Repairing the Rhino brush hog

Richard is my partner in our cow/calf business.  He was Papa’s partner for more than twenty years so he has been at it for quite a while.  Richard turned 80 years old this year, but don’t let that fool you.  He is powerfully built and I have difficulty keeping up with him due to my jellified body from too many years behind a desk.  Richard is constantly advising me and trying to bring me up to speed in the business and, in a good natured way, we are constantly at odds about whether his 30 years of experience or my 10 minutes of logical “thinking about it” is the best approach to the tasks at hand.  I trust his judgment completely on the really important stuff.  Recently, our Rhino “brush hog” broke down and it was determined that one of the clutches was failing.

A brush hog is a mean machine that chops down anything that gets in its way.  For clarity here, I insert the Wikipedia definition of a brush hog:

This is a typical brush hog

A brush hog is a type of rotary mower. Typically these mowers attach to the back of a farm tractor using the three-point hitch and are driven via the Power take-off (PTO). It has blades that are not rigidly attached to the drive like a lawnmower blade, but are on hinges so if the blade hits a rock or stump, it bounces backward and inward, and then inertia makes it go outwards again.

The rotary blades are not sharpened in the same way as a conventional mower blade. They are usually quite dull so they whack through dense plant growth, where a sharp blade will get stuck or slowed down. The blades are very heavy, up to an inch thick, so the momentum pulling out is stronger than the forces of the vegetation bouncing in. They are made of heat treated high carbon steel that can withstand strikes with hard objects such as rocks and stones.

The one we pull behind the tractor is called a Rhino “bat wing” because it has a main center blade and a hydraulically adjustable wing on each side that can be set to mow slopes.  We use ours flat and it mows a 15 foot swath with each pass.  There is a drive shaft coming from the main gear box to each of the 3 secondary gearboxes and a clutch device on each of them to take up the shock of initial engagement or hitting hard objects.

Richard decided we would repair it ourselves and proceeded to show me what needed to be done.  “Just remove this nut, slide the drive shaft back and the entire mechanism can be removed for repair.”  “It won’t work” I said, “the drive shaft will only slide back two inches and we need at least three inches to clear the shaft it’s mounted on.”  “It’ll work” he said, “I have faith.”  “You’re wrong” I repeated, “there’s got to be another way.”  “It’ll work,” he said.  “Wanna bet?” I queried.  “Sure, you’re on” he said.  So, with that, we went to work

The task was to remove nut (C) and slide the clutch mechanism (everything between C and D) off the end of the shaft at nut (C).  I immediately recognized that the only lateral movement possible was the distance between (A) and (B), hence we would not be able to slide it far enough to remove it from the end of the shaft at (C)

Initially, the nut (C) would not come lose and I had to use a cutting torch to get it off, quite a delicate task when its important to not damage the threads of the shaft.  We finally got it off, and as I expected, we were not able to move it far enough to release it from the shaft.  What I did not expect was that it did allow enough movement to remove the small drive shaft between the universal joints at (A) and (B) and that facilitated the clutch removal.  So, once again, I consume a portion of “crow pie,” a delicacy that is becoming standard fare on my menu.

Richard gloating and holding up the clutch mechanism