A Hydraulic Question

[Haironyourchest]

My vertical hydraulic electric log splitter manual says not to suddenly change direction of the splitting wedge...that is, if the wedge is on the return stroke, going up, don't suddenly push the power lever and make it go back to power stroke. The machine has a settable stroke stop, and it said to let the ram hit the stop, before applying power again. The reason for this, IIRC, is to avoid a sudden change in direction of flow, which is bad for it, much like allowing your car to come to a complete stop, before shifting to reverse.

 

Makes sense, but.... I've seen digger men yank the controls all over the place, they don't pause before changing direction of the boom, bucket etc. There's the "jiggle the bucket" manouver, to get stuck mud out of it, which is rapidly and repeatedly changing direction of flow to the bucket ram. I've done it myself...

 

What think you, hydraulic experts?

 

 

Edited January 15, 2022 by Haironyourchest

[s o c]

Maybe it’s more about protecting the electrical components than the hydraulic ones.

[Haironyourchest]

Thanks for your input. I wondered this. How would that work do you think? The motor only spins one way, the pump only spins one way, so the reversal of flow is due to a valve change. Maybe a too sudden change in direction makes a kind of resistance shock to the motor?

[Dan Maynard]

Sudden stops in fluid flow can cause huge pressure waves, hence the phenomenon called water hammer in domestic water pipes. I'm not a hydraulic expert but I would guess more expensive hydraulics on a digger are designed to take the shocks, but splitter built down to a price lacks the extra parts.

[openspaceman]

1 hour ago, Dan Maynard said:

Sudden stops in fluid flow can cause huge pressure waves, hence the phenomenon called water hammer in domestic water pipes. I'm not a hydraulic expert but I would guess more expensive hydraulics on a digger are designed to take the shocks, but splitter built down to a price lacks the extra parts.

Pressure relief valves absorb most shocks, port relief valves on individual spools if the shocks are from external loads.