The vehicle PTO engagement and disengagement action uses the main transmission clutch and a control mechanism which physically engage the PTO itself. Typically, an air valve is used to engage the PTO. There are a number of different types of PTO and different engagement procedures.
The PTO TIMER is designed to manage the properly engagement of PTO with two control signals, one for clutch and another for PTO valve. It is factory programmed to specific chassis brands and types. The control and activation signal can be permanent or pulse and positive or negative.