V-belts for Ferguson sickle bar

The other (farming style) alternative, is to run a length of string round the bottom of the vee for a full loop of the two pulleys, and then mark off the start and end point with a pen where the string overlaps. Do not stretch the string, but don't leave it loose, either.

That gives your belt length, and you can then take that to a belt supplier . . . . and start looking.

Hope this helps. First option is easier, but only works for two pulley systems - not three or serpentine systems.

Don't forget to leave the belt adjustment in the 'loose' position when you do this, as you need to allow for belt tightening with age/wear.

Sum of Outer Diameters of pulleys times 1.57 plus 2 times median distance between centers of pulleys. For my 6A-EO-B20 mower this is:

[8"+ 5.5" X 1.57] + [2 X 10.25] = 41.695"

The tricky part is knowing that the DayCo/Goodyear belt numbers need to be adjusted upward by a half of an inch to compensate for the pitch of the belt. So say the DayCo number is 24408 (First two digits are in 32nds of an inch 24/32" belt width by 40.8" length, the last three digits). To get to the compensated effective length that equals the output from the formula above you add a 1/2". So since I needed a belt with a nominal length of 41.695" the DayCo 24410 is a good match - 24/32" = 3/4" width by 41"+.5"= 41.5".

Again, thanks for putting me on the right track. Without your post I wouldn't have known to ask for the formula. wc

JA