Gresham Gas Sampling products

FOX-VPS can offer manifolds to suit all types of Servo & Proportional Valves with either ISO 10372 or ISO4401 (CETOP) interfaces. Accumulators can be fitted to reduce pressure transients during cyclic duties, thus increasing the service life of the hydraulic system. Please discuss your requirement with FOX-VPS engineers to define the most suitable manifold system for your application.

As test specimens become more complex and sophisticated utilising the latest construction techniques and with operational requirements forever pushing design boundaries, inexorably they become more expensive. The Test Engineer’s worst nightmare is to damage the test article with an un-commanded event. FOX-VPS personnel have worked in close harmony with test engineers for many years to minimise this risk, identifying where cost effective, controllable and practical safety features are required.

FOX-VPS has developed a range of Hydraulic Service Manifolds (HSM) to compliment the FOX-VPS hydraulic test actuator range and to facilitate control and distribution of the hydraulic supply. Fitted with a pressure control valve, 3 micron pressure filter and pressure & return hydraulic accumulators, a FOX-VPS HSM provides control, filtration, pressure ripple smoothing and flow augmentation of the pressurised oil supply to the actuator. The HSM isolates the main pressure source from the test actuator (or distribution manifold) and provides interlocked independent control of oil outlets. Main supply pressure is selectable OFF/LO/HI by two solenoid valves with smooth transitions between LO and HI pressures in either direction.

FOX-VPS Hydraulic Distribution Manifolds (HDM) provide an interface between the HSM and individual hydraulic test actuators. Pilot, main and return lines are through drilled enabling a series of HDM to be connected together if desired. Each HDM actuator channel is fitted with an outlet isolating ball valve and a return line check valve. HDM are available as standard with 4, 6 & 8 outlets and are mounted on a sturdy steel frame complete with drip tray. Alternative channel quantities are available on request.

When setting up test rigs it is important for the test engineer to be able to quickly and accurately adjust the settings of the safety relief valves without removing them the system or applying pressure to their associated loading actuator. To address this requirement FOX-VPS produce a detented, laser engraved, micrometer style adjustment conversion for standard Sun relief valves which has a graduated sleeve fixed to the relief valve body and an handwheel pinned to the valve adjustment screw. Each valve has approximately 100 detented positions covering the valve range with settings repeatable to +/- 1 division. These controls can be fitted to any of the relief valves incorporated into FOX-VPS safety manifolds, details of which appear in the Hydraulic Manifold section of this site.

Accurate load limiting of servo controlled asymmetric actuators has been problematic since the servo valve was invented over 50 years ago. Conventional relief valves, whether limiting the individual actuator chamber pressures or the difference between them (cross port), cannot be set to limit the actuator load because the output force is not proportional to the differential pressure across the piston.

Spherical bearings are typically mounted inside a yoke, which is attached to the test article or test frame. FOX-VPS offer two ranges of bearing yokes, which can be attached to either test articles or machine bed-plates. Both types are fatigue rated and are provided with hardened ground pins and mounting bolts.

Commercially available spherical bearings typically offer around 7 degrees of rotational freedom in 2 axes, which is sometimes insufficient for certain types of test. Designed to fit in place of a standard spherical eye end FOX-VPS have devised a spherical ball end joint, complete with backlash adjustment, which provides up to 20 degrees of rotational freedom. Manufactured from high strength alloy steel and coated with a low friction, hard wearing bearing material, these devices can be interchanged with existing DIN648 style eye ends and actuator mounts to provide increased flexibility in the test laboratory.

For applications that require low rotational friction levels during testing, FOX-VPS manufacture a range of Cardan Joints that virtually eliminate lateral forces and moments when rotating under load. Designed to provide +/-8 degrees of rotation about the in plane axis these bearings are fatigue rated and backlash free and are sized to suit FOX-VPS ranges of Hydraulic Test Actuators.