xlr82v2
Platinum Member
- Joined
- Dec 3, 2004
- Messages
- 702
- Location
- Southwestern Illinois
- Tractor
- 2007 Mahindra 3525, 1952 Ford 8N
I've read several posts now here on TBN about tillers really launching objects.
I've been around tractor mounted tillers now for about 25 or so years, ever since my dad got his when I was a young kid (1982, I think, so I would have been 12... I'm 38 now.). I've never seen his tiller launch anything more than a foot or 2 behind the tiller in all that time, and I've seen him or myself hit quite a variety of objects in that time (he has a business plowing and tilling gardens), ranging from small rocks to bricks, to old truck axles. I've never seen anything "go flying". So, I've read all of these posts with considerable skepticism.
Then today, I read another "launch" post in this thread, so I decided to run the numbers to determine the maximum velocity that a tiller is capable of "launching" an object at.
I used my KK2 6' tiller for my test subject, since it is quite representative of the tillers used by members of TBN. These results will hold for any KK2 (excluding the XB "orange" series) tiller, since they all use the same gearboxes, and the speeds will be the same.
Without showing all the math, at 540rpm pto speed, the tine rotor shaft is spinning at 210 rpm on the KK2 tillers. If you want, I can show how I calculated that, but it's easy math. 210RPM is 3.5 revolutions per second.
I went out and measured my tiller, and determined that the tines rotate in an arc with a radius of approximately 8 inches (.667 feet). That calculates out to a circumference of 4.19 feet per revolution. Multiply that by 3.5 revs per second, and that gives you 14.665 feet per second. That's the maximum velocity that the tiller can possibly launch any object at. To state it in a measurement unit that we're all more familiar with, 14.665 fps = 9.999mph. Let's just say 10 mph. And that's if the tine contacts the object just absolutely perfectly to transfer the maximum velocity to the object, without it being buffered by the tilled ground around the arc being described by the tiller tines, or contacting the tailgate and being deflected back down to the tilled soil.
I'll let you make your own decisions about tillers throwing objects, but I remain highly skeptical of the claims made by some on TBN. How far do you think anything can fly at 10mph?
I've been around tractor mounted tillers now for about 25 or so years, ever since my dad got his when I was a young kid (1982, I think, so I would have been 12... I'm 38 now.). I've never seen his tiller launch anything more than a foot or 2 behind the tiller in all that time, and I've seen him or myself hit quite a variety of objects in that time (he has a business plowing and tilling gardens), ranging from small rocks to bricks, to old truck axles. I've never seen anything "go flying". So, I've read all of these posts with considerable skepticism.
Then today, I read another "launch" post in this thread, so I decided to run the numbers to determine the maximum velocity that a tiller is capable of "launching" an object at.
I used my KK2 6' tiller for my test subject, since it is quite representative of the tillers used by members of TBN. These results will hold for any KK2 (excluding the XB "orange" series) tiller, since they all use the same gearboxes, and the speeds will be the same.
Without showing all the math, at 540rpm pto speed, the tine rotor shaft is spinning at 210 rpm on the KK2 tillers. If you want, I can show how I calculated that, but it's easy math. 210RPM is 3.5 revolutions per second.
I went out and measured my tiller, and determined that the tines rotate in an arc with a radius of approximately 8 inches (.667 feet). That calculates out to a circumference of 4.19 feet per revolution. Multiply that by 3.5 revs per second, and that gives you 14.665 feet per second. That's the maximum velocity that the tiller can possibly launch any object at. To state it in a measurement unit that we're all more familiar with, 14.665 fps = 9.999mph. Let's just say 10 mph. And that's if the tine contacts the object just absolutely perfectly to transfer the maximum velocity to the object, without it being buffered by the tilled ground around the arc being described by the tiller tines, or contacting the tailgate and being deflected back down to the tilled soil.
I'll let you make your own decisions about tillers throwing objects, but I remain highly skeptical of the claims made by some on TBN. How far do you think anything can fly at 10mph?
