Rotary Cutter BushHog SQ720 blades not turning.

[wiredhot]

I bought a used Bushhog SQ720 with a 540 RPM Gearbox. It cut fine for about 4 hours then after that the PTO turns fine but the blades will not turn. I am going to open up the top of the gearbox today when I get home, what should I look for and what may be some probable causes for this issue?

 

[sweettractors]

Make sure you do not have a drive line clutch slipping or a shearpin sheared before you go in to the box. In the box, I would look for worn gears or possibly a bad bearing or both. Ken Sweet

 

[wiredhot]

I forgot to mention the tractor only has 28 hours and the PTO has been used maybe 3 hours out of that.

 

[wiredhot]

Make sure you do not have a drive line clutch slipping or a shearpin sheared before you go in to the box. In the box, I would look for worn gears or possibly a bad bearing or both. Ken Sweet

Forgive my ignorance, how do you check for the shearpin?

 

[Gary Fowler]

Forgive my ignorance, how do you check for the shearpin?

Look at the back of the drive line where it attaches to the gear box of the bush hog. If it has a shear pin (or slip clutch) it will be located there. A shear pin is basically two flange hubs with one hole drilled thru them so a bolt can be inserted usually a 3/8" or larger bolt depending on the power rating factor.
Posting some photos of the drive train would help.
I wouldn't go into the gear box as I doubt that is the problem although a quick topping off of the gear box oil with 90W gear oil would be advisable especially seeing that it is a used mower. Gear boxes usually have two threaded plugs, One on top is for filling till the oil runs out of the lower plug.

 

[phiferpharm]

Forgive my ignorance, how do you check for the shearpin?

On a Bush Hog Brand, it's under the cover attached to the gearbox on the Bush Hog. My bet's on the Shear pin, as that is what it's supposed to do. If it is, don't put too hard a replacement bolt in it's place.

 

[wiredhot]

Thanks for the input i'll be sure to check everything out when I get home and will post what I find, also thanks about what weight oil to use in my inexperience i would have probably put in 30W :ashamed:

 

[nybirdman]

Shear pin on the SQ72 is a two minute fix if you have the wrench's and shear bolt available.I have only sheared a couple on mine.My new Landpride has a slip clutch....need to service those every year.
On the SQ72 there is a little door to access the shear bolt,mine is held down by a spring clip.

 

[WM75Guy]

Here is the manual. Look at page 64-3-2 at part#20 & #22, a Capscrew M8 x 1.25 x 50 and nut. You should be able to get them at the hardware store cheaper than the dealer.

http://www.bushhog.com/uploads/documents/BHRotaryCutter420-sq84t-08.pdf

 

[RickB]

Here is the manual. Look at page 64-3-2 at part#20 & #22, a Capscrew M8 x 1.25 x 50 and nut. You should be able to get them at the hardware store cheaper than the dealer.

http://www.bushhog.com/uploads/documents/BHRotaryCutter420-sq84t-08.pdf

Bush Hog MSRP on the bolt is an outrageous 54 cents and the nut is 11 cents.

That said, the dealership I work for has never sold a Squealer wider than 48 inches with a shearbolt driveline. We order slipclutch drivelines exclusively.