Roh'Lix® Linear Actuators
Zero-Max’s Roh’Lix linear actuators are threadless, mechanical, screw-type devices that convert rotary motion into precise linear motion and thrust using rolling-element ball bearings. These adjustable automatic overload protectors will slip when overloaded, providing linear clutching without additional clutch mechanisms.
Roh'Lix Linear Actuator Small or Larger Size Options
The Roh-Lix is available in small linear actuators that are five-inch and five metric sizes, offering between 15 and 200 lbs. thrust capacity. It can be used in horizontal or vertical applications. All bearings are lubricated for life and require no additional lubrication. Hardened-and-ground shafting with a minimum hardness of 58 HRC is recommended; stainless steel shafting and hollow shafting can also be used for specific applications (consult factory).
Roh'Lix Linear Actuator Designed For Horizontal & Vertical ApplicationsThe Roh-Lix is intended for horizontal or vertical axial loading applications. Axial loading allows for even load distribution across all six of the device’s bearings. Sideloads and twisting loads should be avoided since they can lead to uneven bearing loading while shortening product lifespan. Whenever possible, the load weight on the Roh’Lix linear actuator should be supported by a separate linear bearing assembly.
Learn More about the Roh’Lix Linear ActuatorRoh’Lix linear actuators provide a minimum of 90% mechanical efficiency. Springs preload the bearings against the driveshaft, reducing backlash to less than 0.001”. Operational temperature range is -10°F to 180°F. Designed for maintenance-free operation, with lubricated-for-life bearings requiring no additional lubrication.
The Rohlix features split-block construction for easy installation. The two-block halves can be assembled around the shaft, eliminating the need to remove pillow-block bearings, coupling, etc. This split-block design is also beneficial for the removal of the Roh-Lix linear actuator for servicing, such as bearing replacement.
Minimum life expectancy of Roh’Lix units is 2 million inches of linear travel. Over 100 million inches of linear travel may be achieved with proper application parameters. Occasional overloads are acceptable and are a design feature of the Roh’Lix; however, frequent overloads will lessen the working life due to resulting wear.
How the Roh’Lix WorksThe Roh’Lix linear actuator converts rotary motion into linear motion using rolling-element ball bearings that trace a helix pattern along the drive shaft. This movement produces a rolling helix, or Roh’Lix for short. Works with electric motors that are generally connected to the linear actuator by flexible coupling or a belt.
The Rohlix consists of six preloaded bearings that contact the shaft at varying angles. As the shaft rotates, the bearings trace out an imaginary screw thread pattern, moving the Roh-Lix linearly along the shaft and converting rotary motion into linear motion. The lead, or distance the Roh’Lix moves in one shaft revolution, can vary from 0.025” to 3 times the shaft diameter. Lead is determined by the angle of the bearings in the Roh’Lix block.
Thrust settings on Roh’Lix linear actuators are easily adjusted via coil springs and socket-head cap screws. Thrust settings can be optimized so that no extra force is applied to the bearings, maximizing performance, and extending working life. The coil springs maintain a constant tension against the adjustment screws, so thrust settings do not change once set.
To select the correct Rohlix model for a given application, one must first determine the thrust requirements and the desired lead. Thrust requirements can be determined using the following formulas:
Vertical Applications: F = W + µW
F = thrust requirements (lbs.); µ = coefficient of friction; W = weight of the load being moved
Required lead can be determined based on driveshaft speed and linear speed required.
Driveshaft RPM = 60 x linear speed ÷ Roh’Lix lead
Driveshaft RPM = speed of the shaft driving the Roh’Lix; Linear speed = travel rate of Roh’Lix (inches/second); Roh-Lix lead = lead of Roh’Lix unit (inches/shaft revolution)
Operating Characteristics of Roh'Lix ActuatorsAll Roh’Lix Linear Actuators provide the following operating characteristics:
High EfficiencyThe rolling contact between the outer races of the six ball bearings and the driveshaft provides a smooth, quiet linear motion, resulting in a minimum of 90% efficiency.
Low BacklashRoh’lix bearings are preloaded by the coil springs to reduce backlash to less than 0.001 inches, which helps maintain consistency throughout the life of the bearings.
Positioning AccuracyThe Roh’lix is a friction drive device and, as a result, will show an accumulated error that is, in general, up to 0.002 inches per shaft revolution. Where greater accuracy is required, linear encoders can be used to indicate position.
Overload ProtectionThe Roh’lix can slip if an obstruction is encountered in the system. This unique advantage over other linear actuators can prevent damage and costly downtime.
LubricationRoh-Lix bearings are factory-lubricated for life and are designed to run on a clean, non-lubricated driveshaft.
ShaftingRecommended driveshaft material is C-1060 hardened and ground shafting with a minimum hardness of HRC 58. Its hardness will provide optimum life expectancy, and its ground surface provides a uniform friction surface. Stainless steel shafting, although slightly softer, is adequate for many applications requiring corrosion protection.
TemperatureAcceptable temperature range is -10°F to +180°F. Special units are available for higher or lower temperatures.
Maintenance-FreeThe unit is maintenance-free; however, the shafting may require occasional wiping to clean off accumulated foreign matter.
BackdrivingBy applying a thrust load to the Rohlix unit, the shaft can be made to rotate. The thrust load will cause the Roh’lix and any device attached to it to travel along the shaft. Therefore, the Roh’lix should never be used as the sole device to hold the position.
Tandem Roh’lixTwo Roh’lix may be used on a standard shaft in series or parallel on separate shafts. However, the combined thrust rating must be derated by 20%. When installing the Roh-Lix units, be sure to tighten the thrust adjustment screws an equal number of turns so that they share the thrust load equally.
Features & Benefits of Roh'Lix Actuators
- For horizontal or vertical axial loading applications
- Designed to slip when overloaded, providing intermittent overload protection
- Easy to install
- Working lifetime expectancy of 2 million to over 100 million inches of linear travel, depending on application variables
- Easily adjustable thrust settings
- Five-inch sizes and five metric sizes are available, providing up to 200 lbs. of thrust capacity
- Two Roh-Lix linear actuator units can be used in tandem to increase thrust rating
- Special shaft diameters, leads, and block sizes are available
- Right-hand lead is standard, left-hand lead available upon request
- Maintenance-free bearings are lubricated for life and require no additional lubrication
Application of Zero-Max Roh’Lix Linear ActuatorsWith a lifespan between 2 million and 100 million inches of linear travel depending on the application and operation settings, Zero-Max Roh’Lix Linear Actuators provide ease of use in the following applications:
- Materials Handling
- Semiconductor Manufacturing
- Test Equipment
- Inspection Equipment
- Core Cutting Equipment
- Door Openers and Actuators
- Video Imaging Devices
- Adjustable Web Guides
- Optical Comparators
- Parts Feeders
- Gantry Robots
- Medical Equipment
- Transfer Cables
- Back Gauges
- X-Y Tables
- Many others