Rolaram - A Powerful Linear Motion Solution

Screw Jack has developed the Rolaram linear actuator range to provide a powerful yet flexible linear motion solution for applications where historically hydraulic or pneumatic solutions were used.

The Rolaram linear actuators are designed to satisfy medium to high duty actuation applications with 5kN to 400kN loads at speeds of up to 7000 mm/min as standard. Higher speeds are available as special designs.

From the beginning design of the Rolaram actuators was based around two key building blocks the "actuation unit" and the "drive unit". Together these units were designed and selected to meet the product performance criteria for load, speed and duty. The building blocks specified would also have to be compact for their performance rating and be able to offer key mounting, drive and feedback configurations.

The actuation unit is based around a basic lead screw assembly. To meet the performance range two types are used; a high quality ball screw and nut for medium duty applications and a roller screw and nut assembly for medium to high duty applications. The roller screw design is essential to meet the high duty.htmlect while keeping the unit compact and providing the customer with a practical life rating for the unit. Roller screws in general have higher dynamic load carrying capability than ball screws for a given working envelope. The roller screw assembly in the Rolaram is Screw Jack own Spiracon design. The Spiracon design consists of a multi-start screw with an involute thread form and a number of planetary rollers with annular grooves, which engage with the screw. The rolling action results in a high efficiency mechanism, while the line contact and hardened and ground construction achieves a high dynamic load carrying capacity along with almost no axial backlash or wear. The lead screw assembly is packaged inside a ram arrangement with internal and external guides and seals to provide a sturdy enclosure. At the drive end of this assembly is a thrust housing which carries the load from the lead screw to a mounting that allows the unit to be secured to the surrounding structure.

The "drive unit" which is attached to the "actuation unit" provides the rotary motion, which the lead screw converts to linear motion. The "drive unit" is either a helical or bevel gearbox that allows the motor to be mounted either parallel, in-line or at right angles to the actuation unit. This allows the actuator to fit into most application spaces without special modifications. The mounting options for the units are equally varied and flexible and include the classic trunnion to clevis and double clevis arrangements.

As each actuator will require a varying level of motion control for each application the units have the capability to have a wide array of feedback devices fitted. These include encoders (incremental and absolute), limit switches (mechanical or proximity sensors) and clutches.

Since their initial design the actuators have undergone extensive tests both in-house and in industrial applications throughout the world. The results have been successful even when operated to the extreme with some units operating on a continuous cycle basis 24 hours a day and others operating in harsh environments.

Screw Jack Group
268# WenErXi Road , Fraserburgh
Aberdeenshire AB43 8TE
Scotland ( UK)

Tel: +44 (0) 1346 513131
Fax: +44 (0) 1346 516827
Email: [email protected]

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