Vane Type PS Pumps

[Citroënbender]

A simple pondering.

If the bore size of two pumps is the same, and their applications similar (barring maybe a 10% difference in stroke), is it odds-on they will have a similar vane count?

[dunga]

Originally Posted by Citroënbender

A simple pondering.

If the bore size of two pumps is the same, and their applications similar (barring maybe a 10% difference in stroke), is it odds-on they will have a similar vane count?

The higher vane count will give a smoother delivery power steering pumps usually have a flow control valve in the output so it delivers a constant volume to your rack/ steering box the excess flow is delivered back to the reservoir the volume of the pump is matched to the requirements so what is important is the metered flow of the pump if swapping pumps is what you are looking at doing.

[slowsnake]

Originally Posted by dunga

The higher vane count will give a smoother delivery power steering pumps usually have a flow control valve in the output so it delivers a constant volume to your rack/ steering box the excess flow is delivered back to the reservoir the volume of the pump is matched to the requirements so what is important is the metered flow of the pump if swapping pumps is what you are looking at doing.

I was in Qld in the 70'S and worked at every meatworks in every major city on the coast from Rockingham to Cairns, I was replacing all the ammonia pipes to suit the new compressors, I always wondered why they chose screw compressors over vane?

They were Atlas Copco compressors but no engineers to question, it was just " fit that there, machine grout, then run ya pipes " but I was always asking "why" about everything I did, do you have a reason about the benefit of vane over screw?....pumping ammonia not fluid or oil.


Cheers Billy

[dunga]

Originally Posted by slowsnake

I was in Qld in the 70'S and worked at every meatworks in every major city on the coast from Rockingham to Cairns, I was replacing all the ammonia pipes to suit the new compressors, I always wondered why they chose screw compressors over vane?

They were Atlas Copco compressors but no engineers to question, it was just " fit that there, machine grout, then run ya pipes " but I was always asking "why" about everything I did, do you have a reason about the benefit of vane over screw?....pumping ammonia not fluid or oil.


Cheers Billy

Your talking refrigeration now similar but not hydraulics.

[slowsnake]

But I thought vane was better than screw, more efficient maybe, I asked an engineer mate 30 years later he said vane was better?...all these years later I still think about it, it interests me, and this thread sparked it off again, crazy eh, so your answer kicked it off in my head, I can read about the pros and cons but not experience?

You have an opinion on it, I know it's off track, but any input welcome, for my own curiosity


Cheers Billy.

[383hq]

Originally Posted by slowsnake

But I thought vane was better than screw, more efficient maybe, I asked an engineer mate 30 years later he said vane was better?...all these years later I still think about it, it interests me, and this thread sparked it off again, crazy eh, so your answer kicked it off in my head, I can read about the pros and cons but not experience?

You have an opinion on it, I know it's off track, but any input welcome, for my own curiosity


Cheers Billy.

I've worked with enough process engineers for the following (general) summary:
Vane = more efficient (lower operating cost)
Screw = potential for greater volumes pumped (don't confuse pressure with volume)

I'd imagine that in refrigeration Volume was important due to the PV=nRT relationship and adiabatic expansion (or something like that)
As an aside Just had a new inverter RC air con installed - it runs at 100psi, replacing a 20 year old unit that required 250psi, so improvements have been made in these areas....

[dunga]

Originally Posted by slowsnake

But I thought vane was better than screw, more efficient maybe, I asked an engineer mate 30 years later he said vane was better?...all these years later I still think about it, it interests me, and this thread sparked it off again, crazy eh, so your answer kicked it off in my head, I can read about the pros and cons but not experience?

You have an opinion on it, I know it's off track, but any input welcome, for my own curiosity


Cheers Billy.

screw pumps generally operate at relative low pressures hydraulic pumps can be grouped into 3 types gear vane and piston there are variation of these types but generally that's it in my experience i have never seen a screw type hydraulic pump (that's not to say they don't exist) only screw air compressors water pumps and sludge pumps etc..

[Citroënbender]

Originally Posted by dunga

The higher vane count will give a smoother delivery power steering pumps usually have a flow control valve in the output so it delivers a constant volume to your rack/ steering box the excess flow is delivered back to the reservoir the volume of the pump is matched to the requirements so what is important is the metered flow of the pump if swapping pumps is what you are looking at doing.

I’m looking at changing the drive from a single vee to poly. Have had ongoing issues with premature wear, the run is short; too short and there’s no extra tensioner - just drive and driven pulleys. It drives about 300% of engine RPM.

Have been scoping a similar arrangement that has no similar issues with tension/wear on a 4 rib poly-vee driven pump with very close driven ratio and the same bore in the pump body. The only other difference I know is the stroke of the “possibility” rack is about 20-30mm more, and I wouldn’t be swapping it in.

So, my take on the situation is, they redesigned it for a later model and got it more right.