Tiller Agric Tiller Problem

[Rockin' G Ranch]

I have an Agric AL50. The bolts holding the gearbox to the tiller keep either backing out or shearing off. I drilled and tapped the 2 holes in the gearbox to a size larger bolt, installed larger hardened bolts and a plate to prevent the bolts from backing out. Well, they don't back out - they now shear off. Have any of you had this happen and what did you do to remendy it?
I am considering installing a U bolt around the shaft carrier pipe and secure it to the top of the tiller housing between the gear box and the top chain sproket.

 

[wushaw]

I have the 45" gear driven model, it is only a year old and no shearing of the bolts on mine....atleast not yet.

Have you tried grade 8 bolts?

 

[Rockin' G Ranch]

I have the 45" gear driven model, it is only a year old and no shearing of the bolts on mine....atleast not yet.

Have you tried grade 8 bolts?

Yes. The larger new bolts I installed are grade 8. The only support for the gear box and drive carrier to the top chain sproket is the 2 bolts. Most other tiller manufacturers have other supports between the gear box and chain housing or support pipe to the other side of the tiller. That's why I thought the additional U bolt support would help.

 

[wushaw]

Ok are you talking about the two bolts holding the top/angled gearbox in place there on the R/H side of the gearbox?

http://www.tractorbynet.com/forums/...lf/76824d1179120240-tiller-stand-dsc00352.jpg

 

[Rockin' G Ranch]

Ok are you talking about the two bolts holding the top/angled gearbox in place there on the R/H side of the gearbox?

http://www.tractorbynet.com/forums/...lf/76824d1179120240-tiller-stand-dsc00352.jpg

Yes. The 2 bolts (that you can't see in the picture) on the RH side of the gear box in your picture. The bolts go through a piece of angle iron welded to the top of the tiller housing in to threads in the tiller gear box.
Bolts marked #11 in attached picture.

 

[wushaw]

Well that is interesting. The only thing I can think of is something is causing alot of torque to sheer them bolts off.

Does everything else operate smooth, nothing binding up or anything like that.

If all else fails then you could add another bracket to pick up the bolts on the back side to assist in holding the gearbox in place.

 

[Rockin' G Ranch]

Well that is interesting. The only thing I can think of is something is causing alot of torque to sheer them bolts off.

Does everything else operate smooth, nothing binding up or anything like that.

If all else fails then you could add another bracket to pick up the bolts on the back side to assist in holding the gearbox in place.

The tiller vibrates a lot when working and that shaft has a lot of torque in it. Those 2 bolts take the brunt of the vibration and torque. I figure the combination of vibration and torque back-out or shear the 2 bolts. That's why I thought a U bolt between the right-angle tiller gear box and the chain cover would help.

 

[wushaw]

U bolt with a spacer would help.

 

[LoneCowboy]

something si wrong
it shouldn't vibrate like that
and those bolts shouldn't shear
I probably have a 100 acres or more of tilling on my 5' agric over the last couple years and those bolts are still fine.

you're fixing the sympton, not the problem. something is torqued down below.

 

[Rockin' G Ranch]

something si wrong
it shouldn't vibrate like that
and those bolts shouldn't shear
I probably have a 100 acres or more of tilling on my 5' agric over the last couple years and those bolts are still fine.

you're fixing the sympton, not the problem. something is torqued down below.

Thanks for the responses. Any ideas what could be causing the over torqueing problem?????? The tines rotate freely by hand when the PTO is not attached to the tractor. The only thing I can think of is very hard clay undercoating the bottom of the tiller housing causing very little if any clearance for the tines. This happens after tilling for a while in some of my more loamy fields. the bolts have backed out or sheared off at least a dozen times.
By the way, I don't have a clutch or shear bolt on the PTO drive to the tiller. Could this be part of my problem? I know I should have one but I wouldn't think it would solve this problem.
If anyone has anymore ideas I would appreciate the help. Thanks.

 

[Rara Avis]

You have filled the gearbox with oil right?...
Have you checked to see if there is any fragments in the gearbox oil?

If you put a runout on the upper shaft...is there any warp?

Is there any bind in the chain?

 

[JerryG]

Is the PTO shaft to long and bottoming out?

 

[Rockin' G Ranch]

You have filled the gearbox with oil right?...
Have you checked to see if there is any fragments in the gearbox oil?

If you put a runout on the upper shaft...is there any warp?

Is there any bind in the chain?

Gearbox has fluid and does not appear to have fragments.
The shaft also appears to be straight and when the 2 bolts are out it is still in line with the chain cover and support bracket.
Thanks for the response.

 

[Rockin' G Ranch]

Is the PTO shaft to long and bottoming out?

Thanks for the response. I checked and the PTO shaft is not bottoming out or in a bind in any way.

I'm going to add the extra U bolt support between the tiller right angle gearbox and the chain cover. I will let you all know how this turns out and try to add some pictures.
Again, thanks for the responses and if anyone has other ideas please let me know.

 

[Rara Avis]

So if you were to check before complete failure...are the bolts initially starting their break away on the gearbox side of the bolt?

It so, it appears that the top transfer shaft is flexing/lifting the gearbox on the chaindrive side for some reason...

Another question is which direction does the top transfer shaft turn?
Looking at it from the chaindrive side...if the top shaft is turning towards the tractor then one might expect the rear bolt to be shearing off first...

Looking at it from the chaindrive side...if the top shaft is turning away from the tractor then one might expect the front bolt to be shearing off first...


Something else to look at is there unusual wear pattern on the chain tensioner or any of the teeth on the cogs?

 

[pitt_md]

To start with I have to second the opinion that something is binding when under load. It may turn freely by hand but when given some resistence something in the driveline shifts to cause this binding. I would suspect the grearbox components. Tillers can come across some very ugly stuff in the course of duty. I would NOT run this anymore without some type of protection (shear pin/slip clutch). Your putting your tractors PTO at risk.

 

[SCDolphin]

I would certainly want a shear pin or a slip clutch in the driveline somewhere so I did not tear up my tractor