I have a CAT 307 excavator which I'm to understand is classified as a Midi excavator, If I understand correctly there are three classifications, Mini, Midi and I guess Maxi? or maybe full size? Idk. I assume weight would be one way they are classified, if so where would the midi fall in that classification? from what weight to what weight? But are there other ways to tell?
There is no real consensus on size class as different mfg's all call them different things. Generally speaking a 6-ton class machine is the largest mini, 7 to 10-ton class are midi, and 120-130 class are the smallest of the full size excavators.
I usually consider anything on rubber tracks as mini. I really haven't heard the "midi" term used, but MG84's description makes sense to me.
They had to come up with something to differentiate. It would have probably been less confusing to start the term "micro" for the littlest ones, but here we are. There is a hell of a difference between a 301.5 and a 305.5, and they're both considered a "mini".
As @MG84 states, there is no agreed consensus on what tonnage constitutes what class, although the “mini/midi/full-size” definitions are almost universally accepted. Personally I would class anything less than 5T as a mini, and from 5-10T as midi. This is because when minis first appeared on the market there was nothing on offer as small as a 1.5T machine, so the definition size-wise of a mini has somewhat reduced over the years as a greater variety of model weights have become available.
Sounds right, My 307, less the blade and thumb is rated at 7 metric tons, at the time it was built in 1994 there wasn't much between the 307 and the 311 which would be the 120 class. I asked because I've not heard many referred to as Midi, although now CAT makes a 310 which probably fits into the Midi class. There is also probably other manufacturers building in that range now also.