Here you can dig deeper into different ways of braking industrial linear actuators, which is always necessary to ensure that the actuator stays in its position, whenever power is off. Our expert Hunter Stephenson explains the basics in this video.
The purpose of using a brake in an actuator is to ensure the actuator stays in its set position, when the power is turned off. There are three ways of ensuring a brake functionality in an actuator. Either the actuator is self-locking, which means that it does not need a brake to keep its position when power is off. Or it is necessary to integrate a mechanical or an electrical brake in the actuator. LINAK® actuators are either self-locking or feature different versions of mechanical brakes.
The disc brake: The disc brake is normally stacked directly on the spindle, where the discs squeeze together around the spindle to stop the movement. Being placed in direct contact with the spindle exposes the brake to both high force and heat. This type of brake is a wear part that is designed and tested to match the actuator life. The location of the brake directly on the spindle should also be considered in relation to the actuator’s build-in dimensions.The single acting brake: The single acting brake contains an internal spring, which means that the brake works in one direction – either in push or pull. For an actuator with this type of brake it must be specified whether it needs to perform in push or in pull.The dual acting brake: The dual acting brake is a very strong brake. This type of brake is integrated in the industrial LINAK® actuators, as their high-efficiency performance require a brake ensuring a high self-locking ability. Actuators with a dual acting brake can run in both directions without activating the brake as long as the movement originates from the electric motor. If the movement originates from the spindle, and in either direction, the brake will activate and keep the actuator in position.
Self-locking ability is one of the key selling points for electric actuators, as it prevents the actuator from back driving. In LINAK® actuators, self-locking ability is defined by the actuator being able to run with a full load and duty cycle; and when stopped, it will move a maximum of one spindle revolution before the actuator is locked in full stop.
There are several factors that influences the self-locking ability of an actuator. Spindle type and spindle nut, gear box and brake design, and DC motor control are just some of the main design considerations that affects the actuator’s ability to withstand loads when stopped.
Did you know?
The position of a brake in an actuator influences the size and power of the brake needed.
When developing a new actuator, there are limited places to add a mechanical brake in the design. For example, on the spindle, in connection with the gears or directly on the motor’s rotational shaft.
The further away the brake is from the spindle, the lower forces are required to brake. However, the endplay will typically increase. So, the design must take these factors into account.
Theoretically, a brake placed between the actuator’s motor and gearing would be even more efficient, since it would reduce the endplay and require lower forces for braking.