When you’re having a hard time turning the steering wheel, a mechanic will take a look at your entire power steering system. Some of the potential problems with your power steering system – such as being low on power steering fluid, or having a broken power steering belt – are quick and straightforward repairs.
A power-steering system should assist the driver only when he is exerting force on the steering wheel (such as when starting a turn). When the driver is not exerting force (such as when driving in a straight line).
Most modern cars use what's called a serpentine belt to run the engine accessories: the air conditioning compressor, alternator, power steering pump, and radiator fan are all run by the same belt. If one of these fails, the belt can snap, leaving you with an engine that will quickly fail due to either overheating or lack of electrical power.
The input from the steering shaft forms the inner part of a spool-valve assembly. It also connects to the top end of the torsion bar. The bottom of the torsion bar connects to the outer part of the spool valve.
After the issue in the power steering is resolved, the power steering fluid will usually be flushed. This guarantees that the system is in the best shape before you continue driving, and that any sludge or contamination caused by the malfunctioning system is no longer in the power steering fluid.