Directional valves include integrated electronics
Designated the KB Series, these new Vickers valves reportedly combine advanced electrohydraulic technology with integrated electronics in a single package. Available in NFPA size 03 through 05, KB valves carry a 5,000 psi rating. Vickers integrates all electronics and transducers into the valve envelope, eliminating "stuck-on" electronics. Doing so makes the package much less susceptible to external damage. Users can place KB valves directly on the motor or cylinder. In addition, the KB Series provides protection against moisture and washdown, allowing full submersion in one meter of water for as long as 30 minutes. Vickers, Inc. FAX: 810-641-4232.
Award-winning pump available in new size
An SAE B flange and 15-tooth input shaft allow mounting the Series 45 57-cubic-centimeter/revolution variable displacement pump from Sauer Sundstrand into existing 45 cubic-centimeter/revolution open-circuit pump applications. The pump recently won the AE50 award from the American Society of Agricultural Engineers as one of the 50 best engineering developments introduced to the agricultural marketplace. A 74 cubic-centimeter/revolution version of the Series 45 will be introduced this fall. Sauer-Sundstrand Company, FAX: 515-239-6618.
Vane pumps meet mobile/industrial needs
Series PFVH and PFVI fixed displacement single and tandem vane pumps from Parker Hannifin's Pump and Motor Division are claimed to be dirt tolerant and generally quieter than competitive gear pumps. A ten-vane design, the PFVH is intended for mobile applications. Designed for the in-plant environment, the 12-vane PFVI is meant for machines like metal forming presses and general power units. The pumps come in displacements from 2.3 to 11.8 cubic inches per revolution. They deliver 12 to 98 gpm at 1,200 rpm and 100 psi. Series PFVH pumps operate at speeds as high as 2,700 rpm and provide continuous operating pressure of 3,000 psi; PFVI pumps operate at speeds to 1,800 rpm and deliver continuous operating pressure to 2,500 psi. Parker Motor and Pump Division, FAX: 216-486-3153.
Gear pump with manual override
An integrated package, the Power-Packer(R) electrohydraulic pump consists of a bi-directional motor powered by 12V dc, reservoir, gear pump, and manual-override bi-directional hand pump with a displacement of 0.37 cubic-inch/stroke. This pump is designed to satisfy the hydraulic actuation requirements of RV slide-rooms, powering the room in or out. Weighing 1.4 lbs without oil, the pump features relief valves in both ports. It can produce 160 cubic-inches/minute of flow at 600 psi. Maximum pressure for the pump is 1,200 psi, and recommended working pressure 800 psi. Relief valves can be set anywhere between 0 and 1,200 psi. Power-Packer, a unit of Applied Power Inc. 414-781-5000.
Variable displacement pumps run quietly at rated pressure
Upgraded versions of the VPV vane-type hydraulic pumps, WhisperTM Pumps from Robert Bosch are rated at 3,000 psi continuous. Many applications require attention to pump noise. Made in sizes from 1 cubic inch to 10 cubic inches, Whisper Pumps offer low noise while operating at maximum flow. The VPV-16 (1 cubic inch) generates 67 dBA at 3,000 psi and 1,800 rpm. Its larger stablemate, the VPV-164 (10 cubic inches) generates 77 dBA at the same pressure and speed. Concerning the pumps' performance, Pump Product Manager Jim Chester of Bosch Fluid Power says that "3,000 psi continuous operating pressures for a variable volume vane pump is quite an achievement. No one else has been able to do this." Robert Bosch Fluid Power Corp., FAX: 800-611-2660.
Controller handles closed-loop jobs
Intended for almost any hydraulic application that demands precise, closed-loop control of pressure, flow, speed, force, or torque, the microprocessor-based Venus controller from Denison drives hydraulic actuations directly using pulse width modulation. A feedback device represents the controlled system parameter, and an error amplifier in Venus compares the command signal with the feedback device's signal. An error signal is then fed to the driver stage. The new controller produces three outputs: high-current, low-voltage, and low-current. The first is a two-channel PWM driver with current feedback for precise control of coil current despite changes in coil resistance. System configuration is done from an RS232 port. Denison Hydraulics, FAX: 937-644-4554.
System provides on-demand power braking
Engineers mechanically link The Citation Power Cylinder Brake System's brake pedal to a modulating valve. Moving the pedal operates a pressure switch or mechanical switch, and starts a dc-powered motor/pump. The motor/pump produces flow to the valve. Initially, there's no pressure in the brakes, because the fluid has an unrestricted path to reservoir. As a user depresses the pedal, force on the modulating valve's piston increases and it begins to restrict the return port connection. Backpressure on the pump is communicated to the brake actuator. As pedal input increases, so does flow restriction (and brake pressure). If electrical power fails, the valve's piston seals the return port, and the spool acts as an unboosted master cylinder. The system "is independent of the main hydraulic system," explains Operations Manager Paul Spratt of Commercial Intertech, "so it's energy efficient." The system consumes no power until the user actuates the vehicle's brakes. Commercial Intertech, Vehicle Systems Division, FAX: 612-533-0082.
Proportional valves satisfy open- or closed-loop applications
This direct-operated valve, the Model WRSE from Rexroth Corp., regulates the direction and volume of fluid flow to an actuator. Doing so permits precise control of position, force, and velocity. By controlling actuator acceleration and deceleration, machine cycle times can be optimized. A high-end proportional valve, the WRSE is suitable for closed-loop position and speed control, as well as open-loop applications. Valve electronics are integrated into the electronic enclosure on the valve. The valve interface conforms to standard ISO/-ANSI/NFPA D 03 and D 05 mounting configurations. Maximum pressure rating is 4,600 psi with nominal flow rating of 10 gpm for the D 03 size and 20 gpm for the D 05 size. The Rexroth Corp., Industrial Hydraulics Division, FAX: 610-694-8467.