rotary cutter deck cracking

[Kaon99]

This past weekend I noticed the deck on my 48" rotary cutter (brushhog/bushhog) is cracking in two places. The deck is roughly octagon shaped. On each side, at the corner where the slant side meets the parallel side, the deck has a 1" crack that seems to be getting bigger. The steel is very thick, so I was very surprised to see the cracks. I have used the rotary cutter in some heavy brush, but I am not aware of doing anything drastic enough to crack the deck. I talked to Terry at Power-Trac and he said he had never seen a cracked deck on a rotary cutter.

I think the deck can be easily welded so I am not too concerned. However, I suspect the deck had a defect in the steel, so am making this post to see if any of you have had a pt mower deck crack. I will appreciate any information you can give me. Thanks- Ken in Mississippi

 

[MossRoad]

Sorry to hear that. /forums/images/graemlins/frown.gif

I have less than 10 hours on our 48" brush hog from PT. No signs of wear on the deck. Just blown out tires(replaced with solid tires) and a missing blade(hit a rock and cracked off the bolt). Other than the tires, I've been very impressed with mine in the short time it has been used. We'll use it more when/if we move to our property.

Do you have a way to take a picture of it and post it here?

 

[smartguyz]

Hi MossRoad -

I expect my Brush Hog's tires will not survive the blackberry brambles that are in its future. Where did you get solid tires, and what size did you get? I think that the tires may be the same size as for the 48" finish mower, so this would leave a spare pair of tires for the finish mower.

Thanks,

Rob /forums/images/graemlins/grin.gif

 

[Kaon99]

Mossroad,

That's a good idea. I will take some pictures soon and post them. I am quite puzzled as to how I managed to break a heavy steel deck. Maybe the pix will generate some theories.

On another topic: I solved my rotary cutter flat tire problem (so far) by putting in heavy duty slime-like sealer from NAPA ($12 for 32 oz - 16 oz in each tire) and pumping the tires up to about 40 psi. I have used the rotary cutter to clear an acre of head-high kudze and to clear out sapllings, thorny bushes, etc., with no further problems.

Look for some pictures soon. - Ken in Mississippi

 

[Kaon99]

Here are some pictures of the two cracks on my 48” rotary cutter. This post shows the right-side crack from a couple of feet away. The following posts show a close-up view of each side. If you have any theories as to what caused the cracks, I would like to hear from you. Thanks. – Ken in Mississippi

 

[Kaon99]

Here is a close-up view of the right-side crack. - Ken in Mississippi

 

[Kaon99]

Here is a close-up view of the left-side crack. As you can see, the two cracks are in the same places relative to the front of the cutter and are practically identical. My guess is either the steel is defective or else I somehow put a terrific strain on the front end of the cutter. At any rate I think I need to make an appointment with the local welding shop.

Ken in Mississippi

 

[SnowRidge]

</font><font color="blue" class="small">( My guess is either the steel is defective or else I somehow put a terrific strain on the front end of the cutter. At any rate I think I need to make an appointment with the local welding shop. )</font>

Ken, I stared at those photos without seeing any obvious cause.

My guess is the steel was under stress from the day it was welded up, and the vibration over time finally caused it to crack, thus relieving the stress--but it's only a guess.

SnowRidge

 

[MossRoad]

Hmm. It almost looks like a tremendous load was placed on the front, causing it to pull out like that. I'd just get it welded up and see if it returns. Do you use the hog in FLOAT? Maybe it came out of FLOAT or something and the entire weight of the tractor went onto the front casters instead of the front wheels. Imagine going towards a steep incline, the curl function of the joystick all the way back and not in FLOAT. The front casters could bear the entire weight of the tractor causing the front wheels to come up. Just thinking out loud. Hmm... Maybe somone dropped it on the front casters in shipping and it is just now becoming apparent. Hmm.. this is puzzling. Thanks for the pictures. I'll inspect mine the next time I pull it out of the garage in a few weeks.

 

[Bob999]

It appears to me that the load and stresses from the front castor wheels on the rotary cutter are trasfered to the plate steel that forms the top of the deck. Excessive loads would tend to cause this plate to flex.The joint you show as cracking would be stressed by any deflection caused by the loads from the front castor wheels. The thing that struck me about the cracks is that there is gap in the lower inch or so that suggests that there was never a solid weld all the way to the bottom of the skirting. It certainly wouldn't be the first case of defective welding.

An alternative theory is that the absence of draft control on the 425 puts higher loads in this area as compared to the decks that are used on the 1400 and 1800 series tractors. The manual for my 1845 says"...weight can cause damage to the gage wheels on the back of the mower and the caster forks on the front of the mower."

 

[smartguyz]

</font><font color="blue" class="small">( An alternative theory is that the absence of draft control on the 425 )</font>

What is "draft control"?

Thanks,

Rob /forums/images/graemlins/smile.gif

 

[Bob999]

Draft control is an hydraulic circuit that automatically picks up a portion of the load of the mower (or any other implement). On the 1400 and 1800 series tractors the draft control is electrically actuated and is adjustable for the amount of "lift".
The draft control transfers a portion of the weight of the mower to the tractor. This transfer improves traction and reduces stresses on the mower wheels. It also reduces turf damage by the deck wheels.

 

[DavidJ]

From the pictures you posted it looks like a design or manufacturing problem. I suspect that if you weld them up they will not reappear. Just to be sure you could strap them with some thin flat bar.

 

[Kaon99]

mystery solved!

Saturday morning, as I was loading up my rotary cutter for a trip to the welder, I had it at eye level and noticed something that I had missed when it was on the ground: the whole deck was bent downward by at least 1.5 inches. Suddenly it all became clear, and the reason for the cracks on the sides of the deck was obvious. Also, I had been wondering why my rotary cutter seemed to be cutting closer and closer. Now I know why. The deck was being bent downward more and more so that at the front , the tip of the blade got closer and closer to the ground. When I got to the welding shop several farmers had bushhogs there being repaired. I noticed that every one of them had angle iron or the equivalent welded across the top of the deck to keep the deck rigid. The welder had to turn my rotary cutter upside down and use a come-along and a big wooden block to pull the deck straight (actually reverse bowed a little to account for spring-back). Then he welded some angle iron on the edges to hold the deck straight when he released the come-along. He next turned the deck over and welded two heavy pieces of angle iron on the top to make sure the deck stayed rigid. He finished up by spray painting the whole rotary cutter. Total cost was $80 plus a $10 tip, plus a half day of my time. Moral of the story. With heavy use, the rotary cutter deck will bend and become permanently bowed downward. It has nothing to keep it rigid except the deck plate itself and some flat reinforcement strips on the underside. On a 4 foot span neither is sufficient to prevent permanent deforming of the deck. Terry says they have never had a problem with the rotary cutter deck, but if that’s true, its because no one has reported it. In my humble opinion, and with due respect to Power-Trac, the lack of support (like angle iron or the equivalent) for rigidity on the rotary cutter deck is a design flaw. If you use the rotary cutter hard, you WILL bend the deck. It is an easy fix to stiffen up the deck. I am enclosing some pictures of my fix. The first one shows the whole deck. The second one shows a close up of the angle iron that was welded on the top and sides of the deck. I hope no one has the problem I had, but I will be surprised if some of you don’t. Ken in Mississippi.

 

[Kaon99]

Re: mystery solved! another picture

Here's a close-up of the angle iron reinforcement. Note that the angle iron pieces on the top are welded to both the deck and the big vertical plates that attach to the deck. Ken in Mississippi

 

[johara1]

Re: mystery solved!

i'm glade you got it fixed,and it didn't seem like a bad price. i think the top of the deck should be heaver,all the strain is on it and it is the lightest metal thickness.no body else had that happen,you would have to believe in the tooth fairy to believe that.like they never had the governor come apart never left tools in a machine, put the wrong blades on the mower,low on oil. they make there share of mistakes too,the mowers are the weak link, the cut great but they not that durable.

 

[MossRoad]

Re: mystery solved!

Thanks for the pictures. That welding job for $80.00 seems like a good deal, too.

Just a question, do you always mow with the joystick in float? The the only thing I could figure that would put enough load on the deck to bow it down would be if the joystick came out of float. Then the weight of the tractor could be transferred to the mower deck. I just can't see how the weight of the loader arms could put enough weight on the deck to bow it down in the middle if it was in float and the dump/curl was centered.

But you have the deck in front of you and you have the cracks, so something happened to it. And I only have a few hours on mine, but there is no obvious wear on mine.

Who else has the 48" brush hog here on TBN? Any of you have these cracks? Let's keep an eye out for them. If we get them, we can use the (from here on officially named) Kaon99 modification. /forums/images/graemlins/smile.gif

 

[duane]

Re: mystery solved!

I'm wondering if it's the way the PT connects to the decks. It connects up high, so that pushing the mower (or bushhog) puts an overturning load on the deck. In heavy ground, this loads up the front castors and puts a bending moment on the deck structure.

 

[bryce]

Re: mystery solved!

Ken. Are you putting down pressure on the deck when hogging? If the hog is carrying some of the weight of the tool carrier, then the deck would bend over time. Robert

 

[Kaon99]

Re: mystery solved!

MossRoad,

Except for special situations where I want to hold the rotary cutter off the ground (like over a rut, or stump), I always mow in the "float" position. Sometimes when I lower the rotary cutter (and other attachments, too) I miss the float position and briefly put the weight of the power-trac on the mower deck. I think the finish mower potentially has the same problem as the rotary cutter. From now on, I will be more careful when I lower any attachment.

On a different topic, how do you post multiple pictures and how do you put pictures in with your text? I have noticed some TBNer's doing that. I would appreciate whatever information on posting pictures that you can give me.

Thanks. - Ken in Mississippi