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Purpose Built Forwarder Thread (OSA, FMG/Bruunett, Entracon, Norcar/Logset etc)

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One for the Bruunett 578F aficionados:

 

What sort of pressure should my hydraulics system be making?

 

I ask because the main lift on the crane seems to be 'weaker' than I remember.

Other functions appear to be fine.

 

Plumbing a gauge into the lift ram service gives me 1000psi at high tickover, rising to 1100psi at working revs (1700 rpm approx.)

Tapping into other services is giving 1500psi at tickover rising to 1600psi at working revs.

 

Even these higher figures look low to me, but perhaps someone can tell me if they're in the ballpark for such an old machine?

 

My Operator's Manual is telling me about relief valves in the system ranging between 2175psi and 2750psi, so I'm thinking that normal working pressures should perhaps be up around the 2000psi mark.

 

All filters have been changed and the system refilled with fresh Hy-Tran.

The return filter above the cab in particular was a disgrace, partially collapsed and clogged with bits of instant gasket and rubber off skived hoses!

 

I strongly suspect that some of this debris is fouling in various relief valves and giving me my poor lifting performance issues.

 

To my mind, it's looking like I'll be stripping down the pump and valve chest to clean it all out.

Anyone have any experiences or tips to impart before I get the spanners twirling???

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While I'm pondering these things...

 

Who made the valve blocks for these old Bruunetts, does anyone know?

 

I can't see any sort of identifying mark or text on mine.

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Sorry no ideas about the Pressures required for the 578 however it may be worth cleaning and checking the relief valve and making sure it is functioning correctly.

 

I have just had the valve block rebuilt on my 678 by Clarks in Scotland, Talk to Dave Clark, they had all the parts and were very helpful so I would 100% recommend them if it does need doing. The block on the 678 is made by Monsun Tison and the model is a HV07, no idea if a similar one using pilot pressure was used on your machine.

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One for the Bruunett 578F aficionados:

 

What sort of pressure should my hydraulics system be making?

 

I ask because the main lift on the crane seems to be 'weaker' than I remember.

Other functions appear to be fine.

 

Plumbing a gauge into the lift ram service gives me 1000psi at high tickover, rising to 1100psi at working revs (1700 rpm approx.)

Tapping into other services is giving 1500psi at tickover rising to 1600psi at working revs.

 

Even these higher figures look low to me, but perhaps someone can tell me if they're in the ballpark for such an old machine?

 

My Operator's Manual is telling me about relief valves in the system ranging between 2175psi and 2750psi, so I'm thinking that normal working pressures should perhaps be up around the 2000psi mark.

 

All filters have been changed and the system refilled with fresh Hy-Tran.

The return filter above the cab in particular was a disgrace, partially collapsed and clogged with bits of instant gasket and rubber off skived hoses!

 

I strongly suspect that some of this debris is fouling in various relief valves and giving me my poor lifting performance issues.

 

To my mind, it's looking like I'll be stripping down the pump and valve chest to clean it all out.

Anyone have any experiences or tips to impart before I get the spanners twirling???

 

Haven't a clue sorry. There are pressure test points on left hand side of the bullhead below the windscreen - I'll dig out the manual.

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That's fantastic information folks, thanks!

 

According to a bit of Google image searching, the valve chest does indeed appear to be a Monsun Tison HV07.

No pilot controls on this old girl, it's 'directly' operated by a system of levers and links that would please Heath Robinson!

 

This particular valve seems to have been pretty commonly used on lots of cranes and lifting equipment, so it's not utterly unknown in the hydraulics service sector.

 

Next task, find a schematic/exploded view of the valve!

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Follow up on the Brunnett low pressure problem:

 

I disassembled the seat box, control levers, and the forest of steel pipes and unions and got that valve chest out of there and onto the workbench.

After much further disassembly, cleaning, and close examination of all the internal pressure relief valves and seals (all of which were spotlessly clean and appeared to be in prefect working order), I discovered that the main relief valve was loose, and took almost a full turn to snug it back against its seat.

The main relief valve is the only external one on the whole assembly, and is easily accessible in situ on the machine!

Feck :blushing:

 

I nailed that whole thing back together again and ran a pressure test.

BINGO! 2100psi!

Much success :001_smile:

She's now lifting like a champion.

 

 

Now, about those 30 year old 'flexible' hoses that aren't entirely happy with this new situation...

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Some might find this interesting

Wish I could get/afford this swap over system on the botex to fit a clam shell for grindings and chip and even a little shear grab for clearing work quickly and easily!

 

Sent from my D5803 using Arbtalk mobile app

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