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Discussion Starter · #1 ·
I believe it was AWM who recently mentioned about lowering the rpms to lessen the grass buildup on the mower decks. On a related note, I have a few properties with many planting beds and so I turn down the rpms to lessen the grass being blown into the beds but it still gets in anyway. Its been beaten into my head that we always need to keep the rpms up to get adequate air to these engines that work so hard.

Just wanted some opinions about whether we risk damage to the engine when we throttle down these mowers for a minute or 2 here and there?? thanks
 

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Many times I've run mine at lower than full blast. Most people on realize that the fan cools the motor, but many neglect to realize that the crank generates airflow inside the motor to also help keep it cool.
 

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I drop mine down sometimes. I use a syn oil in the motor, change it every 40-50 hours. The syn should also help it run cooler, also have 15-50 mobile 1 in the hyd system. I also have a cooler that mounts on the outside of my hyd filter housing, supposed to extract the heat.
 

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IMHO I believe mower rpm for the sake of the motor is a non issue.

the motors are designed to run at any speed up to the max rating.

but for the sake of discussion...as the rpm's are lowered so is the cooling effect of the crank fan, however...so is the heat generating combustion of the engine.

it always operates within its tolerances.

GEO
 

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Originally posted by geogunn
IMHO I believe mower rpm for the sake of the motor is a non issue.

the motors are designed to run at any speed up to the max rating.

but for the sake of discussion...as the rpm's are lowered so is the cooling effect of the crank fan, however...so is the heat generating combustion of the engine.

it always operates within its tolerances.

GEO
Hold on - 1st are we talking about a 21" HP or a Z or a WB. Todays engine are designed & built to run their best at full RPM. On a Z running one for long periods of time on less than full rpm will not only cause engine problems but also pump & wheel motors. On a HP slowing down the rpm slows down blade speed. On a WB blade speed suffers & if it is a hydro the pump & wheel motors suffer. Slowing one down for a short time (to help keep stuff out of beds) shouldn't have an effect on the engine. But it is not a good idea to run them at less than full RPM
 

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Originally posted by redbull
Hold on - 1st are we talking about a 21" HP or a Z or a WB. Todays engine are designed & built to run their best at full RPM. On a Z running one for long periods of time on less than full rpm will not only cause engine problems but also pump & wheel motors. On a HP slowing down the rpm slows down blade speed. On a WB blade speed suffers & if it is a hydro the pump & wheel motors suffer. Slowing one down for a short time (to help keep stuff out of beds) shouldn't have an effect on the engine. But it is not a good idea to run them at less than full RPM
sir--can you back your statment up with proof of what you are saying?

the point of the original post wasn't to debate lower rpm as it relates to blade speed.

I must now admit that I have a great deal to learn about this subject if you would please document what you are saying.

inquiring minds want to know.

GEO
 

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I feel I can back up this statement by reading the engine/owners manuals (specific the engine manuals) that come with the verious units out there. Most manufactures use the same engines. Or you can contact the manufacture direct. All I said was the engine were designed to run their best (most efficient) at full rpm.
 

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Originally posted by redbull
I feel I can back up this statement by reading the engine/owners manuals (specific the engine manuals) that come with the verious units out there. Most manufactures use the same engines. Or you can contact the manufacture direct. All I said was the engine were designed to run their best (most efficient) at full rpm.
redbull--as for effieiency of rpms, blade speed and cutting, there is no disagreement.

however, actually you said:

Originally posted by redbull
On a Z running one for long periods of time on less than full rpm will not only cause engine problems but also pump & wheel motors. On a HP slowing down the rpm slows down blade speed. On a WB blade speed suffers & if it is a hydro the pump & wheel motors suffer. Slowing one down for a short time (to help keep stuff out of beds) shouldn't have an effect on the engine. But it is not a good idea to run them at less than full RPM
perhaps you didn't really mean it when you said " less than full rpm will not only cause engine problems but also pump & wheel motors" but you did say it and that is why I questioned your statment.

in any event, I keep my 14 kaw cranked wide open as much as I can.

GEO

GEO
 

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thanks redbull--I'm suprised to hear that. it seems like there oughta be a warning sticker on it somewhere but there isn't.

my main concern is keeping leaves from gathering around the top fan and cutting off the air flow.

GEO
 

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Originally posted by redbull
I feel I can back up this statement by reading the engine/owners manuals (specific the engine manuals) that come with the verious units out there. Most manufactures use the same engines. Or you can contact the manufacture direct. All I said was the engine were designed to run their best (most efficient) at full rpm.
Have you ever put a tach on a new machine? I always do. Most come at 3600 or just a little under. Then once you engage the blades the rpm's drop some. You may only be getting 3400 rpm's. If running at 3600 was a must don't you think the mfg's would up the rpm's to allow for working conditions. Or maybe the mower mfg's would be concerned over this.
 

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Discussion Starter · #12 ·
Now you engine experts are making me dizzyyy....lol. You've all answered my question in one way or another...basically I wont be harming anything by turning down the rpms for a few seconds here and there...thanks guys
 
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