4WD Compressor for backup air for starting a Mack

Hi All.

I live is OZ and most of the macks in OZ have an air start tank to start the truck.

I in a few ocations have been left with out any air to start the truck. and in the cold can take a bit to start.

this is my proposal to place 12v 4WD compressor on to the truck to fill up to 90psi the air tank.

does any body know the volume of the air start tank?

and does any body think that my plan will work?

i have heard of stories of blokes having a small motor with a compressor to chug away for a bit to fill up the air start tank.

thanks heaps.

-Monty

Bushranger Max Air II Air Compressor

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Bushranger Max Air II Air Compressor
The Max Air II is a handy compressor to have on board when you're out bush or on the sand. It makes reinflating tyres easy pumping up 31x10.5" tyres from 15 to 30psi in around 1 minute and 25 seconds, and 33x12.5" tyres in 2 minutes.

It comes with a carry bag, air hose, and features a snap on air outlet with a protective heat shield, and cast air filter attachment to make replacing filters simple. All compressor components are fuly servicable and the unit may be vehicle mounted and hard wired if required. The Max Air 2 pushes out around 52.5 lpm @ 30 psi, and offers a maximum of 72 litres per minute.

Specifications:

Maximum Air Flow: 72 litres per minute
Maximum Voltage: 13.8 volt
Maximum Amperage Draw: 29 A
Maximum Working Pressure: 150 PSI
Maximum Restart Pressure: 200 PSI
Maximum Ambient Temp.: 70

Monty,

It could work. The worry would be would the compressor cope with long running. As the stat's you provide it does consume 29Amps and as the volts drops the compressor would also slow down. And in most applications the quoted 13.8V is usuall only achived when the engine is running. Suggest you discuss with manufacturers of compressor to ascertain its abilities to run for long periods.

I don't have an air start vehicle but what is the minimum pressure required to turn one over?

As I remember one of the guys once telling me that if he runs out of air he deflates his tyres into the air tank to help start the truck. When started then reinflates tyres. Obviously this wouldn't get 90psi!

But maybe it would be enough to start a truck that is being stupporn. Also he told me once that if that didn't work he then calls the onsite truck tyre repairs to pump up the tyres and the truck. Obviously this wouldn't work outside of main locations!

hay jBlair thanks for the reply.

thanks for the responce, i had not thourght about the volts dropping as the battery drains. if the worst thing to happen i can get some jumper leads and a battery from someone to keep up the juse.

the starting range is between i think 60-90psi.

yes i have heard of using the tyers but as this thing is bob tail most of the time currently i will be redusing the pressure in the tyers to improve the ride, so that means that there wont be much pressure in the tyers to start with, so there goes my backup plan, thats the reason for the small compressor.

thats another good idea ring the tyer mob.

-monty

What about a petrol compressor mounted on a rack behind the cab...or even hidden in a tool box?

hay Andy.

yes a smal one would also do the trick, mouinted some where discretley!

Two suggestions..

1. How about mounting a second backup air tank that you can shut off to preserve air pressure? Charge it once.. switch it into the compressed air "circuit" when you need it?

2. Put a small bike pump in your toolbox


Dunc.

Hey Dunc you have solved the problem, why did i not think of a bike pump.!!!!

the air tank has two taps on it to store the air,

why did i not think of a bike pump.!!!!

I'm guessing you're joking Using a bike pump it might take about 2 weeks to fill a decent size reservoir

Dunc.

The air pressure to kick over a Mack has got to up and over about 50/60 lbs in the air start tank, under 50 and it will not throw the motor at all.
If your gunna carry any sort of compressor, then make sure it is petrol driven and able to pump up to 110/120 lbs, hide it in the toolbox best you can.
An electrical pump will just not cut it, think of the small batteries that your carrying on the truck and what their capable of doing, then think about what the pump is gunna suck outa them real quick.
Air start fitted to a truck equals very small batteries, Cyril Anderson had them fitted up that-a-way and ALL others just followed along, there are a few electric starting Macks around and they got the BIG compliment of batteries fitted to 'em.
The time honored solution is to carry a long air lead so you CAN take air from your tyres to fill the air start tank.
You normally only get three good hits from the air tank, then you might be lucky if it throws the motor on the fourth attempt, fifth attempt forget it, out with the hose and start drainin' the tyres.
If you only have 90 lb in each of the eight rear tyres, then if you drain the front axle four tyres only, you will have at least 75/80 lb in the air tank. Drain all the 8 tyres and you will have the max your tyres are carrying in the tank.
As each tyre is drained, the air pressure in the tank and that last drained tyre is equalized, so as you proceed up the tyres, you are taking less out of each tyre.
You normally only have the front bogie lookin' real flat on one side only, then the others in varying degrees of flat.
If the motor don't start after the first four hits, something is bad wrong and you better start lookin' for the problem, before you do any thing else and fix the problem before even attempting any more shots at it.

Been there, done that, on a bloody ccccold morning at Guyra, not quite snow overnight, but close enough, not bloody funny, I can tell you that.
Had to drain the front axle and then got me bum scratches on a can-o-heart starter, half a can emptied down the throat, hit it again then away we go, maximum revs and them some more, lots more actually, till the heart starter thinned out, what a relief to hear it screamin', meant the cab heater was gunna work.

Think real hard about wastin' your readies on the electric pump.

regards greenie [smiley=vrolijk_1.gif]

Guys,

Can I chuck me 2 bobs worth in for good charm?





We have an air start MIR700 Mack (pictured above) at work - great sound when ya hear her start! She starts off the key instead of a button after the key is turned on!! It almost sends shivers up me spine, let me tell ya! If she runs out of air in the starter tanks, our driver gets the big long hose out and connects it to a 3 phase compressor with a bl@@dy huge reservoir on it - he only takes out enough air to fill the tank and tries starting her again! It is only ever rarely this happens - twice since I've been working out there (almost 2 years! [smiley=thumbup.gif]) - but it always would happen I guess!

Joe