OT Bolens rev choices when mowing

I'm looking for answers to the old question: at what speed do I run my finishing mower?

It's a recently-acquired '81 Bolens G174. That's a 41" wide, 17 hp, 4WD, diesel tractor with tall wheels and turf tires. It came with a 3 pt. hitch-mounted Woods 48" finish mower, model RM48YM-2. The thing cuts like a bandit, but the manual's specifications call for PTO settings of 840 rpm or 1000, giving blade rpm of 3126 or 3722. At top speed that's 16,380' per minute, or about 180 miles per hour tip speed.

Then we come to the Bolens's 3-speed PTO. At 2700 rpm, it offers choices of 472, 752, and 1177.

I have put a tank and a half of diesel through it so far, mostly cutting hay out from between young trees -- pretty heavy work. I don't run it at anywhere near full speed, more like 2/3, and it cuts very well at PTO selection 2. When the blades get dull the tractor doesn't lose speed, just beats the daylights out of what it can no longer cut.

My question is for someone who owns a similar tractor with a 2 cylinder Mitsubishi engine: how fast is full speed? (2700?) what's idle? (1000?) what's a reasonable speed for cutting in 1 High? For very intricate or heavy cutting I drop down to 3 Low, but it's a huge drop in ground speed and the mower plugs more readily.

The tractor has impressed me with its strength and versatility. I'd like to know if reasonable revolution choices can hurt it, or can experience with other old engines carry over to the 2 cylinder Japanese wonder.

Thanks,

Rod in Forfar

1947 Massey Harris 30
1960 Massey Ferguson 35 (Perkins)
1995 TAFE 35DI
1981 Bolens G174
2006 Simplicity Regent (Kohler 18)
1979 Troy-Bilt Horse II tiller


Walnut Diary

After I wrote the above it was still daylight, so I tried a run around with the PTO on 3, or the fastest setting. The mower whined like an airliner, but it cut well until the engine bogged in a bunch of dead grass. The tractor doesn't have the power to wind the blades at that speed. So it comes down to 2, or the middle speed.

Today I burned a half-tank of fuel mowing around seedlings. I experimented with higher revolutions and gradually became comfortable with the tractor's operation at about 80% throttle with the PTO on 2, or something proportionally less than 750 rpm.

The planting equipment tore the field up quite a bit, so one set of wheels was encountering rough going most of the time. Steering was better when I engaged 4WD. The ride also became a lot more comfortable when I added a pillow.

Amazingly tough little brute, that Bolens.