The tires and wheels on your vehicle were aligned and balanced carefully at the factory to give you the longest tire life and best overall performance. Adjustments to wheel alignment and tire balancing will not be necessary on a regular basis. However, if you notice unusual tire wear or your vehicle pulling to one side or the other, the alignment might need to be checked.
If you notice your vehicle vibrating when driving on a smooth road, the tires and wheels might need to be rebalanced. See your dealer/retailer for proper diagnosis.
Chevrolet Cobalt Service & Repair Manual. General Service
Two basic types of power assist
mechanisms are used: vacuum assist diaphragm assemblies, which use engine
vacuum or in some cases vacuum pressure developed by an external vacuum
pump. The second type is a hydraulic pressure assist mechanism, which use
pressure developed by an ...