By Josh Cosford, Contributing Editor We don’t hear much anymore regarding sequence valves, and probably for good reason. A sequence valve is like a self-regulating inline relay that opens when work pressure overrides the spring setting. It’s a form of hydraulic automation that provides sequential operation for two or more functions using one fluid supply…

What should you do when it comes time to decide if you should repair or replace your aging air compressor? There are a few things you should consider. Air compressors are like motor vehicles — if they are used continuously, hardly shutting down, they should not be expected to run for a long time without […]

By Josh Cosford, Contributing Editor “Fluid power” is the all-encompassing term to describe how we achieve work through pressurized matter pushed through enclosed circuits. In short, fluid power is hydraulics or pneumatics, sometimes simultaneously (hydropneumatic accumulators, for example). Inherently, we know they’re different because one uses oil and the other air, but what else is…

By Josh Cosford, Contributing Editor Many unique hydraulic applications offer the power and reliability needed by CNC machines. Hydraulics provides an invaluable tool for machine tool designers to perform powerful and practical functions to improve the performance and reliability of their CNC lathes, mills and other machines. A machine tool is a machine that cuts,…

By Josh Cosford, Contributing Editor A clutch is a mechanical device that disconnects a driveshaft from its input shaft, pausing output torque. Clutches — hydraulic or otherwise — often use friction to engage the input and output ends of the assembly. The friction material is not unlike the compound employed by vehicles for their brake […]

NBR is an acronym for nitrile butadiene rubber but goes by many other names, such as nitrile or buna. NBR is a synthetic rubber compound made from acrylonitrile and butadiene. Buna is renowned for its natural resistance to oils, fuels, water and many other chemicals. You may use NBR for most hydraulic applications, especially those […]

Contributed by Steve Skinner, on behalf of Webtec LLC It’s probably fair to say that modern machinery is less prone to unexpected breakdowns than its counterparts of 30 or 40 years ago. This is due mainly to an increased emphasis on reliability engineering together with the availability of low-cost sensors, monitoring devices and digital communications. […]

Some electropneumatic pressure regulators work by combining three important elements: the mechanical valve, the solenoid, and the controller.  The mechanical valve is comprised of the valve body, spring, and spool. The valve body is typically machined from aluminum or brass. It includes a port for the unregulated air to enter the valve. Internally machined is […]

By Josh Cosford, Contributing Editor The metal tube assemblies used in hydraulic plumbing applications offer one of the most reliable methods to transfer fluid under pressure. Still, their factors for design and installation are sightly more complicated than hose assemblies, which are traditionally more popular. Mills make seamless tubing used for hydraulic systems by pushing […]

Contributed by Vicki Burt In a rodless air cylinder — also called a rodless slide — motion is transmitted through the body length by an internal piston moving with the cylinder, driven by compressed air. The piston is attached to a shuttle or carriage, which supports the load and moves it in a linear direction […]

Contributed by Frances Richards Pneumatic cylinders, also called air cylinders, pneumatic actuators, or pneumatic drives, are relatively simple mechanical devices that use the energy of compressed air and turn it into linear motion. Lightweight and low maintenance, pneumatic cylinders generally operate at lower speeds and less force than their hydraulic or electric counterparts, but are […]

By Josh Cosford, Contributing Editor The line that separates the performance of servo and proportional valves has blurred in recent years. Some may consider a servovalve to be any valve capable of accurately positioning your actuator with closed-loop control. However, in everyday hydraulic circles, many industry professionals describe a servovalve as a valve with a […]

Contributed by Darryl Powell, Doc’s Hydraulic-Pneumatic Training LLC When specifying pneumatic cylinders, you may think that the most important information needed is the bore size and stroke. While these details are certainly important, the application’s requirements are more critical. For example, several questions should be considered: is the cylinder in a wet environment (maybe salt […]

By Josh Cosford, Contributing Editor Most consider a hydraulic hose to be maintenance-free. They’re often installed and forgotten until they need replacement, hopefully not under conditions of catastrophic failure. Contrary to popular belief, hydraulic hose does not enjoy infinite service life. Like any component manufactured from metal and rubber, you may undoubtedly expect failure in […]

Contributed by James Czegledi, Engineering Manager Quality-built hydraulic and pneumatic cylinders are designed to last for long life, and when installed and maintained properly, cylinders are expected to meet or exceed projected lifecycles. However, misalignment and/or side load on the rod bearing and/or the piston can cause premature damage leading to cylinder failure. Cylinder side…

Hydraulic reservoir design is critical in power unit performance, so selecting the right style elements will ensure efficient circuit design. If you have a hydraulic system, you have a reservoir. Full stop. Even “reservoir-less” systems still require an expansion tank to hold excess fluid. Aside from such unconventional designs, hydraulic reservoirs offer benefits above and…

Logic elements are fantastic little creatures. Sometimes call DIN valves or slip-in cartridge valves, they are the most basic valve design capable of controlling direction, flow and pressure. Their simple poppet construction nearly guarantees reliability while flowing upwards of a thousand gallons per minute or more. Unlike most of the Symbology series, this one requires…

Heat exchangers help remove heat from hydraulic power units, helping to maintain fluid viscosity and reduce wasted energy. For all its myriad benefits, hydraulics still has a fundamental downside — heat. Adhering to the Laws of Thermodynamics, we must accept that any energy conversion results in increased entropy. In other words, converting mechanical energy from…

A flow meter is a mechanical or digital device manufactured to measure and indicate flow. The most common flow meter is the mechanical variable area construction type, which employs a spring-loaded orifice-equipped piston. As flow passes the piston, the pressure differential moves the piston assembly against the spring, displaying the flow rate reading. A flow…

Knowing which style of pressure gauge is right for your fluid power system is critical in ensuring consistent, efficient operation. Contributed by Carl Dyke, LunchBox Sessions Pressure gauges are unsung heroes in many hydraulic systems. They are neither directing flow nor controlling pressure. If the pressure gauge is damaged or goes missing, the machine may…

Since the dawn of the industrial revolution, manufacturers have tapped abundant natural resources to produce goods that lasted a few years and were then thrown away. Consumers go on to buy new ones and ensure the production cycle, and profits, continued. This “take-make-waste” model worked pretty well, in part because raw materials and energy were…

I’ve explained other compound symbols in previous Symbology lessons, although not from the specific perspective of intentionally using two or more combined symbols to make one complete, functional component. The detailed version of the pressure compensated pump symbol combines tiny cylinders with 3-way, 2-position regulators and a smattering of other small symbols to make one…

Mobile machinery design has its challenges, but it has many benefits as well. A hydraulic pump need not mount near a hydraulic reservoir, and in fact, could be many feet away. A pump may be near the transmission of the vehicle or at a PTO shaft near the truck’s front bumper. As well, valves and […]

Any book or lesson in fluid power worth its weight in gold will discuss the importance of electrical and electronic control of hydraulics. In fact, over the past few decades, most advancement in hydraulics has been in how it’s controlled rather than improvements in the foundational components such as valves, pumps and actuators. Understanding electrical…