How Does a Push Mower Work? A Simple Explanation
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How does a push mower work? It turns a cutting blade at a set height as you walk it across the lawn. The blade is driven either by a spinning reel that works like scissors against a fixed bed knife, or by a single rotary blade that spins fast and cuts by impact. The power comes from your own pushing, which turns the wheels and gears on a reel mower, or from an engine or electric motor on a rotary model. The rest of the design, including the deck, the height lever and the handle, supports that one basic task.
Quick answer
- A reel push mower cuts with a spinning reel and a fixed bed knife, and the wheels drive the reel as you push.
- A rotary push mower spins one blade on a vertical axis, driven by a gas engine or an electric motor.
- Cutting height is set by the bed knife on a reel mower, and by a lever or wheel mechanism on a rotary mower.
- Battery and corded rotary mowers rely on a motor instead of an engine, and the listings in this guide state the power source for each model.
The two basic cutting systems
Every push mower falls into one of two cutting systems. The difference matters because it changes how the mower cuts, how it sounds, and how much maintenance it needs.
Reel cutting. A reel mower has a cylinder of several blades, called the reel, that spins as the wheels turn. The blades pass across a fixed horizontal bed knife. Grass is trapped between the two and sliced, the same way scissors cut paper. The cut is clean and close, and the mower has no engine, so there is no fuel or spark plug to maintain. Reel mowers work best on fine, flat turf that is kept short and cut often. The listings here describe reel mowers with a cutting height range of about 0.5 to 1.75 inches for shorter grass, and a 5-blade model with a height of 0.5 to 1.75 inches as well.
Rotary cutting. A rotary mower has one blade, mounted on a vertical shaft, that spins at high speed underneath the deck. The blade cuts by impact rather than by a scissor action. A rotary deck handles taller and thicker grass, and it is the most common design for home lawns. The cut is rougher than a reel cut, and grass tears more easily when the blade is dull. Rotary mowers are sold with gas engines, corded electric motors and battery motors.
What makes the blade turn
On a reel mower, the power is the push itself. The wheels are connected to gears, and the gears turn the reel. The faster you walk, the faster the reel spins, so pace matters for a clean cut. There is no engine or battery, which is why reel mowers are quiet and light.
On a rotary mower, something else drives the blade. Gas models use a small four-cycle engine. The listings in this group describe a PowerSmart 18 inch gas push mower with a 144cc 4-cycle OHV engine and an auto choke for easy starting. Battery and corded models use an electric motor. The Greenworks listings describe 40V and 48V battery systems, and the EGO listing describes a 56V 4.0Ah battery with a brushless motor. The motor turns the blade through a shaft, and the battery or cord supplies the electricity. A brushless motor is a type of electric motor that has no brushes to wear out, and the listings name it as a feature.
How the cutting height is set
Height is one of the most useful adjustments on any push mower. The method depends on the cutting system.
On a reel mower, the height is set by the bed knife. Moving the bed knife closer to the reel makes a shorter cut, and moving it farther away makes a taller one. The listing for the American Lawn Mower 14 inch reel gives an adjustable blade height of 0.5 to 1.75 inches, and the Great States 14 inch model gives the same range.
On a rotary mower, the operator usually adjusts height with a single lever that moves all the wheels together, or with a mechanism on each wheel. The Greenworks 40V 17 inch listing describes six cutting heights, and the EGO listing describes seven height positions from 1.25 to 4 inches. The PowerSmart gas mower lists five positions from 1.5 to 3.9 inches. Rotary decks usually sit somewhat higher than reel decks, which helps them handle uneven ground without scalping the lawn.
The deck, the handle and the grass path
The deck is the metal or plastic housing that holds the blade or reel. It guides the grass into the cutting zone and controls the path of the clippings. A side discharge deck throws clippings out to one side. A mulching deck chops clippings finely and returns them to the lawn. A bagging system collects them. Several listings in this group describe a 2-in-1 or 3-in-1 deck, which can mulch, bag or side discharge depending on the setup.
The handle links the operator to the machine. A handle that folds or adjusts changes how far you reach and how the mower stores. The EGO listing describes an adjustable handle height. Good handle position reduces strain on the back and wrists during longer mowing sessions.
Comparison: reel versus rotary push mowers
| Feature | Reel push mower | Rotary push mower |
|---|---|---|
| What cuts the grass | Spinning reel against a bed knife | One high-speed blade |
| What drives the blade | Your pushing, through the wheels and gears | Gas engine, corded motor or battery motor |
| Typical height adjustment | Bed knife position, 0.5 to 1.75 inches in listed models | Single lever or wheel mechanism, 1.25 to 4 inches in listed models |
| Maintenance | Blade and bed knife sharpening | Blade, engine or battery care, and the deck |
| Best fit | Fine, flat turf kept short | Taller and thicker grass, larger lawns |
Values come from the listings named in this guide. A value that a listing does not state is left out.
Choosing a push mower by the way it works
Start with the grass you have. If your lawn is short, flat and well kept, a reel mower can give a clean, quiet cut with no fuel. If the grass is taller, thicker or uneven, a rotary mower is the better tool. Next, pick a power source that fits your yard and your routine. A gas model needs fuel and periodic engine care. A corded electric model needs an outlet and a cord. A battery model needs charged packs and a battery platform you may already own. Check the listing for the battery count, the included charger, and the cutting width.
Finally, check the height range. A wide range lets you cut a lawn short for a neat look and taller for dry weather. A narrow range limits you to one height. Many listings state a range, so compare the figures directly.
Mistakes to avoid
- Using a reel mower on tall or thick grass. It can bend the grass rather than cut it cleanly.
- Setting a rotary deck too low on uneven ground, which can scalp the lawn.
- Letting the blade go dull. A dull rotary blade tears grass and leaves brown tips.
- Choosing a battery mower without checking the battery count and charger. Several listings in this group include only one pack.
- Starting a gas or electric rotary mower with the blade engaged. Always disconnect the spark plug or remove the battery before you work on the blade.
FAQ
Does a push mower need an engine to work?
No. A reel push mower needs no engine or battery, because the wheels drive the reel as you push. A rotary push mower needs a power source to spin its blade, which is supplied by a gas engine, a corded motor or a battery motor.
What is the difference between a reel and a rotary push mower?
A reel mower cuts with a spinning reel and a fixed bed knife, a scissor-like action. A rotary mower spins one blade at high speed and cuts by impact. Reel cuts are cleaner and suit short turf, while rotary mowers handle taller grass.
How is the cutting height adjusted on a push mower?
On a reel mower, the bed knife position sets the height. On a rotary mower, a lever or wheel mechanism sets it. The listings in this guide give height ranges, from about 0.5 inches on a reel mower to about 4 inches on a rotary model.
Why does a push mower need sharp blades?
A sharp blade slices grass cleanly. A dull blade tears the grass, which leaves ragged tips that turn brown. On a reel mower, a dull bed knife or reel has the same effect, so keep both sharp.
Is a battery push mower the same as a rotary one?
Many battery push mowers are rotary mowers. The battery powers an electric motor, which turns the blade. The Greenworks, EGO and Greenworks 48V listings in this guide describe battery rotary push mowers with different battery counts.
What should I check before buying?
Check the cutting system, the power source, the cutting height range, the deck type and the included battery and charger. Read the listing for the deck width and the number of height positions, and check the handle style for your height and reach.
Bottom line
A push mower works by moving a blade past the grass at a set height. On a reel mower, the wheels turn a scissor-like reel. On a rotary mower, a motor or engine spins one blade. Pick a reel mower for short, flat turf and a rotary mower for taller or thicker grass, then choose a power source and height range that match your yard.
Sources
Lawn mower (Wikipedia), opened for the descriptions of reel and rotary push mowers, their drive, and how cutting height is set.
Related reading: How a Cordless Lawn Mower Works and Greenworks 48V 17-Inch Push Mower Review.
