60" deck making noise

[DrabHorse 2]

Hi, just recently bought a 520H with a 60" deck. I've cut a few times with it now, not exactly sure how much ground, but i use about a tank full per cut. I'm starting to notice it has a very low pitch ,but loud, hum sound from the deck that is kind of a rhythm up and down sound about every 3 - 4 seconds. It actually is not as noticeable until I'm wearing ear covers or ear plugs, as if the ear protection is blocking out most of the background noise except this low hum noise. It is almost loud enough that I would expect to feel a vibration from it, but I haven't noticed that.

I did look over the deck before mounting it and the blades were fairly new and looked straight, and turned smooth, and greased the spindles(did not take belt off and turn each spindle individual) The belts and pulleys look like new and the mule drive is also great condition.

Any experience with something like this? I'm guessing a spindle bearing or an out of balance or bent blade? I'm really wondering if anyone would know if it would be more likely to be one or the other? thanks

p.s. I was really surprised how much that deck fills up the space under the tractor, there really isn't much room for it to lift up and down. And I have been cutting on the highest height setting and I wish it could be set just a little higher. How often is greasing the deck spindles required and how much (pumps of grease) from a standard grease gun? thanks I'm going to have alot of questions with this one since its new to me

[Duff 206]

The hum you describe rising and falling every three or four seconds is probably what in the sound biz they call a "harmonic" vibration. (Along with all the other crazy stuff I've done in this life, I've been a sound engineer in the live and recorded music industry). Your ear protection will block out most background noise but certain low frequencies will still get through, such as the humming sound. Out of curiousity, does it go away when you throttle down a little, or does the length of time between the high and the low notes of the hum increase or decrease as deck speed changes?

If you hear but cannot feel it (yet), chances are it's something as simple as the sound of the rotating spindles going in an out of sync with each other as the blades rotate. If there's no palpable vibration, I wouldn't worry about it too much. It's also possible one or more of the blades is a tiny bit out of balance which would introduce an audible but not necessarily palpable vibration. If it starts to get worse I'd pull the blades and have them checked for balance, and if that doesn't solve it, then pull the belts and rotate each spindle to see if one feels looser than the rest or feels like a bearing is getting rough.

I don't know anything about the 60" decks in terms of lubrication or what WH recommended. On all my decks (WH 37SD and two JD's) I hit the spindles with a couple pumps of grease every time I take the blades off for sharpening, or about every 25 hours of mowing time, whichever is more frequent. Others may have a better answer for you on this. While you don't want to blow too much grease out around the spindles so it gets on the belts, too little will ultimately mess up bearing life.

Good luck!

Duff :D

[DrabHorse 2]

Thanks Duff, It seems you understand exactly what I was trying to describe. I mowed alittle with it today and I tried to hear what would happen when moving the throttle down, the noise would move alittle farther apart between cycles, and the length of the hum would last longer.

It kinda bothers me when running it full throttle because of the frequency of it, it has that uncomfortable feeling in my head.

I guess the first chance I get I will check the blades for balance.

[gwgdog66 23]

:D

I have no experience with a 60" deck. But, I just rebuilt the spindles with new bearings on my 42 " RD deck. With the new seals in place it took 18 pumps per spindle until the grease gun got hard to squeeze. You know it is full then. My mower deck manual recommends greasing the spindles every 25 hours. The key thing is when it gets hard to pump they are full, if you force it, you can blow a grease seal.

[DrabHorse 2]

I ended up finding a few things that were wrong on the deck. First I noticed that the deck belt was starting to roll and get in a twist so I straightened it out but it quickly rolled again. I noticed the tensioner pulley arm looked loose and I thought it might be worn on the bushing, but it was actually lightly frozen on the bushing and the whole thing with the mounting bolt was loose and that is what was rotating, so I got that fixed up how it should be and it was alittle better but the belt was still running crooked. I pulled the deck to get a better look and eventually figured out that the belts were on wrong. On the center spindle the drive belt goes in the bottom groove and the deck belt runs in the upper groove, it had been on there the other way, I wonder for how long. So now with the correct speed and gearing through the pulleys, it runs quieter (slower) and with more power.