4 blades for 1850 brush hogs

[wasabi]

while changing blades recently I noticed the doughnuts are drilled in four place. The slightly used 1850 I acquired has two blades per, but a recent post suggested four would be more effective. It seems four migh help prevent the occasional stuck blades. Does anyone with a PT brush cutter use four blades instead of two with better results?

 

[woodlandfarms]

Only 2 for me. But I run heavier blades and am in really thick brush. I thought the same thing as well. Might be a nice finish mower with 4 blades...

 

[ponytug]

Dear Wasabi,

If you are trying to do brush, two is better than four, since having four usually runs slower. The available energy goes as the square of the rotational speed, so a slight change in speed is a big loss in available energy. If the motor is overpowered and can handle four...I don't know. Give it a try.

All the brush cutters that I have run (all four of them) only had two blades, even on the big ones.

All the best,

Peter

while changing blades recently I noticed the doughnuts are drilled in four place. The slightly used 1850 I acquired has two blades per, but a recent post suggested four would be more effective. It seems four migh help prevent the occasional stuck blades. Does anyone with a PT brush cutter use four blades instead of two with better results?

 

[wasabi]

thanks for the feedback. I'll stick with two until I finish "recovering" our overgrown eight or so acres of meadows, then maybe shift to four for maintenance. appreciate the thoughts!

 

[J_J]

If the weight of the blade assembly's remains the same, even with 4 or more blades, the speed and force should be the same. If you add two more blds to the existing bld assembly, the bld tip speed will decrease.

 

[wasabi]

If the weight of the blade assembly's remains the same, even with 4 or more blades, the speed and force should be the same. If you add two more blds to the existing bld assembly, the bld tip speed will decrease.

I wonder if the increased cutting power of four blades would be offset by reduction of tip speed. it would seem on the surface that twice as many whacs per revolution might help with the mulching action...perhaps slower groundspeed would help?

 

[American Bulldog]

The thing I don't like about the 4 blade setup is that when a blade swings back, it will hit the blade behind it. Not sure if that is a good idea. They could bind up on each other, and possible damage each other. As someone said, they have never seen a bush hog mower like that. Probably a good reason for it.

 

[American Bulldog]

If the weight of the blade assembly's remains the same, even with 4 or more blades, the speed and force should be the same. If you add two more blds to the existing bld assembly, the bld tip speed will decrease.

Why would the tip speed decrease? If there is more weight, the mower will actually have more momentum, which may power it through more things. The old physics equation F=MA holds true here. Changing the mass, M, will change the acceleration, A. F is the Force, which will be the PTO GPM (constant). The top speed will stay the same. The mower will take longer to get up to speed, and it will take longer to slow down.

 

[J_J]

More weight, more drag on the hyd motor. I have tried it for a fact, by putting another bld 90 degrees to the other bld on the spindle of my Dixie Chopper. It slowed down the rpm. If you can get the same weight mass with 4 blds, there will be no change in rpm. If one bld hits another, that is a disadvantage. With a proper design, that will not happen.

 

[J_J]

If you want the blade tip speed higher, you will have to increase the engine rpm, or change the pulley size. If you are thinking about the center spindle, which is turning at the same rpm as the hyd motor, additional weight on the spindle will slow it down, and you would compensate by increasing engine rpm if possible.

What happens when you are cutting something thick and heavy? Blades will slow down, and since there is more drag on the hyd motor, the engine will slow down. Most people slow the fwd speed, or increase engine rpm. or both.

A heaver blade will have more impact force on whatever it is contacting. Grass weeds, sticks, etc.