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FEATURE MACHINE BUILDING, FRAMEWORKS & SAFETY A level solution for platforms


Self-synchronising actuators from Thomson Linear are playing an important role in the work platforms designed and manufactured by Spika, with actuator synchronisation creating new possibilities to meet customer challenges


S


pika Design and Manufacturing from


Montana provide commercial and custom industrial work platforms to automotive, aerospace and military aviation manufacturers to support a wide variety of assembly and maintenance operations. Such platforms could be used to access sections of a heavy duty pickup truck or even the nozzle on a rocket motor. Here, not only is safety essential, but so is maximum height variability, customisation, cost efficiency and fast delivery times. In order to meet requirements, the


company specifies electromechanical linear actuators that automate the raising and lowering of the platforms and the articulated stairs that enable access to them.


ON THE LEVEL Most of the platforms that Spika provides to its customers are 1m wide and 3-5m long and, at this scale, keeping the platforms level is important for safety as well as productivity. A typical electromechanical configuration


might include four actuators acting for a single stage to achieve up to 3ft of height variability, or two actuators on each corner to obtain up to 2m of height variability. Additional actuators are used to adjust variable pitch stairs to make it easier for workers to access the adjusted height. Height adjustment ranges of up to 2m can be controlled from push buttons located on the platform. Although a significant improvement


over the trailer jacks previously used, variations in factors such as load distribution and floor consistency resulted in uneven platforms. An unbalanced load, for example, would cause one actuator to top out some centimetres before a lower one, making for a somewhat jerky ride while adding mechanical stress. So, Spika engineers installed


electromechanical actuators to keep the platform balanced. Initially, they had deployed an early generation of self- synchronising actuators, but as customers


16 DECEMBER/JANUARY 2020 | DESIGN SOLUTIONS


against which all other actuators synchronise. All actuators are constantly driving to a set speed, regardless of load changes. When actuation starts from the same fully retracted position, the result is a smooth, synchronised, movement that will handle uneven and even shifting loads.


MEETING THE CHALLENGE According to the company, actuator synchronisation has created new possibilities to meet customer challenges. As an example, a tier-one aerospace manufacturer needed a platform that would fit around the nose of an aircraft, thereby requiring a cantilever to extend an additional 15ft from the platform. Raising and lowering the extension from the base platform required five actuators. Although there were castor beams supporting the extension underneath, the extension load put additional stress on the actuators. “Synchronisation is very valuable for


increasingly demanded greater height variation on heavier loads, the engineers sought a more robust solution. After evaluating several options, the


company decided that Thomson Electrak HD electromechanical linear actuators would provide the speed and strength needed to keep up with the changing and increasingly uneven load conditions they were encountering. With speed capacity exceeding


38mm/second and strokes up to 1000mm, the actuators provide Spika with smooth synchronisation in large and demanding applications. Their static strength of up to 18 kilonewtons is consistent across the entire product line. “Having consistently high static strength


for each actuator is important,” said Spika director of business development, Jeff Ruffner. “OSHA requires load testing of all platforms to a four times safety factor. With Thomson’s consistent 18-kilonewton strength, we are confident that we have covered the testing range for any application we choose.” Thomson actuators achieve smooth


synchronisation by using an imbedded microcontroller that allows for communication between each actuator on the common circuit. The actuators use only two wires to connect to a power supply and two to connect to other actuators in the system. Any actuator can then be used on the circuit to drive the system via three low-current wires connected to a simple switch or discrete I/O on a PLC. In a typical configuration, Spika


engineers designate an actuator as the master, providing the reference point


In instances where there are heavily cantilevered and uneven loads, such as this platform for accessing the nose of an aircraft, actuator synchronisation is key. It eliminates the need to add counterbalance weights, enabling the actuators to adjust accordingly to improve system operation


heavily cantilevered and uneven loads like these,” said Ruffner. “In the past, it was not uncommon for companies to hang the weight off the back of the platform to counterbalance such cantilevered arrangements. Electronic synchronisation, however, eliminates the need to add counterbalance weights for these types of loads because the synchronised actuators can sense speed changes and adjust independent actuators accordingly to improve system operation… By employing a platform of ours that can provide various access points safely, they can enhance the health and safety of their employees while saving on insurance costs.” Ruffner explained that as actuator


advances enable new efficiency challenges to be met, the company is getting more and more unique requests. “One aviation customer posed the challenge for sliders to extend simultaneously to follow the contour of the work object as the platform rose. And once it reached 50% of its height, they wanted the sliders to retract. This is the kind of thing where we might draw on the additional intelligence and communications built into Electrak HD actuators to connect to a programmable logic controller, which could control interactions with servo motors and drives to enable more complex operations.” Whatever the future of industrial work


platform automation brings, it is likely that self-synchronising actuators will have an important role to play. Innovative engineering companies like Spika will be able to take full advantage of that potential to deliver even safer and more cost-efficient solutions to customers.


Thomson Linear www.thomsonlinear.com


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