Mowing mowing wow that fast? finish, rotary and flail

nomad · Sep 5, 2003

( 
The point that the grass is cut is the entire area between V4 and V2. It is an arc. )

Thanks. Talking about the speed distribution along that arc will be really difficult. Let the designers do that. Lets assume we are designing so that it cuts only at the point 1. - So, the question is V1 value has any effect on V0 value or vice versa? Since all transmission components in the overall system (tractor+attachment) are the gears we can consider that there is only one V1 value for each V0 value. But, the value of V1 is high and this may cause air turbulence around the blade. So, a small change in V0 tractor speed too may cause an unwanted air turbulence around the blade. Drive your mower faster - you'll see the deck will fly up because of increased V1 blade speed. Also, the magnitude of V0 tractor speed will change the grass cutting direction of the blade. What does your user manual of mower say about the speed of tractor? Follow it - if you have the insurance, you will be refunded.

Henro · Sep 5, 2003

So, the question is V1 value has any effect on V0 value or vice versa? 

V0 is independent of V1. You can have the tractor sitting still or moving at different speeds, and the mower will still be turning at the same speed, if the engine is running at the speed that makes the pto turn at say 540 rpm at all times.

In a gear tractor the number of V0 speeds will be limited by the number of gears you have. With a hydrostatic there are many more V0 opportunities.

The engine is the master here. Both the mower speed and the tractor speed are slaves to the engine speed.

Sort of like me and the wife...I let you guess which is which there... /forums/images/graemlins/blush.gif

Sprocket1 · Sep 5, 2003

Rear mounted mowers only have 1 set of blades like conventional lawnmowers do. Why don't we put a third or fourth blade on the same shaft? Wouldn't it take less hp to cut the same ground speed? Just kiddin'. I think.

MossRoad · Sep 5, 2003

The way I look at it, if you are standing directly in front of point V1, the blade will move across you at V1 speed and through you at V0 speed. If you are standing directly in front of point V4, the blade will move through you at V4 speed + V0 speed. And there is probably some formula to figure out how fast it moves through you anywhere along that arc that we are talking about. And don't forget that anywhere between V1 and V2 the grass will get cut at a slower speed than the grass that is between point V4 and V1 because the blade will be coming at the grass from it's rear. So, a blade of grass standing directly in front of point V2 will actually be cut from the side facing away from point V2, or V2 minus V0. Of course the difference in speed will be so small that no one will notice, because the tip speed is so great in comparison to V0.

 What does your user manual of mower say about the speed of tractor? 

8-9 MPH is as fast as my tractor will go. I can mow that fast all day on level ground if the grass is not too high. I have to slow down on bumpy ground because the mower deck starts to bounce and I get an ugly cut. I also don't like to mow that fast because my yard is only 100 yards deep and things like trees and flowerbeds come at you too fast to be safe. But out in a ball diamond I cut pretty darn fast. /forums/images/graemlins/grin.gif

MossRoad · Sep 5, 2003

If you are driving down the road at 55 mph, and there is a fly in the back seat.
How fast does he have to fly to get to the front seat? 

Assuming the windows are up and the vent fans are off, the air inside the car is already going 55 in relation to the ground, but about 0 in relation to the interior. With that said, I'd have to say the fly has to travel about as fast as it takes to get from a trash can to potato salad. /forums/images/graemlins/shocked.gif

slowrev · Sep 8, 2003

If you are driving down the road at 55 mph, and there is a fly in the back seat.
How fast does he have to fly to get to the front seat? 

Not sure but we are all travelling might fast even when sleeping. The earth is revolving on its axis, and orbiting around the sun, our solar system is travelling in the Milky way galaxy, our galaxy is travelling in the universe, etc.. I wonder how fast we are travelling when sitting on our backsides ? Kinda makes my head hurt just thinking about it.

nomad · Sep 9, 2003

( So, the question is V1 value has any effect on V0 value or vice versa? 

V0 is independent of V1.

)

Yes, V0 is independent of V1, but this is so if you want to cut the grass irregularly. Lets take simple drawing here again

Lets say the vectoral summation of V0 and V1 is V01. This speed vector has another arrow direction, that is, the grass cutting direction. If V0 increases/decreases, the cuttting angle changes. Ok, this change in cutting direction can be neglected. But V1 is high speed which may cause air turbulence around the blades because of small effects. And, small change in V0 can be considered a small effect that may cause air turbulence under the deck. So, don't mow faster than you are adviced in the user manual. Not slower either as your tractor will burn more oil for same area when V0 is slow.

markct · Sep 9, 2003

well first off ya all got sucked into arguing with nomad, anyone who has seen his discusions on agtalk wouldnt do that. but one thing i have to add is that i recall hearing somewheres that the theoretical topspeed of a disk mower is around 30 mph. that would require real flat fields and alot of HP, i do know of someone running a disk mower with a ford 8600 in road gear which is about 18 mph

nomad · Sep 14, 2003

( well first off ya all got sucked into arguing with nomad, anyone who has seen his discusions on agtalk wouldnt do that. )

Your "first off all" part was the main reason why you posted under my post, wasn't it? Yes, sure so. Now, what one wonders is that did you get educated by Nomad on newAgtalk and this education hurt your feelings a little? Please, consider what Nomad did there to you only as a favor. If you don't appreciate the favor, please, at least do not call it "sucking". Of course, you don't have to appreciate the favor of educating you and it's your freedom whatever you do or say here. But then, you got such a reply then. Anyways, I won't reply you if you reply again by a post off the topic. Thanks.
By the way, 30 mph was a good number. All were saying that 5-10 MPH written in the user manuals. 30 MPH is 3 times more than people mentioned. I will not be surprised if another one comes and says 90 MPH which is again 3 times of 30 MPH. We are getting close to my 200 MPH . LoL