loose unit

This story starts with the base meaning of unit as being a part of a whole.  So a locomotive is called a unit because it then needs to be attached to the train (the line of carriages) to become the  whole (what we call the train). 

In America this meaning was transferred to vehicles, a practice which Australians adopted. So in Australian English a big unit is a massively strong vehicle, ute or truck.  A big unit in football (League, Union and Aussie Rules) is a guy who, when he has tackled you, makes you think that you have been run over by a truck.

A loose unit is, I think, a variation on this phrase and describes someone (let’s face it, a bloke — this is all bloke talk) who is a law unto themselves, a maverick.  Complete disregard for the rules.  Does stuff that others would regard as hair-raisingly risky or shocking.  There is the instance of the  ‘well-lubricated and well-mulleted loose unit’ who stripped off and streaked down a carriage on the Lilydale line in Melbourne in 2019. To ‘equal amounts of shock and applause’ although the Metro said sternly that this type of behaviour was completely unacceptable on public transport.

Both Australians and Americans like to think that they admire mavericks but in fact both cultures are pretty conservative and law-abiding, so maverick and loose unit can be used in a way that is complimentary or derogatory depending on the attitude of the speaker.

For the loose cannon we need to go to the storm-tossed ship with a cannon that has come loose from its moorings.  The idea was perhaps popularised by Theodore Roosevelt who said: ‘I don’t want to be the old cannon loose on the deck in the storm.’  A loose cannon causes havoc.  A person who is a loose cannon demonstrates no skill or finesse in their chaotic blunderings. They leave destruction in their wake.

Morrison referred to Albanese as ‘a loose unit on the economy'.  I think that loose unit and loose cannon have collided and the use of loose unit with the tinge of admiration is being forgotten. At the moment Macquarie Dictionary covers the idea of the maverick but may have to add the idea of the unpredictable person causing indiscriminate damage.