The vast majority of self-propelled gasoline walk-behind mowers are rotary type, meaning they cut the grass with a horizontal blade attached to the vertical drive shaft of the engine. The deck is a protective housing component and an integral part of the mower that supports the engine and wheels and controls the airflow to maximize the cutting and bagging efficiency. Most decks are steel, but some are aluminum alloy or high-impact plastic. Most non-commercial models (called residential or consumer models) cut a swatch 21 or 22 inches wide. Most people prefer self-propelled models, even if yards are flat and small enough to be candidates for a push model.
Some people find it easier to maneuver a front-wheel-drive mower in a complex landscape because you can easily tilt the mower back on the rear wheels to stop or change directions. However, if the mower you choose has controls that enable you to easily vary ground speed and engage or disengage the drive, a rear drive is probably a better way to go. With rear drive it is easier to mow a straight line and the traction is better, especially when bagging, because more weight is over the rear wheels.
Mulching decks and blades cut clippings small so that they decompose quickly, returning nutrients and water to the soil. Bagging clippings leaves a clean lawn, but end up being more work since you must either dispose of or compost the clippings. Mulching is usually the best option since most states ban the disposal of lawn waste into landfills, and because composting large quantities of grass can be problematic. If your lawn is overgrown, the best option is to broadcast (spread) the clippings through a side-discharge opening leaving larger clippings to dry out on the lawn, which then may require raking.
Three-in-one models—mow, mulch, and bag—are the most popular and versatile models. Two-in-one models either mulch and bag, or mulch and side discharge. Changing between modes is usually quick and easy andoften requires no tools. You may want to avoid buying a mower that requires tools and has small parts that may get lost. Grass-catcher bags are available for side-discharge mowers but they get in the way while mowing and also hold less than. People who want to bag should only consider a rear-bagging model. In addition, premium bagging or mulching blades can give better results than the standard multi-purpose blades; however, the extra-fine clippings derived from these blades tend to clump more because the clippings are often wetter.
Standard low-wheel models have the same size wheels (diameter of about 8 inches) on the front and on the rear. High-wheel models, which can cost $20 to $40 more for an otherwise identical mower, have larger wheels (diameters about 9 to 12 inches) on the rear for a smoother motion over bumpy turf. Wheels mounted on a full-length solid-steel axle are more durable than wheels attached to cutting height adjusters. When buying, pay attention to the quality of the wheel, and make sure that the height-adjustment assembly is easily replace in case the wheels wear out.
Noisy, two-cycle engines (requiring oil mixed with gas) are outdated now. Today’s four-cycle engines range between 5.5 and 7-horsepower, are quieter, and are more efficient. All engines within this range are adequate, but if you have coarse grass, or a large or hilly lawn, you many need more horsepower.
Overhead valve or overhead cams offer greater efficiency and durability, and are quieter than standard side-valve engines. Today there are more low and moderately priced mowers are available with OHV/OHC engines.
Starting a self-propelled mower is now easier and more reliable than in the past. Some gas caps dispense fuel stabilizers to keep gas fresh. The automatic choke recover system (ACRS) on some engines allows the user to set the choke when starting a cold engine then return to the operator’s position to start the engine. The choke slowly returns to the open position as the engine warms up. Other engines start with no priming or choking—just pull the recoil starter once or twice .
Before you buy, check out the following for convenience and ease:
- Look for a key-start model.
- Try the cutting-height adjusters, typically at each wheel.
- Make sure the handlebars are at a comfortable height and can be easily adjusted, especially if there will be more than one use.
- Check to see if the handles fold easily for compact storage.
- Make sure the handles are comfortable to hold.
- Make sure the control bail is easy to hold in place.
*All self-propelled mowers are equipped with a lever or bar, called a control bail, which is held against the handlebar for the blade to rotate. This federally required safety feature ensures that the blade stops when the operator leaves the operating position (releases the bail). Some bails are noticeably more stiff and uncomfortable to hold in place.