Zero Turning Radius mowers have separate hydraulic pumps driving the left and right wheels, and each side is controlled separately.
 
One tire can be turning forward while the other is turning in reverse so the mower can pivot around its own center. This feature allows amazing versatility in trimming while mowing. Zero Turning Radius mowers have taken over the commercial riding mower market, and homeowner models are available. Should you consider one for your lawn?

Advantages
The biggest advantage of Zero Turning Radius mowers is their ability to maneuver easily and trim around obstacles. They can easily spin around after a mowing pass and be immediately ready for a return pass with no clutching, shifting or braking. Speed control is infinitely continuous from full forward to full reverse, and speed changes can be very smooth. Mowing effort and mowing time are dramatically reduced for lawns with small areas or many obstacles.

Disadvantages
A primary disadvantage is cost; these machines tend to be more expensive than comparably sized tractor mowers. However, for a fair comparison, they should be compared with top-of-the-line tractor mowers since they fit that category. Another disadvantage is that Zero Turning Radius mowers are dedicated machines, not garden tractors. They are not designed to do anything except mow. Some commercial Zero Turning Radius mower manufacturers offer other accessories such as brushes or dethatchers, but these are normally not available for home lawn Zero Turning Radius machines. If you want a garden tractor, a Zero Turning Radius mower is not for you.

Operational Factors
Most Zero Turning Radius mowers are steered with two levers, one operating each hydraulic pump (Figure 1). Some use a single joystick for speed and steering control (Figure 2). When using a Zero Turning Radius mower, be careful to avoid turf damage or accidents. If the lever(s) are moved too rapidly, a wheel can slide or spin, causing a loss of control and unexpected steering reactions. Tire sliding or spinning can also damage turfgrass. Smooth, deliberate movement of the steering mechanism is highly desirable. One manufacturer offered a model with a steering wheel (Figure 3), but it has been discontinued.

Learning to Use One
Zero Turning Radius mowers are easy to operate, but they are very different from conventional garden tractors. Most folks are used to driving with a steering wheel and pedals; most Zero Turning Radius mowers use levers. If you are the type who can’t walk and chew gum at the same time, expect to spend time learning to operate a Zero Turning Radius. You can be driving one in a few minutes, but it may take several hours of actual operation before you are marginally comfortable and a full season before it feels natural to you. Once you become comfortable with one, you’ll never go back to anything else!

Availability
Homeowner Zero Turning Radius mowers are available from some companies. Some are smaller versions of commercial machines.  Some homeowners buy commercial machines. The commercial machines are more expensive, but they are powerful and very heavy duty. They are priced similar to a large, high-quality garden tractor.