Linear technology key to turbocharger test rig

A linear slide and digital reader are being used on a special test rig for analysing the air flow in the latest generation of turbochargers. Dean Palmer reports

One of Europe's leading turbocharger manufacturers is using linear slides on an airflow test rig for its products. Fundamentally, a turbocharger comprises a turbine and a compressor connected by a common shaft supported on a bearing system. It converts waste energy from the exhaust manifold into compressed air that is then 'pushed' into the engine. This allows the engine to produce more power and torque which improves the overall efficiency of the combustion process. Bearing supplier R.A. Rodriguez supplied the linear motion element on the turbocharger manufacturer's special purpose test rig. To ensure the concentricity of positioning two components, the linear slide had to be short stroke, manually operated with repeatable accuracy in all planes. The slide selected by Rodriguez was from its IEF Werner range of hand-operated slides. Made from GG25 cast iron to provide greater stability, the slide section is 150mm wide with a 50mm stroke. The unit has a 20mm diameter spindle with 1mm pitch and accuracy to +/- 0.02mm over a 300mm stroke. The slide was supplied with special fixing holes and a bronze, adjustable pressure plate for establishing a light pre-load in the slide to ensure accurate positioning. To identify position, the linear system works in conjunction with a linear digital reader and is required to carry a load of around 20kg. IEF Werner linear slides can also be supplied with dovetail, cross roller or Teflon guides. The latest addition to the range, the DOMILINE, is a variable-combination adjustable system, which can be specified in different variants and widths, with and without mechanical locking devices, with a spindle, pneumatic or motorised drive.