What are these things? (A lawnmower deck question)

[LEAKYSEALS951]

What are these things?
I'm replacing the blades on my rear swisher trail behind finish cut mower. The thing works great, except, cut grass doesn't smoothly blow out the side, it gets stuck and left under the center blade area.

I always assumed there was no rear curved metal pieces to guide the grass, but, today while changing blades, I noticed there were. There were also two triangular shaped metal pieces on the leading edge- which I've never seen before on a mower deck, but they seem like they would impede the grass flowing across the width of the deck efficiently.

So I'm wondering what they do. Help mulching? Strengthen the deck? The result of some high tech mower deck wind tunnel test?

I'm changing the blades right now, and I'm thinking I'm going to cut them off, but they must be there for some reason. What is the reason?

What do you think?

[oldE]

I expect they are there to control air movement under the deck so the grass stands up for an effective cut.
My MTD built mower has similar structures.
Best
Les

[Don Ro]

^^^
I agree.
My old 36" dual blade Kees and Exmark mowers had those under-deck.
Also could have something to do with directing the cut grass out into the catch bag.
.
Edit: " Help mulching? The result of some high tech mower deck wind tunnel test?"
.
D) All of the above.

[LEAKYSEALS951]

Thanks for the responses.
My 62 deere deck and my 50 inch ford deck don't have them. This deck is a 66 inch.
This mower deck has the finned blades for uplift, which none of my other decks have.

It would be foolish to think I know better than the actual mower company in terms of airflow, but it doesn't work now. It just "seems" the middle blade would throw clippings backwards into the chute side blade instead of across the deck straight to the chute.

I'm going to go pick up a new oil filter now and pontificate more on this most pressing matter!

[LEAKYSEALS951]

This thread wouldn't be complete without some in-depth research paper:

downloads.hindawi.com/journals/ijrm/2005/763964.pdf

[Baz]

Purple Tabebuia in bloom behind the SUV?

The triangles help direct clippings.

[LEAKYSEALS951]

Interesting guess on the tree! I have been told it is a Redbud

Lady Bird Johnson Wildflower Center - The University of Texas at Austin

[Baz]

Originally Posted by LEAKYSEALS951

Interesting guess on the tree! I have been told it is a Redbud

Lady Bird Johnson Wildflower Center - The University of Texas at Austin

That's probably correct then - I was just guessing. They both bloom in early spring and are both very prolific.

The Eastern Redbud has a heart shaped leaf and the Purple Tab a compound leaf so that would be a way to positive ID it.

Thanks for the reply and info!

[drcoastline]

Originally Posted by Baz

Purple Tabebuia in bloom behind the SUV?

The triangles help direct clippings.

That was my guess, the triangles deflect clippings back into the blades. The tree looks like an Eastern Redbud.

[LEAKYSEALS951]

Definitely a heart shaped leaf from what I remember!
Red buds grow in our yard/area like weeds. We love em'.

And now for an amazing discovery I'm sure EVERYONE has been on the edge of their seats waiting for...

I went ahead and cut one of the triangles off. I agree with everyone- they are there to direct the clippings, but why ( I thought)

As I drove around looking for parts today, I got to thinking about the flow they would create.

In the first pic, I can almost see how the flow goes... The triangles keep the grass in a circular motion, but that causes it to have to change direction at almost a right angle as the next blade over changes it's direction.



But I want more of a laminar flow across the front:



The area near the triangles is too far away from the blades, and is a lower flow area. The high flow areas have a burnished appearance, whereas the triangle areas have moldy grass buildup:



So figuring the thing didn't work worth a darn anyway I cut the chute side triangle:



And went out and mowed the lawn. There was still crap dropping off the bottom, but if was dropping off right at the still existing triangle the most. I have marked the triangle locations with a magic marker. The triangle is on the right, the clipped triangle is on the left. I redrove the tractor over a cut patch to show how much debri the existing triangle/ mower was leaving. Compare it to the left side:





So basically, cutting off the triangle helped. This is FIRST WORLD PROBLEM stuff and MUST be solved!!!

I am thinking the next step will be to cut off the other triangle, and then, build a new leading edge closer to the blades if that doesn't help!

In conclusion, I need a life!

[Don Ro]

You sound like one of those guys who'd modify a hockey puck.

[drcoastline]

I think the purpose of deflecting the clippings is to deflect them back into the blades mulching them more.

[Don Ro]

BTW, if your grass is too tall take only a half swath...otherwise the under deck gets overwhelmed.

[rusnak]

Those blades need a tad more pitch, and I wonder if it would make sense to open up an air inlet on the topside of the deck, to increase flow?

[Crowbob]

Those triangles were meant to retard build-up in the under deck prior to the introduction of Gator blade technology.

Plus, you have way too much time on your hands.

[Gogar]

I'm glad you cut one of them off. Surely you know better than the company who designs and builds lawn mowers 24/7.

[ckelly78z]

Without those diverters under your deck, all the grass from one side would plug up the other, there would be no air flow, and the grass from one blade would be fighting with grass from the other blades.

[scottmandue]

They hold together the fabric of universe so whatever you do don't.... oh snap...

[widebody911]

Have someone else drive the mower while you watch from underneath. Reach your hand in, and you should be able to feel the air currents.

[pete3799]

I'd look under my 3 point hitch finish mower to see what mine looks like but alas it's buried in snow at the moment.