It's how much power the tractor can continuously deliver to an auxiliary piece of equipment.
66 PTO horsepower and 72 engine horsepower.
The 3020 has 63.1 drawbar horsepower and 71.4 PTO horsepower.
27 hp pto
36 horsepower at the PTO and 30 at the drawbar
A 4040 has 77 drawbar horsepower and 91 PTO horsepower.
About 45hp with about 36hp at pto
36 at the PTO, 30 at the drawbar
23 drawbar horsepower MAX, 26 belt/pto horsepower MAX
PTO means Professional Tryout!!!!
the first john deere 3130 had 89 horsepower with the last of them having about 95 horsepower according to the books but most them that tested had 100+ horsepower
As far as I can find it has 35.93 hp [26.8 kW] at the PTO.
A John Deere 8530 had 330 engine horsepower, 276.3 drawbar horsepower, and 312.7 maximum PTO horsepower.