air versus electric starters

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I noticed the unique air sound when the bus starts up on the older ones. The older buses that have air start are 2 stroke engines like the Detroit Diesel 6v92ta. Newer buses (ie 4 stroke Cummins ISM)I guess use electric starters like cars. So what the advantages/disadvantages or air vs. electric starters? Thanks.
 
I haven't seen air starters on any relatively new equipment- only on old junk. Same goes for hydraulic starters. Clayton has pretty much spelled out the main drawback of air starters- and this becomes a major issue as equipment becomes old and leaky. There are LOTS of trucks & equipment out there that won't hold air overnight (though the air starter usually has its own isolated tank). I suppose one advantage of an air starter is that the air leaks HAVE to be fixed (to a point) for the equipment to remain useable.

The obvious advantage of electric starters is that just about any semi-literate can use jumper cables. Start dealing with gladhand couplers, air hoses, etc. and the number of operators who can successfully start the equipment drops exponentially.
 
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I'm responsible for being sure four 2000 kW Cat gensets will start and run at any time. One of the bosses decided we should have air starters to back up the TWO per engine 50MT starters. I made up a list of pros and cons. Basically, I told them the same thing. Without air and in a blackout, where would I get compressed air from?? With my current arrangement, I have two pairs of 1300 amp 8D batteries in parallel per engine. I have a cart with two 8D's, a charger and cables. Then I keep two starters and a battery charger in stock. PLUS my best friend owns a battery store. I have 24 hour access to batteries. That was the end of the air starter discussion.
 
When I worked for a Class I railroad we purchased jet snow blowers. The jet engines used were military surplus J-34-34 and J-35 Jet engines orginally equipped with electric start/charge systems. Most of our track equipment had hydraulics installed, so it was natural to set the engines up with hydraulic motors to spin the jet engines up to 17% to 18% RPM to light them off.
We never used air starters on the diesel engines powering track equipment, but would use two 4Ds or 8Ds for the 24V systems. Electric starter on diesels in sub 0 temps is a good way to go. I have seen air starters in Russian Aircraft Radial engines! They do sound different during start-up!
 
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I worked at a location once where they had three Cat D399's. One was the prime engine. It started on batteries. Once it was up to speed and making 480 volts, the other two had 480 volt AC starters. Darndest thing I ever saw, never saw it again.
 
I heard air starters at the local US post office maintaince building last year. I think he said they were more economical cause they have to shut the engine off everytime they get out of their truck. That big Fairbanks Morse engine that I started a thread on below, is started with air. But I remember going thru a room with about a million batteries hooked up together, so they probably use the batteries as back-up. Also when I started in the petroleun industry in the 70's, the Exxon tanker fleet had air starters. We were always told that the air starters were safer because of not throwing sparks in case gas vapors were present. Don't know how true that was, but that was the reason we were given. I want to here that big Fairbanks Morse start up with air!
 
Originally Posted by NYEngineer
I'm responsible for being sure four 2000 kW Cat gensets will start and run at any time. One of the bosses decided we should have air starters to back up the TWO per engine 50MT starters. I made up a list of pros and cons. Basically, I told them the same thing. Without air and in a blackout, where would I get compressed air from?? With my current arrangement, I have two pairs of 1300 amp 8D batteries in parallel per engine. I have a cart with two 8D's, a charger and cables. Then I keep two starters and a battery charger in stock. PLUS my best friend owns a battery store. I have 24 hour access to batteries. That was the end of the air starter discussion.


High pressure cylinders obviously. A 6 pack of 300CF cylinders charged to 3000Psi would do it
 
Our black start stuff has hand cranked diesel compressors as the back-up backup backup…

When it needs to start, then manual intervention that doesn't need a ute and a friend with batteries
 
With air starters you do not need a big battery bank, just a small AGM will do you. When you have compressed air available, they can be good. They do not have the cold weather performance decline of battery systems. Jump starter cable is an air hose.

Modern electric starters are very good now.

Rod
 
I know with the fleet of Freightshaker tractors at our plant coupled to tanker trailers, they've got so many air leaks, they'd never be able to shut'em down.

I haven't noticed in a few years, but the outfit that provides the bus service for our school system had a bunch of older rear engine school buses that had air starters in them. More than once they had to send the mechanic to air one up because it wouldn't restart.
 
The Coast Guard cutter I was on back in the seventies had air start for the 12 cylinder Cooper Bessemer engines. That was fun to listen to.
 
Originally Posted by huffmuds9320
I noticed the unique air sound when the bus starts up on the older ones. The older buses that have air start are 2 stroke engines like the Detroit Diesel 6v92ta. Newer buses (ie 4 stroke Cummins ISM)I guess use electric starters like cars. So what the advantages/disadvantages or air vs. electric starters? Thanks.

I remember as a kid hearing that distinct sound of a 6V-92TA starting up with an air starter - the local transit agency also specified air starting on their Detroit Series 50s as well. I'm thinking air starters get the engine up to speed quicker and seem to be more reliable than electric starting but also tradition as well from the days GM ruled the bus industry.

The newest hybrid buses downsized to a Cummins ISB or a standard-sized ISL. The latest version of BAE Systems' HybriDrive spins the diesel engine with the drive generator to start it, very much like a Prius. A quick, instantaneous start.
 
Here is a video I recorded back in 2017 during the SF Muni heritage weekend. This bus has an air starter and powered by a 6V92TA.

https://www.youtube.com/watch?v=56hdWrNTPRs

Some of the buses with the newer BAE HybriDrive will shut off the engine when at a stop. It does start back up very quickly. Surprised me the first time I rode it, thought the bus stalled out. The other buses use the Allison hybrid system.
 
Originally Posted by huffmuds9320
Here is a video I recorded back in 2017 during the SF Muni heritage weekend. This bus has an air starter and powered by a 6V92TA.

https://www.youtube.com/watch?v=56hdWrNTPRs

Some of the buses with the newer BAE HybriDrive will shut off the engine when at a stop. It does start back up very quickly. Surprised me the first time I rode it, thought the bus stalled out. The other buses use the Allison hybrid system.

I remember riding those as a kid!

And I was on one of the newer BAE-equipped New Flyers, it did seem strange the bus was in auto-stop but I thought it was cool. Auto-stop/start as part of a hybrid system I have no qualms about, the motor(s) in a hybrid drive are much more stout and spin the engine quicker than a 12/24V conventional starter.
 
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