Blades Collide on 62D Mower Deck

[kb2520]

I have a 2011 JD 2520 with a 62D Mid Mount Mower. In preparing for mowing season, I pulled the blades off the mower, sharpened them, and reinstalled. This I've done at least twice per season since 2011 without issue. Today though, I complete the process of installing the deck on the tractor. With the deck raised and medium RPM, I engaged the PTO as a test. There was a terrible thunk, so I quickly switched off the PTO and shut down the machine. Upon inspection, two of the blades slapped each other as they passed. There was evidence of this in the metal. As I rotated the blades by hand, sure enough they hit each other.

Have I just gotten lucky with the alignment all these years? From the output end, does the first blade need to be positioned North and South, second blade [middle] East and West and the third blade North and South? I honestly do not know if this makes a difference or if I've done something else incorrectly. Sorry for the dunce question, but I could use some input. Thank you!

 

[Deere Dude]

My guess would be that one blade wasn't centered on the spindle which would offset one maybe an 1/8" or so.

I never heard of tractors having timed blades. Little garden tractor types but they have special belts also.

 

[Industrial Toys]

I assume there are three. Are they all the same length? I can't for the life of me believe there is a mower where the blades are synced. IF they were, the pulleys would have to have teeth to accommodate a timing belt.

 

[beenthere]

Agree with wrong mounting of blades. Once mounted correctly, they won't hit each other..

 

[KennyG]

I wonder if you have two blades mounted wrong (not over the spindle shoulder). On my 62D I don't think one mounted wrong would cause a hit. Upside down won't make a difference in clearance. Take them off and start over and you should be fine.

 

[bigtiller]

Maybe you didn't get the blades fully seated on the spindle before putting the nut on. It should be a close fit with no slop, and with no question about north/south and east/west orientation.

 

[ovrszd]

Yep, I'm with most others here. You didn't get them properly seated on the shafts. This should be evident by the fact that the blades aren't tightened up against the spool, bit of a gap on top of the blades??

Funny story bout something like this. Many years ago I was running the road grader going by the house of an elderly couple whom I knew very well. The man was on his JD mowing. The wife was standing in the driveway watching. His deck was doing a HORRIBLE job of mowing. When Lois saw me she started waving for me to stop. I got out and as I approached her she said "can you look at our mower and see what's wrong. Bill just sharpened the blades and it isn't working well at all." I said sure. Bill saw me and stopped. A bit embarrassed he said "I don't know what's the matter with this thing." I said let me take a look. I laid down on the ground and looked under the deck thru the discharge chute. Sure enough. The blades were on upside down. As politely as I could I explained my findings to Bill. He really got red faced then. I said pull in the garage and I'll help you swap them. I did it with the deck still on the tractor. He had removed the deck and turned it upside down when he removed/reinstalled them. Laying upside down he had installed them like they would go had the deck been right side up. By the time I got done we were all laughing about it and having a good visit. Couple weeks later I went in my shop to find a case of my favorite Beer sitting inside the door.

 

[Aquamoose]

By chance, were these “replacement” longer blades that you just happened to be lucky that they were synced to not hit each other up until now?

 

[ovrszd]

By chance, were these “replacement” longer blades that you just happened to be lucky that they were synced to not hit each other up until now?

As someone else mentioned, only way to stay "in synch" would be notched belt and pulleys. By design the blades are "creeping" all the time.

 

[Industrial Toys]

I have a mower currently and had another that had different length blades on the center deck. Albeit larger commercial multi wing mowers. Almost any blade I have seen sits very tight on the bolt, to the point of being difficult and annoying to remove. So, I can't see the off-center thing.

An upside down blade should not be any longer at either edge.

 

[beenthere]

It is possible on the Deere deck to not center the blade correctly onto the shoulder. It would not run well at all.

Hopefully kb can/will come back and set us straight as to what he finds wrong.

 

[Industrial Toys]

If that's the case, it's probably the cause. Are you saying, the blade holes are that much bigger than the bolt? Not sure I have ever seen that, even on my JD Belly mower.

 

[beenthere]

Yes, the hole in the blade is larger diameter than the diameter of the bolt.

This from jdparts shows the spindle (key 25), the blade with the larger hole that fits the shoulder on the spindle, and the smaller bolt to just hold it tight to the spindle. If the blade isn't fit up to that shoulder, then it isn't centered and the bolt isn't doing it's job of holding the blade onto the spindle.

 

[Industrial Toys]

I take your word for it, but the picture doesn't show this. That would be a bad design if you ask me, in case the shoulder gets damaged. Can't see any advantage.

A friend just got a couple of JD425s. Any comments, positive or negative I can pass on?

 

[ovrszd]

It's a good design. Exactly places the blade. Takes load off the bolt. JD has been using this design for +30 years.

 

[beenthere]

IT
Not a bad design at all, as the blade is held on larger 3/4" diam spindle shoulder, and the bolt only has to serve to hold the blade on that shoulder. Clearly you do not understand what is happening here.

 

[Industrial Toys]

I don't recall that on my JD 770.

I have a lot of commercial mowing equipment, different makes. Seen everything thing from reverse fine thread bolts to my cushman that has long bolts that go right through the spindle with a nut on top. Never seen that collar design. Strange, if it's that good.

 

[BigBlue1]

By chance, were these 途eplacement longer blades that you just happened to be lucky that they were synced to not hit each other up until now?

He just took them off to sharpen and then put them back on. No mention of replacements.

As for the original problem, I've seen various JD 3-spindle mower decks over the years and I've never seen one that allows the blades to touch each other, no matter what clock position they are installed in. I'm in agreement with the prior comments that this had to be a case of the blade not being seated on the center of the spindle shoulder.

Rob

 

[Industrial Toys]

Funny, my friend said one of the machines was surging at idle and he accounted it to finding a misplaced O ring type gasket on the carb to engine connection. He thought, maybe from new.

 

[Oldoak]

IT
Not a bad design at all, as the blade is held on larger 3/4" diam spindle shoulder, and the bolt only has to serve to hold the blade on that shoulder. Clearly you do not understand what is happening here.

Although I don't think it is the cause of the problem of the blades hitting each other, I do think JD's design is BAD. On the mower deck for my X758, the holes in the blades are considerably larger than the spindle shoulder. That inordinate amount of clearance doesn't allow for precise centering of the blades on the spindle which can cause the blades to be out of balance. Not good engineering! And yes they were original blades and JD replacement blades have the same sloppy fit.

Other than that single issue with the mower deck, I certainly love my X758!