60" 7 iron vs 54" or 62" deck on 700 series

[KennedyDiesel]

To me it sounds like the 7 iron series should be the standard on the premium Deere models. I mean you have a premium machine that produces mediocre results in most cases. Not saying that they all cut poorly, just not inspiring.

It seems the Ztrak models definitely seem to move more air.

 

[KennedyDiesel]

If my specs are correct:

Old 54" uses 3 blades at 18.625" long for 55.875" total or .9375" overlap

New 54" uses 3 blades at 18.875" long 56.625" total or 1.3125" overlap

7 iron 60" uses 3 blades at 21" long or 63" total for 1.5" overlap (1.57" published spec)

Ztrak 54 uses 3 blades at 19" long for 57" total or 1.5" overlap


As for blade speed, I'm not sure what gear box ratios are used on teh various decks or what pulley diameters are used to alter this. Looking at the Meg-Mo system with 4 cutting edges per spindle one would think that this would act as doubling the speed...

 

[JDTank]

If my specs are correct:

Old 54" uses 3 blades at 18.625" long for 55.875" total or .9375" overlap

New 54" uses 3 blades at 18.875" long 56.625" total or 1.3125" overlap

7 iron 60" uses 3 blades at 21" long or 63" total for 1.5" overlap (1.57" published spec)

Ztrak 54 uses 3 blades at 19" long for 57" total or 1.5" overlap


As for blade speed, I'm not sure what gear box ratios are used on teh various decks or what pulley diameters are used to alter this. Looking at the Meg-Mo system with 4 cutting edges per spindle one would think that this would act as doubling the speed...

Not exactly. If you have a 4 cylinder engine instead of a 2 cylinder engine, that doesn't double your speed, you just have more cylinders and pistons.

You might have 4 edges, but all 4 are traveling at the same speed as a deck with only 2 edges per spindle. Personally, With how fast the blades are spinning, I don't believe 2 extra blades would make any difference. If you have a slow deck speed than yes, but not with today's decks spinning at some 17,000 ft per minute.

 

[KennedyDiesel]

But it does twice the work per revolution. Near equivalent to double speed.

 

[Carl Bert]

But it does twice the work per revolution. Near equivalent to double speed.

Not even close, RPM is RPM. It wouldn't matter if there were a hundred blades on there. Look at it this way. If one blade was spinning at 7000 rpm, you would get a nice cut. If you had a wheel with 10x the amount of blades or 20 blades, spinning at 700 RPM, or 1/10th the speed. Do you think you would get as good of a cut. Better yet, would it cut the grass at all. I don't think so.

 

[KennedyDiesel]

How many times does a cutting edge sweep across the cutting field per inch traveled forward with 4 cutting edges versus 2?

 

[JDTank]

How many times does a cutting edge sweep across the cutting field per inch traveled forward with 4 cutting edges versus 2?

How many times the blade passes doesn't matter, it's the speed of the blade that matters.

Like Carl Bert said, if your blades are going to slow, it doesn't matter how many blades you have, they still won't cut or deliver a good cut. It's a selling gimmick, and nothing more. All you need is one mower blade going at a high speed, and you will get the same results as having two blades on the same spindle.

Having 4 cutting edges on one spindle is one of the stupidest ideas I have ever heard. Your significantly increasing the stress on the spindles, and the belts to turn those spindles which now have more weight hanging off of them. You now have double the edges to sharpen, maintain, and purchase.

This is like if you told someone you put premium gas in there car, and they drove it saying "wow what an amazing difference" when in reality you put in regular gas. It's all in your head.

 

[Carl Bert]

How many times does a cutting edge sweep across the cutting field per inch traveled forward with 4 cutting edges versus 2?

I get what you're saying, and it does make sense. My question is, if this concept actually does work, then why not 6 or 8 blades per wheel. Why just 4?

 

[KennedyDiesel]

I got a chance to cut a section of pasture today. Wet and thick as the humidity is high and drying is poor. Chance of T-storms is high so I didn't want to delay and risk getting rained out. I've been exceptionally lucky this year with rain coming shortly after spraying weeds and again shortly after mowing. I did the first few rounds with the 455-54 with Predator (Gator) blades then switched to the x748-54c with std cut perf blades. Quite a noticeable difference in cut and sound. It seemed that the 54c was turning faster or at a minimum moving more air. The 455 could have lost some RPM on the governor over the years but to my ear it sounds plenty fast. The 54c had more wind and finer clippings along with a much better cut than the old 54 with the fancy blades. If the 60" deck is THAT much better than the 54 it must be truly awesome.

Next step is to remove both decks and evaluate ratios and pulley diameters between both 54's to see if I can find a difference. Interested to see how well the 54c cleaned out with the hose attach. It seemed kind of lame, but at a glance it appeared to do a decent job.

I think I am well on my way to buying a new tractor even though I'm sure what I have is good for another 16+ years.

 

[JDTank]

I got a chance to cut a section of pasture today. Wet and thick as the humidity is high and drying is poor. Chance of T-storms is high so I didn't want to delay and risk getting rained out. I've been exceptionally lucky this year with rain coming shortly after spraying weeds and again shortly after mowing. I did the first few rounds with the 455-54 with Predator (Gator) blades then switched to the x748-54c with std cut perf blades. Quite a noticeable difference in cut and sound. It seemed that the 54c was turning faster or at a minimum moving more air. The 455 could have lost some RPM on the governor over the years but to my ear it sounds plenty fast. The 54c had more wind and finer clippings along with a much better cut than the old 54 with the fancy blades. If the 60" deck is THAT much better than the 54 it must be truly awesome.

Next step is to remove both decks and evaluate ratios and pulley diameters between both 54's to see if I can find a difference. Interested to see how well the 54c cleaned out with the hose attach. It seemed kind of lame, but at a glance it appeared to do a decent job.

I think I am well on my way to buying a new tractor even though I'm sure what I have is good for another 16+ years.

...Why are you going to bother with ratios and pulleys? Quite frankly..who cares? If the deck cuts better, that isn't information you need to know, and quite frankly it won't tell you anything that matters.

There is no question the 7 Iron deck is literally one of the best you can buy in the world, if not the best. The cut quality, build quality, and discharge quality is amazing to say the least. It was designed specifically for wet, heavy, thick green grass, and commercial use. The biggest advantage is the sheer size. It is a very deep deck vertically and horizontally, so it has a lot more room than a standard deck to process clippings and maintain airflow. If you look at the underside of a 7-Iron, there is virtually nothing there for grass to get hung up on. Anything protruding under the deck gives grass a place to hold on to, and than collect.