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could a Discovery II air suspension compressor inflate tyres?


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#1 freeagent

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Posted 29 June 2006 - 07:35 AM

does anyone know if the little compressor used in Disco II's to run the air suspension could be used to inflate tyres? i've seen a P38 compressor being used for this purpose, and it works realy well... but i don't know if the Disco II pump is smaller, as it only has to inflate the rear air bags.....

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#2 SteveG

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Posted 29 June 2006 - 08:05 AM

does anyone know if the little compressor used in Disco II's to run the air suspension could be used to inflate tyres? i've seen a P38 compressor being used for this purpose, and it works realy well... but i don't know if the Disco II pump is smaller, as it only has to inflate the rear air bags.....

cheers
m@tt.


Yes you can. The flow rates are not great, but both units are 100% duty cycle

Steve


#3 simonr

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Posted 29 June 2006 - 08:07 AM

The disco unit is a better design than the RR and will likely last longer too!

Si

#4 freeagent

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Posted 29 June 2006 - 08:15 AM

ok thanks....
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#5 BogMonster

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Posted 29 June 2006 - 11:04 AM

would think it will be v slow process? takes a long time to inflate a pair of springs if they have gone flat overnight!
2002 Discovery II 4.0 V8 auto • 2006 Defender 110 SW 300Tdi • 2011 Ford Ranger XLT crewcab

#6 simonr

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Posted 29 June 2006 - 11:25 AM

would think it will be v slow process? takes a long time to inflate a pair of springs if they have gone flat overnight!


I used to use a RR one - and it was not too bad. The answer of course is to use a reservoir. For a while I used my spare tyre as a reservoir. It seemed fine up to the max pressure of the compressor (about 140psi) although probably not reccomended!

When I first tried it, I was hoping the tyre would explode - just to see what happened ;) but didn't have a compressor capable of generating enough pressure (200psi was as much as I could get) :( Figured that running at half the max I tried would probably be OK.

(Don't try this at home kids!)

Starting at 120psi, it had enough air to inflate the four tyres from 18psi to 30psi pretty quick or enough to change a tyre with a rattle gun. It took about half an hour to get the spare up to pressure.

Si

#7 Turbocharger

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Posted 29 June 2006 - 11:49 AM

Are these mechanically- or electrically-driven compressors? Are they belt-driven from the engine, if the former?
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#8 SteveG

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Posted 29 June 2006 - 11:51 AM

electrical, air con compressors on P38 and Disco II are belt fed though :)

Steve


#9 Turbocharger

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Posted 29 June 2006 - 12:30 PM

No no, electrical is good since I've filled the easy space on the engine with winch gubbins. Does anyone happen to have specs on current draw and CFM? With one of these running continuously and a bus air tank hidden somewhere, I could have onboard air without the mess of moving the FEAD about.
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#10 freeagent

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Posted 29 June 2006 - 12:51 PM

thats just what i want to do with one... 12V feed and a little air tank from a HGV....
does anyone happen to know the CFM and current draw....
i reckon i could put it on my loadspace, where one of the dickie seats should be (only got 5 seats)

m@tt.
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#11 David Sparkes

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Posted 29 June 2006 - 07:22 PM

"The RR air compressor has been criticized by some for being inadequate in capacity and too expensive, but in reality it is a sturdy industrial 1/5 horsepower 20 amp "Wobl" piston unit made by Thomas Pumps, one of the best-known manufacturers in the world. It is a member of the Thomas Pumps 315 model series (see details below), has a flow rate of about 0.96 cfm at low pressure, and according to justcompressor.com (http://www.justaimli...ssor_thomas.htm) it can fill a 3 gallon tank from 0 to 150 psi in 4 minutes 45 seconds. It is commonly used by low rider fans to pump up their vehicles. It has to keep the 10 liter (2.5 gallon) Range Rover air tank charged up to 10 bar (150 psi), which is a much higher pressure than most off-road air compressers can reach. The compressor also has a much harder life than the average air compressor, having to operate in hot under-the-hood conditions (it is rated at 158 degrees ambient) for hundreds of hours rather than a few minutes at a time. "

Read here for alternatives:
http://www.rangerove...sor.html#thomas

While interesting, a lot of that information has now been rendered redundant, as overhaul kits for the original compressor are available at a reasonable price from www.rover-renovations.com
Yes, I am a satisfied customer.
There are instructions on the site to assist in repair. Ignore the advice if you like wasting money by wrecking the piston ring.

A note about the original 38A installation.
Despite what I've copied above, the pump is protected by a 30 Amp fuse, I suggest you replicate that protection.
There is NO thermal cut out in the pump. There is a normally closed contact, connected to Earth, which opens when overheating occurs, but it's up to 'you' to create a circuit where this disconnects the operate path for the switching relay. Is it stating the obvious to say that this contact is not designed to switch off a hot inductive circuit directly? Perhaps not, but it is stated just in case. Use relays to switch the pump.

HTH

#12 GBMUD

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Posted 30 June 2006 - 02:49 PM

Being too tight to spend 175 on an ARB compressor for my ARB, I got a RR suspension pump for free from SimonR - the one he used on his spare tyre I guess. I made a reservoir from a ~8" length of heavy wall 4" box section, tapped some 1/4BSP(?) holes in it to fit a pressure switch (90PSI), pressure guage, PCL connector and ARB solenoid. It has been working fine for some years now and, since I run BFG M/Ts on 8-spokes it spends a fair amount of it's time re-inlating tyres with carp in the bead. Very quiet too. I have also inflated air matresses - one I forgot about and it got a little too "hard". D'OH! :) See me at Billing, 7 Sisters, TonyC's for a demo.

Total spend was less than about a tenner I think.

Chris

#13 SHAVED_GORILLA

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Posted 30 June 2006 - 03:02 PM

Are aircon pumps any good for onboard air?

SG
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#14 Turbocharger

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Posted 30 June 2006 - 03:13 PM

Chris - do you have any feel for the current draw of the pump?
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#15 GBMUD

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Posted 30 June 2006 - 04:08 PM

No. But given the mention of 30A fuses above, I am using VERY thin wires! IMHO nothing like 30A but, running at 90PSI and not 150PSI may make a difference to the load on the motor.

Chris

#16 landrover598

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Posted 30 June 2006 - 04:40 PM

Chris, That sounds ideal for the on board air i've been meaning to install for a while now. I don't want to go to all the hassle of the air con route for something which won't get a lot of use

I'll have a nose at your setup at 7S if you don't mind :D
David Lang
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#17 GBMUD

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Posted 30 June 2006 - 05:47 PM

It will be a pleasure to meet you David. :)

Chris

#18 Mark

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Posted 30 June 2006 - 06:12 PM

Are aircon pumps any good for onboard air?

SG


Yep. There are a couple of good write-ups on using aircon pumps for OBA in the tech archive...

Mark

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#19 SHAVED_GORILLA

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Posted 30 June 2006 - 08:51 PM

Must have a look then.

Cheers

SG
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#20 freeagent

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Posted 30 June 2006 - 08:59 PM

thanks for all the replies... looks like the air suspension pump, with a small tank is the way to go... i've got a pressure switch, loads of air line conections and stuff... so hopefully it wont cost the earth.... <_<

cheers
m@tt. :)
currently without a 4x4 as life is getting in the way!




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