Does this qualify as a shit day?

[openspaceman]

1 hour ago, Mick Dempsey said:

That would require the presence of an individual with competence and experience on that work site.

 

If said person was there I would imagine he/she would have made their presence felt before the stuff hit the fan.

 

I suspect the relief valve was letting oil through.

 

Yes but how? My point was that there is a check valve on each ram port that won't let oil out until there is a positive pressure at the other port, there must be a relief valve on each of these also.

[Mick Dempsey]

3 minutes ago, openspaceman said:

Yes but how? My point was that there is a check valve on each ram port that won't let oil out until there is a positive pressure at the other port, there must be a relief valve on each of these also.

Clearly you know more about this stuff than me so I’ll stop theorising.

[Mick Dempsey]

10 hours ago, openspaceman said:

Yes but how? My point was that there is a check valve on each ram port that won't let oil out until there is a positive pressure at the other port, there must be a relief valve on each of these also.

Guy on another forum echoes your thoughts.

Thinks the guy on the ground is lowering the basket otherwise the crane (the one holding the basket) would tip.

[Mick Dempsey]

17 hours ago, openspaceman said:

Yes but how? My point was that there is a check valve on each ram port that won't let oil out until there is a positive pressure at the other port, there must be a relief valve on each of these also.

More info…

[openspaceman]

31 minutes ago, Mick Dempsey said:

More info…

Thanks again, it had been puzzling me all morning and I had hoped someone with understanding of MEWP mechanics would chime in.

 

I had decided it was possible by using counterbance valves rather than check or overcentre valves.

 

These would need the full pressure of the hydraulics to the opposite side of the ram to develop before oil would be let out, this would labour the pump somewhat but if the boom became overloaded it would lower. before it snapped.

 

The only thing different from normal this would need is for the spool that controls the lift to be a motor spool (i.e. both services connected to tank in neutral).