I have just torn down an old New Holland 462 (7'-10" cut) mower. It had dropped a bearing in the gearbox. Now that it's all apart and I can see that someone else had been in there before me. The last time it was rebuilt must have been after a catastrophic failure in the bar. There was evidence of gears and bearings having been gouged into the case and bits and pieces smashed here and there. Several of the disc shaft bearing holders which are only accessed from inside so you have to split the case to get at them, showed signs that bearings had frozen up inside and gone bang, taking metal with them. Also the underside of the bar is severely rusted and I checked carefully for pinholes before proceeding. It's a learning thing. Never park your cutter bar in the dirt for the season!!!!!!
From a design standpoint on the new mowers with the segmented gearboxes that isolate the various sections is a good idea because it may minimize cross contamination. From a practical maintenance standpoint these things are all incredibly complicated bearing eaters. The New Holland maintenance manual says to change the spindle bearings every 1000 acres. Are they kidding?
The designs which allow the spindles to be changed out from on top get my vote but they all need to come up with a more robust drive mechanism which is modular and easy to repair. I wonder if anybody has tried hydraulic motors in the bar. I looked at Krone's design which has the drive train running big gears and the spindles taking power off the side of the main drive gears with smaller gears. That way they get the RPM at the spindle without the high RPM at the idlers. The gears are still all together in the same oil bath. I don't see any of them with oil coolers or filters which seems to be a no brainer given the environment they work in.
The disc mower concept is a terrific one, the execution is a fluster cluck of patent claim jumping and upper management manipulation if you want my opinion. If you are going to spend 5000 to 8000 on a mowing machine shouldn't it either be easy to repair and also last a long time or cheap to replace if it's only going to last 1000 hours. The designs I see today are neither.
