Miscellaneous Mechanical Components
The high pressure oil flows through a control valve (directional control). The control valve
Figure 8 Basic Hydraulic System
changes the direction of oil flow, depending upon the desired direction of the load. In Figure
8 the load can be moved to the left or to the right by changing the side of the piston to which
the oil pressure is applied. The oil that enters the cylinder applies pressure over the area of the
piston, developing a force on the piston rod. The force on the piston rod enables the movement
of a load or device. The oil from the other side of the piston returns to a reservoir or tank.
The hazards and precautions listed in the previous chapter on air compressors are applicable to
hydraulic systems as well, because most of the hazards are associated with high pressure
conditions. Any use of a pressurized medium can be dangerous. Hydraulic systems carry all the
hazards of pressurized systems and special hazards that are related directly to the composition
of the fluid used.