No Oil Pressure - AJP8 Auxiliary Drive Shaft Failure
Discussion
spitfire4v8 said:
Elegant it ain't.
Only because of the coupling to the ZF PS pumpIf they had designed their own PS pump and mated it directly to the oil pump using the same shaft then that would be very elegant, but a significant extra cost
It is also essential to protect the PS coupling from debris that can fall in and jam the mechanism, that is most definitely a design fault
...onwards and upwards!
Jhonno said:
Didn't fancy going electric PS whilst it was all apart Paul?
The PS pump weighs but a few ounces, a pound at mostThe Saxo pump weighs nearly as much as me, and requires a lot of additional cabling, and takes up ten times as much space
Using power from the alternator, and then converting it back to mechanical energy probably means a loss of at least 50% efficiency relative to a direct mechanical drive
Sorry, but I'm not a fan
However, I will make sure to use the PS coupling cover that a very generous PHer sent to me
ukkid35 said:
Jhonno said:
Didn't fancy going electric PS whilst it was all apart Paul?
The PS pump weighs but a few ounces, a pound at mostThe Saxo pump weighs nearly as much as me, and requires a lot of additional cabling, and takes up ten times as much space
Using power from the alternator, and then converting it back to mechanical energy probably means a loss of at least 50% efficiency relative to a direct mechanical drive
Sorry, but I'm not a fan
However, I will make sure to use the PS coupling cover that a very generous PHer sent to me
I would say, given that manufacturers are all switching to electric PS in the name of efficiency, that they are are probably better compared to mechanical pumping losses.. They aren't a massive drain on the alternator, I will have to measure mine now!
Jhonno said:
Yeah the Saxo pump is a bit bigger, but only requires 6 wires, and a relay.
I would say, given that manufacturers are all switching to electric PS in the name of efficiency, that they are are probably better compared to mechanical pumping losses.. They aren't a massive drain on the alternator, I will have to measure mine now!
But aren't they mainly electrically operated steering columns, rather than hydraulic racks with electric pumps?I would say, given that manufacturers are all switching to electric PS in the name of efficiency, that they are are probably better compared to mechanical pumping losses.. They aren't a massive drain on the alternator, I will have to measure mine now!
And I bet it's nothing to do with efficiency, and all to do with cost
ukkid35 said:
Jhonno said:
Yeah the Saxo pump is a bit bigger, but only requires 6 wires, and a relay.
I would say, given that manufacturers are all switching to electric PS in the name of efficiency, that they are are probably better compared to mechanical pumping losses.. They aren't a massive drain on the alternator, I will have to measure mine now!
But aren't they mainly electrically operated steering columns, rather than hydraulic racks with electric pumps?I would say, given that manufacturers are all switching to electric PS in the name of efficiency, that they are are probably better compared to mechanical pumping losses.. They aren't a massive drain on the alternator, I will have to measure mine now!
And I bet it's nothing to do with efficiency, and all to do with cost
Can't comment on cost, but I was lead to believe it was efficiency.
said:
The hydraulic energy is now produced by an electrically driven pump rather than a belt driven pump, as in traditional hydraulic power steering systems. Therefore, engine power can now be used to move the vehicle and power minimal ancillaries/auxiliaries via the drive belt rather than be wasted pumping hydraulic fluid unnecessarily. As the power produced by the engine can now be used more efficiently, there is a fuel saving in the region of 0.3 l/100km (or an extra 3.75 MPG) and a reduction of CO2 emissions in the region of 7g/km.
A quick Google came up with this. However, if EPS isn't for you, fair enough. I saw the advantage as reduced load on the aux shaft and ease of replacement if nothing else.
The key thing about ‘on demand’ electrically driven pumps are that they are only operated when they are needed. If you have a belt driven pump off the engine then it is working all of the time so the overall efficiency is lower.
For oil and water pumps there is another advantage that the electrically driven ones can be operated at speeds that are not a fixed ratio to the engine RPM which allows improved performance and or further efficiency benefits for the engine a a whole.
For oil and water pumps there is another advantage that the electrically driven ones can be operated at speeds that are not a fixed ratio to the engine RPM which allows improved performance and or further efficiency benefits for the engine a a whole.
Jhonno said:
there is a fuel saving in the region of 0.3 l/100km (or an extra 3.75 MPG)
I feel sorry for anyone who converts a Cerb to electric PAS expecting a 20% improvement in fuel economyI had had the dubious pleasure of driving home from Zolder with no PAS, and there was no perceptible difference in fuel economy
I do appreciate that on a small engined daily hydraulic PAS, aircon, heated seats etc are all going to affect economy
The Cerb fuel economy is so poor, that when I brought the Cerb back from Germany on the back of a truck, the truck used less fuel carrying the Cerb than the the Cerb would have done by itself
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