Dangers of Hydraulics Query

savageseadog

savageseadog

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I recently met someone who had a nasty accident with a cherry picker which resulted in him being blinded in one eye.
He was struck in the face by a hose end that had come undone in some way. Obviously pressurised .
I'm puzzled because hydraulic oil is incompressible so if a hydraulic system breaks, theoretically a small amount of fluid will release and not much else could happen . Or does it?
 
Hydraulics don't work just by pressure, they must do work so the pump has to displace considerable amounts of fluid very quickly. Just like a fireman's hose if it gets dropped but with 3000psi behind it a hydraulic hose is going to thrash around viciously.
 
savageseadog said:
I recently met someone who had a nasty accident with a cherry picker which resulted in him being blinded in one eye.
He was struck in the face by a hose end that had come undone in some way. Obviously pressurised .
I'm puzzled because hydraulic oil is incompressible so if a hydraulic system breaks, theoretically a small amount of fluid will release and not much else could happen . Or does it?
Click to expand...
Well, the pressure in our hydraulics is around 3500psi. When the hoses let go, Newtonian laws come into play. The force applied to the free hose end (and then kinetic energy in the flailing hose) is enormous. I've had one go in a tractor cab and it's a frightening experience. Sympathy to your acquaintance.
 
Apparently the picker wasn't powered or working but the platform was off the ground. The hose broke when he stepped on the platform.

I know that large air and blasting hoses are fitted with ties or restrained to stop them from flailing about.
 
savageseadog said:
Apparently the picker wasn't powered or working but the platform was off the ground. The hose broke when he stepped on the platform.

I know that large air and blasting hoses are fitted with ties or restrained to stop them from flailing about.
Click to expand...

Hydraulic hoses don't just "break", I suspect there was some existing damage. Proper visual checks are a must.
 
Hydraulics are a ridiculously dangerous thing, when it goes wrong. Often the result can be an atomised release that can and has been known to cut through skin and bone in an instant.
 
Back in 82 i was working in Mikes boatyard & we did an old 32ft admiralty cutter up. She had been sunk & all the wiring was ripped out.
The yard engineer had first aided the engine & one day Ray the chippy & i went to run the engine a Ford 4D up afloat out the back of the yard. Ray wasnt in a good mood which was common.
We coupled up a battery & I was in front of the engine working the controls on the diesel pump manualy, Ray stood astride the gearbox & shorted the solenoid out with a screwdriver to start it, He told me to push the cold start button in which i did.
Of course the engine roared into life. At that point one of the hydraulic hoses in the gearbox blew out the engineer having only done the union up finger tight. I hit the stop button but the engine had to reach full revs before it would stop. It emptied its gearbox of oil in about 5 seconds flat, the armoured pipe flailed around like a wild thing & Ray copped the lot, up his nose in his mouth, eyes the lot. Some of it went over my head over the wheelhouse & hit the shed ten yards away. He was dripping. The language was awful. I sculled him ashore & the boss who was standing on the slipway laughing took him to hospital.
Fortunately he had no lasting ill effects.
It wasnt the first or the last time that Ray had accidents like this, he had a real short fuse & when he was throwing a wobbler things used to happen!
 
The stored energy in a flexible hydraulic hose when the pump is running is considerable, similar potential lethality to a ship's mooring line letting go, which is why hoses are controlled with various restraints. With older machinery maintainers sometimes do not bother to reinstate those restraints and they become commensurately less safe.
 
Keith 66 said:
Back in 82 i was working in Mikes boatyard & we did an old 32ft admiralty cutter up. She had been sunk & all the wiring was ripped out.
Click to expand...

Sorry for thread drift ....... but you don't remember her name, do you?

My Dad owned 'The Jan' for around 15 years from around the mid-sixties.

She was a converted 32 foot, centreboard, Admiralty cutter, with 'Built by John Brown's Shipyard, Clydebank Works, 1939' carved inside the transom.

She gave me many happy memories of pottering around the east coast, and the near continent, as a teenager.

Dad kept her on a swinging mooring at Hullbridge.
 
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