keep 24 Volt? or go 12V

[Lin]

You should qualify those statements to make it clear you are only talking about gear driven 50DN's. 

[luvrbus]

It applies to all gear driven alternator or generators Cat had no luck with a gear driven charging system either belts are the way to go all they do burn off and slip that doesn't happen with gears

[bevans6]

As I understand it, the alternator is fine but the planetary gear drive that steps up the speed from the cam-shaft is what wears, gets out of alignment, and causes problems.  I wouldn't have one, either, just based on not having the special tools to set it up and maintain it properly.  If you are interested, it's in this section of the MC-9 manual  http://www.buses101.com/PDF_Files/MCI%209%20Maint%20Manual%20in%20PDF%20format/MC-9%20-%20Maint%20Manual%20Section%207.pdf

Brian

[sledhead]

So its all Geoff's fault that I have to look for a new 24 v alt. ha! ha!

Now with only having the 24v  bus blower motor ( heat ) and the vanner 50 amp  how large of a 24 v alt. should I need and were do I find one ?  
thanks   dave

[luvrbus]

They will break the cam shaft also even the special cams made for the 50D Don Fairchild is always looking for that cam for the 8v92 if it was not a problem DD would not make a special cam to drive the 50D

[Boomer]

I talk to busnuts all the time who blissfully truck on down the road with gear driven 50DN's and have no clue about the miles that are on them.  They get a little nervous when I explain the ramifications of no maintenance.  We operated a lot of them, millions of combined miles and never had a failure, but.....we rebuilt each and every one ourselves at between 75-100K miles, way cheaper than an engine.   This consisted of a Kirk's Automotive kit with the big bearings, genuine Delco-Remy diodes, new insulators, the whole bit.  Bearing material going through the gear train will certainly wipe out the whole engine, bent valves, cracked heads, the works.  On older MCI's many 50D's were driven through an alternator adaptor.  Detroit Diesel would not allow MCI to bolt the alt directly to the engine (when GM was building buses) so the adaptor had to be used.  This added another dimension of possible failure, the adaptor bearings.  And, the weight of the big alternator plus the adaptor jumping around on the back of the engine required the support bracket be used.  If you don't have one guys, get one and put it on.  Typical prices I hear to overhaul 50D's are around $1,000.  Back then, our overhaul kits were around 300.00, and it took us about 6 hrs to do the complete job.  For shade tree mechanics that want to do this job a special alignment tool is a requirement for installation and the tool is expensive.

[Lin]

Dave- We have a 45 amp, 24v, single wire alternator.  The vehicle electrical is all 24v; that's really only lights, driver's heater, and various accessories as well as charging the batteries, of course.  The alternator seems to be more than enough.  They must be available online or an auto electric shop should be able to build one.

[luvrbus]

Yep Boomer, Kent/Moore was very proud of the J 29893 tool to setup the 50D on the DD engines

[bevans6]

So its all Geoff's fault that I have to look for a new 24 v alt. ha! ha!

Now with only having the 24v  bus blower motor ( heat ) and the warner 50 amp  how large of a 24 v alt. should I need and were do I find one ? 
thanks   dave

The 24V bus evaporator/heater motor (in my MC-5C, your is probably similar) is around 1.5 hp.  The condenser fan motor is 2 hp, but you probably don't have it any more.  1.5 hp, including efficiency losses, is probably around 1500 watts, or 55 amps at 28 volts.  Assume triple to start, but the batteries supply that.  It's breaker is 80 amps, so that tracks.  Add in your 50 amp warner (which I have no idea what that is), and you are at around 105 amps.  Automotive alternators (like the ones on trucks, etc) you figure 50% of rated maximum for continuous, so you would want a 210 amp rated alternator, which you would probably have to spin at 6,000 rpm (to figure your pulley ratios).  That is, quite frankly, a honking big 28 volt alternator, the 50DN originally in my bus was rated at 235 amps, but it could run at that rating for a long time.  There are big alternators that can run close to maximum output continuously, but they are about as big and costly as the 50DN, in that ballpark anyway.

So bottom line, the factory OEM climate control is what the big alternator was for, and by retaining the factory heater motor you still have half that system in place, so you still need a pretty big alternator.  I think there are 200 amp 28 volt choices around.  You can run two 125 amp units in parallel, that works fine usually.  The factory belt drive setup on the MC-5C has a four sheave pulley, you could really easily run two belts each to a pair of alternators and mount them where the factory 50DN was, if you could find one of those pulley drive assemblies.  It would be redundant too.

Brian

[TomC]

Geoff's system of running two alternators off the transmission A/C drive is a good one-that is if you have the gears inside the transmission to use. My bus was a Portland, Or bus without A/C-hence I do not have the inside gears for the A/C PTO. I still use my gear driven 50DN. I had it rebuilt about 4 years ago. Not had any problems with it. You could replace the gear drive with a pulley setup. Good Luck, TomC

[sledhead]

I just priced out a new 12v 145 amp. 1 wire for $140 + $30 core charge =$ 170

24 v 70 amp 1 wire for $ 253 + $35 core charge = $ 288

I have the org. lower pully for the a/c and will build a mount to run off that
thanks    dave