Category Archives: Linear Motion

Linear Motion

How to specify a ball screw

Powertransmissions - How to specify a ball screwBall screws are available in a range of types, styles, and sizes. A few tips, though, will help you match the right ball screw with the right application.

1. You will have the best success with specifying a ball screw if you know the following information about your application:

Duty Cycle—the cycle rate, dwell times, and lifetime expectation.

Environment—harsh or rugged, wash down, heat extremes, or other requirements.

Load—the mass being moved.

Orientation—how the ball screw be mounted (vertically or horizontally).

Precision—what is the positional accuracy and repeatability need to be.

Speed—velocity and acceleration requirements.

Travel—stroke length.

2. Consider a preloaded ball screw

Preloading Ball Screw 300x292

Ball screw manufacturers can increase the rigidity of the ball screw through preloading—a step that reduces axial clearance between the ball nut and the screw shaft. In addition, preloading enhances positioning precision and repeatability. One of the more common preload options is the use of oversized balls. But other methods include the use of a double-nut. Manufacturers may also offset the raceway spiral, which can force the balls into a preload condition.

3. Know your need for speed

Manufacturers offer information on the operational speed limits that their ball screw system can handle. Variables that go into this determination include temperature, operating limits of the bearing and inertia of the bearing’s moving components.

The critical speed of a ball screw is the lowest speed at which the ball screw shaft is in resonance, i.e. where screw whip occurs. It depends on screw length and the end bearing mounting support. To prevent critical speed, select a larger screw diameter, choose the right bearings, and use proper screw supports.

Ball Screws Speed Calcs 282x300

Formulas to help determine critical speed

4. And of course, the next tip is to always use a good lubricant. Oil and grease are the common choices. Avoid ones with solid additives as they can clog the recirculating system.



Source: Linearmotiontips

Introducing Materials in Motion Guide from Thomson

Powertransmissions - Introducing Materials in Motion Guide from ThomsonThomson introduces Materials in Motion – a new guide to innovative motion solutions from Thomson for building better, faster and smarter material handling equipment. The guide provides an overview of the products and technology available from Thomson, including rod-type and rodless linear actuators, round and square rail linear guides and bearings, ball and lead screws, linear slides and systems, Micron®planetary gearheads, Deltran wrap spring and friction clutches, spring set brakes and resolvers. Readers will also benefit from detailed application illustrations that highlight the benefits of these technologies as applied in a variety of handling applications, including trucks and mobile lifting aids, transporting car chassis, palletizing food containers, vertical lift modules and automatic storage, assembly line engine handling and aircraft wing handling.

“In a modern production environment, moving material quickly, accurately and efficiently is a big challenge. Using the optimal motion products can give OEMs a competitive advantage by designing machines that help their customers save time and money,” says James Marek, Business Unit Director, Thomson Systems. “With more than 70 years of motion control expertise, combined with unmatched product line breadth and a commitment to agnostic machine design, Thomson is well positioned to deliver unbiased standard, modified-standard and full custom design solutions that help automotive, aerospace, food, medical and other material handling machine builders gain that competitive advantage.”


Source: Thomson

Schaeffler Fully integrated linear actuator and rolling bearing units designed for solar tracking systems

Powertransmissions - Schaeffler Fully integrated linear actuator and rolling bearing units designed for solar tracking systems

Photovoltaic (PV), concentrating photovoltaic (CPV) and concentrating solar power (CSP) systems operate more efficiently when their mirrors, collectors and PV modules accurately track the course of the sun during the day. The more precise and trouble-free these systems are, the more efficient and profitable the solar power plants operate.

By offering its linear actuator and bearings for swivel drives as a complete system, Schaeffler has taken another step towards the full integration of precision solar tracking systems for azimuth and elevation axes.

The linear actuator responsible for stroke movements in the elevation axis was custom designed to withstand the harsh operating conditions typically found in solar power plants. The linear actuator is designed for dynamic loads of up to 5kN and static loads of up to 15kN. The actuator can reach a stroke travel of up to 1,000mm at a stroke speed of 5 mm/s.

The complete mechatronics system comprises the rolling bearings for the individual bearing positions, screw drive spindle and spindle nut, extension tube, compact housing with cover, seal, drive technology (motor and gearbox unit), the sensors, and rod end for connecting the actuator. The innovative design and high flexibility of the unit allow the stroke length and mounting to be matched precisely to individual customer requirements.

The linear actuator can operate in high temperatures and is protected from dust, sand, wind and rain. Due to an encapsulated housing, a reduced number of fully-sealed joints, as well as an integrated motor, gearbox unit and entire drive technology, the linear actuator is able to operate maintenance-free. The sealing components provide the actuator with an IP66 protection rating, which prevents the ingress of contaminants such as water and sand. With its low-maintenance requirements and bearing supports, the linear actuator provides an operating life of up to 25 years.

The high precision axes ensure that the solar power plants generate optimum power output on a continuous basis. Schaeffler’s linear actuator concept can also be adapted for use in other sectors or applications depending on the technical and geometrical requirements.

Bearings for precision swivel motion

Schaeffler’s AXS angular contact rolling bearings and FAG X-life tapered roller bearings support the swivel drives that adjust the azimuth axis. These bearings have a high load carrying capacity and can be set clearance-free. This is an important prerequisite for high rigidity and positioning accuracy and therefore the efficiency of the entire tracking system.

The AXS series of rolling bearings have cylindrical rollers and raceways that are arranged at an angle to the bearing axis. The roller and cage assemblies comprise cylindrical rollers that are snapped into high-rigidity plastic cages with very close spacing. This means that high load ratings are achieved. A special feature of the AXS series are the conical bearing rings. These are manufactured using forming methods, making them cost-effective. In addition, turned bearing seats are sufficient for supporting the bearing rings. This reduces the cost of adjacent components.


Source: Schaeffler UK

Smalley Steel Ring Company Launches New Linear Spring Series.

Powertransmissions - Smalley Steel Ring Company Launches New Linear Spring Series.Smalley Steel Ring Company announces the release of the new Linear Spring Series. The new Linear Springs offer a selection of spring loads that react along a straight line, as opposed to a conventional spring that fits in a circular cavity. This means a linear spring may be located in an axial direction but providing a radial force.

Smalley Linear Springs are a continuous wave formed wire length produced from spring tempered materials. Linear Springs act as a load bearing device having approximately the same load/deflection characteristics as a wave spring. Axial pressure is obtained by laying the linear spring flat in a straight line.


Linear Springs are now available as a standard part fromSmalley. Over 200 standard sizes are available from stock in both carbon and stainless steel. Smalley offers No‐Tooling‐Charges™ on special Linear Spring designs. Exotic alloys are available upon request. Smalley engineers are readily available to assist with your spring design.

Smalley offers complete information on the Linear Springs including a new catalog supplement featuring several series of standard springs that have varying loads but fit the same cavity. The Linear Springs are produced in a wide variety of materials to withstand most environments.

Smalley Linear Springs are a continuous wave formed (marcelled) wire length produced from spring tempered materials. They act as a load bearing device having approximately the same load/deflection characteristics as a wave spring. Axial pressure is obtained by laying the expander flat in a straight line.


Standard Sizes from Stock
Linear Springs are now available as a standard part from Smalley.
Smalley engineers are available to assist with spring design.


Stock Sizes

  • Carbon & Stainless Steel
  • Over 200 Sizes


  • No Tooling Costs™
  • Exotic Alloys Available

Source: Smalley

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