Chapter
Cylinders
Copyright Goodheart-Willcox Co., Inc. 125
Objectives
After studying this chapter, you will be able to:
✓ Describe attributes related to the different
types of linear actuators.
✓ Identify the different components used in
hydraulic cylinders.
✓ List the different methods manufacturers use
to dampen a cylinder’s stroke.
✓ Explain different methods used for sensing a
cylinder’s position.
✓ Explain the difference between tension and
compression cylinder loads.
✓ Describe how to compute cylinder speeds.
✓ List different types of valves that can be
integrated into a cylinder housing.
✓ Explain the principle of cylinder regeneration.
✓ Identify several items that can cause a
cylinder to drift.
✓ List the problems that occur when metering-
in or metering-out an overrunning load.
✓ Explain the different methods used for
synchronizing hydraulic cylinders.
✓ List unsafe actions to avoid when servicing
and diagnosing hydraulic cylinders.
Types of Linear Actuators
Hydraulic cylinders are linear actuators that
convert fl uid energy into linear mechanical energy.
Like hydraulic motors, cylinders are the output
devices that perform the heavy lifting for mobile
equipment. Examples of work performed by the
hydraulic cylinders are a haul truck dumping a
heavy payload, or an agricultural tractor lifting
and moving hay bales, or a combine swinging an
unloading auger.
Mobile equipment requires the use of several
different types of hydraulic cylinders:
• Single acting.
• Double acting.
• Single rod.
• Double rod.
• Ram.
• Telescoping.
Single-Acting Cylinders
A single-acting cylinder requires only one
hydraulic hose and is hydraulically actuated in
just one direction. The cylinder uses an outside
force to return the cylinder back to its original
state. The two common methods for returning a
single-acting cylinder is a spring or some type of
weight, which is the most common. See Figure 6-1