Mower Leaves Strips

[mqs]

I have a third season Gravely ZT 50 and about 4 acres a week to mow--lots of new trees and a pond to slow stuff down. The mower will leave strips of unmowed grass, behind front wheels. This occurs more frequently when grass is strong and growing quickly--we have had a lot of rain in our little corner of SD recently. This happens with new blades, sharpened blades. I have releveled and whatever Gravely customer assistance recommends--nothing helps. Is this a problem with machine design or is there something else that can be done about it. It's really aggravating to see those strips pop up. It gets a little better if I drive very slowly--but then I might as well be on my old MTD mower for getting the work done.

 

[Briana]

Welcome to LawnWorld!

We moved your thread to the Mower & Equipment Operation forum.

 

[Retiredcarguy]

Seems like one or more blade may be too short. Yes, crazy as it seems. Deck design takes blade match and complete coverage into consideration. Possibly the "strip" may only be on the left or right side of your deck to give you a clue.

I would stop and fully shut down your machine as you cut and see strips right behind you. While on hands and knees, follow the strips back to your deck to see the exact location source of them.

Good luck on your close up inspection!

 

[djdicetn]

I have a third season Gravely ZT 50 and about 4 acres a week to mow--lots of new trees and a pond to slow stuff down. The mower will leave strips of unmowed grass, behind front wheels. This occurs more frequently when grass is strong and growing quickly--we have had a lot of rain in our little corner of SD recently. This happens with new blades, sharpened blades. I have releveled and whatever Gravely customer assistance recommends--nothing helps. Is this a problem with machine design or is there something else that can be done about it. It's really aggravating to see those strips pop up. It gets a little better if I drive very slowly--but then I might as well be on my old MTD mower for getting the work done.

Trick question here....how did the Gravely perform the first season(and maybe second season) you mowed with it. If the answer indicates that there wasn't a problem with the uncut strips my guess is that you did not purchase a ZTR that was designed to mow 4 acres/week(the Gravely ZT is the entry level Residential ZTR Gravely offers and is designed....like ALL entry-level residentials...for homeowners with < 1-2 acre lawns). I know everyone tries to find the best mower that they can afford, but IMHO you cannot really expect that Gravely ZT to hold up(performance-wise) with a 4 acre/week requirement. You say that it happens more when you let the grass get too tall. My advice would be to try mowing more frequently where you are not cutting more than 1/3 of the total height(if the grass is 6" tall, set the deck at 4" which cuts 2/6 of the total height). Unfortunately if you want your grass cut at 2" high you would have to cut twice(at least) if you let it grow to 6" high. Realistically, if you want your grass maintained at 2" high you need to mow it when it is 3" high. If you are trying to mow 5"-6" grass at 2" any residential ZTR would have a major problem cutting 4 acres cleanly. I apologize if I have offended you in any way, but I think you have too high of expectations for an entry-level Residential ZTR:0(

P.S.
I guess the shorter answer would have been "yes, there is a problem with the machine design for what you are tasking it to do".

 

[lawn mower fanatic]

Here are some general reasons a mower can miss a strip of grass on each pass. One reason just pertains to 2-blade mowers, but maybe one of these will help.

• The blade tips are worn.
• Your overlapping may be insufficient: The tires push down grass during each pass. If you line up your tires with tire marks from the previous pass, the grass does not get a chance to stand back up during either pass. Overlap more than the width of your tires on subsequent passes. This will allow the blades to draw up the trampled grass from each previous pass and should produce a nicer looking cut.
• Right hand turns: Twin-blade mower decks are designed with the discharge on the right side. The left blade is positioned slightly forward and in front of the right blade. During left turns this cutting overlap is maintained. This provides cutting overlap when traveling in a straight line. The tractor operator should therefore make mostly left-hand turns when cutting grass.
• Improper cutting deck adjustment: This can produce a vacuum imbalance that, under certain circumstances, causes airflow to push outwards from the front of the cutting deck. Consult your tractor Operator's Manual for specific Deck Leveling and Deck Engagement adjustments pertaining to your specific model tractor.

(Uncut Strip - Riding Mower)

 

[djdicetn]

Here are some general reasons a mower can miss a strip of grass on each pass. One reason just pertains to 2-blade mowers, but maybe one of these will help.

• The blade tips are worn.
• Your overlapping may be insufficient: The tires push down grass during each pass. If you line up your tires with tire marks from the previous pass, the grass does not get a chance to stand back up during either pass. Overlap more than the width of your tires on subsequent passes. This will allow the blades to draw up the trampled grass from each previous pass and should produce a nicer looking cut.
• Right hand turns: Twin-blade mower decks are designed with the discharge on the right side. The left blade is positioned slightly forward and in front of the right blade. During left turns this cutting overlap is maintained. This provides cutting overlap when traveling in a straight line. The tractor operator should therefore make mostly left-hand turns when cutting grass.
• Improper cutting deck adjustment: This can produce a vacuum imbalance that, under certain circumstances, causes airflow to push outwards from the front of the cutting deck. Consult your tractor Operator's Manual for specific Deck Leveling and Deck Engagement adjustments pertaining to your specific model tractor.

(Uncut Strip - Riding Mower)

VERY GOOD info lmf!!!! I started to say something about checking the deck's leveling/pitch, but honestly I'm not as experienced with some of these problems as some of you guys. I still believe the OP undersized the machine for the job at hand, but some of the suggestions you gave may very well help his problem. At least I hope so. I don't know how long the previous MTD rider he had lasted, but my guess would be that mowing 4 acres weekly he shouldn't expect more than about 8-10 years of service out of that ZT 50 before he starts having major problems with the engine, transaxle or other components that were not designed for that kind of usage:0(

 

[mqs]

Seems like one or more blade may be too short. Yes, crazy as it seems. Deck design takes blade match and complete coverage into consideration. Possibly the "strip" may only be on the left or right side of your deck to give you a clue.

I would stop and fully shut down your machine as you cut and see strips right behind you. While on hands and knees, follow the strips back to your deck to see the exact location source of them.

Good luck on your close up inspection!

I will give it a try--but I will have to careful none of my farmer neighbors see me crawling up behind the mower. Might be too hard to explain.

 

[sjessen]

Based on the original post it seems the deck does not have the vacuum to lift the grass so that it can be cut quickly. Reading between the lines it appears the wheels are pushing the grass down coupled with the wet conditions creating the problem.

You might try mowing a bit shorter to see if it helps. Am assuming the belts are good and the deck is operating properly. Engine speed at 3600 rpms.

Not familiar with this mower but 4 acres a week shouldn't be a big deal for it.

 

[mqs]

It does appear that lower cutting level leaves less stripping. This is OK provided we stay as wet as we are right now. Before mowing yesterday I cut side by side comparing my preferred level with a cut one step lower. The deck was scraped and clean. The lower cut did not leave a trail while my usual level did. My old MTD lawn tractor did not leave a strip at the preferred level--just takes twice as long to do the job. Darn thing just keeps chugging along at less than half the cost of the Gravely. Gravely needs to investigate--design flaw!!!

 

[sjessen]

Higher lift blades might help.