When you say the floors are 3/4" plywood is that all that is the floor or is that 3/4" plywood on top of an underlayment that adds further thickness to the floor? I ask as 3/4" plywood by itself is not likely to be a sufficient flooring material, especially if on 24" centers, in a shop where one will be rolling around pieces of equipment that may weigh anywhere from a few hundred to better than a thousand pounds that make contact with that floor at just 3 or 4 concentrated points.
As to how well 3/4" plywood will hold up when rolling heavy equipment around, that depends in part upon the quality of your plywood and it's laminations as well as how concentrated the weight is upon those wheels. Narrow wheels focus the force in a much more compact area than if the same weight were moved around on larger wheels with their larger contact patch. So building or equipping heavy items with larger casters where practical can make a big difference not only in ease of movement but also in the wear they deliver to your flooring.
Finishing the flooring with treatments like polyurethane can further strengthen the plywood as the polyurethane soaks into the wood a little ways and literally bonds the fibers together while also presenting a durable film that resists damage to the floor and makes spills easier to clean up. However, doing so may require that you add some grit or chips into the finish to reduce the risk of slipping as such smooth finishes can become rather slippery if sawdust gets trapped between the soles of your shoes or feet and the smooth flooring. Adding grit or chips can improve your grip. Alternatively you can simply elect to leave the floor unfinished which has its own advantages as it presents a surface with generally good traction but anything you spill upon it, aside from water, mineral spirits, and alcohol (and other clear evaporating liquids), will tend to become a permanent addition to the floor's decor. You can also opt for surfaces like vinyl tiles if you feel your floor requires added protection from wear and tear.