HELP!!!!GRAVELY COMMERCIAL SERIES PTO

[agoodoldsoul]

FRIENDS...IF ANYONE CAN TELL ME WHAT'S WRONG WITH MY PTO I WOULD BE SO GRATEFUL. I HAVE BOTH 72 AND 73 COMMERCIAL 10A AND 12 MODELS BOTH DOING THE SAME THING. THROW ROD SEEMS FINE...REPLACED SHIPPER SHAFT AND TRUNNION BLOCK...DOG GEAR IS NEW...WHAT THE %&$%&!!! COULD IT BE THE CLUTCH ON THE ATTACHMENT OR WHAT? HELP!

 

[JFS2295]

It usually helps when someone actually states what the problem is, and not in all capital letters.

 

[agoodoldsoul]

It usually helps when someone actually states what the problem is, and not in all capital letters.

Just found out my friction discs in the safety slip clutch are toast. Getting ready to replace them...any idea how to adjust the springs. One source says to snug the six bolts then back off one half turn and the other says to compress the springs then back off the half turn. Then tighten lock nuts. I'm fully aware of the torque values for the clutch to overcome, but I don't have that tool. Over...

 

[RichardTX]

Adjusting the safety clutch is a trial and error thing. I have found that 1/2 turn back from a fully compressed spring can be too loose. I would try that as a starting point and go from there.

 

[agoodoldsoul]

Thanks for the input Richard. I'm not leaving anything to chance, i ordered one of those safety clutch adjustment tools for my torque wrench. Thirty dollars and fixing it right is a lot cheaper than destroying more expensive systems on the machine. I'm a pretty good wrench, but sometimes I over analyse.

 

[RichardTX]

I don't have one of those tools. I considered it sort of pointless as Gravely never published any specs for torque. Let me know what it says when you get it.

 

[Tony_S]

The closest I've seen to any specifications for adjusting the clutch is from this 1960 manual that mentions field adjustment. Perhaps there is a shop or service manual available with more detailed adjustment.

Here's the text without illustration:
"Each Gravely Model L Attachment has a Gravely Safety Clutch,
which prevents sudden shocks from harming the attachment or tractor.
It is very important that these Clutches be adjusted correctly. If
they are too loose, the Tractor will not drive the attachment efficiently.
If too tight, it is possible that a sudden shock may injure the
transmission or the attachment.
The illustration (Plate 13) shows the proper method of field
adjustment. Place a flat bar in the driving slots of the Slip Clutch.
Hook a pair of spring scales on the bar 12" from
the CENTER of the Clutch. Then adjust the spring tension by
tightening or loosening the 6 bolts EVENLY so that it takes 30 to 36
pounds of pressure to make the clutch slip."

Tony

 

[RichardTX]

36 ft lbs doesn't seem like a lot. I will have to see what my rotary plow is set to. It slips too much and needs to be tightened.

 

[Tony_S]

Hmmm...if my fulcrum calculation is correct, thats about 100# of force to make it slip figuring the 36# at 12"...but I don't know if that's right. Sounds reasonable I guess.

 

[RichardTX]

One foot-pound is defined as the torque created by a one pound force acting at a perpendicular distance of one foot from a pivot point.

That is why I came up with 36 ft. lbs.

36 ft lbs isn't much. It is about the maximum torque for a 3/8" grade 5 cap screw.