one service. Those electro hydraulic units are ok for straight lifts but not multiple ram systems in my view

[Stock]

Taking that there are 5 rams and say at 500mm full stroke with a 50mm bore will require a volume of oil 7.22 litres, (slew ram one is open other is closed)

valve chest + pipe work @ 7l= a total of 14.22 depending on pipe lenghts etc. To have this operating reasonably quickly you would need at least 11l/min pump delivery. Reserve volume for such a pump to keep oil and pump temp down will need to be 44l.

Indicated fluid volume required would be 58l or so.....................

[Gridley]

I`m with the rest on this.These units are for slow low capacity needs like Transit tippers and tail lifts.Admittedly you don`t need a lot of capacity as oil going from the resevoir via the pump to a cylinder will be replaced with oil coming back from the other side of the cylinder so the capacity needed is only the volume of the piston rods in the cylinder.
If his pto uses a lever operated by an air cylinder to engage/disengage the pto it would be a cheap fix to put a cylinder and an electrically operated air solenoid on there.Lot simpler too.

[jackpreacher]

If his pto uses a lever operated by an air cylinder to engage/disengage the pto it would be a cheap fix to put a cylinder and an electrically operated air solenoid on there.Lot simpler too.

I can't be sure but I think he has an electrically operated air solenoid right now. He hasn't got back to me yet with the specification but I take the point that the power pack I posted earlier is too small.
He got stranded a few months back with the crane at full reach and had to get a tech bod out - can't imagine how much that cost...brrrrrrrrrrr...

[Stock]

Jack he shut down is a safety feature on most of the modern ones if you over reach or over load they freeze. It also probably got a safety device to prevent the truck being driven wit the PTO engaged.........................

[Gridley]

Jack he shut down is a safety feature on most of the modern ones if you over reach or over load they freeze. It also probably got a safety device to prevent the truck being driven wit the PTO engaged.........................

Agree with that,but it should be possible to overide it to recover from the situation.
I remember my BIL who works for a builders merchant complaining that one of theirs was like that and that when it froze the only way out was to lower the load.As he said the load was not always in a good position for lowering as they did a lot of drops over walls etc at private properties.

[jackpreacher]

. It also probably got a safety device to prevent the truck being driven wit the PTO engaged.........................

Now that's interesting as yesterday, when it wouldn't work, he said that he'd driven it a few miles still engaged-or thats what I think he said. We debated at the time whether or not he could have damaged it. No, DEFINITELY, he said was engaged

[jackpreacher]

Taking that there are 5 rams and say at 500mm full stroke with a 50mm bore will require a volume of oil 7.22 litres, (slew ram one is open other is closed)

valve chest + pipe work @ 7l= a total of 14.22 depending on pipe lenghts etc. To have this operating reasonably quickly you would need at least 11l/min pump delivery. Reserve volume for such a pump to keep oil and pump temp down will need to be 44l.

Indicated fluid volume required would be 58l or so.....................

That figures - thanks Stock. The tank on his Hiab is fairly substantial. In simplistic terms could THAT small 24V unit be plumbed into the already installed tank?

[Stock]

Yes. but whether the 24v pump will deliver sufficient volume is the question..........

go to page 28.............the unit is bolted to the tank...............

One would need to consider the duty cycle of the motor and if it is a modern truck what way would the ECU behave with the high amp draw of such a motor...........then there would be the need for a larger alternator and additional batteries............


http://www.parker.com/literature/Lit...50_1303-uk.pdf

[jackpreacher]

I've not heard from him since posting this thread so I assume he's just had the solenoid repaired - thanks for the responses anyway - I'll show them to him when he deliver next

[jackpreacher]

UPDATE

I've not heard from him since posting this thread so I assume he's just had the solenoid repaired - thanks for the responses anyway - I'll show them to him when he deliver next

Well it seems like he disconnected the pneumatic/electric control and welded on a length of bar with a handle that manually puts the HP into the PTO. .....my kind of engineering

[Muz]

Well it seems like he disconnected the pneumatic/electric control and welded on a length of bar with a handle that manually puts the HP into the PTO. .....my kind of engineering

Aye who needs electrics anyway