Rotary Cutter Generic question on 7-8 ft. rotary cutters

[froggy]

This is a generic question regarding rotary cutters. I generally see that most tractor owners when they move up in rotary cutter size from six footers tend to go with eight foot mowers rather than seven footers. Was wondering what the merits of the eight footer over the seven footer are? There has to be more than the eight footer is a multi-spindle and the seven footer is not. Wear and tear on the tractor? What else am I missing?

 

[BobG_in_VA]

Not sure if you're missing anything...When I bought the 60HP tractor, I bought the heaviest 7ft single spindle I could find. That was 5 or 6 years ago. It cuts almost like a finish mower in shorter grass and will destroy a 3" sappling so fast you hardly realize you ran over it...it weighs in vicinity of 1200-1350lbs. Has twin tailwheels. Set of blades (2) is about $80. I personnally don't need anything any larger. BobG in VA

 

[zzvyb6]

Don't dismiss the multi-spindle effect. It helps empty the deck and keeps the deck length down. I personally like the extra width because I run it with a high offset. That lets me get under evergreen tree branches and closer to fences and fence corners. Blades are smaller and lighter, too.

 

[john_bud]

Multi spindle is shorter and that makes it lighter. Cost of steel etc, that probably makes it cost competitive with the 7' single spindle. (I haven't looked in a LONG while....)

 

[jinman]

At 540 PTO rpm, it seems that the single spindle 7' cutter would have much higher blade tip speed than the 8' cutter with two blades. The heavier blades and higher tip speed seems to make the 7' cutter preferred for brush and small tree applications.

The dual spindle 8' cutter would probably also have dual tailwheels and make a better cutter for grass/weeds and very small brush along with not extending back as far behind the tractor.

. . . just my random thoughts.

 

[Bird]

A friend and neighbor had a 7" single spindle Howse with two tail wheels, until his son destroyed one of the tail wheels. Fortunately, they were on a bar so they could be adjusted side to side, so he just moved the one remaining wheel to the center. And I know why he had a 7' one; he found a bargain on a used one. A couple of times he mentioned wishing it was about 10' wide instead of 7.

 

[kthompson]

At 540 PTO rpm, it seems that the single spindle 7' cutter would have much higher blade tip speed than the 8' cutter with two blades. The heavier blades and higher tip speed seems to make the 7' cutter preferred for brush and small tree applications.

The dual spindle 8' cutter would probably also have dual tailwheels and make a better cutter for grass/weeds and very small brush along with not extending back as far behind the tractor.

. . . just my random thoughts.

Not beating you up on the tip speed but when looking at finishing mowers looked very careful and found what seems to be true on tip speed is not always held.

Don't forget they may use different gear box ratios for the different cutter and the multi spindle has extra gearing on all I have seen. As to the size of the blades the may use different size stump jumper or blade mounts and still use the same size blade on different size cutters. All of this will vary from one brand to another and probably model to model with some brands.

Just pulled numbers from Bush Hog's web site and if any body knows cutters it is them (hey we call them rough cut Bush Hog for a reason):

On their 287 7 ft (single spindle) the tip speed is 14,514 fpm; on their 278 8 ft (multi spindle) the tip speed is 16,856. The specs on the blades are the same, 1/2" by 4" with no length given that I saw. Now guess the weight difference with both 3 pth the 7 ft weighs 27 pounds more. Not saying all metal thickness are the same nor the same height sides and such.

No idea on which would cut what the best. Never have used a multi spindle rough cut myself but they make some that will cut serious stuff on front end of logger skidders.

 

[heymack]

I am (was...not sure) in the market for a 7 footer until I talked with a couple dealers and at length with one manufacturer directly. The biggest drawbacks of single spindle 7' shredders are its overall length (puts a lot of weight a long way from the back of the tractor), followed closely by the overall weight of most heavier units and fiinally blade length. Considering the first two attributes, these shredders can pose safety problems for all but the sturdiest tractors with plenty of counterbalance weight up front. The main drawback of 7 & 8 foot multi-spindle units is the added cost, generally at least $1000 more for a comparable duty unit. However, these shredders tend to be stubbier thus making them inherently safer by putting weight up closer to the tractor.

 

[jinman]

Just pulled numbers from Bush Hog's web site and if any body knows cutters it is them (hey we call them rough cut Bush Hog for a reason):

On their 287 7 ft (single spindle) the tip speed is 14,514 fpm; on their 278 8 ft (multi spindle) the tip speed is 16,856. The specs on the blades are the same, 1/2" by 4" with no length given that I saw. Now guess the weight difference with both 3 pth the 7 ft weighs 27 pounds more. Not saying all metal thickness are the same nor the same height sides and such.

Hey! Nobody's beating up anybody. You are just pointing out very good info from an iconic brand of rotary cutters.

It seems you are right about blade tip speed for the more expensive BH models. However, the Squealer models tend to follow exactly what I stated with the higher tip speeds in the single spindle models vs the dual spindle model (approx 14 kfps vs 11 kfps). So even within BH's line of cutters, it would be wise to look at the specs and know what you are going to get. Certainly on the higher end cutters, there seems to be more consistency.

I think BH did not spec the blade length because they expect you to know that a larger diameter single spindle cutter has a longer blade. Since stump jumpers are there to protect the gearbox, I'd bet their size remains constant in a single model and spindle arrangement no matter what the blade length.

All this says is that all rotary cutters are NOT created equal. As a buyer of any premium brand and configuration, I would want to check to make sure the cutter I was buying was best for all my needs. Heck, I might even find an excuse to buy two cutters.

 

[have_blue]

If you have a lot of grass, every foot counts. On 10 acres, an extra foot can probably save you almost 2 hours of cutting time. That last hour or 2 is always the worst part of mowing.