In some very rare cases -- less then 1% of applications-- certain system criteria may have an impact on the shifting of dual coil, 3-position, 4-way and 5-way valves. Most applications using these dual coils valves have no issues at all. However, should your valve appear to be shifting slowly, sluggishly, or in extreme cases, not at all, the bright side is; there is a very simple solution! No, the solution is not beating the valve with a wrench (although we have heard this) but a simple switch of the (+) positive and (–) negative terminals, on ONE of the coils, will most likely perk up your system.
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I once went on a troubleshooting call where the top coil of a dual coil valve would not shift the valve, but instead would actually energize the bottom coil position of the valve. Huh, say what? Upon investigating, it turned out that there were four issues going on: 1) the machine's electrical system had a residual trickle voltage in the system that never dropped current to zero when de-energizing the bottom coil; 2) the coils had diodes; 3) fine particle contamination; and 4) both coils had the same polarity. Polarity, in this case, means that both coils used the same terminal for the plus (+) side/battery and the other terminal for the minus (-) side/ground.
Tags:
cartridge valves,
solenoid operated four way valves,
solenoid operated five way valves,
solenoid valves
For over 25 years, HydraForce has produced the highest quality cartridge valves in the industry while providing exemplary customer service. Despite the slide in US manufacturing over the last two decades, HydraForce has defied the odds and flourished in an unstable manufacturing climate. For the 25th anniversary of HydraForce, we decided to interview our Founder and President, Jim Brizzolara, CFO Joe Reifenberg, and VP of Sales and Marketing, Tony Casale to get a history lesson on what it took to succeed in this market, and what they see in the future for HydraForce:
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Tags:
cartridge valves,
HydraForce,
Hydraulics Industry,
compact controls
For over 25 years, HydraForce has produced the highest quality cartridge valves in the industry while providing exemplary customer service. Despite the slide in US manufacturing over the last two decades, HydraForce has defied the odds and flourished in an unstable manufacturing climate. For the 25th anniversary of HydraForce, we decided to interview our Founder and President, Jim Brizzolara, CFO Joe Reifenberg, and VP of Sales and Marketing, Tony Casale to get a history lesson on what it took to succeed in this market, and what they see in the future for HydraForce:
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Tags:
cartridge valves,
HydraForce,
Hydraulics Industry,
compact controls
Torque is the combination of tangential force acting at a distance from the axis of rotation. Proper torque is absolutely necessary if you want optimal performance from your valves. Proper torque prevents your cartridge valve from backing out under high pressures/high cycles, ensures proper operation of the valve's spool and prevents leakage. However, you must take caution when applying torque to a valve as over-zealous torque is one of the more common start-up or post-service issues (along with contamination, which was discussed in a previous post).
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Tags:
cartridge valves,
cartridge valve serviceability,
hydraulic cartridge valves,
proper installation of cartridge valves,
handling of cartridge valves
When designing a hydraulic manifold, engineers will use a 3D model of a cavity in their CAD/3D modeling software in order to model the proper flow paths of the manifold. Unfortunately, due to various software compatibility issues and inconsistencies in model configuration, the manifold designer has to copy the 3D outline of the cavity, make a 2D outline, then use the 2D outline to create a 3D model. Not only is this process time consuming, but it involves several unnecessary steps.
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When designing a hydraulic manifold, engineers will use a 3D model of a cavity in their CAD/3D modeling software in order to model the proper flow paths of the manifold. Unfortunately, due to various software compatibility issues and inconsistencies in model configuration, the manifold designer has to copy the 3D outline of the cavity, make a 2D outline, then use the 2D outline to create a 3D model. Not only is this process time consuming, but it involves several unnecessary steps.
8 Easy Steps to create a 3D Hydraulic Model:
Tags:
manifold design,
creating 3D models
The proper performance of a hydraulic system is usually attributed to major components such as the motor, pump and valves. However, there is another unsung component that contributes equally to a system's overall performance: the orifice. In most traditional main hydraulic valves, orifices are built into the casting or dismounting components mold by the component’s constructors. In a cartridge valve manifold (otherwise known as a hydraulic integrated circuit), you start with a blank sheet of paper. Therefore, it is important to know where and when an orifice can change the performance of your system. |
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The orifice is one of the most versatile components that we can add in our hydraulic circuit. The orifice can be used to limit the amount of oil in one part of our system, to bleed a pressure line to tank, or to transform a nervous and aggressive circuit into an efficient and highly controlled one. Often times the orifice has to simultaneously manage a very small amount of oil, control a dynamic flow rate and dump a system’s compensator. In many applications -- especially for hydrostatic transmissions -- it is important to control the dynamic pressure of the system to avoid pressure spikes and pressure ripple.
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Tags:
Load Sensing,
pressure control valve,
proportional flow control valve,
combine pressure control valve and flow regulator,
hydraulic integrated circuit,
Orifices
How many times have you dialed in your Proportional Valve Driver to perfection only to find everything out of whack the next time you use the machine? If this sounds familiar, then you have probably experienced the effects of temperature-induced coil variations coupled with the use of a Voltage Controller that lacks current feedback. Although there are other factors that can cause performance variations, using the wrong driver in particular will cause major issues (if you need a little background on this subject click here). So, if you are tired of experiencing headaches over inconsistent or unrepeatable proportional function control, consider the following.
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Photo courtesy of Tesla Society of N.Y. |
The first thing to keep in mind is that you should ALWAYS use a PWM (Pulse Width Modulation) device to drive your Proportional Cartridge Valves. There are two types of PWM coil drivers: Voltage Control and Current Control (or current feedback) drivers. Both types will control the output voltage applied to the coil proportionally to the input or control signal by varying the PWM duty cycle of the output. The voltage applied across the coil with its respective resistance controls the current that generates the magnetic force needed to move the valve actuator.
A voltage-only driver is an open-loop device that outputs one specific voltage for each specific input signal. Knowing that coil resistance is temperature dependant, we can conclude that the valve output with this type of driver will also be temperature dependant.
Current Drivers on the other hand have the added feature of current feedback.
By closing the loop on current, the controller in essence monitors coil resistance and adjusts the voltage to compensate for any changes in resistance. So, after you have run your machine hard for four hours, you may see some hydraulic performance changes but the proportional performance should remain constant. That means no more jerky fine-feathering control when the machine is cold, and no more having all your functions slow down, or dealing with a deadband increase when it warms up.
The bottom line is this: unless you would be happy with the control of your machine changing with temperature, always specify valve drivers or machine controllers with current feedback on the outputs. HydraForce uses current feedback on all our valve drivers and machine controllers, but no matter who or what you use, save yourself some aspirin and make sure you use current feedback.
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Tags:
cartridge valves,
proportional valves,
Proportional Valve Drivers
Most of you reading this know the common benefits of hydraulic cartridge valves (click here for an excellent refresher). However, there are several key benefits routinely overlooked or misunderstood throughout the industry. HydraForce has dedicated significant efforts to innovation in cartridge valve technology — including the consolidation of multiple valve functions into a single cartridge, higher pressure and flow ratings, and improved machine control solutions.
Now, let’s talk about the benefits that go along with these improvements:
1. Performance
Traditionally, directional control functions were not considered a strong suit of cartridge valves. When searching online for a supplier of Directional Control Valves, a Google search will scarcely yield a "Cartridge Valve" return in the results. This has mostly to do with the limited flow capabilities of early cartridge valves. However, a lot has changed over the years, and today’s market could not be more ripe with Directional / Stack valve alternatives.
The bridge circuit below (named for its hydraulic similarities to the electronic "Wheatstone Bridge") has several key attributes which make it ideal for directional control. For starters, by having individual cartridge valves at the inlet of your A and B ports you get the distinct advantage of both meter-in and meter-out capabilities. Another advantage of this circuit is the ability to scale the appropriate cartridge valves for optimal flow. Other benefits include low-leakage poppet-type valving, lighter housing weight and the ability to achieve float or motor functions.
View/Download Directional Bridge Circuit graphic as:
PDF file (127 KB) | DXF file (201 KB)
HydraForce i-Design HF3D file (zipped 29 KB)
While we can’t deny there are inherent advantages of traditional directional stack valves, there are good reasons to consider this cartridge-valve alternative when designing your machine.
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Tags:
proportional valves,
benefits of cartridge valves,
Directional Control Valves,
cartridge valve serviceability,
Directional Stack Valve Alternatives,
Bridge Circuits
Daniel Bernoulli – this 18th century Swiss mathematician – has left quite the impact on the modern fluid power industry. One of his more popular discoveries is known as the Bernoulli Principle. This principle states that an increase in a fluid's speed decreases its pressure. If this is true, and we know it is, then the opposite must also be true: that a decrease in a fluid's speed increases its pressure. This principle applies to both the lifting of a wing on an airplane, as well as the lifting of a cartridge valve poppet.
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Tags:
cartridge valves,
solenoid operated four way valves,
Bernoulli Principle,
cartridge valve poppet,
HydraForce,
solenoid operated three way valves,
solenoid-operated direct-acting spool valves,
spool-type cartridge valves,
solenoid operated five way valves
I think everyone is familiar with the term “you can’t get blood from a stone.” This directly relates to the lack of system performance when under-sized sensing valves are used in a load sensing circuit. Several times a year we receive calls from people stating that they can’t seem to get the required or anticipated flow out of a valve or a particular leg of their circuit.
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Tags:
cartridge valves,
Priority Valves,
Cartridge Valve Pressure Compensators,
by-pass cpressure compensator
