Bush Hog Speed

JT White · Aug 5, 2022

When I bought my Yanmar, it came with the Howse Bush Hog and the gent told me to use it in #2 pto position, in second gear and at 2300 engine rpm's. I have followed that setting for the most part since day one. I don't know the PTO speeds of which there are four and if I run it in, say 3rd PTO and 3rd transmission gear at 2300 engine rpm's, will it destroy my bush hog gear's? I do 5 acres with several trees and would like to get it done a bit faster. Do I stay with the original settings? Thanks.

oosik · Aug 5, 2022

I'm not sure what you are referring to by - #2 PTO position or #3 PTO position. Most normally - your Bush Hog should be used with the PTO rotating at 540 rpm. Your Yamaha should - in some way - show you when the PTO is at that rpm. Either by a digital readout - or a hash mark on the rpm dial.

OR - your owners manual might indicate what rpm to run the engine at to achieve 540 PTO rpm.

Your tractor gearing will then determine the "speed of travel".

The pastures I mow have smooth and rough areas. Even in the smooth areas I rarely go over 4 mph. Higher speeds tend to take any joy out of the mowing. Things will happen plenty fast at the more manageable speeds.

JT White · Aug 5, 2022

oosik said:
I'm not sure what you are referring to by - #2 PTO position or #3 PTO position. Most normally - your Bush Hog should be used with the PTO rotating at 540 rpm. Your Yamaha should - in some way - show you when the PTO is at that rpm. Either by a digital readout - or a hash mark on the rpm dial.

OR - your owners manual might indicate what rpm to run the engine at to achieve 540 PTO rpm.

Your tractor gearing will then determine the "speed of travel".

The pastures I mow have smooth and rough areas. Even in the smooth areas I rarely go over 4 mph. Higher speeds tend to take any joy out of the mowing. Things will happen plenty fast at the more manageable speeds.

Thanks for the input. My PTO has four positions. #2 is the PTO position I run the Bush Hog in. I also run the tractor in second gear. My tractor is a YANMAR and I have no manual, nor does my engine tach tell me anything about PTO rpm. I wasn't sure of what the hogs speed could or should be. So I have run it in PTO 2 and transmission Second gear at 2300 rpm's.. I'll have to do more research.

big bubba · Aug 5, 2022

suggest posting this in Yanmar Equipment on the forum for your transmission/ pto speeds if you don't have a pto rpm.. as mentioned, 540 pto rpm is what you're after. also, if you're concerned about tearing up the gearbox, just check the g'box temp after a session. if it were stressed, you should be able to tell
24 posts in 11 yrs must be a record

JT White · Aug 5, 2022

Thanks I'll look into it, but I would have figured that most if not all Bush Hods would operate at roughly the same PTO speeds. Just trying to get a handle on it.

seville009 · Aug 5, 2022

I run my bush hog a full rpms. I just adjust the tractor speed as necesssary - slower in thick stuff, faster in thin stuff.

LS Tractor Owner · Aug 5, 2022

JT White said:
Thanks I'll look into it, but I would have figured that most if not all Bush Hods would operate at roughly the same PTO speeds. Just trying to get a handle on it.

They do---- 540 PTO rpm. All tractors will reach this speed at different engine RPMs. For example: My little LS MT125 hit the 540 PTO rpm at 2930 engine rpm. My LS XG3025 hits the 540 PTO rpm at 2510 engine rpm. They are both 25 hp, one a Yanmar, the other a Mitsubishi engine.

As BigBubba stated, go to the Yanmar forum, ask for information on your MODEL of tractor.

oosik · Aug 25, 2022

Example - my Kubota M6040 hits 540 PTO rpm @ 2160 engine rpm. It's 62 engine hp.

LD1 · Aug 25, 2022

Found this on another thread

4 SPEED PTO
PTO 1 540 @2200
PTO 2 1000 @2200
PTO 3 ENGINE SPEED
PTO4 OVERDRIVE

Seems Unless you have a 1000rpm bushhog, even running it in PTO speed 2 would be dangerous. Spinning a bushhog rated for 540 at 1000rpm is a recipe for disaster.

Seems them yanmars had some pretty high TOP speeds....lol

But If I were you I'd do two things...

1. figure out if the bushhog is a 540 or 1000rpm gearbox.

We can help you with that if you tell us the gearbox ratio and how wide the cutter is. To figure the gearbox ratio.....spin the pto ONE complete turn and see how many times the blade carrier turns. For a 5' cutter.....1.5:1 or 2:1 is pretty common for a 540 gearbox. Something around that ratio would give blade speeds of ~12700-16900fpm. And if thats what it is, and you are spinning it at 1000rpm pto....you are spinning the blades close to double that....which is NOT good.

2. Second thing to figure out is your actual PTO speed. Searching it has come up with some conflicting information so I cannot gaurentee the information I posted was correct. But for under $50 you can get a tachometer. Either contact or non-contact type. Run the tractor and see what your PTO speeds "actually" are.

https://www.amazon.com/Mengshen-Tachometer-Non-Contact-Rotation-Measurement/dp/B01CZFCZTQ/ref=asc_df_B01CZFCZTQ/?tag=hyprod-20&linkCode=df0&hvadid=260742848592&hvpos=&hvnetw=g&hvrand=15604926294491669276&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9015010&hvtargid=pla-430392893645&psc=1