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Bus Discussion => Bus Topics ( click here for quick start! ) => Topic started by: PNWorBUST72 on March 05, 2018, 04:36:57 AM

Title: Two Alternators on 8v71?
Post by: PNWorBUST72 on March 05, 2018, 04:36:57 AM
So people have talked about adding a 2nd alt to my bus to help with the battery charging.

Is there a particular process or place people use to do this? 
Title: Re: Two Alternators on 8v71?
Post by: oldmansax on March 05, 2018, 04:51:02 AM
I had a second 12V alternator for the house bank on my '72 MCI. Ran it off the old AC pulley. Had  switch for the fields so that I could run it only when I wanted.

TOM
Title: Re: Two Alternators on 8v71?
Post by: Geoff on March 05, 2018, 05:22:26 AM
On an MCI you can run a double pulley off the back of the blower drive and make mounts for two alternators.
Title: Re: Two Alternators on 8v71?
Post by: PP on March 05, 2018, 09:38:35 AM
On my bus there is the big 24V for the coach batteries and then a 12V for the house bank. The gauge on the dash only shows me the performance of the 24V when running. the mounting and belt setup is pretty simple and straightforward, just make sure they're rotating in the proper direction if you add one for the house bank. ???  ;D
Will
Title: Re: Two Alternators on 8v71?
Post by: PNWorBUST72 on March 05, 2018, 10:53:21 AM
Apparently the previous owner rebuilt the gear driven oil cooled one already before I bought it.

Can you guys give me some pics of what your talking about?  I am still getting to know the old girl...  :)

Title: Re: Two Alternators on 8v71?
Post by: HB of CJ on March 05, 2018, 11:24:41 AM
If memory serves the old Detroit 671N and 8V71N mills used in the fire apparatus had two, (2) alternators.  Also two, (2) starters?  Two starter buttons also.  Crazy stuff.  Long ago.  Far away.
Title: Re: Two Alternators on 8v71?
Post by: Utahclaimjumper on March 05, 2018, 11:44:01 AM
 One of the advantages of alternators is, they don.t care which way they turn other than the cooling fins.>>>Dan
Title: Re: Two Alternators on 8v71?
Post by: luvrbus on March 05, 2018, 12:07:59 PM
If memory serves the old Detroit 671N and 8V71N mills used in the fire apparatus had two, (2) alternators.  Also two, (2) starters?  Two starter buttons also.  Crazy stuff.  Long ago.  Far away.


Lol my fire truck has 2 starter buttons but only 1 starter I don't know why it has 2 starter buttons ?
Title: Re: Two Alternators on 8v71?
Post by: busfan on March 05, 2018, 01:29:41 PM
If your in a sunny place maybe Solar panel would do?  Pretty easy to hook up these days.
Title: Re: Two Alternators on 8v71?
Post by: Templar52 on March 05, 2018, 02:26:36 PM
LUVRBUS.  One button is for small fire and the other one for major fires.
Title: Re: Two Alternators on 8v71?
Post by: Geoff on March 05, 2018, 02:28:04 PM


Lol my fire truck has 2 starter buttons but only 1 starter I don't know why it has 2 starter buttons ?

I have three start switches--  1 up front, one in the middle, and one at the back.  Dumb joke, the middle one is for the genset.
Title: Re: Two Alternators on 8v71?
Post by: HB of CJ on March 05, 2018, 08:21:24 PM
I stand corrected and thank you.  The old Seagrave V12 900 something cubic inch gasoline engines had two starters.  Two starter buttons.  The engine would crank and start with one button pushed but we pushed both buttons.  The Detroits only had one starter.

When the shops re powered the apparatus with DDs the two starter buttons were left.  I wonder how they worked.  Long ago far away.  About 1974.  Service engine life was very short.  I remember helping the shops do engine changes.  Much fun and a learning process.
Title: Re: Two Alternators on 8v71?
Post by: chessie4905 on March 06, 2018, 03:53:21 AM
I have 4 start buttons. Two up front, one of for generator. One in middle at generator. One at rear at engine. Your move.....☺
Title: Re: Two Alternators on 8v71?
Post by: PNWorBUST72 on March 06, 2018, 04:22:05 AM
Can anyone with 2 alt's share some pics of placement /mounting please?  :)
Title: Re: Two Alternators on 8v71?
Post by: oldmansax on March 06, 2018, 05:28:35 AM
I can't, don't have that bus anymore.

TOM
Title: Re: Two Alternators on 8v71?
Post by: PP on March 06, 2018, 08:32:10 AM
Can anyone with 2 alt's share some pics of placement /mounting please?  :)

I will see if I can make this picture small enough to load.  ???
Will
Title: Re: Two Alternators on 8v71?
Post by: Utahclaimjumper on March 06, 2018, 09:14:54 AM
  Detroit 8V71s are enimic enough with out loading them down with questionable equipment that can be dealt with in other ways.>>>Dan
Title: Re: Two Alternators on 8v71?
Post by: PP on March 06, 2018, 10:22:25 AM
Yes, remember this setup is on an 892. I also wasn't aware that Alternators run in either direction. Good to know.
Title: Re: Two Alternators on 8v71?
Post by: PP on March 06, 2018, 10:24:28 AM
I can't reach the back of my coach right now because its hanging out over a swamp so I shot this through the side door. It's really hard to post pics here. Everything I tried short of uploading a miniature file wouldn't work. ???
HTH Will
Title: Re: Two Alternators on 8v71?
Post by: PNWorBUST72 on March 06, 2018, 06:02:13 PM
So are those sitting where the AC was and just running off those pulleys?

Are they 12v and a 24v?
Title: Re: Two Alternators on 8v71?
Post by: PP on March 07, 2018, 09:09:07 AM
So are those sitting where the AC was and just running off those pulleys?

Are they 12v and a 24v?

The small one is 12V and connects directly to the house bank. The large is the 24V. Both are on pivot mounts with belts running directly off the main pulley on the front of the engine. If the water goes down in the next few days, I'll try to get a better picture. It's really a simple setup. This coach has never had over the road air, just up front defrosters because it was never a passenger bus. Went straight from Prevost factory to Marathon.
HTH Will
Title: Re: Two Alternators on 8v71?
Post by: PP on March 07, 2018, 01:37:55 PM
Okay, the tide went out and the swamp went down so I was able to get behind the beast. Hope these help give you an idea of what you need or want to do.
Will
Title: Re: Two Alternators on 8v71?
Post by: Geoff on March 07, 2018, 01:55:43 PM
What is the cam pulley turning?
Title: Re: Two Alternators on 8v71?
Post by: PP on March 07, 2018, 04:37:35 PM
What is the cam pulley turning?

Power steering pump.
I should add, that's where most of the oil spotting you see is from, not the engine.
Will
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