Linear actuators are inarguably one of the leading products of the motion industry. Their extensive utility makes them a prime choice in a variety of motion control applications, be it hi-fi robotics or the rustic agriculture industry. These benefits, however, are not all there is to linear actuators. Their complex build demands significant planning by engineers. Important aspects to be considered prior to procurement are loading analysis, actuator selection, and mounting design; ignoring any of these can lead to wastage of resources and time.
This article discusses mounting strategies while also touching on some key factors to keep in mind while installing linear actuators.
Common Ways to Mount a Linear Actuator
Linear actuators come with a wide assortment of mounting options. It is easy to get caught up in choosing the right one for your product range. Thankfully, it is also quite easy to categorize these options. Most linear actuator providers offer either motor-end mounts or trunnion mounts.
This style of mounting utilizes both ends of the motor as pivots. In other words, the actuator is free to rotate about both its ends, like a door/window opener.
Figure 1: A Clevis & Pin Motor-End Mount
The pivoting action is usually achieved by a clevis and pin assembly. The motor ends are joined with the clevises via a lock pin, which provides the bearing surface.
Apart from the clevis-pin assembly, the pin joint can also be created using screw-in attachments with bearings pre-installed in them. This option has extended pin joint life and smoother rotation.
Figure 2: Mounting Ends with Bearings
Mounting a linear actuator using trunnions is another industrial practice. Trunnions are better known as linear actuator mounting brackets and are designed to firmly grip the outer body of the actuator. The trunnion itself is bolted to a rigid surface. A TV lift is a good example of this.
Figure 3: Trunnion and Clamp-Style Mounting Brackets
Clamp-style bracket mounts are also popular among consumers. They are best suited for applications where the actuator’s cylinder is not in contact with any surface and requires some additional support for stability. Furthermore, various types of plates and flanges are also available in the market that provides a similar, stationary mounting setup. The plate/flange goes on any portion of the cylinder and can be bolted to a fixed support.
Figure 4: Plate-Type Trunnion Mount
Motor-End vs. Trunnion Mounting: A Comparison
The aforementioned mounting styles have their merits and demerits. The table below provides a comparison among them:
Technical Considerations for Better Mounting
Mounting of a linear actuator is much more than choosing between motor-end and trunnion mounting. No matter what product your company is producing, installing a linear actuator that optimizes its functionality can prove tedious at times.
Below we have highlighted some crucial points you must consider when installing your linear actuators:
A major aspect to be factored in while mounting linear actuators is vibration. Unattended vibrations can lead to premature failure of your linear actuator and product. In addition to this, vibrations are also a source of noise, which is undesirable and can be a nuisance.
The best way to tackle vibrations is to absorb it right at its source, or as near it as possible. For this reason, it is effective to have a mount placed on the motor/gearbox housing itself, or beside it on the cylinder. Doing so allows the vibration pattern to flow out of your setup rather than being transferred to the shaft, which is the most susceptible to vibration failure. It should be noted, however, that this is not a big issue with normal, low-powered applications. For example, a 12V linear actuator mount with low stroke length may not require as much planning as an industrial-grade, long stroke length actuator that vibrates a lot.
Mounting linear actuators with vibration absorption in mind might be considered a professional practice, but ensuring precise alignment is nothing less than an industrial standard. A linear actuator with misaligned mounts can easily bend, buckle, or twist; inefficiency and the possibility of breaking are the end results in each case. Perfect alignment warrants that the mounts must be parallel to each other with respect to every plane. Even the slightest angularity means that undesirable moments will be produced inside the actuator that will harm its structure.
An important consideration worth including here is using a third mounting bracket for the linear actuator. Three-point mounting is complex owing to the fact that the third mount can induce non-linearity in the application. With two mounting points, the actuator has some wiggle room, even while mounted, that allows it to adjust its axis along the line created between the two mounts. However, when a third actuator mounting position is introduced, this wiggle room reduces significantly. Consequently, if any of the three mounts are wrongly positioned (not in-line), the actuator can easily bend. The below images depict a 3-point mounting strategy implemented by one of our customers:
Outdoor linear actuator applications need special forethought with regards to ingress. Although actuators are available with impressive IP ratings, it is always best to protect them against the environment they are situated in.
The trick is to mount your actuator as high and downward-facing as possible, especially when mounting a linear actuator vertically. Keeping it high means that it is safe from the dirt on the ground. Mounting the motor upwards (downward-facing) will prevent dust and water from sliding on the shaft-end seal due to the action of gravity. This buildup can harden and then penetrate through the shaft-end seal when the actuator retracts.
We hope this article provided helpful insight into linear actuator mounting strategies. If you need any further guidance regarding actuator mounting, do not hesitate to contact us for professional advice.