1 I-3300-SRevised 1/1/85 Balanced Piston Relief ValvesCG/CS/CS5-03/06/10 SeriesCT/CT5/CG5-06/10 Series Vickers Relief ValvesOverhaul Manual2 Table of .. A. Purpose of Manual1.. B. Related Publications1.. C. Model Code2.. A. General2.. B. Basic Parts2.. of Operation3.. A. Pressure Relief3.. B. Venting3.. C. Remote Control3.. A. Installation Drawings4.. B. Circuit Connections4.. C. Piping and Tubing4.. D. Fluids and Seals4.. and Maintenance4.. A. Inspection4.. B. Cleanliness4.. C. Adding Fluid to the System4.. D. Hydraulic Fluid Recommendations5.. E. Overload Protection5.. F. Product Life5.. G. Troubleshooting Chart5.. A. Unit Removal5.. B. Service Tools5.. Standard Tools5.. C. Disassembly6.. D. Disassembly (C*5 Models)6.
2 E. Inspection, Repair and Replacement6.. F. Assembly8.. and Test8.. A. Start-Up8.. B. Test8.. EEaton Hydraulics, Incorporated 2000 All Rights Reserved3 Section I IntroductionA. Purpose Of ManualThis Manual describes operational characteristics, mainte-nance requirements, and Overhaul information for Vickersbalance piston Relief Valves . The information contained here-in pertains to the latest design series as listed in Table **-30CT/CS/CG-H10-**-30CT/CS/CG-06-**-50 CT/CS/CG-H06-**-50CS-03-**-50CS5-03-**-* *-90CT5/CG5-*06/*10-**-**-90 Table 1B. Related PublicationsService parts and installation dimensions are not containedin this Manual . The parts and installation drawings listed inTable 2 is available from any Vickers application &ServiceDrawingCG-06-**-20CG-06-**-40CG- 06-**-50CG-H06-*V-50CG-H10-*V-30CG-10-** -20CG-10-**-30CS-03-**-20CS-03-**-40CS-0 3-**-50CS-06-**-20CS-H06-*V-50CS-H10-*V- 30CS-10-**-20CS-10-**-30CT-06-**-20CT-06 -**-40CT-06-**-50CT-H06-*V-50CT-H10-*V-3 0CT-10-**-20CT-10-**-30CS5-*03-**-**-70 *-**-70CS5-*03-**-**-80 *-**-80CS5-*03-**-**-81 *-**-81CS5-*03-**-**-90 *-**-90CG5/CS5/CT5-*06-**-**-70CG5/CS5/C T5-*06-**-**-80CG5/CS5/CT5-*06-**-**-81C G5/CS5/CT5-*10-**-**-70CG5/CS5/CT5-*10-* *-**-80/81CG5/CS5/CT5-*10-**-**-90 Table 2
3 InstallationDrawingI-3302-SI-3306-SI-336 8-SI-3366-SI-3399-SI-3301-SI-3697-SI-330 1-SI-3305-SI-3369-SI-3304-SI-3367-SI-369 9-SI-3304-SI-3698-SI-3301-SI-3305-SI-336 9-SI-3367-SI-3699-SI-3301-SI-3698-SI-336 4-SI-3679-SI-3691-SI-3364-SI-3679-SI-369 1-SI-3365-SI-3680-SC. Model CodesVariations within each basic model series are covered in themodel code. Table 3 is a complete breakdown of the modelcodes covering these units. Service inquiries should alwaysinclude the complete unit model code as noted on CodeH - High flow(06/10 valve size only)11 Vent PressureV- High ventOmitted - Standard & low vent modelsExternal drain featureY- Sequence ValveOmitted - Standard Relief12P - Manual override( A & B pilot stage models only)1346987128102367 Multi-fluid capability (Viton Seals) Relief valvePort connectionG - Manifold or subplate mountedS - SAE straight threadT - NPTF Pipe ThreadSpool function(Pilot stage models only)13 Valve size03 - 3/8 inch06 - 3/4 inch10 - 1 1/4 inchPressure RangeB - 125-1000 PSIC - 500-2000 PSIF - 1500-3000 PSI13 DesignTable 3.
4 Model Code Breakdown1011124 Solenoid controlled(Pilot stage models only)9 Pilot stage(Solenoid controlled models only)A - Spring offsetC - Spring centered55 Section II DescriptionA. GeneralRelief Valves are devices used to limit maximum pressure inhydraulic systems. When system pressure starts to exceedthe pressure setting of the Relief valve, a controlled amount ofhydraulic fluid bypasses through the tank port and limits thesystem pressure to the valve setting. A fine incrementedadjustment assures precise regulation over wide Vickers Relief valve provides a fast response with very lowpressure override characteristics because of its two-stagebalance piston design. The balance piston Relief valve is sonamed because in normal operation it is in hydraulicbalance.
5 Further details are discussed in Section Basic PartsRelief Valves consist of two sections: the cover section andthe body section. The cover section includes a pressureadjustment screw, a heavy spring, a poppet, a seat, and avent connection. The body section includes a piston, a lightspring, a seat, and the port III Principles of OperationA. Pressure ReliefFigure 1 illustrates the basic valve operation. The valve pres-sure setting is determined by the adjusting screw positionwhich varies the heavy spring compression. The balancedpiston is normally held against the seat by the light pressure is present in chamber A and is connectedto chamber B through orifice closed position of the valve is shown in Figure 1A. Withsystem pressure less than the valve setting, the pilot poppetis held against its seat by spring force.
6 Pressures in cham-bers A and B equalize through orifice C. Thus, the piston ishydraulically in balance and held against its seat by the Screw(System Pressure)ToTankACIn Figure 1B the valve is shown throttling fluid to the tankport. This occurs when system pressure exceeds the heavyspring setting and forces the poppet away from its then flows through orifice C and chamber B, past thepoppet into chamber D, and down through the drain hole inthe center of the piston to the tank pressure in chamber B is limited by the setting of the heavyspring. When pressure in chamber A exceeds chamber B sufficiently, pressure unbalance overcomes the force of the light spring and lifts the piston. Excess fluid then flows pastthe bottom of the piston to the system pressure drops below the valve setting,thepoppet reseats.
7 Control flow through orifice C stops and pressures in chambers A and B are again light spring then forces the piston toward the seat whileorifice C continues to equalize pressure between chambersA and B. When the balance piston is closed against its seat,all flow through orifice C VentingThe High-Vent option ( V in the model code) is used whenit is necessary to maintain pilot pressure for other Valves inthe system. This option provides a faster valve de-venting(closing) action. Higher pressure (approximately 80 PSIG) ismaintained when the valve is vented because a heavierpiston spring is Valves can be vented to unload pump delivery to tank inthe following manner:Connect a shut-off valve to the vent port of the main Relief B above the Balanced piston can be opened to tank(see Figure 1B).
8 This removes pressure at the top of thebalanced piston. Pressure in chamber A overcomes the lightspring, unseats the Balanced piston, and diverts all pumpdelivery to solenoid controlled directional valve (C*5) may be used to vent flow to tank. This directional valve is mounted on top of a standard Relief valve to form a single package. See Figure Remote ControlThe main Relief valve may be adjusted from a remote locationby using another adjustable valve similar in function to themain Relief valve pilot stage (see Figure 2.) Flow past thepoppet of the remote control valve is directed to tank. Thefollowing rules should be maintained for optimum results:Figure Keep hydraulic lines (tubing) as short as Set main Relief valve 200-300 PSIG above maximumoperating pressure.
9 DO NOT exceed the valve pressure Set remote control valve to maximum operating Check system for stability characteristics. If the systemis unstable, reduce the line length and/or proceed to step Install an orifice in the vent opening of the main reliefvalve cover and in the pressure port of the remote control NOT go below inch diameter or a malfunction couldresult. Orifices should be as large as possible to prevent exces-sive pressure drop and still maintain noise free IV InstallationA. Installation DrawingsThe installation drawings listed in Table 2 will show installa-tion dimensions, port locations and operating , subplate and bolt kit information is also tank line must be piped directly to tank tominimize back pressure. The drain line from theremotely operated valve (vent valve) must also bedirectly piped to tank.
10 Any pressure in the drain lineis additive to the pressure setting of the Circuit ConnectionThreaded type CT/CS Valves are usually connected directlyin the pressure line. Circuit flow passes through the portslocated on opposite sides of the valve body. The bottom port(opposite the cover) is the return flow port and is connectedto tank. These Valves may be teed into the pressure line byplugging or blocking one of the pressure outlet type gasket mounted Valves are teed into pressure tee is connected to the pressure port of the valve sub-plateor manifold. The return port is connected to tank. The valvemust be mounted against a flat, ported mounting or replacement of CG Valves is simplified in that pipingneed not be Piping And Tubing1. All pipes and tubing must be thoroughly cleanedbefore installation.