Well..... probably I should have said it better. But unlike the foot throttle and return spring in a car & truck engines, old style tractors were constant speed engines with a vengence. They tended to have a hand lever throttle held by a friction clutch to set the basic operating rpm and that is where the engine ran.
Simple to make, and for field work that is what you want. Even loaders with HST - where a variable RPM would be an advantage - tended to run the motor at a constant RPM and required the operator to vary speed and torque with a foot pedal that controlled the transmission HST pump and volume rather than contolling the engine RPM.
The result is that for the longest time - many decades - tractor motors didn't automatically return idle when the load was removed. They lugged when loaded and raced when not. I don't know what to call that - so I started using the term of a completely or total manual throttle. Maybe I should have said HAND throttle instead of manual... that makes more sense. I meant a throttle made to set the RPM and work at that speed & not very adjustable. .
For tractors to return to idle seems a no brainer to us today, but it wasn't common on farm tractors for way too long. The first time I saw it on a tractor was on a Kubota where it was a feature called "auto throttle" - In their advertising, Kubota called it "auto throttle" and were really proud of a new control that would automatically adjust for load & automatically idles if there no load. On a gas engine, a throttle return spring would do about the same thing and had for the past 100 years.... But on a tractor it was about 2007 is when I first saw it & thought it very civilized....
Tractor design is much held back by tradition. For example, going downhill with a FEL bouncing the front axle and no front brakes is a crazy and foolish way to save a few dollars manufacturing. Imagine if your family car only had brakes on one end and tended to slide out unless you backed down hills..... positively archaic....but in the US, most tractors are built that way & always have been.
rScotty
rScotty
