POWER TAKE-OFF (PTO)
Peterbilt Motors Company 8-12
PTO INTEGRATION – 579 FAMILY
PTO CONTROLS
The 579/567 models use Electric Over Air (EOA) or Electric Over Hydraulic (EOH) controls to supply the signal to activate
the PTO. The EOA controls are recommended for manual or automated transmissions. The EOH controls are
recommended for automatic transmissions.
The EOA controls feature a valve that is located under the left hand side of the cab as shown in Detail “B” of Figure 8-20.
The valve converts an electrical signal from the PTO dash switch into an air supply. This air supply is then plumbed to the
PTO activation port for manual transmissions, or a pressure switch for automatic transmissions (automatic transmissions
require an electrical signal for PTO engagement).
The EOH controls will send an electrical signal from the PTO dash switch to the transmission harness that will activate the
PTO function of the transmission.
FIGURE 8-20.
The EOA controls are used to engage the PTO, but to get the engine to go in to PTO mode a signal must be sent from the
PTO to the engine. When pin 2 (PTO engaged signal) of the chassis PTO connector is grounded, the engine will go to
