Bumper system

A bumper system for use with a compressor variable vane system comprises a synchronizing ring 46, a bumper 32, a shim 38 for defining a gap between a bumper pad 47 and the bumper 32, a pin 36 for preventing rotation of the bumper 32 relative to the synchronizing ring 46, and a device for fully trapping the shim 38. In a first embodiment (Fig.2), the device for fully trapping the shim 38 comprises a sleeve 34 passing through the synchronizing ring 46. In a second embodiment (Fig. 5), the device for fully trapping the shim 38 comprises a pin 72 which passes through the synchronizing body 46. In a third embodiment (Fig. 6), the device for fully trapping the shim comprises a fastener 30 with a shoulder (82).