I would use the owner manuals of each and every piece of equipment to set up a maintenance cycle per machine. When each equipment was serviced, log what exactly was done.
I would think it would be easier to delegate your crew leader(s) responsibility of maintenance on machines. There is no way around it though, you need to double\make sure the maintenance is being done.
We just do the maintenance on all machines at the end of a route cycle. (filter, basic cleaning ect..) Oil changes once every 4 cycles of my route. This is easier for everybody to remember and habit for us. Oh, on rain out days, cleaning of the filters is automaticly done. I still pay my guys whether we cut grass or not.
J-LC Landscaping & Maintenance Gardening
C-27 CA. Contr# 770044