New ARB Compressor Cutaway Pic and thoughts

[me3@neuralfibre.com]

Check this out -


What do you notice about the crankshaft?

Hmm, I wonder how they made that work?

If it's what I think it is, that's one hell of a piston ring seal.

Paul

[MightyMouse]

as I understand it - its a "rocking" piston system. Other compressors do this as well, especially the short stroke / large bore "diaphragm" type.

Personally I prefer the traditional piston/gudgeon pin/conrod/crank design but thats based on nothing more than preference.

Time will tell if I'm wrong.

[RV80]

I got one. Only used it once so far. I'm impressed with it. I ran it to a small tank for reseating beads and am using 1/2 inch air line and a proper tyre pressure guage and it works well...

[-Scott-]

It's not an uncommon design in air compressors of this size. Some of the big names in the industry use it, so I don't see why ARB can't get away with it.

[GRPABT1]

Ok I have NFI WTF you guys are talking about. Wanna explain it in laymans terms?

[-Scott-]

Ok I have NFI WTF you guys are talking about. Wanna explain it in laymans terms?

The piston is rigidly fixed to the conrod, so it doesn't stay "square" to the bore. As the crankshaft goes around, and the conrod changes angles, the piston changes angles too - it "wobbles" in the bore.

[guzzla]

Would that classify it as a wobble plate compressor like some air con comps ?

It looks like it.

[RED60]

Would that classify it as a wobble plate compressor like some air con comps ?

It looks like it.

No. The traditional wobble plate in air conditioners is a different system. It's difficult to explain on here, especially cause I'm a slow typist... look it up on google.. they'll have diagrams that will show how an a/c compressor works...

[RED60]

Ok I have NFI WTF you guys are talking about. Wanna explain it in laymans terms?

The piston is rigidly fixed to the conrod, so it doesn't stay "square" to the bore. As the crankshaft goes around, and the conrod changes angles, the piston changes angles too - it "wobbles" in the bore.

Perhaps "rocks" in the bore as it goes up and down would be more correct..

[me3@neuralfibre.com]

as I understand it - its a "rocking" piston system. Other compressors do this as well, especially the short stroke / large bore "diaphragm" type.

Short stroke / large bore would make it harder to seal - wider rocking angle.
Long stroke / narrow bore would make it easier as far less rocking angle.

Long stroke may increase average piston velocity though.

The crevice volume would be huge, I'm suprised they can get enough pressure out of it (compression ratio)

Any idea on how the piston seal (ring) manages to seal? It looks like some type of folded thing. Further, would the ring be symmetrical around, as the wear would be uneven.

Thanx
Paul

[rvh96]

They get seriously hot when running and in a very short time

[MightyMouse]

BTW this isn't relevant to the ARB unit - just discussion....

Short stroke / large bore would make it harder to seal - wider rocking angle.
Long stroke / narrow bore would make it easier as far less rocking angle.

With a diaphragm style you have no option.... it doesn't use a piston simply a rubber sheet attached to the conrod that is "stretched" up and down by the conrods motion, and also adsorbs the angular change. Obviously the "stroke" is limited by the elasticity of the diaphragm - to get capacity a large bore is required.

Old style auto fuel pumps worked on a very similar principle.

Commercially these are often called "oilless" compressors as by their design they can produce "clean" compressed air.

I also had a 12V unit that worked on the same principle it was / is quite a popular design

[RED60]

Short stroke / large bore would make it harder to seal - wider rocking angle.
Long stroke / narrow bore would make it easier as far less rocking angle.


Thanx
Paul

You've got it the wrong way round... draw a diagram.. it'll be apparent straight away... generally speaking short stroke/large bore is the least angle.....

[-Scott-]

Short stroke / large bore would make it harder to seal - wider rocking angle.
Long stroke / narrow bore would make it easier as far less rocking angle.


Thanx
Paul

You've got it the wrong way round... draw a diagram.. it'll be apparent straight away... generally speaking short stroke/large bore is the least angle.....

Correct me if I'm wrong (I know somebody will ) but I believe it's the rod/stroke ratio which determines the maximum angle.

[GRPABT1]

Ok I have NFI WTF you guys are talking about. Wanna explain it in laymans terms?

The piston is rigidly fixed to the conrod, so it doesn't stay "square" to the bore. As the crankshaft goes around, and the conrod changes angles, the piston changes angles too - it "wobbles" in the bore.

Ooooooooooooohhhhhhh I see now, shit that seems dodgey as. Is it possible to run ARB lockers with another compressor cause I keep hearing more and more bad things about these.

[MightyMouse]

"rumor" has it they are better than the old design and apparently out flow them.

Having had a bad run with the old design - I'm not certain if thats a huge positive or not.

[bigcam]

i give mine a hard time, running 2 lockers and pumping up tyres after every trip, its a bit slow when pumping tyres with the valve core in, if its out it scoots along really really well. about 5 mins for 33" from 15 - 35 psi.

it foes get hot and cut out though, usually after the 2nd tyre on a hot day and 3rd on a cold day.

its in the engine bay so is starting pretty hot though.

i have found that water cooling is effective, i just trickle some water over the head and motor every 5 mins or so and she keeps going until all tyres are done. so far im very happy with it.

it is possible to run lockers form another setup but the ARB one is neat, the loom is good and so far it has been 100% reliable.

[dbongard]

Is it possible to run ARB lockers with another compressor cause I keep hearing more and more bad things about these.

Hi guys, just wondering if I could interrupt and ask exactly what 'bad things' are being said?
So far we're really excited about this unit!
Our market research shows that you'd need to spend over $500 to get anywhere near our flow rate, and over $800 to get the same features (note : our RRP is $290.00)
The warranty rate has been almost non-existent, the sales have already doubled our expectations, and the first magazine to write up a market comparison against all compressors available in this country (within a price range that almost doubled the cost of ours!) - found it outperformed everybody else.

Oh, and it's the only 12V automotive compressor in the world that is bolted together on Aussie soil!

it foes get hot and cut out though, usually after the 2nd tyre on a hot day and 3rd on a cold day.

Our first units were built with a lower temperature cut-off circuit than we now use - but that was just because we wanted to err on the safe side. What most people don't realize is that motor magnets actually start to de-magnetise when they reach about 130°C. Most compressors on the market (including our previous model) do not have thermal protection, and so they suffer a reduction of performance every time they get that hot. You could solder up the switch if you want to...but we figure most guys want to keep their compressor for a long time.

As for the 'wobble piston' design; short stroke, large bore, & long rod = only a few degrees of wobble angle, and therefore no broken seal edge, and carbon fibre seal longevity which we have not successfully been able to wear out yet, even after hundreds of hours of run time. You'll also notice how light yet fully-braced the new piston assembly is. The weight reduction and high rigidity allowed us to drive a killer flow rate out of this thing - which would have cooked a reciprocating piston unit! (gudgeon pin socket meltdown!) That's also why we shopped around Timken Germany for the right high shock (yet light weight) roller bearing for the con rod, and then pressed the highest rated (largest) ball bearing we could fit between the motor bolts behind the piston (but you'd have to pull the motor apart to see it).

...but I could babble on for hours about this unit.

Back to the question: has somebody actually heard something bad about it?

daniel
Air Locker

[GRPABT1]

I haven't heard anything specifically bad abou this new desgin yet, but I have heard of many failures with the old units. You can't build a repution on failure then try to claim brilliance. What is the exactly flow rate and PSI on these things? Cause I'm sure it can be matched for cheaper than you claim.

[bigcam]

i stuffed around with cheaper compressor, tanks, manifolds etc. etc and in the end shelled out the (honestly minimal $300) for this unit.

i dont work for arb but i reckon it's great, it gets covered in water and mud, gets a fair work out and has been going fine for 6 months.

i havnt heard anything bad but havnt heard of many running them. The old compressor was a bloody old design and this one doesn't seem to use any of the same parts. but it comes down to maintenance too. alot of compressors are under the bonnet int he heat and cold covered in grease oil, mud and water and dont evey see a squirt of WD or a pull down to check all is ok. and then ppl complain when they fail..

[MightyMouse]

but I have heard of many failures with the old units. You can't build a repution on failure then try to claim brilliance.

I think this is a very critical point, in fact it pretty much explains the thread IMO. Sure the old units are going / gone - but they had their share of problems and its going to take time and experience for people to form an opinion ( good or bad ) on a new design.

Some of us will just never go back to electric compressors willingly

"Bolted Together" that could be just an accidental choice of words - or it could mean made from imported parts. If so, its not quite as Aussie as could be, but with the low production cost in Asia it must be very difficult to fully manufacture locally at a competitive cost.

I hope it performs and lasts to your customers expectations.

[carrot]

...but I could babble on for hours about this unit.

Yay, it's great to have someone familiar with the design of a product here on the forum to support it (and answer questions, cop complaints, etc)! Are you an ARB engineer / CAD monkey / PR guy / ... ?

[Simo63]

I had one of these installed when I had new lockers put in my 80 series 12 months ago so probably got one of the earlier ones with the lower cut out temp It was installed by an ARB shop and I was told that it is really only designed for the lockers and not for inflating tyres (and looking at the poor little thing I thought to myself that it would take a week to inflate a 33) but reading here that people pump up their tyres with them?

Got to say that I was dubious about trying something so new and unproven at that time but I was told that they were heavily tested so listened to that advice. And I wasn't that unhappy not to be getting one of the older ARB units as I've had them before (and the real early ones that you can no longer get parts for too) and they were not that impressive a unit IMHO. Subsequenttly I have a portable Blue Tongue that I have fitted into a box for inflation purposes (had it for years and it's still going like a train ).

Has anyone else received the same advice as I did re not for inflating tyres?

And dbongard from ARB, what are your thoughts? Is it okay to inflate tyres with one of these?

Cheers
Simo

[dbongard]

What is the exactly flow rate and PSI on these things? Cause I'm sure it can be matched for cheaper than you claim.

Whoa. That is a can of worms that could drag this thread on for months, unfortunately.

I'm not a salesman, I'm an engineer.
I'm not into throwing mud around, so I'll just say this:

We designed and built a computerized contained-volume flow dyno to help us build a better compressor. The box our compressor comes in says it flows 76 litres per minute (open flow) - and it does. Our unit has a 50% duty cycle rating, because that's what the computer determined it was. Our compressor will run at 100 PSI quite comfortably for its entire life cycle because we designed it to operate Air Lockers at 100 PSI (and we like it when people use Air Lockers).

I can show you a compressor for $40 off the shelf with a box that claims in big bold letters that it flows at 85 litres per minute, has a 100% duty cycle, and a working pressure of 300 PSI. We bought one (we have pretty much bought one of everything at one time or another) and put it on the dyno. The flow rate weighed in at well under 20 litres per minute and as for the duty cycle and working pressure...well, I can't really say, other than it did reach 67 PSI and we now have put in adequate ventilation in the testing room to clear smoke and fumes.

The vast majority of 12V air compressors are bought by people who will store the unit safely away in case of a rare emergency involving blowing up their kid's bike tyre, a basket ball, or repairing a boat trailer flat. This usually involves less than 50 PSI, usually only one small tyre, and usually only once every few years - if ever. It doesn't take much for the cheap range of compressors out there to keep up with these demands because this is exactly what they were designed for - and nothing more, regardless of what the box says.

I'm not about to name names though. I'd suggest you just get a hold of any of the compressor comparison articles published in Australian four wheel drive magazines. They will tell you how it really is. Sometimes their journalists come to ARB and use our dyno. They make us stand back and let them test...and they even bring their own sample of our compressor so that they know we haven't hot-rodded one specially for the test. They'll generally tell you how much and what you really get for it.

Otherwise, the next time you pick up an item that has a brand name you have never heard of, and it isn't named after the store you are buying it from, then just remember this:

In Australia there is no effective way to police the claims made by brand-X product distributors. Even if you were successful in challenging the performance claims made by an Australian distributor of cheap import products (which must be demonstrated at your expense) then the distributor would merely be required to remove them from the shelves. And since it is generally the distributor who selects the brand-X name to start with, then they can simply bring the next shipment in under a different name.

Daniel
AIR LOCKER

[bogged]

You can't build a repution on failure then try to claim brilliance. .

yea the 55 series cruiser was a dog, so nobody can claim the 80 or breadbox to be any good..
I read it on the net

[damo83]

I got one of the new ARB compressors for xmas and used it for the first time last weekend. I got it for the sole purpose of inflating tyres and I was more than happy with it. I pumped my 33x12.5's from 18psi to 35psi in about 3-4mins each, one after the other and it didn't cut out. After I finished it was really hot (found that out the hard way when I went to unplug the air hose!) so next time I think I'll give it a rest between tyres. Mine is the portable model which came in the carry case.

Anyways just thought I'd add my (very limited) experience so far.

Cheers
Damo

[MjWatt]

ive had mine since about xmas and am really happy with it. does a 35 from 12psi to 35 in about 3-5 minutes. I can get all 4 done with out it cutting out.

I have noticed the fittings getting hot, but so far has not affected the performance of the compressor. Mine is mounted under the drivers seat so i might keep an eye on it.

[dbongard]

I had one of these installed when I had new lockers put in my 80 series 12 months ago so probably got one of the earlier ones with the lower cut out temp It was installed by an ARB shop and I was told that it is really only designed for the lockers and not for inflating tyres (and looking at the poor little thing I thought to myself that it would take a week to inflate a 33) but reading here that people pump up their tyres with them?

Our new unit only hit the shelves in late June. So you have our CKSA12 which is this one's much smaller cousin. It was designed as a rough and tumble little diff-actuating pump, and it was designed to be small and inexpensive. Personally I like it as a tyre filler for smaller vehicle tyres, but the marketing dept. was worried that people wouldn't like the speed - so we say NOT RECOMMENDED FOR TYRE FILLING. Go ahead if you want to!

...I wasn't that unhappy not to be getting one of the older ARB units as I've had them before (and the real early ones that you can no longer get parts for too) and they were not that impressive a unit IMHO. Subsequenttly I have a portable Blue Tongue that I have fitted into a box for inflation purposes (had it for years and it's still going like a train ).

My wifes Holden Astra will blow the doors off of Enzo Ferrari's first sports cars, stop quicker, and last at least 100,000 km's longer...but that doesn't mean Ferraris are rubbish. It's all an evolution.

You can't build a repution on failure then try to claim brilliance.

Granted - but failure is a bit harsh. We still get guys in here with 12 year old ARB compressors who use them every weekend and swear by them. And I didn't think I had made any brilliance claims. It was reported that somebody on a forum had 'heard bad things' about a product that we really take allot of pride in, so I was sent in to find out more details. And I'd rather you heard the 'claims' from other people with objective experience, but it seems that bigcam is the only guy I have read on this forum who has actually used one before and nobody even acknowledged his opinion.

I'm starting to lose my faith in objective forum debate.

Daniel
AIR LOCKER

EDIT: I gotta be quicker! OK, 3 guys on this forum have used one.

[7017]

I've got one of these i can't put a bad word at one of them at the moment, I've used mine about 10 times now and works for what i need it for.

[Simo63]

Our new unit only hit the shelves in late June. So you have our CKSA12 which is this one's much smaller cousin. It was designed as a rough and tumble little diff-actuating pump, and it was designed to be small and inexpensive. Personally I like it as a tyre filler for smaller vehicle tyres, but the marketing dept. was worried that people wouldn't like the speed - so we say NOT RECOMMENDED FOR TYRE FILLING. Go ahead if you want to!

Thanks for that, I didn't realise they were different units. I will stick to the advice I got from the fitters and not use it for filling tyres (its not fitted with the connection anyway).

My wifes Holden Astra will blow the doors off of Enzo Ferrari's first sports cars, stop quicker, and last at least 100,000 km's longer...but that doesn't mean Ferraris are rubbish. It's all an evolution..

What's your point here? I wasn't saying that the newer versions weren't better in fact quite the opposite. If I thought they weren't better I wouldn't have got one fitted with the new lockers. What I was saying was that the earlier versions didn't impress me IMHO. Please try harder to understand what I was saying in the first place before getting all defensive

I'm starting to lose my faith in objective forum debate.

A forum is for open discussion. Nothing here should make you lose faith unless hearing an opinion that you don't agree with will make you lose faith. Please try to be open minded.