The P/O removed the 50DN and replaced it with a belt driven 75A 24V, driven off of the 2 belt camshaft pulley off the rear of the engine (flywheel end). The alternator is bad. I bought a used Bosch 150A 24V alternator from the local tour bus garage. On the newer buses they run tandem alternators. Anyway I have no mount that fits this bosch and also no pulley. The pulley on the 75A that I removed is too small for the larger shaft of the Bosch alternator. We have a small truck scrap yard here, but they don't have anything that is 24v as it seems all the trucks these days are 12v, or so the guy told me.
The previous alternator was attached to the frame rail on the rear street side with an adjustable rod to take up the slack in the belts, so it is not directly attached to the engine. I have no idea how the original belt driven 50DN was attached.
Does anyone have any words of wisdom in how to mount this alternator and also what size/type pulley etc and where to acquire a two belt pulley. These newer alternators all seem to be driven off of the large flat serpendine type belts. I don't know what size pulley I would need.
I'm stuck until I get an alternator installed.
thx,
Russell
MC8
Lexington Ky
Do you have a model number for the Bosch so we can look up the rpms needed to supply 150 amps,bar room guess it is going to spin 2.5 or 3 times the engine speed and fwiw the drive on the back turns the same rpms as the engine. These guys can help you with the right pulley for the Bosch www.blanchardelectric.com (http://www.blanchardelectric.com)
good luck
Thx...I will try to get the model number Sunday afternoon. My next question is does it matter which way it spins but I guess a model number will help with that too. I've read that some matter and some don't but it seemed to revolve around the fan on the alternator rather than the alternator itself.
Russell
MC8
Lexington Ky
OK... got the numbers from the alternator.
BOSCH
0-120-689-552
under that is:
T1>>28V 70/140A
under that is:
Made in Germany
Only one label on the thing and this is it. Thx to anyone that can shed some light on this for me.
Russell
Russell, Since no one else answered, I'll give t a shot, your generator is OEM on a lot of buses. It's a type T1 Bosch.
More info here:
http://www.saase.us/application_pages/Bosch_T1_Alternator.php (http://www.saase.us/application_pages/Bosch_T1_Alternator.php)
They can probably get the correct pulleys for you.
If not, Give Kirk's Auto up in Detroit a call 800.321.5989
http://www.kirksauto.com/ (http://www.kirksauto.com/)
Quote from: rcbeam on March 20, 2011, 02:21:52 PM
OK... got the numbers from the alternator.
BOSCH
0-120-689-552
under that is:
T1>>28V 70/140A
under that is:
Made in Germany
Only one label on the thing and this is it. Thx to anyone that can shed some light on this for me.
Russell
thx Dallas... I'll check out the sites and see what I can come up with. I'm probably making this more complicated than it is.
Russell
Russel, that alternator uses a 3.0:1 to a 3.6:1 ratio it can spin up to 18,000 rpm without problems the trucks all use 3.6:1 because they idle for long periods
good luck
At 3.6 to one, the engine running up at 2300rpm will give an alternator speed of 8280rpm-a long way from 18,000rpm. I haven't ever heard of a alternator running that high. I know that the 50DN runs at 6500rpm max. Good Luck, TomC
Check it out on the Bosch site Tom I told Russell it could spin 18,000 not telling him to turn 18,000 rpm fwiw Prevost turns the 200 amp version at 3.6:1
good luck
It almost seems like 18,000 rpm would have to be a typo.
That just seems way beyond the practical design limits of a common large rotor.
Maybe 8K?
Ted
I don't know if it is a typo or not they sure make reference about the bearings and other alternator manufactures max rpm,new Delco alternators are high rpm now also they are supposed to be more fuel efficient in the long run according to all the manufactures
good luck
lubrbus that is good to know. Thx for the ratio info. Now I have no clue how to relate 3.6:1 to pulley size. Is this just a simple math problem and I'm having a brain fart or is it more complicated. Would the cam shaft pulley be 3.6 times the circumference of the alternator pulley?
Russell
I think I may have answered my own question on the ratio. I googled "calculate pulley ratio" and found a site.
I uses the pulley diameter, not circumference. So I guess the driving pulley would be 3.6 times the diameter of the driven pulley.
Whatcha think?
Russell
Quote from: rcbeam on March 21, 2011, 04:05:09 PM
I think I may have answered my own question on the ratio. I googled "calculate pulley ratio" and found a site.
I uses the pulley diameter, not circumference. So I guess the driving pulley would be 3.6 times the diameter of the driven pulley.
Whatcha think?
Russell
Diameter, radius, and circumference of a circle are all linear in relation ship. Therefore, you can use any one of the three when calculating ratios.
You calculation is correct; find an alternator pulley 3.6 times smaller than engine pulley.
Russel the pitch of the belts come into play when figuring the ratio also I know the drive pulley is a little over 6 inches in dia and is 1:1 drive , but I forgot what the pitch (angle)is on the drive and you will need to know that to get the right ratio pulley then Kirk's or Blanchard can furnish the right pulley.
Any of you guys know what the pitch is ?
good luck
Luvrbus: I measured the camshaft pulley on my bus and it is 5". I can't find a suitable alternator pulley anywhere in town. I talked with a guy from an alternator supply house on the net today (can't remember the company just now) and he looked it all up for me and said there was no suitable size double pulley that would fit the Bosch T1. I was trying to make it work in a situation it was not designed for. It would not put out enough low speed power because of the pulley size. The big reason was the large shaft. NOW, if i go to a small shaft alternator he said I had tons of options. Quite a few manufacturers make 24V, 150A small shaft alternators.
SO, I'm going to take the used alternator back to the tour bus guy and tell him it just isn't going to work and I'll buy a new small shaft alternator. I really need this problem to be over so i can get on with other problems. I've wasted several weeks on this so far.
One thing for sure, I've learned about pulley sizes, ratio's, and today I read about pitch. Not an expert by any means, but I now know more than I knew there was to know about pulleys.
I appreciate everyone's help.
Russell
MC8
Lexington Ky