|
Why they are used:
Overall, proportional valves are used in applications that require moderately accurate control of hydraulic fluid. To control a positively loaded cylinder, to control a hydraulic motor, to control hydraulic pressure within a system, or to accurately maintain the amount of pressure within a system.
The control source can be moved “proportionally” meaning it can be stopped in a number of positions, rather than the full ON-OFF of a directional valve. As a result, a proportional valve creates a smooth transition of fluid direction within a system, from one port, to equal pressure in both ports, to flow in the other port.
Proportional Valves are sized according to the size of the port or flange connections, and are rated at gallons per minute or with reference to a standard mounting pattern.
Pressure Control:
The fluid is ported out once the desired pressure is reached.
Flow Control:
The fluid is ported out once the desired speed us reached.
Directional Control:
The fluid is ported to the opposite port to control its direction.
Proportional Valve Repair Basics
- Visual inspection and evaluation on test stand for initial comparison to manufacturer's specifications
- Valve is disassembled into individual parts
- Every part is chemically cleaned with solvents
- Torque motor is dismantled down to wires and magnets
- All parts are inspected and checked to ensure they are within manufacturer's tolerances and specifications
- Failed parts are replaced with original manufacturer components
- LVDT’s are fully tested and flow or pressure calibrated
- Valve body is inspected to ensure it is within manufacturer's tolerances
- Body spool assembly is also checked for wear
- If needed body and/or body spool assembly is replaced with new Viton seals from the original manufacturer and a new filter from the valve manufacturer
- Torque motor and body are reassembled and tested to 100% of the performance specifications for flow and pressure established by the manufacturer
- Once tested to manufacturer's specifications, a test report and computer plot is included with the repair.
|
