You have a riding mower or tractor and it's been reasonably well cared for. It runs great
but the lawn just doesn't look right after its cut. The mower is leaving streaks, stingers or
step cutting. Maybe your rider is scalping. Could it be the deck or just some maintenance
item you have missed. Let take a look.
First, lets caution everyone that outdoor power equipment is inherently dangerous. Some
precautions need to be observed. Use common sense. Turn the unit off, remove the key. By all
means disconnect the spark plug(s). Engines can start or kick back if turning the blades by
hand cranks the motor over, unlikely but it happens. Wear heavy leather gloves when working
around the cutting blades. Never defeat the interlocks installed by the manufacture. Do not
leave guards or deflectors off when you are done. Most important, read your owners manual.
The next thing to check are the basics. When did the problem start? Did you just install
new blades? Don't laugh, are they on upside down? We often see mowers come to our shop for
cutting problems that are as simple as low air pressure in the tires. If the tire pressure is
not as recommended per the manufacture the deck could easily be of by a 1/4" from side to side.
This is one of the main causes of step cutting.
Step cutting is sharp ridges left in the lawn surface. Step cutting is usually caused by mower
deck damage, misadjustment, or mower blade damage. Normally the deck just needs to be
re-leveled. To check for this, park the unit on a flat surface. Manually turn the blades
perpendicular with the direction the tractor is sitting. Now simply measure the outer tip
of the left blade to the surface your parked on (don't measure from the deck shell its got
to be from the blade tip). Write the measurement down. Go to the right side of the tractor
and measure from the tip of the right blade to the surface. The two measurements should be
the same. Do not fret it if 2 measurements are within an 1/8" but if its a 1/4" or more you
need to correct it. The next thing to do is to turn the blades and measure again. If the
measurements are not the same, one of the blades is probably bent. Other things to check
for are damage to the deck shell, bent or loose spindles.
Streaking is another common complaint. Streaking is when thin strips of uncut grass are
left behind the mower. Streaking is usually caused by operator error or poor blade maintenance.
Streaking can occur if the engine speed is too low. All mowers are designed to run at full
throttle. Believe it or not you are doing more harm to your engine by running it slower
than wide open when you are mowing. Plus engineers spent a lot of time designing your deck
to give the best cut at that blade tip speed. Blades need to be spinning at the correct
blade tip speed. They need to be sharp and not have too much wear on the uplifts. The
speed and uplifts pull the grass up just like the barber lifts your hair up with a comb to
get a straight cut. The air movement within the cutting deck is very important. Decks plugged
with grass clippings can not move the air the way they were designed to do.
Another cause of both streaking and step cutting is the design of the tractor and deck
themselves. If the operator does not over lap the cutting row enough or makes very tight
turns marks can be left in the lawn. The easy way to see the cause of this is to use a
jack to raise one rear wheel of the tractor a little off the ground. If your tractor
does not have a full free floating deck doing this will cause the deck to tilt.
This tilting in tight turns and when one wheel is lifted higher than the other by uneven
ground contours will leave marks. Sorry but the only fix for this is slow down, make wide
turns, over lap cuts more or buy another tractor with a free floating deck.
Scalping is the one thing that I bet everyone has done at least a few times. Scalping is
when the mower deck comes close to or hits the ground. Scalping can be caused by the mower
deck misadjustment, unevenness in the lawn, or by mower deck bouncing because the ground
speed is to fast. So Check the items above for a mechanical problem. Slow down or raise the
deck if its just to low. If that doesn't fix the scalping you need a landscaper not a
mechanic like me. Happy Mowing.
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