When it comes to hedge trimmers, one of the most important features to look for is a high-performance gear system.
A quality gearset provides smoother operation and greater torque for improved productivity but also contributes to long-term reliability and durability.
Although traditional spur gears serve the industry well, advancements in gear technology, particularly the development of two-step planetary gear systems, have opened the door to even better performance, especially for battery-powered machines.
In a planetary gear system, the motor drives a central “sun” gear, around which multiple smaller “planet” gears rotate. These are all enclosed by an outer ring gear with internal teeth and connected via a movable arm, known as the carrier.
The carrier turns at a reduced speed relative to the “sun” gear, which allows the machine to achieve high torque without sacrificing performance.
STIHL’s HSA 140 and HSA 150 hedge trimmers set a new benchmark for battery-powered cutting performance and are the first in the STIHL range to incorporate a two-step planetary gear system.
As the most powerful cordless hedge trimmers STIHL has produced, these models deliver cutting performance on par with the trusted HS 82 petrol range, while offering the added advantages of lower running costs, minimal maintenance, and zero emissions.
In a two-step planetary design, the carrier also connects to a second “sun” gear, effectively duplicating the process to further reduce the speed of the output shaft.
One of the key advantages of planetary gear systems is their high torque offering. Torque is essential for professional hedge trimming equipment as it allows the tool to cut through thick stems without the worry of jamming blades. This reduces the time spent on tasks and prevents any damage to the machine used.
The two main factors allowing planetary gearsets to deliver higher torque compared to a standard spur gear are a dispersed load transfer and a high reduction ratio. With a dispersed load transfer, the energy load is shared between eight smaller planetary gears, distributing it evenly to create a higher torque capacity.
Although the efficiency of a gearset can vary depending on multiple variables, including the machine’s operating speed and its lubrication, planetary gear systems are considered to be more energy efficient compared to their spur gear counterparts.
This is particularly true in high-torque applications. Unlike spur designs, the typical efficiency loss of a planetary gearset is a small 3% per stage. This means that 97% of the tool’s power is effectively transferred to the connecting rods and blades, which allows for a high level of efficiency. This is crucial for professional landscapers who need maximum performance from their tools to stay productive all day long.
Planetary gears are smaller and more space-efficient than traditional spur gears, they allow manufacturers to create slimmer, more ergonomic machines without compromising on cutting capability or torque. The result is a tool that feels well-balanced in the hand, is easier to handle in tight or awkward spaces, and supports more precise cutting along edges, borders, and shaped hedges.
Longevity is granted by planetary gear systems as they evenly distribute loads across numerous planet gears, rather than relying on one pair of gears to carry a high load.
