To put a spanner in the works

This is a spanner.

The works is another term for a machine.

What would happen if you put a spanner in the works?

It would break and stop. That's exactly what workers used to do when they needed a rest from the demanding machines that they worked with.

Becoming a slave to machinery was already a worry in the time of Charlie Chaplin.

Here's an extract from the film Modern Times.

Swings and roundabouts

Should we move apartment?

I've seen one that's much bigger but it also costs more.

It's swings and rounabouts.

It's out of the city centre in a lovely area in the countryside but I'll spend more time getting into work.

It's swings and roundabouts.

What you gain on the swings, you lose on the roundabouts.

If you like swings and you are looking for something a bit special, you might want to go to New Zealand. It would have to be a big roundabout to lose whatever you gained from this one!