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How does PTO work on a lorry?

PTO, or power take off, is a way in which power can be diverted from the engine to power hydraulic or mechanical equipment. It’s very common on agricultural machinery, and its use on tractors, through a rotating shaft, causes frequent injury and even death, so much so that the Health and Safety Executive produces guidance material.

However, on a lorry, it’s mostly different. Power take off is used to drive hydraulic equipment and there’s a huge variety of applications:

  • Bin lorry compactors
  • Hydraulic truck loader cranes and truck-mounted cranes
  • Power line maintenance for powering the bucket that lifts the engineer to the line
  • Car transporter ramps (the ones with two levels)
  • Container side loaders that self-load containers onto a skeletal trailer
  • Tipper lorries with hydraulic rams that lift the front in order to tip materials out the back
  • Lorries with attachments such as augers
Truck loader crane at a building site

PTO is used where a battery would not have enough power or durability.

The driver switches PTO on using a switch in the cab. The revs should be increased to between 800-1000rpm to give the best performance, unless the unit has automated rpm increase as power is required.

PTO switch

If the driver increases the revs, there will be a rotary knob to do this.

PTO control

In units that have automated rpm, it’s often a switch, for example on this Palfinger crane remote control unit.

Palfinger crane remote control showing a switch on the left that will increase rpm if pushed to the left or auto rpm if switched to the right.

PTO has some disadvantages:

In some cases, batteries are used instead, for example for a taillift.

Taillift controls on a small curtainside lorry

For chiller trailers and lorries, there is a separate chiller unit with its own fuel source.

Darren has owned several companies in the automotive, advertising and education industries. He has run driving theory educational websites since 2010.

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