RPM for a 22" residential push mower

[GearHead36]

The grass police won't be by to arrest you.

I'm not worried about the grass police. But I WOULD like my mower to work as designed. It's been a reliable workhorse over the years, but I've never been particularly satisfied with the cut quality.

 

[GearHead36]

Follow your engine and or mower manuals for max revs.

I still have my original paper mower and engine manuals, and they don't mention RPMs at all.

 

[*CPB*]

Is there a balancer out there that is better than the cones, but doesn't cost a fortune? I'm just a homeowner. I have several blades to maintain each year, but I don't have a need to balance hundreds of blades like a shop would, so I can't justify a top of the line balancer.

It's definitely NOT running at 5800, so I'm pretty sure the tach is giving the right readings.

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[Dwayne Oxford]

The spec is 3100 to 3200 RPM's for a 21 or 22 walk behind. Those cone balancers are useless. Simply drive a large nail in the wall and wipe a bit of grease on it to balance. If it is a star hole, simply place a similar sized socket in the blade hole to balance. Balance is important on the long blades; even new blades are off many times. I simply grind a groove on the lift/back side of the blade to balance. I have a busy outdoor power equipment shop and use the this tool to balance. You simply can't beat one of these tachometers for small engines.

..."can't beat one of these tachometers"...??

 

[thesilentone]

You are chasing the holy grail.

Specification is one thing, regulation is another.

Despite a machine having an optimum design efficiency, it must also comply with a whole raft of regulation, such as hand arm vibration, noise and emissions.

In many cases, equipment leaves manufacturers set up to meet regulations as opposed to operate at optimum.

 

[BTBO]

The spec is 3100 to 3200 RPM's for a 21 or 22 walk behind. Those cone balancers are useless. Simply drive a large nail in the wall and wipe a bit of grease on it to balance. If it is a star hole, simply place a similar sized socket in the blade hole to balance. Balance is important on the long blades; even new blades are off many times. I simply grind a groove on the lift/back side of the blade to balance. I have a busy outdoor power equipment shop and use the this tool to balance. You simply can't beat one of these tachometers for small engines.

I too have a Magna-Matic blade balancer. It works like nothing else---very accurate. I have a ZTR and bought the MM thinking it was worth the price vs having to replace spindles prematurely.

 

[beeev]

I too have a Magna-Matic blade balancer. It works like nothing else---very accurate. I have a ZTR and bought the MM thinking it was worth the price vs having to replace spindles prematurely.

Ditto here.
You can even check them for straight before wasting any time sharpening with the MM.
As far as the tachometer you bought, is it a quality piece or a Scamazon cheapie?
I would have trust issues on some knock offs.
When it comes to tools, get the best quality you can afford.
Buy once, cry once. The proven good stuff gives a lifetime of use/reliability imo.

 

[Wrenchit]

I know that the blade tip speed is limited by ANSI to 19000 FPM. Which, on a 22" blade, equates to 3299RPM according to my calculator. I recently bought a tachometer, and found that my residential push mower, with a 22" blade, is running at 2750 RPM. So I started increasing it. When I got to 2950, it seemed like it was running really fast, and had a lot of vibration. So I backed it down to 2900, and the vibrations seem to get better. So my question is, of course, what speed should I set my engine to?

Engine: Briggs 128T05-5123-B.
Mower: 2011 Toro Recycler w/Personal Pace.

I still have the owner's manual and the engine manual. Neither mention engine RPM settings.

Not sure if this is the right forum, but the only other blade tip speed discussion I could find was in this forum.

The maximum torque achieved for your engine is between 2600 and 2800 RPM. It drops after that.
A slightly bent crankshaft will cause vibration even with a perfectly balanced blade.

 

[GrumpyCat]

I don't think HP/torque is the primary concern about RPM. In general the cut is better at higher speeds, so while the big deck of a rider has it's disadvantages the faster blade speed over a walk-behind has advantages.

 

[GrumpyCat]

9:05 min

Is it best to take the blade off before or after the Heineken?

I like his "6" extension" balance technique.