SECTION 6 - MOTION CONTROL VALVES - …

1 SECTION 6 - MOTION CONTROL VALVESCONTENTSI ntegrated Hydraulics LtdIntegrated Hydraulics IncCollins Road, Heathcote Ind. Est., Warwick, CV34 6TF, Spinach Drive, Mentor, Ohio 44060, USATel: +44 (0) 1926 881171 Fax: +44 (0) 1926 315729 Tel: (440) 974 3171 Fax: (440) 974 3170 Website: : SECTION contains a most extensive range of overcentre and MOTION CONTROL cartridges, includingnormal, part vented and fully vented versions. Suitable for load holding, load safety and to preventload runaway, giving low pressure drops, various pilot ratios and excellent stability to all types ofmoving cartridgepilot assisted reliefwith check1 CERO vercentrecartridge as 1 CEseries with reliefbalanced1 CEB/1 CEBDO vercentrecartridge as 1 CEseries with reliefand pilot balancedTo CONTROL moving loads and preventload runaway, giving load holdingand hose failure safetyAs 1CE series but with reliefbalanced against back pressureallowing the valve to be used withclosed centre DCV with service linereliefsAs 1CE series but balanced on reliefand pilot areas.

2 For use onproportional systems or applicationswith widely varying back pressures350 bar(5000 psi)300 litres/min(80 US GPM)350 bar(5000 psi)300 litres/min(80 US GPM)350 bar(5000 psi)300 litres/min(80 US GPM)6-1116-1516-1816-2056-2416-1316-1716 -1736-1916-1936-2516-255 SECTIONSERIESAPPLICATIONRANGEPAGE6-1216- 1616-2111 CELO vercentre cartridgewith constantcounterbalancepressureThis valve is used in systems wherethe machine framework introducesinstability, such as telescopichandlers, cranes and concretepumpsFor use on boom lock applicationsgiving load-holding and hose failuresafety. With or without internal relief1 CPB/1 CPBDP ilot controlledcartridges withoutrelief function,unaffected by backpressure6-1356-1756-2256-1376-1396-1 776-1976-2651 CEECLine mountedovercentre withmake up parts in bodystyleMotion CONTROL VALVES with make upchecks and cross line relief functionfor use on transmission systems orsingle rod cylinders when dual reliefis required6-3016-311350 bar(5000 psi)300 litres/min(80 US GPM)1 CEESH/1 CEECSHAs 1 CEEC serieswith brake parts in bodystyleAs 1 CEEC series but with addedbrake shuttle for removal of springapplied park brakes350 bar(5000 psi)300 litres/min(80 US GPM)6-2716-2816-3216-3416380 bar(5510 psi)140 litres/min(37 US GPM)400 bar(5800 psi)

3 300 litres/min(80 US GPM)1 CEE1 CEBBRDRMV1 CEPILOT1 CEEI ntegrated Hydraulics LtdIntegrated Hydraulics IncCollins Road, Heathcote Ind. Est., Warwick, CV34 6TF, Spinach Drive, Mentor, Ohio 44060, USATel: +44 (0) 1926 881171 Fax: +44 (0) 1926 315729 Tel: (440) 974 3171 Fax: (440) 974 3170 Website: : CONTROLMANLIFTWHEEL MOTORTYPICAL CIRCUIT EXAMPLESLoad holding and load safety provided by dualovercentre VALVES protecting the operator from hosefailure and giving him a smooth overcentres preventing load runaway intransmission systems forward and VALVES are required where back pressuresvary as above in proportional valve circuits where flowis metered in and out of the directional CONTROL lowering and soft stop for winches usingovercentre combined with brake shuttles for springapplied adjustment range and Max setting figures shown throughout this catalogue give the design range for each valve.

4 Higher or lower values may be attainable but should not be used without first contacting our Engineering must ALWAYS be carried out using an appropriate gauge and it must NOT be assumed that screwing an adjusterto its maximum or minimum position will yield the maximum or minimum stated design setting for that or cylindermounted BoomLocvalves incorporating1 CPB(D) cartridgeand additional reliefcartridge overcentre VALVES aresuitable for use on the boom anddipper cylinders of an excavator tohelp the manufacturer or usercomply with standard bar(5800 psi)550 litres/min(145 US GPM)6-400to6-491 SECTIONSERIESAPPLICATIONRANGEPAGEOVERCEN TRE VALVES leakage characteristics with maximum leakage of up to for VALVES up to 200 L/min capacity and up to 4ml/minfor VALVES with 300 L/min cartridge has three ports, a cylinder port (1), a valve port(2) and a pilot port (3).

5 If pressure, above the setting of thevalve is applied to the cylinder port it will open as a applied to the valve port pressure will open a lowpressure check allowing free flow into the cylinder applied to the pilot port acts over a larger area onthe poppet than the area referenced to the cylinder port, sothe valve will open at a low most applications the relief setting should beapproximately times higher than the maximum loadinduced pressure. This ensures that with the maximum loadon the actuator the valve will remain closed until pilotpressure is applied. The pilot pressure required to open thevalve will depend on the pilot ratio that is the ratio betweenthe relief area and the pilot area. The pilot pressure can becalculated:Pilot pressure = Valve Setting - Load PressurePilot RatioA typical application would entail mounting the overcentrevalve in or on the end cap of a cylinder (fig 2).

6 The cylinderport of the valve being connected to the full bore area of thecylinder, the valve port to the directional CONTROL line A and thepilot connected to the annulus inlet, line B and so to thedirectional CONTROL line B. As soon as the pressure rises in theinlet port of the annulus (line B) to retract the rod to a pointwhere it reaches the required pilot pressure the actuator will There are now many types of overcentre or MOTION controlvalves available to the designer of hydraulically operatedmachines, each one has its own place and specific benefits tothe user. The function of these VALVES can be divided intothree basic Load Holding; where the overcentre valve prevents themovement of a load when the directional valve is in theneutral position.

7 Permitting the use of open centre directionalvalves and negating leakage past the spool of closed centredirectional Load CONTROL ; where the overcentre valve prevents theactuator running ahead of the pump due to the load inducedenergy thereby eliminating cavitation in the actuator and lossof Load Safety. In the case of hose failure an overcentrevalve mounted onto or into an actuator will preventuncontrolled movement of the load. When a boom is used asa crane then hose failure protection is vital as the loss of loadcontrol could cause damage to people or of these functions is applicable to linear or rotarymotion. The standard overcentre valve (fig 1) can be described as apilot assisted relief valve with an integral free flow check.

8 Thedifference between this design of valve and a pilot check isthat the check valve will open fully as soon as the pilotpressure is sufficient to open the valve because the onlyresistance to opening is the pressure locked in to the cylinderport. With an overcentre valve the pilot pressure has toovercome the force of the spring which is reduced by loadpressure. This ensures a gradual opening and a metering ofthe flow as it passes the poppet. Integrated Hydraulicsovercentre VALVES consist of a poppet that seals flow from anactuator, a check element, which permits free flow to theactuator and a pilot SECTION that opens the poppet allowingflow from the actuator at a controlled rate. There are twobasic designs, each with several variants. The direct actingdesign, whereby the pressure in the actuator acts on the fullarea of the nose of the poppet, is ideal for flows up to 200L/min whereas the differential area design, whereby thepressure acts on an annular area, is suitable for flows up to300 L/min.

9 Being of poppet type both designs exhibit excellentPILOT (3)VALVE (2)CYLINDER (1)BA123 Figure 1. 1CE Standard Overcentre ValveFigure 2. Overcentre valve mounted in end cap ofcylinder 21/03/2007 11:54 Page 2begin moving at the flow at which the pressure setting wasmade. If the load causes the flow to increase then the inletwill be starved of oil and the pressure will begin to drop at thisport. The reducing pressure will be sensed at the pilotallowing the spring to begin to close the valve preventing loadrun-away. In this way the valve will continually meter,controlling the load throughout its movement. When thepressure needed to move the load is higher than the pilotpressure needed to fully open the valve the only restrictionproduced is the pressure drop due to flow in the fully opencondition.

10 With the standard overcentre the spring chamber is ventedthrough the poppet to the valve port which creates a problemif there are varying or high back pressures. Pressure in the valve port increases the effective setting ofthe valve by a factor equivalent to the pilot ratio plus one. Thismeans that if there is a standing back pressure of 50 bar witha pilot ratio of 5:1 the effective relief setting would beincreased by 300 bar. This creates problems if the applicationdemands a closed centre directional valve and the utilisationof service line reliefs. The relief VALVES will operate to limitinlet pressure but will not act if there is an external load whichneeds to be limited. The overcentre will not allow oil past theseat due to the back pressure created by the service linerelief VALVES .