POWER TAKE-OFF (PTO)
Peterbilt Motors Company 8-2
AUTOMATIC TRANSMISSIONS
On Allison transmissions there are two locations for PTO’s. The Allison 4000 series has PTO locations at 1 and 8 o’clock
viewed from the back of the transmission. See Figure 8.5. The 4000HS transmissions do not have any PTO locations.
The 3000 series Allison transmissions have PTO locations at 4 and 8 o’clock (Figure 8.6). For more information on using
PTO’s with an Allison transmission go to www.allisontransmission.com and refer to the “Rugged Duty Series Brochure”
and “PTO Request Flyer” which is available in a 1000/2000 version and a 3000/4000 version.
Some PTO configurations will have clearance issues with other components on the truck. With manual transmissions, a
6-bolt PTO on the right will typically clear most components when the DPF and SCR are under the cab. This is also true
when 30 and 45 degree adapters are used. The 8-bolt bottom mount PTO will not have any issues unless you are
running a driveshaft back to another component and the truck has a crossover style exhaust. In this case, the DPF and
SCR would block any routing for the driveshaft. If a wet kit is used in this scenario there is enough room to mount the
PTO and the hydraulic pump without interfering with the exhaust. On Allison 4000 series transmissions, most PTO’s will
fit in the 1 o’clock position without interfering with the cab. If a wet kit is used here, the dipstick housing will most likely
need to be modified as it runs over the top of the transmission to the driver side of the vehicle. The PTO in the 8 o’clock
position is typically ok. The same issue with crossover exhaust would apply here as well. There are some scenarios
where the PTO will be very close to or could interfere with the rear spring shackle on the front suspension. This problem
can occur on vehicles with a set-back front axle and the problem is amplified on the short hood models.
FIGURE 8-5. Allison 4000 Series FIGURE 8-6. Allison 3000 Series
