Drive unit for dental tool

摘要

The drive unit has a shaft (4) which can be set in rotation by compressed air and which is located in roller bearings (5, 6) supported on housing parts (19, 20) by means of elastic rings (9, 10). At least on one bearing (5), in addition to the available bearing gap, air-permeable connecting means (14) are provided between a first spacer (15) fed with compressed air and above the bearings and a second space (16) below the bearings issuing in an outflow channel (17). A support ring (10) is provided which has several notches (14) on its outer periphery which produce the connection between the first and second spaces. A further support ring (20) is provided with a circular cross-section and the housing (1) and/or the shaft in this area is provided with channels for the through passage of compressed air.