Neighbor's mowing practice - slow engine speeds

[DriveHard]

Funny...

When I was a kid...thinking about 7th grade, my father picked up a used mower on the side of the road. Something was wrong with it (too young to know at the time), and the answer to save money was to just open the carb up full, and disable the governor. I ran that mower from 7th grade, push mowing 2 acres at the time until I moved out about age 18, mowing only 1 acre the last half. All that time, that mower ran FULL OPEN, we changed the oil and blade yearly, but nothing special. It was the best mower I have ever used - never missed a blade, and could keep up with my near jogging speed of mowing when I got older and stronger. We only got rid of it after I moved out, and my dad upgraded to a riding mower.

 

[Pablo]

My wife wanted to mow with the ZT

OK hon let’s not have a shouting match ok

Ok

So she timidly climbs up but is 100 scared to even go 3/4 throttle maybe not even 1/2.

She putted about getting used to the steering which she mastered just fine but absolutely would not throttle up. She doesn’t get it and doesn’t mow. It’s a fear of the roaring engine.

 

[DriveHard]

My wife wanted to mow with the ZT

OK hon let’s not have a shouting match ok

Ok

So she timidly climbs up but is 100 scared to even go 3/4 throttle maybe not even 1/2.

She putted about getting used to the steering which she mastered just fine but absolutely would not throttle up. She doesn’t get it and doesn’t mow. It’s a fear of the roaring engine.

I taught my bride and son how to drive the ZT by keeping the blade up, and OFF, and letting them drive it up and down the gravel road...ended up making a competition of it by setting up cones and having them race...it didn't take long until they were full throttle.

 

[SubieRubyRoo]

My wife wanted to mow with the ZT

OK hon let’s not have a shouting match ok

Ok

So she timidly climbs up but is 100 scared to even go 3/4 throttle maybe not even 1/2.

She putted about getting used to the steering which she mastered just fine but absolutely would not throttle up. She doesn’t get it and doesn’t mow. It’s a fear of the roaring engine.

Just tell her running at less than WOT is like her being forced to sit and listen to her "friends" criticize her fashion choices, WOT is like her getting even

 

[nomas]

My wife wanted to mow with the ZT

OK hon let’s not have a shouting match ok

Ok

That reminds me of the time I bought a motorcycle . My wife said teach me how to ride it . NO . Why not ? Because I'll end up yelling at you . Well I want to learn . Fine but I'm not going to do it . She went to a class and learned from a bunch of older , more patient guys and eventually got her endorsement . Money well spent .

 

[skyactiv]

Was 3300 an increase or decrease from stock?

It was an increase. 21” mowers are not set at 3600 RPM despite that number being thrown around for other mowing equipment. Most 21” walk behind mowers are not set at 3k plus RPM. There is a federal blade speed max but mower manufacturers tend to only approach the limit on professional equipment.

 

[bunnspecial]

It was an increase. 21” mowers are not set at 3600 RPM despite that number being thrown around for other mowing equipment. Most 21” walk behind mowers are not set at 3k plus RPM. There is a federal blade speed max but mower manufacturers tend to only approach the limit on professional equipment.

I showed the numbers in another thread. If I can be pardoned for quoting myself, I'll do so rather than retyping all of this

From what I can find, ANSI specifies 19,000fpm(or about 216mph) as the maximum safe blade tip velocity.

For a typical push mower with a nominal blade size of 21", you will hit this speed at ~3,456rpm. The blades I'm familiar with have an actual blade size of around 20.9", which actually gives a bit of a safety margin if you set the governor at ~3400rpms. Drop the blade size to 19"(I have one that I sometimes use to trim) and you find you can actually run at 3800 RPMs and stay under this speed.

As an addendum to this, the older guidelines allowed for 21,000fpm, which you stay under with an actual 21" blade at 3700rpms.

The Duraforce service manual specifies 2900 +/- 300rpms as the governed engine speed.

One of mine I actually ended up cranking the governor a bit higher than that(by making the mistake of not setting it hot) and it will settle down to around 3750 at full "throttle" per the tach semi-permanently attached to it. I normally throttle it down to 3400, but will use the bit of extra oomph if I'm in tall/thick grass. If doing side discharge I will sometimes throttle it way down to avoid or at least minimize throwing grass into the neighbor's yard or too hard against the walls of the house and piling too deep. I normally mulch so that isn't as much of a problem, but the extra speed is nice to keep the deck clear while mulching. These staggered deck mowers, if nothing else, are so efficient at side discharge especially with a good high lift blade that they can throw grass 6-8 feet easily.

This particular one has a single speed self propel transmission, so it's a bit nice to be able to run it faster too. I actually haven't used that mower this year, and instead the few times I've had a Duraforce out have used the 10547 with the 3 speed. I need to adjust the governor on it, but 3rd gear on it even at 2900 rpms will haul me faster than I care to!

The old D engines, which are my favorite, have a mechanical governor where you make gross speed changes by changing one of the springs in it(fine changes can be made by adjusting the clearance between the throttle plate rod and the plate that pushes on it, plus the throttle lever on the mower adjusts a second spring on the governor). The default settings on max throttle, assuming your springs are good, are 3200rpms but they cataloged a spring that would go to 4000.

 

[SC Maintenance]

So this got me thinking. I have a inverter generator - CHONDA - I have never really used - start and run it every few months to keep it operational.

It has eco - enables the inverter which throttles down based on load - only to use at < 1/2 load.

Or full - which I presume just sets it at 3600 RPM - inverter ignored and just goes to generator mode - or whatever electronic configuration mimics gen mode.

If I am in a long outage should I not be running it long term in inverter mode?

 

[z71bill]

"Well, guess what, he worked a couple years at AutoZone"

I got you beat - I went into AutoZone to dump some used oil.

Employee asks me how much oil I have - I say about 11 quarts -

Looks at my buckets and ask - how much do they hold, I have to use the maximum capacity of the container.

I say each one is 2 gallons so 8 quarts each but they not even close to full.

Then the AutoZone genius says - there are 5 quarts in a gallon - so that would be 10 each or 20 gallons.

I say - no a gallon only has 4 quarts, 32 ounces in a quart - 128 ounces in a gallon.

AZ employee gets sort of mad and insists a gallon has 5 quarts.


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I changed the transmission fluid in the Honda - I go to dump the used fluid.

AZ guy says we can't take transmission fluid it is against the law.

I say - well you always have before - it even says it on the side of your used oil container.

AZ guy - I have worked here for over 4 years - it doesn't say that on the container or I would have seen it.

So I say - can we go look? He say OK I will prove to you how wrong you are -

We go back and a big sign on the side of the used oil container says -

Motor oil - gear oil - transmission fluid - hydraulic fluid and a few others

But it does say NO antifreeze / coolant.