How Fast to Run a ZeroTurn Mower

[wag123]

Rotary mower cutting performance has a high correlation to the blade tip speed. For safety reasons, the maximum blade tip speed is mandated by law. OSHA regulations require that a lawnmower blade has a maximum blade tip speed of 19,000 ft/min. The shorter the blade is, the higher the RPMs that it turns. Maximum blade tip speed is regulated by the engine's governor setting at full throttle. Lowering the throttle setting reduces the blade tip speed and cutting performance, so for the best cutting performance a rotary mower should always be run at full throttle.
Most ZTR riders have adjustments that allow you to limit the ground speed when the control levers are moved to their limits. Some ZTRs also have an adjustment that reduces the sensitivity so that it is easier to control.

 

[bmwpowere36m3]

Full throttle and control your ground/turn speed with the levers... there not a ON/OFF, 0/1 deal.

 

[bchannell]

I know there are some who believe that full throttle is somehow bad for the engine, but this is just not true, period. I've worked in a mower shop when I was young, many years ago, and owned literally dozens of OPE over the years, and I've never seen a manufacturer who recommended using any mower at less than it's governed speed. Thats simply how the engines are designed, they're not car engines, they're designed to run at ~3200-3600 rpm governed. You may believe otherwise, but that is not how they're designed, for longevity, airflow, oil lubrication and best power.
If you're having trouble with a hydrostat mower moving in neutral, then the linkages need adjustment to stop that, it's a common adjustment.
Zero turns are invariably "unusual" to drive the first time you use one. They take some getting used to and there are some homeowners who just don't like them because of their quirks. They are more precise to control than a tractor, but they will mow much faster than a typical tractor. They can be tricky on hills and banks. They are an unusual beast, but they can mow pretty darn quick. I don't use one, as my yard and use dictates a tractor, but if I had lots of flat open yard to mow, or many obstacles to mow around, I'd use one. Give yourself some time to learn their touchy tendencies and you'll likely love the thing.

 

[JTK]

Originally Posted By: bchannell
I know there are some who believe that full throttle is somehow bad for the engine, but this is just not true, period. .


Agreed. It's also why lots of OPE engines are set to run at max governed speed as soon as they're started.

I'm not sure anyone in this thread said it's bad for the engine in doing so, but IMO, with 35yrs of working on and using these things, I've never seen a case where a mower and/or it's engine was ruined from using it not at max governed engine speed.

I've also NEVER seen a case where the engine is going to "overheat" because it was NOT run at max RPM. Are there cases where one could? I suppose, but again, from what I've seen. If the engine is throttled back based on the demand for it, it's running cooler anyway because of the slower fuel burn rate.

 

[SteveSRT8]

my newer briggs 26 hp two pot asks that the throttle ALWAYS be at maximum speed. Always.

 

[meep]

also, they don't charge well at lower rpms.

 

[Gebo]

Wide open throttle it is!

 

[bchannell]

Just to add one aspect of running at full governed speed, there is the design criteria that slowing the engine down, will lower the air velocity over and through the cowling/ducting around the engine allowing dust and debris to "settle" out of this slower air stream. Whereas the higher air velocities, of full governed speed, will tend to keep this particulate matter moving completely through the cowling/ducting and exit the engine rather than being able to accumulate inside these passages. Once allowed to accumulate, their effect is also additive over time as they are mixed with oil residue, allowing them to stick to every available surface in the engine and ducts, choking off good airflow.

 

[Broo]

My Toro zero turn has 3 speed selection : TRIM, TOW and MOW.

MOW is way too fast for my terrain and I don't have any seat suspension. I'm not in a lawnmower racing event here ! I'm mowing at the TOW speed, that's faster than my old tractor and I can work in relative comfort. I only use the MOW speed when going on the side of the road to reach another property I take care of.

 

[oily boyd]

Full throttle always:

- blades need to run fast for good cut.
- engine fan needs to run fast for good cooling.
- transaxle fans need to run fast for good cooling.

Your muscle memory will kick in after 2-3 more cuts and you'll be cutting like a pro.

You'll learn that you can cut full speed when grass has only grown a little; slow down and maybe increase overlap when grass is taller.

My experience with a mulch kit on my Hustler Raptor: cut is much better without it and deck stays much cleaner. I had to switch to non-mulching blades, though. Go to the proper forum for your mower and read up!