Air bag jacks / air jacks

Looking through the Vehicle Dependent Expedition Guide (Tom Sheppard) I find myself (again) wondering about the use of an 'airbag' - inflated by the exhaust output, as a jack.

Has anyone actually used this type of device?

More importantly, does anyone know who stocks them so I can get one to try?

My thinking is that they're not really totally dependent upon pure 'pressure' as much as 'volume' of "air". This should not therefore expose any minor weaknesses in the vehicle exhuast system! :-)

Martyn

Guessing that they are round and about 2 foot diameter you have about

40 square inches of area lifting the truck.

The truck is 2800kg, which we will call 6000 lbs.

Therefore, to lift it entirely, you would need about 150psi. But you aren't going to do that - you are going to lift one end, so let's say half that pressure to do the job.

Still quite a lot of pressure, that...

Tim Hobbs

'58 Series 2 '77 101FC Ambulance '95 Discovery V8i

Saying "what" exactly???

That Grumble is heavy... ? You'd be right. (especially as I'd be on the outside watching the bag inflate...) Not that I'm fat anyway - but I do wear very heavy sandals ;-)

I think I need one of these:

Big enough to lift a house, however, Grumble could probably get away with one of these:

Martyn

Gorrit!

So, has anyone actually 'used' one?

Martyn

Erm... Grumble currently weighs in somewhere around 4.5 tonne (44.1KN) when fully loaded :-( I reckon the ELM04 (NATO part stock

5130.99.227.8324) should do a corner, one side, front or back fairly easily. Yes, it is the pressure and stress on the exhaust that worries me, though. Not too sure how good a test that'd be for the promised Rimmer Brothers lifetime warranty!

So, has anyone tried one?

Martyn

We (N&NROC) used to demonstrate using one in a competition vs a highlift jack at Hartington Steam Fair - it worked a treat and was very quick, but we packed it in when a member nearly got flattened - the motor does tend to roll around a bit, as after all, it is a ball! There were no problems as regards exhaust systems, as you right surmise, its volume not pressure.

Richard

My maths is up the spout. pi r squared, not pi r. So divide my pressures by 12, which looks much more reasonable.

Tim Hobbs

'58 Series 2 '77 101FC Ambulance '95 Discovery V8i

I guess maths wasn't your strong subject at school then!!

There are 10 types of people in this world. Those who understand binary, and those who don't.

(Shamelessly stolen from somewhere...)

Martyn

yeah, sounded like something was wrong. that equates then to under 10 psi doesn't it? an exhaust system "should" easily be able to take that sort of pressure. it's proabably about that at the end of the pipe anyway.

yep, that is an absolutely ripper that joke. you can really weed out the nerds with that one (i got it when i was told, so i suppose i'm a nerd) i tell that to my arts student friends and they're like "ha ha, wait, i don't get it." and then all the computer nerds are like "he he he" in a nerdy little giggle. anyway, great joke. i love it.

What sits on your shoulder and squawks 'pieces of seven'?

Tim Hobbs

'58 Series 2 '77 101FC Ambulance '95 Discovery V8i

Parity error

Tim Hobbs

'58 Series 2 '77 101FC Ambulance '95 Discovery V8i

In my defence I did spot my own error!

I am slightly embarrassed to admit that I have a degree in Mechanical Engineering. Maths was my strongest subject at school, but the fun went out of when all the numbers turned into letters...

Tim Hobbs

'58 Series 2 '77 101FC Ambulance '95 Discovery V8i

I've had one for a long time - I think I bought it sometime in the early

1980s, it only gets very occasional use nowadays. I had to replace the tubing from the exhaust to bag a while back which had perished - I used some 50mm plastic tube covered in the nylon sheath which it was supplied with. The original tube was a bicycle inner tube!! It has a cone to fit over the exhaust, a joiner mid point along the hose with a non return valve, another joiner into the bag with a non return valve.

I've only ever used it on sand or (apparently) bottomless mud and its been great - its lifted its fair share of vehicles from light Suzuki's upto a 6 tonne Isuzu which had buried a front wheel.

My only word of caution is that if the exhaust system is suspect it wont work - I found a weak spot in the V8 LR muffler box when lifting a Toyota out of the sand at the waters edge about 4 months back.

has a pic at the bottom of thepage of the sorry vehicle in question. I love using a 30 year old, $2500vehicle to recover $60,000 plus vehicles. We used the air jack to break thesuction, after we'd lifted his exhaust out of the sand and he could run hisengine and use his exhaust, then we used the PTO winch on the LR to drag himup the beach.

Bah! I always liked the idea of such a device. However having 4 exhaust exit pipes I'm not actually sure how it would work.....or maybe I could inflate 4 bags at once

Oh well....back to work....

1 air bag and 1 bag of King Edwards...

Tim Hobbs

'58 Series 2 '77 101FC Ambulance '95 Discovery V8i

On Sat, 27 Sep 2003 10:05:47 +0100, Tim Hobbs made me spill my meths by writing:

Spudulike on the side?

H'mmm...at what pressure does the engine stall ?

Lee