Driver Knowledge Tests

What is PTO or power take-off on a truck?

Power take-off or PTO is a way of diverting power from the engine of a truck to an attachment, a trailer or a separate machine.

On a truck, these are commonly used to:

  • Raise a dump truck’s trailer or body
  • Operate an auger on the end of a truck loader crane
  • Operate a personnel bucket on a knuckle boom crane to inspect power lines
  • Power a garbage compactor
  • Operate a winch on a recovery vehicle or tow truck
  • Operate the hydraulics to lift and lower the top deck on a car transporter
  • Lift a container onto a skeletal trailer using a sideloader.
A boom lift with a personnel bucket (front) and a truck loader crane (back)

When engaging the PTO, the truck’s engine idle will increase as power is diverted where it is required.

The big red button turns PTO on and off. This PTO powers a hydraulic cylinder that lifts the body of a dump truck. There is also control for the spreader.
The long hydraulic cylinder takes its power from the PTO, lifting the front of the tipping body.

PTO and remote controls

Truck loader cranes and sideloaders often have a remote control. There’s sometimes the function to speed up the PTO or to use a variable PTO in respect of the power required for what’s being lifted.

This is the remote control from a Palfinger crane. The switch on the left either increases the RPM or it turns on the automatic RPM function which adjusts the engine’s revs to provide the optimum power, as required.
Tail lifts, lights and some other features do not use PTO as they are battery-powered.

The disadvantages of PTO over battery power are its noise and pollution. The engine has to be at least idling. As the load on the machinery is increased, the engine revs increase, which means more diesel burnt and more volume from the engine.

Some other truck features utilise a separate motor rather than PTO, such as a chiller unit in a reefer trailer.

Darren is an expert on driving and transport, and is a member of the Institute of Advanced Motorists

Posted in Advice