Leaf blades

[JimP2014]

It might be tough to follow above but here is the most basic design concepts I have two different designs one is to use essentially the existing mower deck drive system to power modified blades the other is to completely replace the two blades and have a system similar to a handheld leaf blower. And for the handheld leaf blower type of system the leaves would always be to the right of the discharge chute if you run over leaves probably nothing would happen with them.

Jim

 

[Peva]

Using only a half on one side is going throw everything out balance. Back during the Summer I was restoring a mower that was given back after 10 yrs. While was cutting one blade broke exactly in half leaving one half still attached. I thought the mower was going come out from under the mower; vibrating like heck. The noise even woke up my neighbor that has a hearing problem.

In 16 yrs of repairs it was first time I ever seen a blade to break in half.

I'm going off topic here, but that reminded me of when I was the driver in the Navy for a captain who was over two training fields (Whiting and Ellison near Milton, FL) - one of which was for Bell helicopter pilot training at the time.

One morning, got called with the captain to a crash site at which, while the decorated Viet Nam-war veteran instructor and the Navy student pilot were doing a simulated failed-engine emergency auto-rotate landing, one of the pins about which the two blades rotated in their cyclic motion on the main rotor hub broke in two, so one of the two blades flew off (radially). The helicopter immediately disintegrated in the air from the extreme out-of-balance condition - as you can imagine. Of course, both died. (I also drove the wife and father-in-law of the instructor at the funeral - sad and uncomfortable.)

The entire fleet of that model of helicopter was grounded for an investigation in which they found several other pins with fatigue cracks.

Sorry for this downer post, but I'm getting older and your post reminded me of that incident. Thank you for indulging me.

 

[JimP2014]

I'm going off topic here, but that reminded me of when I was the driver in the Navy for a captain who was over two training fields (Whiting and Ellison near Milton, FL) - one of which was for Bell helicopter pilot training at the time.

One morning, got called with the captain to a crash site at which, while the decorated Viet Nam-war veteran instructor and the Navy student pilot were doing a simulated failed-engine emergency auto-rotate landing, one of the pins about which the two blades rotated in their cyclic motion on the main rotor hub broke in two, so one of the two blades flew off (radially). The helicopter immediately disintegrated in the air from the extreme out-of-balance condition - as you can imagine. Of course, both died. (I also drove the wife and father-in-law of the instructor at the funeral - sad and uncomfortable.)

The entire fleet of that model of helicopter was grounded for an investigation in which they found several other pins with fatigue cracks.

Sorry for this downer post, but I'm getting older and your post reminded me of that incident. Thank you for indulging me.

I'm going off topic here, but that reminded me of when I was the driver in the Navy for a captain who was over two training fields (Whiting and Ellison near Milton, FL) - one of which was for Bell helicopter pilot training at the time.

One morning, got called with the captain to a crash site at which, while the decorated Viet Nam-war veteran instructor and the Navy student pilot were doing a simulated failed-engine emergency auto-rotate landing, one of the pins about which the two blades rotated in their cyclic motion on the main rotor hub broke in two, so one of the two blades flew off (radially). The helicopter immediately disintegrated in the air from the extreme out-of-balance condition - as you can imagine. Of course, both died. (I also drove the wife and father-in-law of the instructor at the funeral - sad and uncomfortable.)

The entire fleet of that model of helicopter was grounded for an investigation in which they found several other pins with fatigue cracks.

Sorry for this downer post, but I'm getting older and your post reminded me of that incident. Thank you for indulging me.

I was not clear in my word description of what I was trying to do, but with those two hand drawings I hope it makes it more clear the one on the left is actually the one that I think would work the best just change the attack angle if you will because using stock high lift blades does throw the grass clippings pretty far and also leaves during the fall so my idea was just to modify those in some way and a balanced way that would increase the exit velocity of stuff coming out from underneath the mower deck.

Jim

 

[sgkent]

the blades need to be an airfoil. They move air up and the deck is shaped to flow the air out the chute. New air moves in from underneath and lifts the clippings and leaves. They make machines that are just air movers, and are basically push leaf blowers. Someone might make one that is drivable. The issue is going to be cost effectiveness. It gets used once a year when the leaves drop. Anything else is easily handled with a hand held. Street sweepers act on a different principle, they use spring blades to sweep up items. Any blade you make must act as an airfoil and not a paddle or it will just move leaves around and around. It's the airflow created by the air foil quality of the blades that moves the leaves, not the blades. They will mulch if the blade is designed to allow slower movement of the leaves. The only reason NOT to mulch is if you are trying to clean the lawn and NOT drop weed seed heads back on the lawn. The Great Plains were such great soil because thousands of years of leaves and grasses decomposed and made top soils that were many feet thick. When we don't mulch the front lawn for example, and collect the clippings, I can see the loss of nutrients in the soil tests, especially water soluble minerals like Potassium and Nitrogen.

 

[JimP2014]

the blades need to be an airfoil. They move air up and the deck is shaped to flow the air out the chute. New air moves in from underneath and lifts the clippings and leaves. They make machines that are just air movers, and are basically push leaf blowers. Someone might make one that is drivable. The issue is going to be cost effectiveness. It gets used once a year when the leaves drop. Anything else is easily handled with a hand held. Street sweepers act on a different principle, they use spring blades to sweep up items. Any blade you make must act as an airfoil and not a paddle or it will just move leaves around and around. It's the airflow created by the air foil quality of the blades that moves the leaves, not the blades. They will mulch if the blade is designed to allow slower movement of the leaves. The only reason NOT to mulch is if you are trying to clean the lawn and NOT drop weed seed heads back on the lawn. The Great Plains were such great soil because thousands of years of leaves and grasses decomposed and made top soils that were many feet thick. When we don't mulch the front lawn for example, and collect the clippings, I can see the loss of nutrients in the soil tests, especially water soluble minerals like Potassium and Nitrogen.

"The issue is going to be cost effectiveness. It gets used once a year when the leaves drop. Anything else is easily handled with a hand held." I originally felt that a good PRICE point and assuming they work really well, would be $25 to $30. I would pay that. You can drive around on your existing riding mover and move leaves like a walk behind or even a leaf blower.

Good point on the airfoil, I see what you are saying. I have never seen a simulation or a real video of how that happens even for just high lift blades, but very cool.

Thanks for your insight SGKent!

 

[Auto Doc's]

Interesting discussion, but I think putting paddles on the blades will try to send air, and therefore leaves off the tips of the blades, rather than out the chute. The two or three blades will fight each other rather than direct the flow out the chute. I think the typical blower is fully enclosed except for an inlet near the center, and an outlet at the edge, like a squirrel cage fan. It doesn't run leaves through it, it runs air through it and chases the leaves away. To approximate that with a mower deck, you'd need to enclose the bottom, and maybe only use one blade. And provide an air inlet. A better approach may be to just use your deck as is, but don't run over the leaves, just chase them with the discharge air. Like cleaning a sidewalk. At some point, you are still going to overwhelm the ability to chase leaves, and have to pick them up. At least I always did with a hand held blower. And with the mower deck you lose the ability to cycle the air flow up and down. I've never used one of those fancy walk behind blower, but I have to believe they work similarly. But what do I know. To settle this, somebody's going to have to build one! Not me, by the way.

Hi Chuter,

Back in the 80's Snapper 26"-30" RER mowers had bolt on "high lift" wings for the single blade intended for high lift bagger operations. The decks acted like a cutter and vacuum cleaner all in one when using the bagger option.

Those would clean up and chop heavy fall leaves easily.

Now, most people want much wider multi-blade decks, and they are not nearly as efficient without a vacuum assist attachment on the decks.