Today's lecture by Mr. Dave Livingston in our reel maintenance class illustrated several key points regarding efficiency of cut and proper adjustment of the cutting units on reel mowers. Two topics covered that I was particularly interested in included bedknife orientation, and the effects of different grinding types and bedknife to reel contact on horsepower usage.
I understood how important it was to keep the cutting edges of the reel and the bedknife sharp, but I did not realize how important the orientation of the bedknife is in relation to the center-line of the reel. A bedknife with a forward placement in relation to the reel is acceptable, if not desirable, for higher cut turf. However, if the same set-up is used on lower cuts of turf, not only can the quality of cut be poor, but serious damage to the plant and cutting units can occur. With this set-up, the reel can not shear grass effectively due to the inability of the bedknife to stand the grass blades up. Also, a forward bedknife orientation leaves the majority of the bedknife to drag along the turf. This constant friction on the turf, and the consequent increase in pressure between the bedknife and the reel, will produce excess heat. With enough build-up of heat, rifling of the bedknife and reel can occur. Once this happens and the metal cools, gaps between the cutting edges will leave grass behind in obvious strips. This problem is now only remedied by re-grinding both reel and bedknife, which in busy seasons is even more of an inconvenience.
The statistics Mr. Livingston provided on horsepower usage were quite surprising to me. The comparison of relief-ground reels versus flat-ground reels, with varying contact, showed horsepower usage that differed substantially. With a slight gap (.002"-.005") between cutting surfaces, a usage of 0.75HP and 0.87HP per cutting unit was observed in relief-ground and flat-ground reels, respectively. While this difference in horsepower is only slight, when multiplied over five reels, the difference is 0.60 total horsepower. Even so, this alone may not be enough to convince a manager to adopt a relief grinding regiment due to the increase in grinding time per reel. However, the difference in horsepower usage between grinding types when a cutting unit is set to have contact between reel and bedknife is staggering. When a relief ground reel is set for contact, a usage of 0.88HP is measured. When a flat-ground reel is set for contact, a horsepower usage of 2.59HP per cutting unit is measured! Over a fairway mower with five reels, that is a difference of 8.55HP. On golf courses with undulating terrain, the difference in horsepower usage may mean the difference in being able to cut uphill or not being able to keep traction. In addition to this, the consumption of fuel is also something to be taken into consideration.
In the two lectures in this class so far, I have developed an increased awareness of the difference properly adjusted equipment makes in regards to efficiency and quality. I look forward to future lectures in this class and hope to come away with a better knowledge of the subtleties of golf course mowing equipment.
(photo obtained from http://toro.com)
I understood how important it was to keep the cutting edges of the reel and the bedknife sharp, but I did not realize how important the orientation of the bedknife is in relation to the center-line of the reel. A bedknife with a forward placement in relation to the reel is acceptable, if not desirable, for higher cut turf. However, if the same set-up is used on lower cuts of turf, not only can the quality of cut be poor, but serious damage to the plant and cutting units can occur. With this set-up, the reel can not shear grass effectively due to the inability of the bedknife to stand the grass blades up. Also, a forward bedknife orientation leaves the majority of the bedknife to drag along the turf. This constant friction on the turf, and the consequent increase in pressure between the bedknife and the reel, will produce excess heat. With enough build-up of heat, rifling of the bedknife and reel can occur. Once this happens and the metal cools, gaps between the cutting edges will leave grass behind in obvious strips. This problem is now only remedied by re-grinding both reel and bedknife, which in busy seasons is even more of an inconvenience.
The statistics Mr. Livingston provided on horsepower usage were quite surprising to me. The comparison of relief-ground reels versus flat-ground reels, with varying contact, showed horsepower usage that differed substantially. With a slight gap (.002"-.005") between cutting surfaces, a usage of 0.75HP and 0.87HP per cutting unit was observed in relief-ground and flat-ground reels, respectively. While this difference in horsepower is only slight, when multiplied over five reels, the difference is 0.60 total horsepower. Even so, this alone may not be enough to convince a manager to adopt a relief grinding regiment due to the increase in grinding time per reel. However, the difference in horsepower usage between grinding types when a cutting unit is set to have contact between reel and bedknife is staggering. When a relief ground reel is set for contact, a usage of 0.88HP is measured. When a flat-ground reel is set for contact, a horsepower usage of 2.59HP per cutting unit is measured! Over a fairway mower with five reels, that is a difference of 8.55HP. On golf courses with undulating terrain, the difference in horsepower usage may mean the difference in being able to cut uphill or not being able to keep traction. In addition to this, the consumption of fuel is also something to be taken into consideration.
In the two lectures in this class so far, I have developed an increased awareness of the difference properly adjusted equipment makes in regards to efficiency and quality. I look forward to future lectures in this class and hope to come away with a better knowledge of the subtleties of golf course mowing equipment.
(photo obtained from http://toro.com)
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