Servo controlled hydraulic valve block query

[Wood wasp]

Hello

 

Hopefully someone who knows a little about hydraulics can answer a query for me. I picked up processor from engineer today and it works grand when empty but once loaded with a tree it becomes clear that there's a lack of pressure/flow as the movements slow right down.

 

The valve block which controls processor is servo controlled and it looks like there's not enough pressure being applied to the relevant valve block function - the levers are not being fully engaged. When the levers are fully engaged manually there is plenty of flow & pressure to machine but via servos the levers are only engaging about two thirds.

 

So... Is it easy to turn up the pressure being applied to valve functions by the servos? Hopefully I can catch up with engineer on Monday but thought I would ask here in the meantime.

 

Hopw that makes sense and thanks in advance for any info

[treequip]

You dont need to turn up the pressure, the pressure is already there but it sounds like the servos need to be set to stoke longer so thay they open the valves fully

[Wood wasp]

OK thanks for that Treequip, I was hoping would be something simple like that. Does it matter if double acting functions and adjustment is what is required?

 

Maybe best that I don't interfere with servos until I speak with chap who put system together!

[treequip]

OK thanks for that Treequip, I was hoping would be something simple like that. Does it matter if double acting functions and adjustment is what is required?

 

Maybe best that I don't interfere with servos until I speak with chap who put system together!

 

Without seeing the system its hard to say but single or double shouldnt make a lot of diference

 

If you paid someone to do the job chuck it back at them first.

[Wood wasp]

OK thanks again. I don't envisage any trouble with engineer making adjustments, was just curious if something simple as I'm not really 100% sure how servo system works. When it's all pipes and no electrics I still can't get my head round how pressing a switch changes flow from one valve block to another!

[treequip]

There must be wires unless its a hydraulic servo but since you said switch.....

 

So heres how a servo works, electrical servos are a coil and magnet system, when you energise the coil the magnet moves, connect the magnet to the valve with a rod and the valve operates when the coil is energised. Proportional controll is a little diferent but essentially the same principal

 

If the system is hydraulic servo the jojstick is a small hydraulic valve that opens a bigger one when opperated. This means the controll can be small, handy and light to opeperate unlike the valve it opperates which is chunky and not at all small and handy.

 

The problen you seem to have is that the coil isnt moving far enough to open the valve fully

[Breezeblock]

check servo pressures and working pressures before you adjust anything

[mechtrev]

first you need to distinguish what type of valve it is, is it proportional or cetop type.

I would say it will be cetop type in which case it sounds like there is a lack of voltage to the coils. This can be addressed by fitting relays to work the coils and the switch works the relay, usually happens as the switch will not pass the current required by the coil.

[Wood wasp]

Thanks all for informative responses as always, all very interesting and good to know.

 

To help clarify re system the crane control levers in cab are mini hydraulic valve blocks which in turn are connected to bigger valves (as per treequips post above). There are also two buttons with electrical connections on tops of levers.

 

To switch control to processor I put foot on switch and the crane levers now work the processor valve block. How engineer managed that when it's a hydraulic system is beyond me.

 

I have every faith he'll sort out the issue with valves not fully engaging, I was just curious as to what issue was and also a touch impatient, I won't touch anything 'till hear back from him!

 

Thanks again for all informative responses