Pneumatic or electric: what should drive a lifting device

Why compressed air is the norm in handling technology

Air is compressible. In almost every technical consideration that is a drawback – in a hand-guided device it is the decisive advantage. A pneumatic drive gives way when the operator pushes against it and absorbs shocks instead of passing them into the load. The balancer that holds a load in suspension and moves with two fingers cannot be built without that compliance.

• Compliant behaviour without elaborate control
• Inherently overload-safe: the drive does not jam, it yields
• Insensitive to dust, damp and temperature swings
• No electronics at the load – important with wet cleaning and flying chips

Where electrics is superior

As soon as a device travels long distances, lifts high loads or runs multi-shift, energy consumption becomes relevant. Compressed air is the most expensive form of energy in a plant – only a fraction of the electricity used arrives as usable work. An electric drive is then not only cheaper but also more accurate: it can be positioned, referenced and integrated into a control system.

• Markedly lower energy input per lift
• Positionable and integrable into plant controls
• No compressed air network needed – important in halls without supply
• Quieter, which tells with many devices in one hall

The point where cost does not decide

In explosive atmospheres the question is not economic. A pneumatic drive has no ignition source of its own; what remains to be evidenced are materials, conductivity and mechanically generated sparks. An electric drive in the same zone needs a suitable type of protection, a matching equipment category and the associated documentation – technically feasible but more elaborate and slower to procure.

What happens on failure

The most important criterion is the one least often named. If the air fails, a properly built pneumatic circuit holds the load via check valve and reservoir long enough to set it down. If the power fails, a brake holds – but only if it is a spring-applied brake and does not stay released. Both solutions work; both have to be explicitly required and verified rather than assumed.

The calculation we set out

We do not compare drives but operating hours. Below about a hundred hours a month energy consumption hardly matters, and the decision falls on sensitivity and environment. Between one and two hundred hours the air consumption in the data sheet is worth a look. Above that, electrics becomes interesting – and the question is then whether the sensitivity can be won back through a controlled axis.