Attention aussiesmg (8V-71 Content)!!

I need to know the gear ratio of the accessory drive pulley on an 8V-71. Any idea?

I don't have an answer, but now I want to know why you need to know this.

I have a customer that uses this engine and wants to drive the A/C compressor off of it. I need to know if it will spin fast enough to do that.

I know a guy whose dad collects old buses, maybe he'll know. I'll send him a message.

So the accessory drive is gear driven? I'd imagine because the RPM range for the engine is lower than the requirement of the accessories?

In reply to RossD:

Yes, it's gear driven. And that's my concern, that it won't spin fast enough to produce the needed energy capacity.

My step dad that is an old school diesel mechanic, said the old Kenworth's ran the A/C off the front accessory. I can probably find a schematic if you need one.

In reply to dansxr2:

On this particular application, the speed is critical, so I need to know specifically how fast it turns in relation to engine speed. So if you have that information, I'd very much appreciate the help!

To calculate the drive ratio, take the difference between the 2 pulleys and divide that number by the lower pulley. For example, if you have a 41 top and a 34 crank, the difference is 7 teeth. 7/34=20.6%. Since the upper pulley is larger than the crank, it is 20.6% underdrive.

I did just find this, this may potentially help, til I get to his shop.

In reply to dansxr2:

Yeah, I do those calcs every day. The ratio I need is the "gear" ratio of the drive gears in timing case. IOW, the shaft that the pulley is mounted on doesn't necessarily turn at the same speed as the crank.

I have 1.95:1 for the blower drive out of the Clark fire truck manual, but that isn't what is going on in that photo.