Driveline on cutter problem?

[mickeyd]

I have a fairly new LP RCR1860 cutter with about 40 hours on it. I keep it well greased but had an unusual thing happen. The HHCS 1/2-13X3 1/2 GR8 bolt that holds the driveline to the gearbox shaft came out while using the cutter. I must assume the lock nut came off allowing the bolt to come out as I would think the torque required to break a grade 8 bolt would have tore up the gearbox first. Anyone else ever had this problem?

 

[Russell King]

First I don't think your shear pin should be grade 8. Grade 2 or grade 5 are all I have ever seen for shear pins.

Please verify the grade is correct. Do you also have a slip clutch? If so, that may be why the pin is higher strength than normal since it does not need to shear.

If the pin fell out then the lock nut was not properly tightened against the first nut. They do have to be jammed together to actually lock.

 

[mickeyd]

Yes it has the, 8146.241.040.1 CO FRICTION CLUTCH, right in front of the bolt that came out. The parts manual and dealer both said that this bolt is a grade 8.

 

[D2Cat]

mickeyd, from what you say, it sounds like the nut came off and let the bolt loose. Replace it and be sure it's locked good and tight. Sounds like an assembly error.

I would suggest you loosen the bolts on the slip clutch and then tighten them only enough to use the mower. They may be too tight for your machine and that eliminates it's purpose.

 

[85Hokie]

Yes it has the, 8146.241.040.1 CO FRICTION CLUTCH, right in front of the bolt that came out. The parts manual and dealer both said that this bolt is a grade 8.

Whatever you use, get a nylon insert nut, some call em aircraft fasteners. Very little chance of it coming off - as long as the nylon DOES grip the bolt thread.

And even though most know, some still think the tick marks indicate the grade.........were as all others know to add two to the tick marks!

 

[bmotojoe]

I also have a landpride with the slip clutch and the grade 8 bolt is there as well. The bolt should have been installed with jam nuts, two nuts. Part of my seasonal maintenance is to check gearbox oil level, slide apart PTO shaft clean and re-lubricate including u-joints, check gearbox mounting bolts, check PTO shaft to gearbox bolt and nuts, check blades for the proper movement. Every other year I pull the complete PTO shaft and slip clutch, disassemble slip clutch pack check for problems and re-assemble clutch. I do lubricate the tail wheel and shaft every time I use the machine.

 

[hodge]

As suggested, besides the bolt coming lose, you need to make sure that the slipper clutch is properly adjusted. It is there to protect the driveline, and if it is set too tight, or if corrosion is adhering the clutch surface to the plate, it can't do it's job. I don't know about your cutter, but my KK tiller manual suggests to loosen the bolts on the clutch every year before getting ready to use, and make sure it can slip. I've learned, in that application, that 9 ft lbs of torque on the bolts was sufficient to allow the tiller to function and still slip when necessary.
On a side note, I believe that the strength rating on a grade 8 bolt is based on pull, not side load. While I'm sure that a grade 8 bolt is harder to shear than a lighter grade, there isn't a direct connect to the rating when used as a shear pin. I seriously doubt that a grade 8 bolt (depending on diameter, of course) would be stronger than the driveline/gearbox. I'm not advocating using a grade 8 bolt in place of a proper shear pin, just commenting on the concern for the gearbox.

 

[mickeyd]

I also have a landpride with the slip clutch and the grade 8 bolt is there as well. The bolt should have been installed with jam nuts, two nuts. Part of my seasonal maintenance is to check gearbox oil level, slide apart PTO shaft clean and re-lubricate including u-joints, check gearbox mounting bolts, check PTO shaft to gearbox bolt and nuts, check blades for the proper movement. Every other year I pull the complete PTO shaft and slip clutch, disassemble slip clutch pack check for problems and re-assemble clutch. I do lubricate the tail wheel and shaft every time I use the machine.

Thanks for the info, I guess because it is so new, 6 months, I expected it to be working correctly from the beginning.