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OT: What casues hydralic whine noise

Bill D

Diamond
Joined
Apr 1, 2004
Location
Modesto, CA USA
Off Topic. As hydralic systems start to take a load and pressure builds up what is causing the high pitch whine? is it tiny leaks in the pump like a whistle, pump cavitation or what? All makes seem to have a similar high pitched whine when loaded. I am talking about presses, compactors etc.
Bil lD.
 
Off Topic. As hydralic systems start to take a load and pressure builds up what is causing the high pitch whine? is it tiny leaks in the pump like a whistle, pump cavitation or what? All makes seem to have a similar high pitched whine when loaded. I am talking about presses, compactors etc.
Bil lD.


Not my personal bag. An expert should be along to discuss the effects of pumps, turbulence, friction, directional changes (an elbow introduces noise), efficiency and speed of sound in a pressurized fluid, etc.

But I CAN share that it is not just an annoying trait.

Sounds generated by, or carried by, fluids can be seriously USEFUL as well.

Old Day Job (Esterline Medical) got curious as to why we had orders for multiple THOUSANDS of our patented "bone vibrator" AKA inertial transducers meant for hearing aids that were not going to folks with hearing problems.

Lots of air miles, rental cars, autographed photos from Jacques Costeau (Air Liquide owned U.S. Divers), Bev Morgan (Kirby-Morgan "Band Mask"), Jim Helle (Hellephone), and a slew of major oil companies as preferred not to be identified...

And... a unit we had built to be "deaf kid abuse proof" had been put to use miles down monitoring flow in seabed oil production rigs by the sound, telemetered up-cable to spectrum-analyzer display screens.

Did that valve open, as commanded? If so, how wide? Does that flow sound the same as what is on-record?. etc.

The other players were using them for diver-to-diver, and diver to surface audio communications over a carrier. 40 Khz or so, with Barium Titanate or Lead Zirconate Titanate piezo transducers ..IF.. I recall correctly. 1972-73, so no certainty of that.

Irony? The transducer product line was later hived-off and basically outlived the original hearing aid side of the firm. At least with any claim to "continuity" about it.

Next time that noise bugs you?

Just think how much less safe, and how much more expensive, our petro products might be if there was no sound to use for monitoring.
 
Slight pump pulsations is normal, Equally the fluid flowing around corners and such is far from quiet turulance in the flow can and does cause cavitation and even on a tiny scale that gets slammed shut fast at typical hydraulic pressures making a right din. The whine when bottomed is probaly also the pressure relief valve opening in part and the corresponding high pressure oil flowing through it and the cavitation there too, do to the density of the oil any noise in hydraulics can and does echo through out the whole system. Sound also travels far faster in the oil hence it effects what and how we hear it.

If you want quiet hydraulics you probably need to talk to the sub guys, if they will talk about it, my best guess though would be as low as possible pressures and low flow velocities, valveing ported like the racer boys do cylinder heads to promote smoother flow. Typical valve parts are normally just drilled passages, lots of sharp corners to whistle at high flows.
 
Whine from the pump/motor, or from the cylinder? When a non compressible
fluid is compressed and pressurized and then forced through a small aperture, such as the valve body or inlet on the cylinder, it will "scream". (Imagine being stuffed into a pair of pants that your 12 year old daughter wears...:eek::bawling:) That is the simple explanation for cylinder squeal. I can get into it further, but it will be a long reply. It's been a long day, I'll read this again later and give some specifics (and probably correct myself)
 
Hydraulic oil absorbs moisture.
At the pump vanes there is compression/heat that converts the water to a gas. This effect will erode the vanes. Analogy is pre-ignition/detonation in a gas engine that over time damages the top of the piston.
It is much like a Thermal Dynamics experiment going on around the pump vanes. Like the cross section of an airplane wing as air flows across it there is a difference that creates Lift..
So, can oil be compressed? To a degree yes. It is mostly the moisture in the oil that is being compressed and then expanded on the low pressure side of the vane to release the air and cause the whine.
Does the pump create pressure? Not really, the pump creates Flow.
John
 
"Have you driven a Ford Lately ?"

Notorious for that wine from the power steering pump,
changed one out, new one still did it.

and did it, and did it, and did it....for hundreds of thousands of miles.
 
"Have you driven a Ford Lately ?"

Notorious for that wine from the power steering pump,
changed one out, new one still did it.

and did it, and did it, and did it....for hundreds of thousands of miles.

That is the belt verification feature. If it stops whining you know you broke the belt.
 
This is a good question. I recently bought my first hydraulic power unit for use around the work bench and would like to understand the factors that influence noise levels.

Notorious for that wine from the power steering pump,
changed one out, new one still did it.

Yeah, for sure. That noise almost always relates to air in the system. I had a couple mustangs that did that. So many hours spent. The cars were autocrossed and road raced reguarly and the steering, along with everything else, would get hot. Merely adding a cooler did not solve the problem.

Many of the re-man pumps have air leaks on the input side of the pump, due to the plastic housings but especially how they would rebuild the plastic input nipple. The molded-in nipples frequently snapped off as the cores were transported. I found it was essential to not buy pumps that had repaired input nipples. And once aerated, it is necessary to flush and bleed the system, and rack, properly.

In one case the problem was the high pressure line to the steering rack. The hard section had been kinked at some point and straightened. The problem resolved once I replaced the line. There was probably turbulence at the kink, leading to cavitation and vibration. I think auto steering systems may be more prone to that because the pressure goes up and down so much, to preserve the road feel.

Low fluid levels would also cause air to enter the system. Air in the system expands when hot and burps out more fluid from the tiny pump housing reservoir. Etc.

Over the years I went through a lot of pumps for race cars (took a bit to figure out the leaky repaired input nipples), changing the flow restrictors to optimize for quick steering and feel, and also the pulleys to under-drive the pumps for extended high engine rpm. Fluid flow volume must also be increased for high speed steering input.

After sufficient absurd amounts of time were spent learning the kinks, the system was quiet, bulletproof and drama-free. Too bad it took Ford even longer to solve their platform P/S issues.
 
The whine in automotive steering is often related to a baffle spot welded in the reservoir as well...the weld breaks, and constant mixing of aerated fluid.

Oh, and the screen in the reservoir as well.




Sent from my iPhone using Tapatalk
 
The whine in automotive steering is often related to a baffle spot welded in the reservoir as well...the weld breaks, and constant mixing of aerated fluid.

Oh, and the screen in the reservoir as well.




Sent from my iPhone using Tapatalk

So Ford has this problem, and yet somehow Dodge, Cheby, Toyota, Honda, Fiat,
mercedes, RollsRoyce, Mitsubushi, Mazda...etc all fixed the problem ?
 
Somewhere I read a history of Saginaw steering division and the reason why the saginaw pumps are better is because they build them better end of story.

Don't quote me on this, but I believe Ford's have been using the cheaper line of Saginaw pumps since they started using the modular engines in the 90's. The little pump that bolts to the side of a Triton or Powerstroke block is Saginaw. They're not as good as the better Saginaw pumps, but not complete shit like what Ford used previously.

What I never got was why the damn E series vans had the good saginaw pumps and everything else Ford was shit. Napa used to have a conversion pump you could buy to retro the old shit Ford pumps. I think they stopped making them.

I've had umpty dozen 12 valve Cummins powered vehicles and never had an issue with their Saginaw pumps. Had them with 400, 500 and even 800K++ miles on them and they still work just fine.
 
Somewhere I read a history of Saginaw steering division and the reason why the saginaw pumps are better is because they build them better end of story.

Don't quote me on this, but I believe Ford's have been using the cheaper line of Saginaw pumps since they started using the modular engines in the 90's. The little pump that bolts to the side of a Triton or Powerstroke block is Saginaw. They're not as good as the better Saginaw pumps, but not complete shit like what Ford used previously.
Anyone I could quote has been 50 years gone, but AFAIK, Ford's link to Saginaw came with what an Uncle called "That G__D__ed ball-feed mechanism" on a Ford tractor's steering. Apparently it had seriously nasty feedback as the front wheels hit plowed field.

Other tractors had worm and sector or cam actuated steering which had low feedback percentages and didn't try to rip the steering wheel back and forth.

No pumps nor power on our small ones. Hydraulic PTO only on that of a wealthier neighbour. - That was the early 1950's, may not have been new tractors even so.

Recirculating ball is all over the landscape now for machine-tools, but AFAIK, THERE is where Saginaw had to pioneer a new level of precision, and tool-up to sustain it. Not a surprise to me they could build seriously good pumps as well.

Ford? Some days they are their own worst enemy. If only they had a patent on that such that it wasn't equally true for the other sods, other days of the week, same model years, year AFTER year.

Any remaining "brand loyalty' as to anything with wheels or heels needs a careful look at each individual "era' and MY within it as they each refine the limits on just how much can be cut before the deliverables "fail too often".

:(
 








 
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