The Framo LinearChain actuator from R.A. Rodriguez was designed for applications involving long strokes and where space is at a premium. These credentials, plus the need to minimise weight, made it the best choice for a new scissor lift destined for aerospace manufacturing and maintenance
Naturally, the customer considered alternative methods of actuation. Hydraulic rams were a clear option, as they are frequently specified for arduous lifting, but their size and the need for additional support equipment ruled them out for this compact design.
Paul French of R.A. Rodriguez explains: “By using the Framo chain drive the customer could achieve a much more streamlined and lightweight construction as it is able to effect a straight lift. A hydraulic ram by comparison would need to be a much bulkier and heavier mechanism in order to push the geometry of the scissor lift.”
The special profile of the Framo LinearChain, with interlocking fingers at one end, enables the chain to roll up for efficient storage in one direction and form a rigid thrust device in the other. It provides high positioning accuracy, needed to allow engineers to work at different heights, and shock-free motion with no elastic hysteresis under load.
In this instance, the Framo LinearChain was specified as a stand-alone unit due to the high torque requirements of the application: 3700Nm. In most cases, R.A. Rodriguez supplies the LinearChain with the complementary Compacta slip-on geared motor, which has a maximum torque of 1600Nm and is suitable for most push–pull applications.
With a maximum reach of 2.5m the scissor lift is able to take loads up to 4500kg at speeds of up to 50mm/sec. The Framo LinearChain is available in three basic sizes allowing stroke lengths of up to 5m and a push force of up to 35,000N, so the specification of the lift was well within the range’s capability.
An important benefit of the chain drive for this application is the small space it occupies underneath the platform, which allows a very low platform start position. This makes it easy for engineers to step on and off whilst carrying equipment. The product is also suited for operation in dirty environments, as its design prevents the ingress of dirt and dust.
Paul French concludes: “Not only did the Framo LinearChain meet the design and performance needs of this application it was also a cleaner solution and a much more cost effective method of actuation too.”
To find out more about the Framo LinearChain actuator from R.A. Rodriguez, go to the website at www.rarodriguez.co.uk.