The wikipedia entry is a very general overview - IMO there's more on the possible engine types and a brief description of various manufactures who've dabbled.

The wikipedia entry is a very general overview - IMO there's more on the possible engine types and a brief description of various manufactures who've dabbled. A couple of decades ago iirc at least one sugar cane harvester [1] was trialled in my locale that used compressed air to power various drive trains used within the harvester. I'm also not sure but there may have even been an air powered tractor trialled as well. The main advantage would be no significant loss of fluid when a pressure line bursts -- a bug bear for hydraulic systems when the lines are deep within the machinery and oil leaks are not readily observed. [1] Most rely on hydraulic oil, powered via hydrostatic drive system.