Double Acting Cylinder

The double acting cylinder is more common than the single acting cylinder. It works at any angle,
and in any application where hydraulic power is needed.

In the double-acting cylinder design, there’s fluid on both the base and rod sides of the piston,
and force is delivered in both directions. Even for applications where gravity (or weight) can assist
retraction, hydraulic pressure is often applied to control acceleration, meter the rate of travel,
and cushion the stoppage.

Travel in one direction always differs from travel in the other, all things being equal: the push action
requires more force, and is slower, but more work output is generated. The pulling action is faster,
but less work output is created.

All of the double acting cylinder product manufactured by Best Metal is piston type. The cylinder
pushes against the piston while the seal prevent bypass.

Seals are a critical component of cylinders, and a major specialty in which Best Metal has earned
a reputation for excellence. Seal design is an exacting science, and each configuration is precisely
engineered to the friction, pressure and dwell times required. All seals experience some pressure loss
over time; the key is to minimize it, while providing absolute failsafes for unintended movement.

In many of our double acting cylinder applications, the cylinder is moved part-way and held at that point
for an entire work shift – or longer. These are applications where Best Metal’s fluid power specialists excel
in their ability to engineer and test seals for critical applications. These applications are also a major reason
why we have become a leading supplier of “mission-critical” double acting cylinder product.

Best Metal is also distinctive in that we build four types of proprietary safety valving into our cylinders.
As a group, these are known as “cartridge valves,” and they include pilot-operated check valves, flow control
valves, internal bypass valves and counterbalance (“CB”) valves. The latter is particularly critical because
it protects against “over-center” conditions.

Finally, Best Metal has invested heavily in cylinder cushioning technology. Stopping fast travel in a precise,
vibration-free and repeatable way – a soft landing, so to speak - has significant advantages. It is a must for
applications such as manually-controlled manlifts, but also highly desirable as a way to reduce mechanical
stressors and lengthen the service lives of the cylinder and associated components.

Best Metal specializes in hydraulic cylinder prototypes and offers a broad range of
hydraulic cylinder mounting options. Let us help with your next application.

For more information on cartridge valves, cushioning and other factors to consider in cylinder design,
see our “factors to consider” page.

Other pages you may find of interest:
Telescopic cylinders
Piggyback cylinders