Any obvious faults

[Johnsond]

Hi All 

Got the engineering guy on nights here to knock up this to show the proposed layout for upgrading the hydraulics on the mill. 12v system is in place, GX and pump are sourced as are return and pressure line filters etc. Just wondering if anyone with any hydraulics knowledge can see anything fundamentally wrong with the layout ??. 
Cheers 

[dumper]

No pressure relief valve?

[Conor Wright]

Engine flows direct to a valve, if this is closed and you try to start the engine you will build pressure. Other than that I see no issue, but I'm no expert, not by any stretch! 

It's an easy fix too, just open the valve first!

I presume there's a pr valve on the block or somewhere on the existing machine.

[thomasvdb7]

Could you put in a non return valve after both the electric motor and engine? That way if you forgot to change the levers round before starting it wouldn't cause pressure problems? And with non return valves you wouldn't need to switch anything. Just either start the 12v or the engine... 

[Johnsond]

Thanks for the input.yeah there is a prv on the existing block, non return valves are an option and would do same job but do occasionally pass a bit. I use kit quite often with a secondary or back up power source and this often entails throwing a couple of valves into position, keeps it nice and simple too. 

[Conor Wright]

Simple works. if it's just you using it I'd go as is, if there's a risk of it being used by an idiot then it may require some slightly more complex idiot proofing. (12v switchover valve/solenoid wired to ignition?)

 

It just struck me, aren't idiots great? They do so much to advance simple things which need a little thought and care in their use so you don't cause damage, into these mega complex creations which require virtually no human input at all. All these advances can be attributed to a bunch of idiots, just blew my mind!

[Johnsond]

11 minutes ago, Conor Wright said:

Simple works. if it's just you using it I'd go as is, if there's a risk of it being used by an idiot then it may require some slightly more complex idiot proofing. (12v switchover valve/solenoid wired to ignition?)

 

It just struck me, aren't idiots great? They do so much to advance simple things which need a little thought and care in their use so you don't cause damage, into these mega complex creations which require virtually no human input at all. All these advances can be attributed to a bunch of idiots, just blew my mind!

No it’s just me using it and I’ll be labelling it up to try and keep it looking reasonably factory spec. Admittedly valve positioning by people can go wrong. Testing one of the back up systems on this job and all the valves bar one were in the correct position, the one that wasn’t dead headed the system blowing the return line and spewing about 20 gallon of hyd oil onto the deck. 

[openspaceman]

8 hours ago, Conor Wright said:

Engine flows direct to a valve, if this is closed and you try to start the engine you will build pressure. Other than that I see no issue, but I'm no expert, not by any stretch! 

It's an easy fix too, just open the valve first!

I presume there's a pr valve on the block or somewhere on the existing machine.

Yes  @Johnsondsays the the pressure relief valve is on the (spool) block then neither pump is protected if the  manually operated valves are make before break. A pressure relief valve between each pump output and tank would solve this but then you may as well put a shuttle valve where the manual valve is and let it do it automatically. The hydraulic high pressure filter is a bit unusual for this sort of use.

 

Normally  on simple 12V pumps built into the reservoir ( as on a tipper) a switch on the spool powers up the electric pump, if so this would need disabling while the petrol pump runs to cut wear on the 12V pump constantly blowing off the relief valve .

[Johnsond]

3 hours ago, openspaceman said:

Yes  @Johnsondsays the the pressure relief valve is on the (spool) block then neither pump is protected if the  manually operated valves are make before break. A pressure relief valve between each pump output and tank would solve this but then you may as well put a shuttle valve where the manual valve is and let it do it automatically. The hydraulic high pressure filter is a bit unusual for this sort of use.

 

Normally  on simple 12V pumps built into the reservoir ( as on a tipper) a switch on the spool powers up the electric pump, if so this would need disabling while the petrol pump runs to cut wear on the 12V pump constantly blowing off the relief valve .

12v system can and will be switched off when petrol motor is running. The high pressure filter was an idea based upon past experience with a pump that failed and fired a load of shrapnel through the system on a mini digger I had but it’s optional, one on return side is definitely going to be fitted. One of main reasons for going this route is the ability to use the hydraulics other than when head is back and connections to alternator/12v systems are engaged. I’ve been caught out a couple of times  with that and also with big Elm/Ash/Oak etc it gives the the 12v system a hell of a lot to do. 

[openspaceman]

I see, so the electro-hydraulic only works when the head is parked?

 

The reason high pressure filters are not used a lot is they are very limited in their size because as this increases the bursting forces increase with the square of the dimension. A return filter is under little pressure (until it blocks which is why there is often a bypass relief) so can have a large filtering area.

 

Scuse the poor drawing

 

 

 

When the electro-hydraulic is not parked the petrol can be started and the shuttle moves to block the electric pump output. Similarly when the petrol pump is stopped the elecric pump provides flow and blocks the output of the petrol pump. The relief valves are safeguards should both pumps become fired up