Belt Drive, Ball Guide

Belt Drive, Ball Guide

Belt Drive

A belt drive consists of a toothed belt which is attached to the carriage of the unit. The belt runs between two pulleys positioned at either end of the profile. One pulley is attached to the motor while the other is mounted in a tensioning station. The belts are made of plastic reinforced with steel cords. High speeds, long stroke, low noise and low overall weight are typical features of belt 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.

Single Carriage

Single carriage units have one carriage. Some linear unit models also have the option of long or short single carriage. The long carriage handle higher loads but will have a longer overall length for a given stroke.

Double Carriages

Double carriage units have two carriages which gives them higher load capabilites than single carriage units. When ordering a double carriage unit the distance between the two carriages needs to be defined. This distance is called LA or Lc depending on the model.

Cover Band

Cover bands are used on some units to protect them from the ingress of foreign objects through the opening in the profile where the carriage runs. They are made of plastic (A) or stainless steel (B). In the case of plastic the cover band seals the profile by snapping into small grooves running along the carriage opening. In the case of stainless steel the cover band seal the profile magnetically using magnet strips mounted on each side of the carriage opening. Some units equipped with cover bands also have a self-adjusting cover band tensioning mechanism. This eliminates any slack in the cover band that can occur from temperature changes, thus improving the sealing degree and the expected life of the cover band.

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