Bill,
I agree with Dennis on the mowing qualities. I have been mowing at about 3-1/2". When I mow often, slow, dry, etc., I can get a good quality cut. I now believe that it is lack of vacuum that doesn't allow any variance in mowing conditions. For instance, I recently let my grass go for 6 days. All of the grass didn't get sucked upright after being bent over by the front of the mower deck. Most of the cut was OK, but where the front tires mashed down the grass it all didn't get cut cleanly, especially where the mower was turning.
I listen to my neighbor's Big Box Green MTD, and the blades sound as if they are moving much faster and they do provide more lift.
I look at some information that says that the US of A has limited a mowers blade tip speed to 19,000 FPM, for safety reasons. This is about 3500 RPM for a 21" blade, which is a common push mower today. I found a mower service manual that says anything below 12,000 FPM will not provide a quality cut.
My 44" deck has blades about 15" long. This yields a Blade Tip Speed of 13,000 FPM, at governed RPM, if the PTO and deck drive pulleys are the same size. I put the speed up pulley on my deck which might give me 10% more speed, but still a blade tip speed below 15,000 FPM. Still significantly lower than the maximum allowed speed.
I think that more speed would help, but I do not think it would be wise to try to speed this deck up 40% as the spindles, belts, and tensioner may not be up to the task.
I have thought about adding some skirting on the deck to try to get more lift but I haven't tried anything yet. It gets complicated, the front of the mower deck bends to grass over, then the discharge area of the deck passes over the uncut grass, which might be blowing the grass from left to right, and then the leading edge of the blade is supposed to lift the grass and cut it cleanly. Would adding some rubber skirting around the back of the deck add any lift? I don't know.
Sorry, for the long post. Does any body have any comments or recommendations.
I agree with Dennis on the mowing qualities. I have been mowing at about 3-1/2". When I mow often, slow, dry, etc., I can get a good quality cut. I now believe that it is lack of vacuum that doesn't allow any variance in mowing conditions. For instance, I recently let my grass go for 6 days. All of the grass didn't get sucked upright after being bent over by the front of the mower deck. Most of the cut was OK, but where the front tires mashed down the grass it all didn't get cut cleanly, especially where the mower was turning.
I listen to my neighbor's Big Box Green MTD, and the blades sound as if they are moving much faster and they do provide more lift.
I look at some information that says that the US of A has limited a mowers blade tip speed to 19,000 FPM, for safety reasons. This is about 3500 RPM for a 21" blade, which is a common push mower today. I found a mower service manual that says anything below 12,000 FPM will not provide a quality cut.
My 44" deck has blades about 15" long. This yields a Blade Tip Speed of 13,000 FPM, at governed RPM, if the PTO and deck drive pulleys are the same size. I put the speed up pulley on my deck which might give me 10% more speed, but still a blade tip speed below 15,000 FPM. Still significantly lower than the maximum allowed speed.
I think that more speed would help, but I do not think it would be wise to try to speed this deck up 40% as the spindles, belts, and tensioner may not be up to the task.
I have thought about adding some skirting on the deck to try to get more lift but I haven't tried anything yet. It gets complicated, the front of the mower deck bends to grass over, then the discharge area of the deck passes over the uncut grass, which might be blowing the grass from left to right, and then the leading edge of the blade is supposed to lift the grass and cut it cleanly. Would adding some rubber skirting around the back of the deck add any lift? I don't know.
Sorry, for the long post. Does any body have any comments or recommendations.
