Crack in Mower deck

[plumb-r 34]

Ist post on the forum. I bought a 1980 C-145A tractor last fall. I just took off the snow blade and was going to get ready to mount the 42" rear discharge mower deck. I noticed that when I got it that the deck had two cracks in it, by each of the brackets that hold the deck to the tractor. The cracks are only an inch or two long. Question is do I just have them welded or should I also have a piece put on from the bottom side of the deck so there is a larger area to bear the weight and stress?

[slammer302 2,155]

I would weld it and add sum large washers on the bottom or a plate on each side. that is a common place for cracking. Good luck that looks like a very nice deck

[tractorhogg 612]

I would try to determine WHY it happened. Was the previous owner abusive, was the terrain very uneven, or something else. As nice as that deck looks I have to think cracks like this have to be caused my confounding factors.

[Retired Sparky 526]

I think stress cracks happen to us all. If you don't have your own welder, find somebody that knows their stuff. I would stop drill the cracks. Which means drill an 1/8'' hole at the end of each crack. That will stop the crack. Thus the term, 'Stop drill.'   A good welder will grind a grove in the crack and then weld over the crack. Your keen eye has prevented some future damage.  

                                    Allow me to be the first to say.          TO   

[953 nut 55,051]

   As @Retired Sparky said, stop drill now. I would do welding from the bottom side and reinforcement from the top side with skip welding (weld 1/2", skip 1/2" etc. etc.) this will keep from causing heat stress. Do it from the top so derbies and moisture aren't trapped between the deck and the patch causing future problems. 

[Retired Sparky 526]

From my own experience I weld top and bottom with no plates.  My deck is 30 yrs old and has many stress cracks welds. I've never had a problem. I stop drill the crack, grind a small grove and weld. Paint the repair with no problems. 

[953 nut 55,051]

@Retired Sparky,I guess weld repairs are a lot like gardening; we do it the way we were tough as kids and as long as we get a good result we did it the right way, even if it was done differently than another's "right way"

 

PS,  , the stop drill method also works for cracks in concrete slabs.

[Retired Sparky 526]

16 minutes ago, 953 nut said:

@Retired Sparky,I guess weld repairs are a lot like gardening; we do it the way we were tough as kids and as long as we get a good result we did it the right way, even if it was done differently than another's "right way"

 

PS,  , the stop drill method also works for cracks in concrete slabs.

[JAinVA 4,619]

There is one thing about the stop drill method that puzzles me.If the idea is that a round hole at the end of the crack will cause the crack not to go further then why did it start at a larger round hole in the first place?I am well aware that sharp inside corners are stress risers but I am curious if the crack isn't welded would the crack continue past the stop drill? Just wondering.JAinVA

JimAnderson

Gloucester,Va

Edited March 28, 2016 by JAinVA

[cleat 5,808]

My side discharge decks have plates on the inside from the factory. They still crack some so no guarantee.

 

This is one of my decks as I received it. Bad welds and lots of cracks. You can see the plate near the rear of the deck.

 

Front mounts had no plates and cracked then were poorly welded up.

 

 

This deck is currently at my welder's being repaired.

 

 

[plumb-r 34]

Thanks for all the fast replies. I didn't think about stop drilling the cracks. I don't own a welder so will have to take it somewhere to get done. Then I'll have more questions.

[clip 185]

On March 28, 2016 at 8:57 PM, JAinVA said:

There is one thing about the stop drill method that puzzles me.If the idea is that a round hole at the end of the crack will cause the crack not to go further then why did it start at a larger round hole in the first place?I am well aware that sharp inside corners are stress risers but I am curious if the crack isn't welded would the crack continue past the stop drill? Just wondering.JAinVA

JimAnderson

Gloucester,Va

 

The propagation energy is focused at the tip of the crack, so stop drilling redistributes that energy over a larger area. It could potentially keep propagating if the energy is high enough. I think there are formulas or guidance offered on how large a hole you need to keep a crack from continuing, but I wing it.

 

I think the reason the crack started at a large hole to begin with was a separate force was acting on it, like a bolt or other connection applying side loading or torsion to the sheet metal.

 

[WHX?? 48,760]

[Retired Sparky 526]

On 3/28/2016 at 8:57 PM, JAinVA said:

There is one thing about the stop drill method that puzzles me.If the idea is that a round hole at the end of the crack will cause the crack not to go further then why did it start at a larger round hole in the first place?I am well aware that sharp inside corners are stress risers but I am curious if the crack isn't welded would the crack continue past the stop drill? Just wondering.JAinVA

JimAnderson

Gloucester,Va

OK, JAinVA,  this is off the top of my head. The stop drill process works because we put the stop drill holes at the end of where the stress crack runs. If the crack goes beyond a larger hole, maybe the stress hasn't found it's end. That may a little heavy thinking for this rainy afternoon.  It is here,  in Maine. OK.

          You asked the question, I'm only trying to fill in the holes.  (Or the cracks, as the case may be.)

               How'm I doing, Pard???

[JAinVA 4,619]

Sparky,

    Makes sense.Now to the next question.If you put a stop hole at the end of the crack and weld it do you leave the hole or weld it shut?

JAinVA

JimAnderson

Gloucester,Va

Edited March 29, 2016 by JAinVA

[JPWH 6,032]

The best way I have found to repair a stress crack is to reinforce the crack. Weld the crack then weld a plate larger than the crack or cut out the cracked area and repair with thicker plate.

 

Edited March 29, 2016 by JPWH

[clip 185]

28 minutes ago, JAinVA said:

Sparky,

    Makes sense.Now to the next question.If you put a stop hole at the end of the crack and weld it do you leave the hole or weld it shut?

JAinVA

JimAnderson

Gloucester,Va

You don't need to weld it if you stop drill it. Most of the time this technique leaves the hole open, or inserts a pin or rivet into the hole which can impart some compressive stresses on the walls of the hole. So generally stopping cracks from propagating can be done with either this method or grinding the entire crack out and getting into good base metal, then rebuilding with weld metal. If I was doing a combination of these two, I'd drill the hole then fill it with the welder, if nothing more than to prevent more tensile stresses near the hole as the metal cools and for cosmetic purposes.

[Retired Sparky 526]

1 hour ago, JAinVA said:

Sparky,

    Makes sense.Now to the next question.If you put a stop hole at the end of the crack and weld it do you leave the hole or weld it shut?

JAinVA

JimAnderson

Gloucester,Va

You close the door Brother.  In my experience. The stop drill hole, relives that pressure. Even when I weld the crack on the bottom of the deck I grind it flush.

[JAinVA 4,619]

The questions I posted were for educational purposes.I always learn from others experiences.I have seen where some  insist on  drilling  a stop crack hole before repair.In certain cases this works well.In other cases this does little  to solve the problem.If the base metal cannot survive  without cracking then it is overloaded or not up to the task to begin with.If the crack is caused by abuse then a welded repair is in order.If the crack is caused by a design fault then additional plating may be needed.That is the beauty of this site you get the opinions of many people with different experiences and backgrounds.I know what works for me but your mileage may vary.JAinVA

JimAnderson

Gloucester,Va

Edited March 31, 2016 by JAinVA

[Retired Sparky 526]

You're like my Dad, retired machinist right.  Because, that's the way he talked.  Good analysis JA.

Edited March 31, 2016 by Retired Sparky

[gwest_ca-(File Mod) 11,031]

Being a square hole to start with perhaps the crack started the day they punched that hole. Does the crack start at one of the corners?

 

Garry

[can whlvr 993]

I have  my original 42 side discharge deck,i welded it several times in many different spots,stop drilled it but it would continue to crack,eventually I had to replace the whole top of the deck,it was a big job but worth it,i didn't own a computer then so finding a replacement was only at the dealer and he wanted 1200 dollars,i think after enough use the metal just is to used up and cant take th abuse anymore,but it was well used so I wasn't mad,heres a pic if you close you can see the outline of the new top,

http://i570.photobucket.com/albums/ss145/canwhlvr/014.jpg[/IMG]

[tunahead72 2,403]

On 3/28/2016 at 6:27 AM, plumb-r said:

Thanks for all the fast replies. I didn't think about stop drilling the cracks. I don't own a welder so will have to take it somewhere to get done. Then I'll have more questions.

 

I can't personally recommend a good welder, but if you give us more specific information about where in Chester County you're located, somebody else here might be able to recommend someone close by.

 

[ericj 1,578]

the later decks had a flat plate brace running between both set of holes across the deck underneath.but I've seen them still crack. my brother showed me the stop drill method years ago when he repaired one of my first decks. I've stopped drilled cracks with out welding since i don't own a welder.

 

 

 

 

eric j