This review is the product of three years of mowing 25 acres of tree seedlings on our property. I started out with a new 60″ Rhino on a 35 hp TAFE tractor but discovered that many of the rows were too narrow for the 5′ 6″ tractor to travel. So I bought a Bolens with a track of 38″, 4WD, suitcase weights and a 17 hp diesel. A 48″ Braber rotary mower mounted neatly onto the 1200 lb tractor and I gained easy access to the shrinking rows between the trees.
It likely had about 200 hours on it when last summer I demolished the gearbox by bellying onto a rock. The bottom of the gearbox casting sheared right off. Braber replaced it under warranty, but I had to do the mechanical work myself. Regardless of lubricant choice the new gearbox is too noisy and damages my hearing, even with earmuffs. I can’t see going deaf to that racket for another ten years, so I’ll probably buy a better mower soon.
But accidents happen, and maybe the replacement was a lemon. My real beef with this mower has to do with its gear ratios* (see below). The Bolens G174 has 3 pto speeds, and I chose the middle gear which provided 750 rpm at the shaft. This worked well. But then I bought a much newer Kubota B7510HST with a 540 pto. This produces a lousy cut in long grass with this mower. The 5′ Rhino’s cut is vastly superior.
So I looked at some parts manuals. There are two 40-45 hp gearboxes available, a 1:1.4 ratio, which this one is, and a 1:1.9 ratio which will likely work well on my Kubota.
So if you have a small tractor with a 3 speed PTO, select the middle gear and this model will do you well. If you have a more modern tractor and want to do a lot of mowing, find a mower with the 1:1.9 ratio or get a 60″ machine. The tip speed just isn’t there for a fine cut unless you turn the shaft more quickly than 540 rpm.
This morning I shattered a blade on another rock and was pleased to find that TSC USA stocks them. Tomorrow with any luck I’ll slip across the border to Watertown and get the parts I need.
* Update While replacing the blades I looked at the underbelly of the replacement gearbox: it’s a 1:1.9 ratio, so it should give the same tip speed at 540 rpm as a 1:1.4 would give on a 60″ cutter. The problem lay in the bent and shattered blades I was trying to force to cut. Things improved dramatically with new blades, at least until contact with a few rocks bent the cutting edges up away from the ground.
Now I need to find better quality, carbon steel blades for the 48″ mower.
the Walnut Diary 