Linear Rod Units

Linear Rod Units

Ball Screw Drive

A ball screw is made up of a rotating screw and a moving ball nut. The ball nut is attached to the carriage of the unit. It does not have a normal thread, instead balls circulate inside the nut making it work as an efficient ball bearing that travels along the screw. Ball screws come in a large variety of leads, diameters and tolerance classes. The tolerance class (T3, T5, T7 or T9) indicates the leadtolerance of the screw. The lower the number, the higher the tolerance. High load capability and high accuracy are typical of ball screw driven units.

Ball Guides

A ball guide consists of a ball rail and a ball bushing. The ball rail is made of hardened steel and runs along the inside of the profile. The ball bushing is attached to the carriage of the unit and contains balls that roll against the rail. The balls in the bushing can be recirculating or have fixed ball positions depending on the type of ball guide. The recirculating type has a longer life and better load capability while the fixed type typically is much smaller. Danaher Motion uses three major types of ball guides in its linear units. Either the compact single rail type with recirculating ball bushing (A), the stronger double rail type also with recirculating ball bushings (B) or the fixed ball position ball bushings type (not shown) which require very little space and are used in the smallest units. Ball guides offer high accuracy, high loads and medium speed.

Slide Guides

A slide guide consist of a guide attached to the inside of the profile and a slide bushing attached to the carriage. The guide can be made of different materials (e.g. polished hardened steel, anodized aluminium) while the bushing is made of a polymer material. There are two types of bushings, fixed and prism. Prism bushings can move in relation to the guide which results in longer life and higher load capabilities. Slide bushings are silent, simple, reliable and robust and can be used in dirty and dusty environments. They are also resistant to shock loads, have a long life expectancy and require little or no maintenance.

3D CAD models are available at this link : www.tollo.com/3d_cad_drawings.htm