Cross-Roller Guide VRG with Rack and Pinion Mechanism for Very Stable Running Characteristics
With the Cross-Roller Guide VRG, THK offers a very smooth-running and high-precision linear guide for limited stroke movements. To make assembly easier and to make the guide system even more compact, THK now also offers this series with a wide center rail.
Fig. 1 Cross-Roller Guide VRG and new type VRG-W with center rail
A special feature of this Cross-Roller Guide is the integrated rack and pinion mechanism which synchronously guides the cage with the orthogonally arranged precision rollers during every linear movement. In this way migration of the cage is prevented which would otherwise occur in linear guides with cages due to vibrations, moments of inertia or shocks and could lead to increased wear and/or disruptions in operation. Furthermore the close contact between the rollers and the cage reduces the leakage of lubricant and also achieves low-wear and low-friction running. For demanding applications the VRG type is also available in a corrosion-resistant version.
Fig. 2 Rack and pinion mechanism for synchronous cage guidance
By installing two parallel Cross-Roller Guides the guide can absorb loads from all four main directions, this can be achieved even more easily with the new center rail. Here only a crossed roller guide needs to be installed to achieve a very compact and precise guide system.
Fig. 3 Mounting example for Cross-Roller Guide VRG-W with wide center rail
Due to its stable, smooth-running characteristics and extremely compact dimensions the Cross-Roller Guide VRG is also suitable for applications with minimal stroke movements. It is dimensionally compatible with the earlier type of VR but has more rolling elements and a higher load capacity. It is ideal for use in optical measuring devices, semiconductor manufacturing systems, optical positioning systems, handling devices and X-ray machines.
