I'm buying a Kubota L4400 and was looking at tiller options. It was my understanding that you would have to have enough hp to run certain equipment, but now I'm hearing conflicting advice going the other way, to equipment that has lower hp requirements. With the 37.5 pto, would there be a problem operating the Woods tiller that recommends "up to 30hp"? I had one cautionary comment about the torque, but others think it will be okay. I don't want to buy new equipment and destroy it. Does anyone here have any advice/experience?
PTO Compatibility
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thatguy
Elite Member
I am not an expert by any means, and I hope someone else will chime in shortly...
But here is my thoughts - with the more HP you may end up shearing shear pins very easily. A neighbor has a big Kubota (+45 hp i would guess) that shears pins like crazy when he bushhhogs because the tractor engine doesnt bog down like his former (and much smaller) tractor did.. I also wonder if a slip clutch could be damaged since the tractor would put more power to the drive line.
Again, just my thoughts...
But here is my thoughts - with the more HP you may end up shearing shear pins very easily. A neighbor has a big Kubota (+45 hp i would guess) that shears pins like crazy when he bushhhogs because the tractor engine doesnt bog down like his former (and much smaller) tractor did.. I also wonder if a slip clutch could be damaged since the tractor would put more power to the drive line.
Again, just my thoughts...
chriswheeler
Platinum Member
Make sure you get one with a slip clutch and set the clutch as per the instructions. The clutch on the tiller should slip before any damage is done. I think in my manual they say to reset once a year. I would rather spend a few extra bucks here and get something I can set to my ground and not have to depend on the shear of a bolt to protect a costly implement. After you get past that issue, other things you might want to consider might be, do you have enough HP to drive the tiller you want in the soil you have.?? Also it is worth considering if you need a tiller wide enough to cover the tracks of the tractor or if you can, or want one that can be offset.
Chris
Chris
greg_g
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</font><font color="blue" class="small">( Make sure you get one with a slip clutch and set the clutch as per the instructions. )</font>
No. The instructions more likely state to set the clutch spring length according to the tractor'sPTO hp rating. In this case, the implement only has a 30hp rated transmission. Setting the slip clutch per instructions will still result in his 37.5 PTO hp being delivered to a 30hp rated tranny.
Correct solution is to replace the implement with one that is sized to the tractor.
Slip clutch solution - in this case only - is to set the slip clutch springs to match the implement hp rating.
//greg//
No. The instructions more likely state to set the clutch spring length according to the tractor'sPTO hp rating. In this case, the implement only has a 30hp rated transmission. Setting the slip clutch per instructions will still result in his 37.5 PTO hp being delivered to a 30hp rated tranny.
Correct solution is to replace the implement with one that is sized to the tractor.
Slip clutch solution - in this case only - is to set the slip clutch springs to match the implement hp rating.
//greg//
chriswheeler
Platinum Member
I stand corrected.
Of course the tillers gear box rateing would have to exceed the HP of the tractor. I set my slip clutch by loostening all of the nuts on the springs, setting the tiller to full depth, slipping the clutch. After the clutch slips, I turn the nut in to touch the spring and 3/4 turn more evenly on all 6 springs. I have never had the clutch slip past this point, however I am not tilling through rocks or stumps. Others settings will differ depending on soil, compaction, rocks, stumps. I can see where someone might want a little better tiller drive and tighten the clutch past the point where the tractors HP would exceed the gearbox in a given tiller, or any other PTO driven implement for that matter.
Chris
Of course the tillers gear box rateing would have to exceed the HP of the tractor. I set my slip clutch by loostening all of the nuts on the springs, setting the tiller to full depth, slipping the clutch. After the clutch slips, I turn the nut in to touch the spring and 3/4 turn more evenly on all 6 springs. I have never had the clutch slip past this point, however I am not tilling through rocks or stumps. Others settings will differ depending on soil, compaction, rocks, stumps. I can see where someone might want a little better tiller drive and tighten the clutch past the point where the tractors HP would exceed the gearbox in a given tiller, or any other PTO driven implement for that matter.
Chris
greg_g
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</font><font color="blue" class="small">( I set my slip clutch by loostening all of the nuts on the springs, setting the tiller to full depth, slipping the clutch. After the clutch slips, I turn the nut in to touch the spring and 3/4 turn more evenly on all 6 springs. I have never had the clutch slip past this point )</font>
I wonder if you haven't actually defeated your clutch's ability to slip at all Chris? I see your clutch is 6 springs, so I don't know if my 8 spring adjustment numbers will work for you. You're welcome to take a look at the attachment anyway.
Looking at the chart you'll see the shorter (tighter) the spring, the more torque is required to slip the clutch plates. More torque equates to more HP. Therefore - assuming correct implement sizing - you adjust the spring length (tension) based upon the PTO hp of the tractor to which the shaft is connected.
With regard to your "3/4 turn method", please note that the entire 20-55 hp torqe range is contained within only 3mm of spring length adjustment. That's over 4000 ft/lbs of torque being controlled withing a spring tension difference of slightly under 1/8 inch.
//greg//
I wonder if you haven't actually defeated your clutch's ability to slip at all Chris? I see your clutch is 6 springs, so I don't know if my 8 spring adjustment numbers will work for you. You're welcome to take a look at the attachment anyway.
Looking at the chart you'll see the shorter (tighter) the spring, the more torque is required to slip the clutch plates. More torque equates to more HP. Therefore - assuming correct implement sizing - you adjust the spring length (tension) based upon the PTO hp of the tractor to which the shaft is connected.
With regard to your "3/4 turn method", please note that the entire 20-55 hp torqe range is contained within only 3mm of spring length adjustment. That's over 4000 ft/lbs of torque being controlled withing a spring tension difference of slightly under 1/8 inch.
//greg//
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Soundguy
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You will want your tractors PTO hp to be lower than the implements gearbox rating... but above the HP rating needed to sufficiently power the implement.
For example.. lets look at a 5' KK rotary mower. it has a 40hp gear box, and needs 20-35 hp to run it acceptably.
If your tractors PTO hp is 50.. you can damage the box if your safety devices fail ( clutch / shear pin ).
Ideally, the shear pin or clutch will activate at a hp level below the implement gear box's max allowed level.
Soundguy
For example.. lets look at a 5' KK rotary mower. it has a 40hp gear box, and needs 20-35 hp to run it acceptably.
If your tractors PTO hp is 50.. you can damage the box if your safety devices fail ( clutch / shear pin ).
Ideally, the shear pin or clutch will activate at a hp level below the implement gear box's max allowed level.
Soundguy
chriswheeler
Platinum Member
After some thought I can see that the 3/4 turn setting could indeed defeat the clutch on mine. Don't think there is any way to tell until the tiller snags on something hidden. I have a Howard HR-8 in,57" or so wide. Manual does give a OAL for the springs to be set but not a torque setting. Springs are tired and the spec is almost longer than the spring is loose. Guess I need new springs. But my tractor is 30 HP at the PTO, and the box on the tiller is 45. Think even if the slip clutch was defeated with the 3/4 turn setting there would be no danger to the tiller, would stall the tractor first. Full depth on mine is 6.6" and I always till at full depth. At full depth there almost isn't any load on the tractor, can hardly tell it is working in ground that hasn't been broken in 5+ years. This slip clutch setting thing could become a big issue with a 100 HP tractor and a tiller with a 45 HP gear box.
chris
chris
Thanks for the feedback. The gearbox rating v. required PTO to run seems to shed light on this. I'm upgrading from a Kubota B7100 with the intent on running a tiller and haying equipment on the L4400. In looking at specs on attachments, I usually see one hp range listed. I guess that's what was confusing to me.
Now am I understanding this correctly - the KK tiller is gear driven, so the hp req of 25-40 would give the max PTO? (With a 37.5 PTO, I am assuming I'm not over the gear box rating.)
As opposed to an attachment that is not gear driven, with a hp req of 20-30, the overage on the tractor PTO would not matter since it's not gear driven?
Now am I understanding this correctly - the KK tiller is gear driven, so the hp req of 25-40 would give the max PTO? (With a 37.5 PTO, I am assuming I'm not over the gear box rating.)
As opposed to an attachment that is not gear driven, with a hp req of 20-30, the overage on the tractor PTO would not matter since it's not gear driven?
Soundguy
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Yes, and no. Even though a unit may not be pto driven.. if you significantly overpower a implement.. you could damage other components inculding the driveline.
You should be fine with your setup mentioned.
Soundguy
You should be fine with your setup mentioned.
Soundguy