Rotary Cutter Rotary Cutter

[OkieG]

<font color="blue"> slowly back into it </font>

Backing into the target is a useful technique, but has been the source of trouble for me. When you back up, if the back of the cutter deck meets resistance, the front of the cutter can raise up if there is appropriate slack in the toplink. The geometry on my small tractor (and probably the BX as well) allows the front of the deck to raise enough to contact the PTO shaft shield. First couple times it seems like no big deal, but the rotating shaft will quickly wear a hole in the shield where it's pinched between the spinning PTO shaft and the front of the deck.

Backing into thick brush and saplings is such an integral part of my brush hogging technique that contact was occuring all the time. The shield was ruined and even though I tried to avoid shaft to deck contact, I knew it wouldn't be long before the shaft and/or deck would be damaged.

Shortening the top link while backing, then slowly lengthening it to drop it on the brush prevents contact. But this very difficult to do with a manual toplink.

There is currently a thread in Customization titled "Your Best Additions to your Tractor". I am fortunate enough to have plenty of implements to play with, and my entry on that thread is a vote for an hydraulic toplink.

Any 3PH implement will increase it's usefulness with an hyd. Toplink. It usually takes some planning (and money) to get one up and running, but the benefits are amazing...especially for a brush hog and boxblade.

Anyway, my long-winded point is--Be careful not to let the deck contact the PTO shield while backing into anything with the blades spinning.

OkieG

 

[KiotiJohn]

</font><font color="blue" class="small">( The shield was ruined and even though I tried to avoid shaft to deck contact, I knew it wouldn't be long before the shaft and/or deck would be damaged.)</font>
OkieG, I've never had a problem with my PTO shaft hitting. Does your brush hog have a slotted connetor at the top link? Mine does and setting that properly is probably the reason I don't have the hitting problem, but I'm not sure. Could it be that the PTO shaft is not exactly the right length? I remember reading something about testing whether the shaft hits while you're originally measuring for cutting the shaft. The shaft should never be able to hit, and mine doesn't, even when backing into ditches etc. with drastic angles. It's an interesting dilema. John

 

[Soundguy]

</font><font color="blue" class="small">( testing whether the shaft hits while you're originally measuring for cutting the shaft )</font>

Shortening a toplink will help that too.

Soundguy

 

[OkieG]

John,
I am certain my ability to communicate has deteriorated. I am not describing well what I wish to convey. I'm sorry if the description of my brush hog problem is poor. Perhaps, a picture or two would help. Maybe I can take a couple and post them later.

The problem isn't that the shaft is too long. For example, the PTO shaft isn't collapsing to it's shortest length and bottoming out with contact inside the shaft (ie shaft too long). Rather, the slack in the 3PH toplink allows the front of the brush hog to raise up enough (when backing up against brush) so that the front edge of the deck contacts the PTO shaft shield.

If the 3PH toplink is shortened (as per Soundguy), there is not enough "slack" to allow contact, which is good. But, there is also a loss of abiltiy to terrain follow through dips, which isn't so good.

It is much too tedious to adjust the manual toplink when frequent adjustments are needed. The hyd. toptink has changed all that for the better, but if I don't take enough slack out when backing, there can still be contact.

I like pictures a bunch...and this is a situation where one might be worth a thousand words. Maybe later today.
Thanks,

OkieG

 

[Soundguy]

The slack should be taken up by a 'U' piect afixed to the rotary mowers toplink connection area. Most mowers I see nowadays have it... if the owner bothered to install it.

Soundguy

 

[OkieG]

John,
I have begun a thread in the Owning/Operating section, so as not to clutter Jim's thread with my problems. Here's the link: How Much Slack Do You Give Your BrushHog?

OkieG

 

[stephan]

If the device is new and it vibrates or makes a lot of noise there is a problem with it. Mine, while running, makes no more noise then the tractor and yes I wear ear protection but as I said that is to prevent noise from the tractor engine.

You could drop the blades and the rotor (arm that holds the blades) from the gear box and run the PTO to see if it still vibrates. It'd be most probable that the vibration would be in the arm and blades if it is in the PTO shaft or the gearbox then that'd be very strange and harder to fix.

Assuming the problem to be with arm and blades measure them with the thought that there is a line exactly in the middle (where the arm attaches to the gearbox) running across the arm where one half exactly mirror the other. Differences in length, weight, thickness etc could be causing the vibration. put the arm back on the cutter and ensure it is tightly bolted/attached to the gearbox. Measure the distance from the deck to the furthest extremity of the arm/rotor. If this measurement is not the same then the gearbox shaft might be bend.

All in all if its new take it back.

 

[edv]

I assume this is a new cutter....A 4 ft cutter "new" for $450 would be considered an economy cutter...and yes many economy cutters have no name, no serial number, etc...

Chances the blades are not balanced, or more than likely the blade carrier is not balanced. Vibrations are common on all cutters at start up..however once they get going the cutter should operate quite smoothly...safety is a concern with any cutter that continues to vibrate...blades can come off!! I would inspect cutter or take it back to the dealer you purchased unit from. You are better safe than sorry.

Edv

 

[nomad]

I have a feeling that yours is probably designed to operate at lower speeed than the other cutters. All cutters are sensitive to the speed. If a cutter is designed to operate at X rpm speed and if you operate it at X+1 rpm speed then, it will most likely vibrate due to its designed balance. If you operate it at X+2 rpm, then smaller unbalanced masses in the blade and the disc will start to play important roles. Remember nothing is zero-mass balanced - always there is some nonhomogenousity in the mass distribution in rotating components. Also, when starting the cutter increase its speed gradually in time. This will help on smooth transition from the rest to the full/rated speed. If you increase the speed suddenly, it will vibrate and damping of the vibrations will take more time.