3511 and PTO problem

I have recently gained ownership of a 1971 3511. It is well used and up till now I have just used it to haul rubbish from one part of the farm to another. I bought myself a brand new 5ft topper and hooked it all up. That's when I noticed that when the 3 point links are in use, the PTO is turning constantly and at a constant speed. I got myself a copy of the handbook and it tells me that the left hand auxiliary drive on position 1 which is for the pump and 540 RPM PTO. Now everytime I start up the PTO turns the Topper shaft and the shear bolt on the universal joint does it's job and shears.

According to the handbook position 3 should be for ground speed PTO. I assume that I should use this setting for using the Topper. Sadly when I choose this setting the PTO doesn't seem to work but also the 3 point link doesn't operate i.e to lift the Topper so I can travel with it.

Apologies if I am vague or have wittered on but am new to tractors. Any ideas why a) the shear bolt shears and b) why the PTO and 3 point link don't work other than in position one?

The ground speed PTO doesnt work unless you drive:

You can use this setting to lift the topper as well: Select this setting, put your hi/lo range in neutral, engage 2nd gear and voila, you have oil to lift the topper, without driving.

For topping, use the 540 setting as 3rd is about 620rpm, 4th is 880 and 5th is 1350 rpm, the latter might become a lethal threat.

Shear bolts arent really appropriate for a topper: For a piece of equipment with a lot of rotating mass like a topper, a slip clutch is a better way to protect it, as it will slip for one or two seconds untill the topper spins at PTO speed: the peak torque will only occur at startup. When the shear bolt breaks, you cant start it up..

If you use a fully threaded bolt, try a partially threaded one, so it carries on the shaft of the bolt, not on the threaded end. Its about 40% stronger on the shaft than on the thread.

The ground speed PTO doesnt work unless you drive:

You can use this setting to lift the topper as well: Select this setting, put your hi/lo range in neutral, engage 2nd gear and voila, you have oil to lift the topper, without driving.

For topping, use the 540 setting as 3rd is about 620rpm, 4th is 880 and 5th is 1350 rpm, the latter might become a lethal threat.

Shear bolts arent really appropriate for a topper: For a piece of equipment with a lot of rotating mass like a topper, a slip clutch is a better way to protect it, as it will slip for one or two seconds untill the topper spins at PTO speed: the peak torque will only occur at startup. When the shear bolt breaks, you cant start it up..

If you use a fully threaded bolt, try a partially threaded one, so it carries on the shaft of the bolt, not on the threaded end. Its about 40% stronger on the shaft than on the thread.

Click to expand...

That's excellent info. It's obvious now. Will try in the morning.

Interestingly, I have now been told that the topper shaft does have a slip clutch but now suspect the shear bolts aren't man enough to cope with the torque on a resting blade. Must admit that I have resorted to mild steel full threaded bolts as I don't have any proper shear bolts.

Will update tomorrow.

Following above advice, I was able to get topper and tractor working harmoniously. Spent a sunny afternoon topping 2 hectares of pasture.

Many thanks.