Someone educate me about my PTO.

[rbattelle]

From which transmission gear is the PTO gear driven? Is the PTO gear spinning whenever the transmission is in gear or neutral? What gear ratio is the PTO gear? Any insight would be appreciated.

 

[Camara]

In the big trucks the PTO gear is always turning. It does so because it is part of the whole lower shaft in the bottom of the transmission. I believe this holds true for our little transmissions also.

 

[rbattelle]

So what's the ratio on it?

 

[jrobinson2]

The PTO drives off of the counter shaft in the bottom of the transmission, it spins any time the clutch is released. There is no PTO on the transmission from the factory, only a mounting point with a block off plate, therefore it has no ratio . You specify the ratio (output RPM @ xxxx engine RPM), rotation direction, LH or RH mount, output option (keyed shaft, splined shaft, SAE flange) and shift option (cable, air, electric) when you order the Power Take Off. Muncie and Spicer are the most common manufacturers. More info here: http://www.munciepower.com/ Go to products, then PTO's, The TG series in the above link would be common in this type of application.

Jared

 

[rbattelle]

I'm still confused. What is the interface between the PTO you buy and the transmission? From reading the installation instructions (Muncie), I assumed there was a gear in there that meshes with a corresponding gear on the aftermarket PTO.



Also, anyone have a feel for how much one of these Muncie units costs? Hundreds? Thousands?

 

[barbwire]

PTO

Originally posted by rbattelle

I'm still confused. What is the interface between the PTO you buy and the transmission? From reading the installation instructions (Muncie), I assumed there was a gear in there that meshes with a corresponding gear on the aftermarket PTO.



Also, anyone have a feel for how much one of these Muncie units costs? Hundreds? Thousands?

I put a PTO on my Freightliner not so long ago, and the unit cost me about $200. 00 (give or take). Anyway, the metal plates on the side of the transmission's is where you bolt the PTOs on. Six 1/4 in. bolts I believe. You shift the pto in and out in the pto unit. the gear in the transmission stays where it is. Hope this helps. BTW, it is somewhat of a project. As you have to shim it for proper mesh (most of the time).

 

[rbattelle]

Muncie's instructions for shimming seem very straightforward, although time consuming. The project definetly seems within my ability, and if I can pick up a basic electric-shift PTO for $200 or so, I'm in as soon as I can figure out how to connect it to an air compressor.

 

[Bob V]

A few things to think about.

1 The transmission has to stop rotating to engage the PTO

2 The set up for our trucks are intermittent use only, you do not want in running all the time.

3 Look where you will need to run the drive shaft off the PTO to get it to the driven unit, keeping in mind drive line angles.

I don't want to say something can't be done, but like most things it is not as simple as it sounds.

I am running a 110 volt compressor off an inverter and it has been working well for me, Less than $300 total

Bob V

 

[jrobinson2]

The interface is one of the center gears on the counter shaft, on a 5 speed this is the drive gear for either 3rd or 4th, there is no separate drive gear, it simply uses one of the existing gears. As was said above this type of drive is usually for temporary stationary use, it will work fine on a large service truck type compressor but for a small utility type compressor it may be a bit cumbersome. You can run the PTO for a short time while moving but the transmission is extremely difficult if not impossible to shift because of the back loading of the gears from the PTO load. I think an electric shift PTO will be closer to $300. I have shimmed PTO's in 20 minutes before but also spent over 4 hours one time.

Have you contacted Brad Kilby? I think he was working on a engine mounted compressor kit for the 3rd gens a few months ago. http://www.onboardair.com/

Jared