Many small and medium power mobile machines - tractors, skid steer loaders, loader/backhoes, etc. - are designed to allow the use of a variety of hydraulically powered attachments. The hydraulic cylinders or motors of the attachments can be operated using the machine's factory-installed directional control valves, usually lever-operated valves.
If automating the hydraulic functions is required (e.g. laser or GPS), it is usually necessary to add electrically operated directional control valves - either on/off or proportional type - to the machine or attachment. It is common to make the connection between the machine's hydraulic system and the add-on valve via quick disconnects on the rear of the tractor. One of the machine's directional control valves is detented (locked) into a shifted position so flow from that valve's work port is directed to the "P" port of the add-on valve. The opposite work port of the machine's valve is connected to the "T" port of the add-on valve through another quick disconnect. This method works well. However, it opens the user to the risk of causing a catastrophic failure of the add-on valve.
If the operator inadvertently shifts the machine's valve handle in the wrong direction, even for a few seconds, flow from the pump will be directed to the "T" port of the add-on valve. Pressure can quickly rise to its maximum setting. The "To" core of the add-on valve likely is rated for only a few hundred PSI. Introducing "system pressure" to the "T" port can damage seals, crack housings and warp low-pressure rated parts.
A long-standing solution to prevent accidental flow reversal is to install a check valve between the "T" port of the second add-on valve and the quick disconnect on the tractor. The check valve allows free flow from the add-on valve to the tractor but blocks flow from the tractor to the add-on "T" port. This solution positively prevents the introduction of pressurized flow from the pump to the "T" port of the add-on valve. However, the check valve causes a higher-than-normal pressure difference through the "T" line of the add-on valve system. This added pressure robs horsepower, causes heat, and can in some cases cause excess pressure at the "T" port of the add-on valve sufficient to damage seals or other valve parts.
The new Flint Valve Saver end cover for the Danfoss
PVG 32 valve series provides an integral solution to
the problem of inadvertent flow reversal. It provides
a cost-effective, professional solution with low
pressure drop. Rather than blocking flow from
reaching the "T" port of the add-on valve, the FVS
diverts flow from the "T" to the "P" cores of the
valve, allowing the oil to pass directly to tank at low
The Flint Valve Saver also provides the tank, pilot pressure and LS pressure gauge ports that allow easy access to determine the critical pressures with each new valve install. Accurately reviewing these pressures allows the machine control technician to provide the installation that will ensure the longest possible service life and allow faster and easier troubleshooting of the automated machine control system in the future.
Automation of earth moving equipment
has significantly improved accuracy, is
much more productive than older
technologies, and lowers costs -
allowing contractors to be more
competitive while providing superior
results. Understandably, customers are
now requesting the automation of
thousands of machinery makes and
Each machine has a unique hydraulic
circuit, with its own unique combination
of brands and types of valves, pumps,
cylinders and other components.
Therefore, during the automation
process of each new model, qualified
machine control technicians work hard
to ensure that various minimum
pressures are available, maximum
pressures are not exceeded, and a
variety of conditions are met to
guarantee productive performance and
long service life to the end user. This
validates the competence of the machine control technician and dealer and provides the performance and service life that keep the customer coming back again and again.
The FVS provides the following features that allow a machine control technician to quickly confirm pressures, settings and conditions, while reducing the number of fittings and hoses necessary to install and confirm correct operation:
1. For applications using a machine's on-board reversible directional control valve and quick disconnects, the FVS protects expensive proportional valves from damage caused by the inadvertent actuation of machine valves by preventing the pressurization of the valve tank port.
2. The check valve incorporated in the FVS has a high flow rate reducing any induced tank port pressure from the check valve itself, increasing service life and reducing power losses and heat.
3. The FVS is integral to the purchased proportional valve. This reduces the number of hoses and fittings necessary to install other solutions.
4. Integral FVS packages provide a much more professional appearance than externally plumbed solutions. Customers paying thousands of dollars for the most modern machine control solutions should expect only the most professional installation.
5. A pilot pressure (PG) gauge port is incorporated in the FVS. Pilot pressure measurements are necessary in some applications, particularly low-flow open-center applications.
6. The FVS incorporates a second LS port allowing the "Daisy Chaining" of multiple LS signals.
7. A tank port (TG) gauge connection is integral to the FVS, allowing a quick, easy reading of the tank port pressure at the tank port gallery of the valve.
8. FVS valve gauge ports allow quick and professional installation of gauges to determine the actual pressures from load sensing, system pressure, pilot pressure and tank pressure. Determining the actual pressures when performing a prototype installation for a new machine model allows the machine control technician to make the most technically competent install, ensuring proper performance and service life for all future installations on that particular machine model. AS the old saying goes, "There's never enough time or money to do the job right the first time, but there's always time and money to do the job over!" The FVS allows the machine control technician to perform the install correctly the first time.
9. FVS modules are in stock and available for your next application requirement with same or next day availability.
© 2015 Flint Hydraulics, Inc
4099 B.F. Goodrich Blvd
Memphis, TN USA 38118
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