Photo of the truck to the winter road

Case Study for Using Linear Actuator for Lowering Light Bars on Utility Trucks

Nathan Bong
Nathan Bong
PA Engineer

There are many applications for our linear actuators across many different industries. As the unit is designed to move an object in a linear motion, it has been used for lowering light bars on utility trucks.  Lightbars are used on vehicles to increase their visibility or to provide visual warning lights for the awareness of other drivers around them. The light bars can sometimes be elevated higher to further increase the visibility, making its presence more prominent to oncoming traffic. Depending on the situations, there are times when the light bars have to be lowered such as when passing a tree with low branches or going through underground parking with low heights. Manually adjusting the height of a light bar may be possible by hand, however, it can get inconvenient and repetitive for a lone driver to consistently get out of the vehicle to make the adjustments and come back in. An electric linear actuator would allow for easier, faster and more convenient adjustments to the height of a light bar.

Photo of a lowering light bars

Challenges

When our customers approached us with their application, we identified three major challenges.

Heavy Lifting

Lightbars can sometimes experience debris or branches from trees above falling onto them. Because of this, an actuator would require a high amount of static load rating in case an accident like this happens when not in motion. The weight of the light bars, metal framing and additional weight of falling branches could add up to more than 100 lbs. For extra safety factor, an actuator with static load ratings of 200 lbs or higher would be preferred.

Space Limitation

Utility trucks may also have space restrictions for installing actuators due to already having other equipment onboard prior to the adjustable light bars. Using multiple actuators synchronously can assist with increased load capacity and stability, however, the complex control system combined with multiple actuators being used would occupy more physical space. The ideal system for utility trucks would be a single actuator that can still manage the load requirements while being stable even when one side of the light bar is a little heavier.

Side Loading

The majority of standard linear actuators are designed specifically for direct loads onto the shaft and not side loads perpendicular to the shaft’s travel. In order to maximize visibility, the light bars can be raised up by fully extending the actuator in the upright position. However, heavy gusts of wind in this position may result in side loads being applied to the actuator’s shaft.

Photo of a lowering light bars on utility truck

Our Solution

After careful examination of our customer’s application, we found the perfect unit to meet all the challenges. Our customer intends using the light bar system when it is not raining which means the actuator will not need to be water-resistant but still requires protection from debris. The PA-03 actuator was able to meet all the specifications required. In particular, the static and dynamic force rating requirements were met easily since a stocked PA-03 can handle up to 600 lbs. The usage of the actuator in dry environments also ensured that the IP43 rating of the PA-03 was suitable. By using just one PA-03 actuator that has the basic two-wire operation, the light bar system conserves space because there is no need for a control box or an additional actuator. Wired control using a DPDT rocker switch is all that will be required for an operator to cycle the actuator. Our recommendation for this application was to look into using guide rails or support beams since the extended actuator will experience side loading from heavy gusts of wind. The end result was 2 additional support beams being installed on each side of the light bar and having the actuator mounted at the center. Adding the support beams protected the actuator from sideloading while also increasing stability in case one side of the light bar gets slightly heavier from fallen debris.

Photo of a lowering light bars on utility truck

Benefits

The customer was very satisfied with our solution since it was able to meet the force requirements, space constraints and still be cost-efficient. We continued to stay in touch to ask for feedback on the performance, and our 18-month warranty made sure our customer is taken cared of in case of unit failures.

PA Product Used

PA-03 linear actuator.

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