MCI Belt tensioner..........

[Iver]

Just curious...
Is it possible, or has anyone used a different method of tensioning the cooling fan belt on a MCI-9?

The factory tension is applied by an air cylinder or in my case, a manual tensioner which moves the squirrel cage gear box up or down.
When that happens, it also moves the squirrel fans up or down in the housings which offsets the fans to the rubber inlet rings.

If the rubber inlet rings can't be lined up with the fans, I would guess you would lose some cooling efficiency.  Cooling a 8v92 needs all the efficiency you can get.

So, I guess my question is can you use an "idling pulley" or two to squeeze the belt inward to achieve the tension or should I assume that MCI knows best and forget the whole idea?

Even if you get the right size belt, it eventually stretches and you need to move the gearbox up to tighten the belt.

Thanks , Iver.

[Busted Knuckle]

Iver,
IIRC (and don't bet on that!) the blower housing end plates are adjustable just for that purpose!
You loosen the bolts and slide the plate into the correct position with the belt at proper tension and then tighten the bolts. (been a lot of yrs and a few beers since I did much work on a 9! )
  BK 

[busnut104]

I removed the air cylinder and used a turn buckle, This is what the local bus co does.

[busshawg]

Hey Busnut104, you wouldn't have a pic of that turn buckle do you?
Grant

[bobofthenorth]

Here's a turnbuckle in similar service Grant.  Its on the frenchy-bus but it is replacing the air cylinder that le Quebecois used to tighten the fan belts.  If you see our smoky friend from Brandon be sure to point out to him the shiny new belts in this picture.

[bevans6]

I think you could use a idler but that you would have to be cunning about how you installed it.  You install them on the slack side, so the tension side is straight.  It's good to install them somewhat near the power pulley in such a way as to increase the wrap of the belt around the pulley, or on the slave pulley likewise, increasing the wrap.  If you are too close, or if you design it so that the belt is bent too much, the belts tend to overheat.  least satisfactory is installing the idler in the middle of the slack side run, the belts tend to whip too much and again overheat.  You are also pushing a fair bit of power through that belt, so you want to have a very decent size bearing system inside the idler pulley or it will break up and fail.

Brian

[DaveG]

Hey all this belt talk, what about Jim Shepard...he was a belt guy wasn't he?

[busshawg]

thanks for the pic, makes sense.

Grant