A basic method for isolating the most recent record:
Find the records, Sort them to make the most recent record first in your found set. Use Omit Multiple Records to omit all but that most recent record.
But in your case, you want multiple "Most recent" records for a set of equipment. For that, I'd use a related table of equipment--one record per machine linked to your table of maintenance records. You can sort your relationship to make the most recent maintenance on any given machine the first related record or you can use a one row portal to show this information and specify a sort on the portal.
Either way, you get a list of Equipment where you can perform your find to get a list of equipment records and see the most recent maintenance on each.
I have used your method in other situations where I need the most recent record to be found. But in this case I need a whole list of the the most recent maintenance record on each piece of equipment at a particular facility. In other words, if I were to look up all of the rental equipment at a location, I might find I have 50 different pieces of equipment on rental. For each of those 50 items, I need to be able to identify the last maintenance record created. I then need to be able to print out or email those records to a customer. (Perhaps you are understanding what I am needing and I am not understanding your first response.)
I suggest that you read my complete response. I mentioned a basic method and then described a way to get what you want by finding the equipment needed and then using either a sorted relationship or sorted portal to list the most recent maintenance record for each item of equipment.