Gear types and electric linear actuator performance | Actuator Academy™


Welcome to the LINAK Actuator Academy video series for industrial actuators. I’m Hunter and in this episode we’ll talk about gear types and how gearing is related to the performance of a linear actuator. An electric linear actuator is built from a motor, gearing and a spindle. These components are typically connected like this. Normally, linear actuators have one gear connected to the motor and spindle. This gearing cannot be changed, so the way the load and speed is adjusted is by changing the spindle pitch. There are many types of gears in linear actuators and in this video we’ll take a look at two types: plastic and steel gears. Compared to gears made of steel, plastic gearing has a lower efficiency and is more sensitive to high temperatures. These challenges do not affect the actuator’s performance or service life as long as the actuator is used within its specifications. For example, if an actuator reaches its endstop each time it runs in or out, the plastic gears will not be affected. To avoid mechanical blocking that will wear out the worm wheel will over time it is necessary to use a motor controller. Since plastic gears are sensitive to high temperatures, it’s important that the surrounding temperatures are taken into consideration when choosing your actuator. For example, high external temperatures combined with the produced heat inside the actuator can damage the gearing, unless the actuator has time to
cool down in between runs. This industrial actuator, for example, can be used in environmental temperatures up to 85°C. Whereas this actuator is perfect for indoor use in temperatures up to 40°C. It’s often visible on plastic gears if an actuator has been damaged due to a high duty cycle or an unintended blocking. This can happen if the actuator runs into a hard stop mid stroke without being able to reach its endstop. Any small damage caused to plastic gear will not cause a dangerous situation because it’s often just one or two teeth that will be affected. So it’ll still be possible to run the actuator, but often at a slower speed. Most LINAK actuators have worm gears, which provide a high self-locking ability and low noise when running the actuator. For some industrial markets actuators need to perform in harsh environments with high loads or high duty cycles, which requires a very robust design. Some LINAK industrial actuators have spur gears made of steel, since they are designed to deliver high efficiency despite very high temperatures. These actuators are naturally noisier when running, but the gearing is extremely robust and reliable. Powerful industrial actuators such as the LA33 and the LA36 both contain steel gearing for high performance. These actuators always run with a high efficiency from the motor and there’s hardly any efficiency loss from the gears. Steel gearing is not hindered by duty cycle restrictions, because the heat generated in a running actuator will not reach limits that will affect the gears. Still, most LINAK industrial actuators have a duty cycle of 20%, so they can get rid of the heat in between running. This ensures that the generated heat does not affect other components inside the actuators. LINAK actuators are designed to get the most out of the motor’s efficiency. Typically a motor’s efficiency is about 72%. An actuator is designed to work within 25% of the area where the motor has its maximum performance. The motor’s torque is always kept the same to ensure a high reliability. A planetary gear is made from smaller gears circling a larger gear wheel. Typically, this type of gearing is very robust and efficient due to the equal distribution of force through the gear wheels. It provides a high gear ratio in a compact size and is used in the industrial actuators such as the LA33 and the LA36. The first unit, the motor and the planetary gear, always has the same performance regardless of the load. This could be, for example, 7 – 8 N m. On the spindle is a significantly higher torque, for example 20 N m. By adding a second gear step speed can be swapped out for force. The advantage of this gearing design is that it also becomes possible to offer several customised variations of one actuator family. With the actuator’s full power available you can choose to move either a high load at a small speed, or the other way around. If you multiply load with speed, you’ll get power needed for the right movement and this will give you a good indication of the type of actuator needed. So that was a bit of information about gear types and how gearing influences the performance of a linear actuator. If you have any questions at all about gears and electric linear actuators please feel free to contact your local LINAK office. Thank you so much for watching.

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