Driving tests

What’s power take-off (PTO) on a truck?

Trucks often have attachments or features that need power to operate. For example:

  • A truck loader crane has both the crane and a mechanical grabber attachment
  • A lines truck has a knuckle boom crane with a bucket for lifting someone to inspect power lines
  • A truck that collects your rubbish needs to lift the bins then compact it
  • A car transporter needs to raise and lower the top deck
  • A sideloader needs to lift a container onto the skeletal trailer
  • A dump truck has a trailer which tips in order to spread aggregate.
Sideloader requires a lot of power – more than a battery can provide – to lift a fully laden container

The way the power is diverted to these attachments and features is through power take-off or PTO. It is used when battery power wouldn’t be sufficient. PTO most commonly drives hydraulics. PTO has to be switched on in the cab to work; it doesn’t operate all the time. When engaged, the engine revs will rise from idle as power is supplied to the attachment.

Within the truck, there will be a switch to activate PTO and either a dial to increase or decrease the engine revs (i.e. to provide more or less power), a remote control or it will automatically adjust the engine’s revs to give the required power.

A traffic management truck with several vehicles behind it with knuckle boom cranes, all of which use PTO to power attachments.

When is PTO not used?

While PTO is excellent for providing a large amount of power to hydraulic cylinders and other machinery, it has some disadvantages, most noticeably that it is noisy due to the engine continually running and it creates diesel fumes which are a pollutant.

Some equipment doesn’t need PTO. PTO is not used for powering chiller trucks (reefers) as they have their own chiller unit and fuel source.

Reefer fuel tank gauge

Some equipment is better off powered by a battery as they are used infrequently or don’t require much power.

PTO isn’t used for tail lifts – they’re usually powered by a battery.

Darren is a member of the Institute of Advanced Motorists and the NZ Motoring Writers' Guild

Posted in Advice
When was the last time you checked your Road Code knowledge?

Try some tests for free!

Road Code car quiz

Road Code motorbike quiz

Road Code heavy vehicle quiz