Pto speed linear?

[buickanddeere]

Does ground speed and pto speed remain linear across the full range of engine rpm's? I've never had my tractor fully up to rated pto speed (engine rpm) while using my rotary cutter. It seems to me a waste of fuel and wear and tear on the equipment to run the engine at rated rpm. You must assume standard transmission and not a Hydrostat regarding this question. Thanks

You are not saving any fuel or wear and tear. It's a farm tractor that is used a few dozen or a few hundred hours per year. It's not a maxed out prime mover for marine propulsion , power generation or irrigation pump duty. Where 24/7 duty at full power is the norm.
The engineers who know far more about the machine than you designed it with a rated rpm to use for good reason. The rotary cutter relies on blade velocity and centrifugal force to operate. Lower rpm reduces both.

 

[npalen]

Some wise acre is surely going to come along here and say that the output speed of a PTO shaft varies during each revolution depending on the angle that the pto shaft is run at.