air starter

[Bluebulldog]

Are there still parts available for the air starters. Or how hard is it to change A air start truck over to electric start?   I was looking into a r that has a 285 air start just to use out on the farm maybe little restoration project for I an my son.   

[mrsmackpaul]

Mack still has rebuild kits for the starter, they have the solenoid and valves as well

 

Paul 

[mowerman]

wow thats crazy,,,i wouldnt have thought that....

[Geoff Weeks]

ASC out of Texas has parts for most of them. I've changed two trucks from electric to air, and it is as simple of un-bolting one form and bolting in the correct replacement. Why anyone would change from air to electric, is beyond me, but it is your truck. You would be going from 23 hp motor to 8-10 hp. 

Air systems can be self-lubing, and can outlast the truck.  The air side is simple, wet tank to inlet check, tank and air (solenoid)Relay.  I have mine hold enough air over 5 weeks of inoperation, to start, and the truck has 10 tires that can boost if the tank is low (but not empty).

To go to electric, you need to add the parts (starter button, relay cabling and enough batteries). your choice.

Edited September 2, 2023 by Geoff Weeks

[Bluebulldog]

Ok. Thanks guys.   Might be that would be a good deal truck won’t be used a lot an be one less thing for up keep.   I only ever seen one of them.   When I was little guy with dad we were looking at a truck seems I ask dad what this was for an about that time it took off.  

[h67st]

2 hours ago, Geoff Weeks said:

ASC out of Texas has parts for most of them. I've changed two trucks from electric to air, and it is as simple of un-bolting one form and bolting in the correct replacement. Why anyone would change from air to electric, is beyond me, but it is your truck. You would be going from 23 hp motor to 8-10 hp. 

Air systems can be self-lubing, and can outlast the truck.  The air side is simple, wet tank to inlet check, tank and air (solenoid)Relay.  I have mine hold enough air over 5 weeks of inoperation, to start, and the truck has 10 tires that can boost if the tank is low (but not empty).

To go to electric, you need to add the parts (starter button, relay cabling and enough batteries). your choice.

I like not having to buy batteries every few years...they ain't cheap. Plus if you run out of air and there's another truck nearby you just hook up the gladhand.

[Geoff Weeks]

In the 25 years or so, I have to replace one tank check, one tank and one relay. Total cost was less than 2 truck starting batteries.  My used units came off Roadway trucks, and had I don't know how many starts on them.

I have been stranded by electric starters many times. As long as I had air, it never failed.

Never had to "go into" the motors themselves, never a need to. Lubed with diesel from the return line from the injector/pump. Gets a shot everything the motor is used.

Edited September 3, 2023 by Geoff Weeks

[BOBWhite]

Interesting. So air start systems have a solenoid activated valve that sends air to the starter? Did they ever make them with a manually actuated lever or valve that you could use if you really hated having a good battery?

I never have been around anything with an air starter but sure have thought about getting one for the stuff we only use once or twice a year. Beats hauling battery's and cleaning connections in a hot shed. 

[MACKS]

4 hours ago, BOBWhite said:

Interesting. So air start systems have a solenoid activated valve that sends air to the starter? Did they ever make them with a manually actuated lever or valve that you could use if you really hated having a good battery?

I never have been around anything with an air starter but sure have thought about getting one for the stuff we only use once or twice a year. Beats hauling battery's and cleaning connections in a hot shed. 

No battery or electric needed,just push the air knob in an off she goes,the sound is awesome…

[mrsmackpaul]

As far as I am aware, so that means SFA

early ones had a air over air system with a manual valve you operated, this opened a big air over air solenoid 

Then they had a push button on the dash like we all had for charging tje trailers 

Same deal, push that and the air over solenoid on the tank opens and it starts

Then there was electric over air over air, this what most people would of seen

Turn the key as normal to start a truck, a electric over air solenoid opetates, this operates the big air over air solenoid and the truck starts

If the battery is flat you can stick a pen or screw driver in the electric solenoid and start it easily 

I believe that in sub zero Celsius temps they wouldn't be much good as I have found the big air solenoid on the tank freezes and I can't start at say 2 or 3 degrees Celsius or lower

If this is likely to happen I wrap the big solenoid on the tank in rags the night before in a attempt to stop it freezing

And even with a 3 start tank you might get 20 seconds of cranking, I dunno if a Mack would start at minus 30 or minus 40 in that time as I have never experienced that type of cold

 

After 9.00.am before I could start this morning, air solenoid on the tank frozen 

 

Paul

[Freightrain]

I swapped my B over to air start.  I rebuilt the air actuated valve and it will hold 90# for 7 months without issue.  So setting the system up correctly is EVERYTHING.  I can't recall where I got the new diaphragms, but likely just googled the valve number.  It was a simple job.  It's been working flawless for 6 yrs now.  

Do not use remote mounted valves, that allows chances of leaks.  Mine is tank mounted.  It is also air actuated(not electric).  I ran lines to the dash and put a button on the dash.  I would have like electric just so I could reuse my existing starter button.  But now it will start with NO batteries at all.

The only upgrade was the installation of an oiler to keep the air motor lubed.  Simple job, just taps into the fuel return line from injection pump.  Puts a squirt of fuel into the starter every time you use it.

I have the large air tank, it came from an R model.  It will crank for 6-9 seconds before dying off.   It never takes more then ONE second to get engine running.  Literally can't release the button fast enough, as it starts that fast.

[Freightrain]

5 hours ago, BOBWhite said:

Interesting. So air start systems have a solenoid activated valve that sends air to the starter? Did they ever make them with a manually actuated lever or valve that you could use if you really hated having a good battery?

I never have been around anything with an air starter but sure have thought about getting one for the stuff we only use once or twice a year. Beats hauling battery's and cleaning connections in a hot shed. 

The early systems had a hand valve mounted in the cab(under the seat, with a handle sticking out) but they tend to leak pretty bad over time and will not hold pressure for long.   I wanted to use that valve in my B, but friend told me to NOT do it due to leakage.  Even though it would be period correct, I wanted reliability.   Now the dash valve is just a remote actuator for the main air valve mounted on the tank itself.  The tank valve cones in either electric or air actuation.

The tank mounted valves, in good shape, will hold for an extended amount of time.

[Freightrain]

9 hours ago, Geoff Weeks said:

 

Never had to "go into" the motors themselves, never a need to. Lubed with diesel from the return line from the injector/pump. Gets a shot everything the motor is used.

 

I had mine apart when I bought it, had to install a new bushing in the nose cone.  Was curious about gaskets for the motor.  Friend told me he just cuts pop can cardboard cases into gaskets.  So, that's what I did and works just fine.   Mine is an Ingersoll Rand...looks just like a 1" impact gun body with a gear reduction on the end.

[Geoff Weeks]

OK, as someone who ran them for over 20 years. Here are my comments to a few of the thing written above:

The way many work, the stater motor uses a "pre engaged" pinion into the ring  gear.  a small (-4or 6 I forget) line from the air start tank goes to either an electric solenoid or air start push button on the dash. They are tighter buttons than normal air buttons and can be used with Natural Gas (so no leakage) in place of air for starting compressor station engines.

 The control air, then moves the pinion forward and opens another port that supplys the big relay valve back at the tank to open. Other (older) unit use inertia type starter pinions.  Most are pre engaged today

Manual valves have gone out because of the reasons stated, the move from inertia to pre engaged and the prone to leak problem.

When running any of the lines that will see tank pressure, use a one piece line with no unions and the minimum number of fittings, The main relay and check valve should be directly mounted to the tank if possible.

 Mine will crank for between 30-45 sec on a full tank, but as other have mentioned an engine can start faster than you can remove your palm from the button, meaning you have many starts on one tank of air.

 Cold weather: They are much better than batteries in cold weather, they don't lose power as the temp drops. Hp required to crank a diesel increase as it gets cold, precisely as batteries lose their ability.  I think the coldest I have cranked cold engine with my air start was -25 (F) I have cranked a warm engine even colder. Air start does require a dry air system, if the air is dry, the valves don't freeze.

 Air contracts as it cools, expands as it warms. I have seen a 5-10 psi variation in my start tank, just from air temp.

 I never used alcohol in my air system but did use a good air drier (AD-4's) and made sure they were serviced. Not only did it keep the start system working in the cold, it kept the brakes working in the cold.

 The inlet check valve is important. it is what separates the trucks main air system from the start system. It has to have a low "crack" pressure in the forward direction and good seal in the reverse direction.  I use Ingersoll- Rand valve made for air start service.  Only time I had trouble with them, was if the truck (valve) sat un used for a few years, they seamed to "take a set" on the rubber disk. One thing I always did when I shut down the truck. I would "fan" the brakes to drop the truck pressure lower that the pressure in the air start tank. This allowed the differential of pressure across the check valve to be 10-15 psi higher in the tank than the truck system and kept a good seal on the check valve.

When the pressure is about the same on both side of the check, there is very little (spring) pressure keeping it closed. You can easily blow through it with you breath. It is a trade off, if you make the crack pressure  higher (more force needed to open) the tank will not charge as high as the truck system can provide, but with the very little spring pressure holding if both systems are at the same pressure, the truck systems leaks slowly the check can also leak slowly. By allowing the start tank pressure to be higher than the truck system at rest, the spring AND tank pressure act on the seal disk and keep it leak free.

 The I-R starters are rated at 33 hp @ 150 psi and at around 120 PSI they are around 23-24 hp.

Edited September 3, 2023 by Geoff Weeks

[Geoff Weeks]

One "drawback" so to speak, is that  as the motors wear, they leak more air internally, but still do the job, just using more air to get it done. So how long they will crank on a tank of air goes down, but the casual observer or inattentive operator will not notice any problem, until it uses so much air that it is hard to supply enough to get the job done.  When I got mine in the 90's they were off Roadway trucks, so saw a lot of starts, but neither needed a "kit" which at the time was around $50 but I know they are more today. One used a little more air than the other, and likely would have benefited from a kit, but neither used enough to be a problem. Both had the diesel injector at the motor to lube them of start.

 Compare this to an electric, which if worn, will have great trouble cranking.

The trend today in air start is away from vane motors and toward turbine starters, almost no wear with a turbine, but require cleaner air (will not tolerate any debris). They have come up with low pressure turbine starters that can run on pressures as low or lower than vane motors.

 Mine (vane) would crank well below 50 psi but needed close to 70 for it to start cranking (move the pinion into the flywheel), but once it starts to crank, it will continue with much lower pressure.

Another common mis conception  is they aren't good at altitude. While it is true that the absolute pressure goes down, the higher you go up, so does the compression pressure in the engine. Also a tank that is charged at lower altitude holds that air at higher, so tank pressure is the same, but cranking resistance goes down. I've seen tank pressure rise to near 140 psi when I started the day in Denver and went up from there. Both altitude and temp (air tank warmed as the day went on) made the tank pressure higher. Also air starters tend to turn the engine over at a faster speed than the same engine cranked by batteries, and with diesels, cranking speed is 9/10ths of the job.

[Geoff Weeks]

One final comment about noise.

Without a muffler, all air motors are LOUD, and make a noise that is like fingernails on a blackboard to many. An air starter on a road vehicle should have an air muffler on it.  Muffled it still sounds different but no where near as loud. I parked my tractor between my garage and my neighbors house, not a lot of space, but they said it never woke or bothered them when I left early. Yes, I asked them, good neighbor are kept good with a little good manors.

 Those that think startling people with loud noises, are a bane to the trucking industry, Jakeing through town at night while people are sleeping, With straight pipes of course and running un muffled air starters to make others "jump" are making all truckers look bad.

 If you have an engine in a marine engine room or a generator in an enclosure, then you don't need a muffler, but a truck does. They are a small "can" filled with metal turnings, that quiets the "bark" while having minimal back-pressure on the motor. With a muffler they still sound like an air start, so if that trips your trigger, yes everyone will still know you are "different' than the crowd, without being an A-hole.

When "over the pits" at a DOT inspection, I always give them a "heads up" of what is coming when they ask me to start the truck. Many will have never seen one with an air starter.

Edited September 3, 2023 by Geoff Weeks

[BOBWhite]

Do newer air start systems have a separate tank for lubrication? Since the return fuel side has to be completely sealed up on some engines and diesel's not as good of a lubricant anymore. 

[Geoff Weeks]

It has a connection for a line, what you connect it to is up to you, however I don't see how the little bit is uses would effect a modern diesel, but stand to be corrected. Air tool oil isn't a whole lot different then diesel, and for lube quality it has to be good enough or the injectors would seize in the engine.

 The lube injector is a simple device, with a spring and a small chamber that is filled from the lube source, when the main line for the start motor gets air, high pressure is generated (large area over small) and the lube gets sprayed in. I can't see why a T in the return line would cause any problem with a modern engine, but am open to an explanation as to why I am wrong.

 The reason diesel is used, is because if a remote lube tank was,  chances are very good it wouldn't get filled.  Lube tanks are used on Natural gas engines with air start

 With diesel available it is a no brainer to use that..

[mrsmackpaul]

I have asked many times on here since I read about air dryers on here

We (as in Australia as a whole) never ran them until maybe the late 90's or the 2000's 

The reason I asked was because I know nothing about them and I feel by their very name they must take the moisture out of the air

I wondered if having one of these would help with the freezing

Mack as far as I know come straight off the wet tank, I feel from what Geoff has said things are pretty much the same in the U.S. so running a good CLEAN compressor is important to reliability 

No joins as Geoff also said in air lines is also important 

The big air over air valve off the tank they run in Australia has funny sized O rings, not metric or imperial but metric seams to be the most workable 

I believe it is a Ingersoll valve 

I have installed a air filter from a Mack gear box between the wet tank and the none return valve as to me this is the weak point in the design, any speck of dirt stuck under a valve can cause issues

I also only remotely fill the tank a seperare air fitting on the air system

There is a air line fitting on the tank for filling but this also increases the chance of dirt getting in the system 

My starter got so worn the vanes would bind in the rotor and fully come out, I rebuilt this years ago and it works fine 

Nothing is cheap to do but our lack of use is probably the biggest down fall today 

 

Paul

[Joey Mack]

I always thought that leaving the spit valve cracked open a little bit on the wet tank, is actually better than an air dryer.  I also thought that I had too much water in air tanks, and done too many repairs to dryers in short intervals.  Not to take away from regular pulls on the air tank cables when fueling, and at the end of the work day.. but just my opinion.

[Geoff Weeks]

My guess on why air driers never were big in other parts of the world has to do with the compressor systems used outside North America. Our compressors have an unloading valve in the compressor it self, while European designs opted for a discharge line unloader. Without a signal line from the air governor, our air driers will not work. 

Air driers have only been around since the 70's or so. Now they are made in configurations that will work with the North American and European style of governor.

 Leaving the spit valve open a crack is just like having an air leak, it cause the compressor to cycle more and therefor puts more moisture in the system.

 I only got dry air out of a wet tank if the drier was working properly. Even with the added use of air start and air wipers, If I saw moisture, I could find a fault in the drier.

 At one point, my 4 axle tractor, hooked to a tandem axle trailer, all air ride, with the above air start and wipers, would go 45 min between purge cycles rolling down the highway! That was a tight system, less than 15 minutes between purge and you have some real work to do. I hear trucks going down the road with multiple purge events in one minute!

I had AD-2, 4's and 9's as well as tried some Rockwell units. I settled on the AD-4 as the best of the bunch, and bought "cores" from wrecking yards to a few on the shelf.

Often the flapper check on the top of the drier element is the problem, it fails and allows the purge volume to escape all at once.  AD 2 and most 4's don't have a turbo cut-off in them so either needs an external one or N-A the compressor.

The colder the air, the less moisture it contains. so if you see moisture in your wet tank in summer, you know the drier is letting you down. Might not see it in winter, unless the drier failed totally. I had some AD-9's that did that, the drier element is threaded into the aluminum base and the threads wear out and the element becomes loose inside and does nothing.

[Joey Mack]

I guess, what I mean by cracking the spit valve, is literally just enough to spit water,,  To me that leak is less than all the other leaks on the whole truck an/or trailer..  as far as cycling the compressor too much,,  its is a good point, but I think with a healthy system, it's ok..  Like I said, just my opinion..  here in my area, the air is always humid.. 

[Geoff Weeks]

I'd have to look in the Bendix book, but compressor duty cycle and that of the drier are low, like 25% max.  Any air leak increases the on time.  You can increase the compressor displacement or decrease the air usage.  On truck compressors often it is only the head that is water cooled, the block is left to air cooling, getting to much heat can pass oil.

[Geoff Weeks]

Paul,

 I mentioned fanning or pumping the brakes on shut down to lower the system pressure, if you notice a fall in the start tank pressure you know you have a leak and can deal with it before you wake in the morning and find the tank empty.

Air driers are what the sound like they are, they remove moisture and hold until the purge cycle, then expel  it before the next compression cycle. They work by both cooling and slowing the air flow, passing it over a large surface area of beads (AD-2) or metal turnings (AD-4 and -9). When the compressor unloads, the purge valve opens and any pressure in the "can" and the compressor line passes back over the media and collects the moisture there, carrying it out the purge valve.

 It doesn't seam to me they should work as well as they do, but they do.

[mrsmackpaul]

The best none return valves for these have a flat rubber disc and are maybe 1 1/4" OD

Unfortunately I can't find these anymore, the newer ones (maybe 1" diameter, take a 15/16 spanner I think) are a half round ball that seats on a sharp edge

I only need a speck of dirt under these and I have a leak

 Paul