MHarryE
Elite Member
- Joined
- Feb 15, 2009
- Messages
- 2,970
- Location
- Northeastern Minnesota
- Tractor
- Kubota M7-171, M5-111, SVL75-2, RTV900XT & GR2120; CaseIH 1680 combine
The cutter gearbox has a power rating and the slip clutch is intended to protect that. Doesn’t mater if you have a 100 HP tractor or 30 HP, if the gearbox is rated at 75 hp the slip clutch is selected to protect that torque at 540 RPM (assuming that you don’t have a 1000 RPM mower). The Bondioli slip clutch can be configured for different torque limits depending on what capacity the OEM buying it from Bondioli wants. So the length in your manual is probably the length selected by your cutter manufacturer. However, nothing in those slip clutches is built so close that it can be dialed in precisely - tolerance on springs, tolerance on friction material, etc. Actually the person saying theirs specifies tightening finger tight, then giving specific turns is the best. Springs have a designed spring ratio, bolts have a specific thread pitch, number of turns gives the closest spring force regardless of what the initial spring length might be.