A hydrostatic mower is a lawnmower that operates on a system of hydraulics rather than using belts and gears to run the machine. It is powered by a hydrostatic transmission, which is made up of a hydraulic pump and a hydraulic motor. The pump generates a pressurized flow of oil to the motor, which in turn moves the wheels that are attached to it. Most hydrostatic transmissions have variable displacement pumps so that different speeds can be maintained. They also operate on a reversible closed loop system, with a fixed amount of oil contained within the pump and motor circuit, allowing the mower to move both backward and forward.
Available as either a walk-behind or a riding mower, a hydrostatic mower is most commonly controlled by one or two foot pedals, but some models are operated by hand levers. Some also have a cruise control feature that allows the operator’s foot to be removed from the pedal while mowing. These mowers are highly appreciated for the ease with which they can be operated; a users simply step or press and go.
There are other advantages a hydrostatic mower has over gear-driven and variable-speed lawnmowers. In general, hydrostatic transmissions offer high power in a compact size, maintain speed more accurately, and deliver a wider range of speeds that can be easily controlled. Hydrostatic mowers also maneuver smoothly and respond quickly, so users can change directions in tight spaces without difficulty. They work equally well under wet or dry conditions and feature dynamic braking, which allows for very quick stops.
A hydrostatic mower requires meticulous maintenance. Hydraulic oil and filters must be kept clean and usually need to be changed every 500 hours, which most commonly equates to once per season. The mower’s components also must be checked and cleaned regularly, since hose leaks or cracked fittings can ruin the entire system or cause the need for very costly repairs. In spite of this necessary maintenance, the hydrostatic mower is still considered more reliable than other kinds of lawnmowers, which frequently experience expensive control- and drive-related component problems, as well as transmission wear.
The disadvantages of a hydrostatic mower include a substantially higher price point. It can cost up to twice as much as its gear-driven and variable-speed counterparts. It is also less efficient, so it requires a more powerful motor along with more fuel than other lawnmowers.