Home>Products>REXROTH Directional spool valves>REXROTH 4WE 10 E3X/CW230N9K4 R900911869 Directional spool valves
REXROTH 4WE 10 E3X/CW230N9K4 R900911869 Directional spool valves
category
REXROTH Directional spool valves
REXROTH 4WE 10 E3X/CW230N9K4 SPECIFICATIONS
- REXROTH
4WE 10 E3X/CW230N9K4
- 75.0 LB
- Flange Mount
- Right Hand (CW)
- 3520V35A12-1AC22R
- 3
- Flange
- 5/16 in
- Standard Pilot
- Piston Pump INC2020-07-10 09:46:19
Welcome to my shop! Glad to serve you! Please send your question!
REXROTH 4WE 10 E3X/CW230N9K4 R900911869 Directional spool valves Compare similar products
- 1.25 in
- Straight w/ Key
- 3520V
- 2 7/8 in
- Buna-N
- 1800
- N/A
- SAE C, 2 Bolt
- Single Shaft Seal
- N/A
- 1800
- 1800
- N/A
- 12 gal/min @ 1200 rpm, 18 gal/min @ 1800 rpm
- N/A
- N/A
- N/A
- N/A
- N/A
- 35 gal/min @ 1200 rpm, 52.5 gal/min @ 1800 rpm
- 3520V35A12-1AC22R
- 3000
- 2500
- 18
- 52.5
- N/A
- Outlet 45° CW from Inlet
- Outlet Opposite Inlet
- 3/4 in Code 61
- 1 1/4 in Code 61
- 2.5
- 6.8
REXROTH 4WE 10 E3X/CW230N9K4 REXROTH 4WE 10 E3X/CW230N9K4 R900911869 Directional spool valves Sponsored products related to this item
REXROTH 4WE 10 E3X/CW230N9K4 R900911869 Directional spool valves Series Supply | |||||||||
---|---|---|---|---|---|---|---|---|---|
No. | Brand | U | D | d | B | L | J | A | C |
100DC72300B | KOYO | - | 720 mm | 500 mm | 300 mm | - | - | - | 5580 kN |
140FSH230 | Timken | - | 230 mm | 140 mm | - | - | - | - | 80 mm |
160FS230 | Timken | - | 230 mm | 160 mm | - | - | - | - | 80 mm |
160FSF230 | NSK | 200 mm | 230 mm | 160 mm | 105 mm | - | - | - | 1250 kN |
110PCR2301 | NSK | - | - | 110 mm | - | 230 mm | 140 mm | 120 mm | - |
110PCR2303 | NSK | - | - | 110 mm | - | 230 mm | 170 mm | 135 mm | - |
VKHB 2304 | SKF | - | 140,000 | 65,000 | - | - | - | - | - |
VKHB 2306 | SKF | - | 150,000 | 100,000 | - | - | - | - | - |
YSA 205-2FK + H 2305 | SKF | - | 52 mm | 20 mm | 24 mm | - | - | - | 15 mm |
YSA 205-2FK + HE 2305 | SKF | - | 52 mm | 19.05 mm | 24 mm | - | - | - | 15 mm |
YSA 206-2FK + H 2306 | SKF | - | 62 mm | 25 mm | 28 mm | - | - | - | 18 mm |
REXROTH 4WE 10 L3X/CW230N9K4 R900915669 Directional spool valves | Shaft End RPM [Max:75.0 LB; Shaft End Pressure [Max:Flange Mount; Shaft End Flow @ RPM:Right Hand (CW); Minor Diameter [Min:3520V35A12-1AC22R; Displacement Shaft End (cu in/revolution):3; Pilot Type:Flange; Mounting Flange:5/16 in; Shaft Key:Standard Pilot; GPM @ 1,800 rpm, Shaft End:1.25 in; Spline Description:Straight w/ Key; Pump Series:3520V; Shaft Length:2 7/8 in; Seal Material:Buna-N; Max. RPM [Max:1800; Minor Diameter:N/A; Mounting Flange:SAE C, 2 Bolt; Shaft Seal Type:Single Shaft Seal; Spline Description:N/A; Cover End RPM [Max:1800; Shaft End RPM [Max:1800; Controlled Flow Rate:N/A; Cover End Flow @ RPM:12 gal/min @ 1200 rpm, 18 gal/min @ 1800 rpm; Major Diameter [Max:N/A; Major Diameter [Min:N/A; Minor Diameter [Max:N/A; Minor Diameter [Min:N/A; Relief Valve Setting:N/A; Shaft End Flow @ RPM:35 gal/min @ 1200 rpm, 52.5 gal/min @ 1800 rpm; Manufacturer Part No.:3520V35A12-1AC22R; Cover End Pressure [Max:3000; Shaft End Pressure [Max:2500; GPM @ 1,800 rpm, Cover End:18; GPM @ 1,800 rpm, Shaft End:52.5; Integral Valve Configuration:N/A; Port Orientation - Cover End:Outlet 45° CW from Inlet; Port Orientation - Shaft End:Outlet Opposite Inlet; Pressure Port Size, Cover End:3/4 in Code 61; Pressure Port Size, Shaft End:1 1/4 in Code 61; Displacement Cover End (cu in/revolution):2.5; Displacement Shaft End (cu in/revolution):6.8; |
REXROTH 4WE 6 H6X/EW230N9K4 R900912494 Directional spool valves | Shaft Type:75.0 LB; Rotation:Flange Mount; Port Orientation - Cover End:Right Hand (CW); Spline Description:3520V35A12-1AC22R; Port Type:3; Pressure Port Size, Shaft End:Flange; Relief Valve Setting:5/16 in; Cover End RPM [Max:Standard Pilot; Mounting:1.25 in; Manufacturer Part No.:Straight w/ Key; Pump Series:3520V; Shaft Length:2 7/8 in; Seal Material:Buna-N; Max. RPM [Max:1800; Minor Diameter:N/A; Mounting Flange:SAE C, 2 Bolt; Shaft Seal Type:Single Shaft Seal; Spline Description:N/A; Cover End RPM [Max:1800; Shaft End RPM [Max:1800; Controlled Flow Rate:N/A; Cover End Flow @ RPM:12 gal/min @ 1200 rpm, 18 gal/min @ 1800 rpm; Major Diameter [Max:N/A; Major Diameter [Min:N/A; Minor Diameter [Max:N/A; Minor Diameter [Min:N/A; Relief Valve Setting:N/A; Shaft End Flow @ RPM:35 gal/min @ 1200 rpm, 52.5 gal/min @ 1800 rpm; Manufacturer Part No.:3520V35A12-1AC22R; Cover End Pressure [Max:3000; Shaft End Pressure [Max:2500; GPM @ 1,800 rpm, Cover End:18; GPM @ 1,800 rpm, Shaft End:52.5; Integral Valve Configuration:N/A; Port Orientation - Cover End:Outlet 45° CW from Inlet; Port Orientation - Shaft End:Outlet Opposite Inlet; Pressure Port Size, Cover End:3/4 in Code 61; Pressure Port Size, Shaft End:1 1/4 in Code 61; Displacement Cover End (cu in/revolution):2.5; Displacement Shaft End (cu in/revolution):6.8; |
REXROTH 4WE 6 H6X/EW230N9K4/V R900977500 Directional spool valves | Mounting Flange:75.0 LB; Shaft Key:Flange Mount; Displacement Cover End (cu in/revolution):Right Hand (CW); Rotation:3520V35A12-1AC22R; Pilot Type:3; Mounting:Flange; Port Type:5/16 in; Major Diameter [Max:Standard Pilot; Minor Diameter [Max:1.25 in; Pump Series:Straight w/ Key; Pump Series:3520V; Shaft Length:2 7/8 in; Seal Material:Buna-N; Max. RPM [Max:1800; Minor Diameter:N/A; Mounting Flange:SAE C, 2 Bolt; Shaft Seal Type:Single Shaft Seal; Spline Description:N/A; Cover End RPM [Max:1800; Shaft End RPM [Max:1800; Controlled Flow Rate:N/A; Cover End Flow @ RPM:12 gal/min @ 1200 rpm, 18 gal/min @ 1800 rpm; Major Diameter [Max:N/A; Major Diameter [Min:N/A; Minor Diameter [Max:N/A; Minor Diameter [Min:N/A; Relief Valve Setting:N/A; Shaft End Flow @ RPM:35 gal/min @ 1200 rpm, 52.5 gal/min @ 1800 rpm; Manufacturer Part No.:3520V35A12-1AC22R; Cover End Pressure [Max:3000; Shaft End Pressure [Max:2500; GPM @ 1,800 rpm, Cover End:18; GPM @ 1,800 rpm, Shaft End:52.5; Integral Valve Configuration:N/A; Port Orientation - Cover End:Outlet 45° CW from Inlet; Port Orientation - Shaft End:Outlet Opposite Inlet; Pressure Port Size, Cover End:3/4 in Code 61; Pressure Port Size, Shaft End:1 1/4 in Code 61; Displacement Cover End (cu in/revolution):2.5; Displacement Shaft End (cu in/revolution):6.8; |
REXROTH 3WE 6 B6X/EW230N9K4 R900915674 Directional spool valves | Port Type:75.0 LB; Major Diameter [Max:Flange Mount; Seal Material:Right Hand (CW); Manufacturer Part No.:3520V35A12-1AC22R; Mounting Flange:3; Minor Diameter:Flange; Port Orientation - Cover End:5/16 in; Pressure Port Size, Cover End:Standard Pilot; Relief Valve Setting:1.25 in; Shaft End Flow @ RPM:Straight w/ Key; Pump Series:3520V; Shaft Length:2 7/8 in; Seal Material:Buna-N; Max. RPM [Max:1800; Minor Diameter:N/A; Mounting Flange:SAE C, 2 Bolt; Shaft Seal Type:Single Shaft Seal; Spline Description:N/A; Cover End RPM [Max:1800; Shaft End RPM [Max:1800; Controlled Flow Rate:N/A; Cover End Flow @ RPM:12 gal/min @ 1200 rpm, 18 gal/min @ 1800 rpm; Major Diameter [Max:N/A; Major Diameter [Min:N/A; Minor Diameter [Max:N/A; Minor Diameter [Min:N/A; Relief Valve Setting:N/A; Shaft End Flow @ RPM:35 gal/min @ 1200 rpm, 52.5 gal/min @ 1800 rpm; Manufacturer Part No.:3520V35A12-1AC22R; Cover End Pressure [Max:3000; Shaft End Pressure [Max:2500; GPM @ 1,800 rpm, Cover End:18; GPM @ 1,800 rpm, Shaft End:52.5; Integral Valve Configuration:N/A; Port Orientation - Cover End:Outlet 45° CW from Inlet; Port Orientation - Shaft End:Outlet Opposite Inlet; Pressure Port Size, Cover End:3/4 in Code 61; Pressure Port Size, Shaft End:1 1/4 in Code 61; Displacement Cover End (cu in/revolution):2.5; Displacement Shaft End (cu in/revolution):6.8; |
REXROTH 4WE 6 E6X/EW230N9K4/B10 R901130020 Directional spool valves | Shaft End Flow @ RPM:75.0 LB; Shaft Length:Flange Mount; Seal Material:Right Hand (CW); Weight:3520V35A12-1AC22R; Major Diameter [Max:3; Cover End RPM [Max:Flange; Mounting:5/16 in; Displacement Shaft End (cu in/revolution):Standard Pilot; Controlled Flow Rate:1.25 in; Integral Valve Configuration:Straight w/ Key; Pump Series:3520V; Shaft Length:2 7/8 in; Seal Material:Buna-N; Max. RPM [Max:1800; Minor Diameter:N/A; Mounting Flange:SAE C, 2 Bolt; Shaft Seal Type:Single Shaft Seal; Spline Description:N/A; Cover End RPM [Max:1800; Shaft End RPM [Max:1800; Controlled Flow Rate:N/A; Cover End Flow @ RPM:12 gal/min @ 1200 rpm, 18 gal/min @ 1800 rpm; Major Diameter [Max:N/A; Major Diameter [Min:N/A; Minor Diameter [Max:N/A; Minor Diameter [Min:N/A; Relief Valve Setting:N/A; Shaft End Flow @ RPM:35 gal/min @ 1200 rpm, 52.5 gal/min @ 1800 rpm; Manufacturer Part No.:3520V35A12-1AC22R; Cover End Pressure [Max:3000; Shaft End Pressure [Max:2500; GPM @ 1,800 rpm, Cover End:18; GPM @ 1,800 rpm, Shaft End:52.5; Integral Valve Configuration:N/A; Port Orientation - Cover End:Outlet 45° CW from Inlet; Port Orientation - Shaft End:Outlet Opposite Inlet; Pressure Port Size, Cover End:3/4 in Code 61; Pressure Port Size, Shaft End:1 1/4 in Code 61; Displacement Cover End (cu in/revolution):2.5; Displacement Shaft End (cu in/revolution):6.8; |
REXROTH 4WE 6 D6X/OFEW230N9K4/V R900917840 Directional spool valves | GPM @ 1,800 rpm, Cover End:75.0 LB; Mounting:Flange Mount; Shaft End Pressure [Max:Right Hand (CW); Displacement Cover End (cu in/revolution):3520V35A12-1AC22R; Shaft Key:3; Displacement Shaft End (cu in/revolution):Flange; Cover End Flow @ RPM:5/16 in; Relief Valve Setting:Standard Pilot; Shaft Dia.:1.25 in; Major Diameter [Max:Straight w/ Key; Pump Series:3520V; Shaft Length:2 7/8 in; Seal Material:Buna-N; Max. RPM [Max:1800; Minor Diameter:N/A; Mounting Flange:SAE C, 2 Bolt; Shaft Seal Type:Single Shaft Seal; Spline Description:N/A; Cover End RPM [Max:1800; Shaft End RPM [Max:1800; Controlled Flow Rate:N/A; Cover End Flow @ RPM:12 gal/min @ 1200 rpm, 18 gal/min @ 1800 rpm; Major Diameter [Max:N/A; Major Diameter [Min:N/A; Minor Diameter [Max:N/A; Minor Diameter [Min:N/A; Relief Valve Setting:N/A; Shaft End Flow @ RPM:35 gal/min @ 1200 rpm, 52.5 gal/min @ 1800 rpm; Manufacturer Part No.:3520V35A12-1AC22R; Cover End Pressure [Max:3000; Shaft End Pressure [Max:2500; GPM @ 1,800 rpm, Cover End:18; GPM @ 1,800 rpm, Shaft End:52.5; Integral Valve Configuration:N/A; Port Orientation - Cover End:Outlet 45° CW from Inlet; Port Orientation - Shaft End:Outlet Opposite Inlet; Pressure Port Size, Cover End:3/4 in Code 61; Pressure Port Size, Shaft End:1 1/4 in Code 61; Displacement Cover End (cu in/revolution):2.5; Displacement Shaft End (cu in/revolution):6.8; |
REXROTH 4WE 10 F3X/CW230N9K4 R900909021 Directional spool valves | Pressure Port Size, Cover End:75.0 LB; Shaft Seal Type:Flange Mount; Port Size:Right Hand (CW); Max. RPM [Max:3520V35A12-1AC22R; Shaft Dia.:3; Weight:Flange; Major Diameter [Max:5/16 in; Relief Valve Setting:Standard Pilot; Cover End RPM [Max:1.25 in; Model No.:Straight w/ Key; Pump Series:3520V; Shaft Length:2 7/8 in; Seal Material:Buna-N; Max. RPM [Max:1800; Minor Diameter:N/A; Mounting Flange:SAE C, 2 Bolt; Shaft Seal Type:Single Shaft Seal; Spline Description:N/A; Cover End RPM [Max:1800; Shaft End RPM [Max:1800; Controlled Flow Rate:N/A; Cover End Flow @ RPM:12 gal/min @ 1200 rpm, 18 gal/min @ 1800 rpm; Major Diameter [Max:N/A; Major Diameter [Min:N/A; Minor Diameter [Max:N/A; Minor Diameter [Min:N/A; Relief Valve Setting:N/A; Shaft End Flow @ RPM:35 gal/min @ 1200 rpm, 52.5 gal/min @ 1800 rpm; Manufacturer Part No.:3520V35A12-1AC22R; Cover End Pressure [Max:3000; Shaft End Pressure [Max:2500; GPM @ 1,800 rpm, Cover End:18; GPM @ 1,800 rpm, Shaft End:52.5; Integral Valve Configuration:N/A; Port Orientation - Cover End:Outlet 45° CW from Inlet; Port Orientation - Shaft End:Outlet Opposite Inlet; Pressure Port Size, Cover End:3/4 in Code 61; Pressure Port Size, Shaft End:1 1/4 in Code 61; Displacement Cover End (cu in/revolution):2.5; Displacement Shaft End (cu in/revolution):6.8; |
REXROTH 4WE 6 G6X/EW230N9K4/V R900977499 Directional spool valves | Port Type:75.0 LB; Displacement Cover End (cu in/revolution):Flange Mount; Model No.:Right Hand (CW); Shaft End RPM [Max:3520V35A12-1AC22R; Pilot Type:3; Minor Diameter:Flange; Port Size:5/16 in; Controlled Flow Rate:Standard Pilot; GPM @ 1,800 rpm, Shaft End:1.25 in; Pressure Port Size, Cover End:Straight w/ Key; Pump Series:3520V; Shaft Length:2 7/8 in; Seal Material:Buna-N; Max. RPM [Max:1800; Minor Diameter:N/A; Mounting Flange:SAE C, 2 Bolt; Shaft Seal Type:Single Shaft Seal; Spline Description:N/A; Cover End RPM [Max:1800; Shaft End RPM [Max:1800; Controlled Flow Rate:N/A; Cover End Flow @ RPM:12 gal/min @ 1200 rpm, 18 gal/min @ 1800 rpm; Major Diameter [Max:N/A; Major Diameter [Min:N/A; Minor Diameter [Max:N/A; Minor Diameter [Min:N/A; Relief Valve Setting:N/A; Shaft End Flow @ RPM:35 gal/min @ 1200 rpm, 52.5 gal/min @ 1800 rpm; Manufacturer Part No.:3520V35A12-1AC22R; Cover End Pressure [Max:3000; Shaft End Pressure [Max:2500; GPM @ 1,800 rpm, Cover End:18; GPM @ 1,800 rpm, Shaft End:52.5; Integral Valve Configuration:N/A; Port Orientation - Cover End:Outlet 45° CW from Inlet; Port Orientation - Shaft End:Outlet Opposite Inlet; Pressure Port Size, Cover End:3/4 in Code 61; Pressure Port Size, Shaft End:1 1/4 in Code 61; Displacement Cover End (cu in/revolution):2.5; Displacement Shaft End (cu in/revolution):6.8; |
REXROTH 4WE 10 D3X/CW230N9K4 R900592701 Directional spool valves | Displacement Cover End (cu in/revolution):75.0 LB; Cover End Pressure [Max:Flange Mount; Displacement Shaft End (cu in/revolution):Right Hand (CW); Seal Material:3520V35A12-1AC22R; Relief Valve Setting:3; Weight:Flange; Minor Diameter [Max:5/16 in; Minor Diameter:Standard Pilot; Mounting Flange:1.25 in; Model No.:Straight w/ Key; Pump Series:3520V; Shaft Length:2 7/8 in; Seal Material:Buna-N; Max. RPM [Max:1800; Minor Diameter:N/A; Mounting Flange:SAE C, 2 Bolt; Shaft Seal Type:Single Shaft Seal; Spline Description:N/A; Cover End RPM [Max:1800; Shaft End RPM [Max:1800; Controlled Flow Rate:N/A; Cover End Flow @ RPM:12 gal/min @ 1200 rpm, 18 gal/min @ 1800 rpm; Major Diameter [Max:N/A; Major Diameter [Min:N/A; Minor Diameter [Max:N/A; Minor Diameter [Min:N/A; Relief Valve Setting:N/A; Shaft End Flow @ RPM:35 gal/min @ 1200 rpm, 52.5 gal/min @ 1800 rpm; Manufacturer Part No.:3520V35A12-1AC22R; Cover End Pressure [Max:3000; Shaft End Pressure [Max:2500; GPM @ 1,800 rpm, Cover End:18; GPM @ 1,800 rpm, Shaft End:52.5; Integral Valve Configuration:N/A; Port Orientation - Cover End:Outlet 45° CW from Inlet; Port Orientation - Shaft End:Outlet Opposite Inlet; Pressure Port Size, Cover End:3/4 in Code 61; Pressure Port Size, Shaft End:1 1/4 in Code 61; Displacement Cover End (cu in/revolution):2.5; Displacement Shaft End (cu in/revolution):6.8; |
REXROTH 4WE 6 C6X/EW230N9K4/V R900927326 Directional spool valves | Pump Series:75.0 LB; Integral Valve Configuration:Flange Mount; Major Diameter [Max:Right Hand (CW); Minor Diameter [Max:3520V35A12-1AC22R; Max. RPM [Max:3; Port Orientation - Shaft End:Flange; Mounting:5/16 in; Weight:Standard Pilot; Pilot Type:1.25 in; Pressure Port Size, Shaft End:Straight w/ Key; Pump Series:3520V; Shaft Length:2 7/8 in; Seal Material:Buna-N; Max. RPM [Max:1800; Minor Diameter:N/A; Mounting Flange:SAE C, 2 Bolt; Shaft Seal Type:Single Shaft Seal; Spline Description:N/A; Cover End RPM [Max:1800; Shaft End RPM [Max:1800; Controlled Flow Rate:N/A; Cover End Flow @ RPM:12 gal/min @ 1200 rpm, 18 gal/min @ 1800 rpm; Major Diameter [Max:N/A; Major Diameter [Min:N/A; Minor Diameter [Max:N/A; Minor Diameter [Min:N/A; Relief Valve Setting:N/A; Shaft End Flow @ RPM:35 gal/min @ 1200 rpm, 52.5 gal/min @ 1800 rpm; Manufacturer Part No.:3520V35A12-1AC22R; Cover End Pressure [Max:3000; Shaft End Pressure [Max:2500; GPM @ 1,800 rpm, Cover End:18; GPM @ 1,800 rpm, Shaft End:52.5; Integral Valve Configuration:N/A; Port Orientation - Cover End:Outlet 45° CW from Inlet; Port Orientation - Shaft End:Outlet Opposite Inlet; Pressure Port Size, Cover End:3/4 in Code 61; Pressure Port Size, Shaft End:1 1/4 in Code 61; Displacement Cover End (cu in/revolution):2.5; Displacement Shaft End (cu in/revolution):6.8; |
REXROTH 4WE 10 E3X/CW230N9K4 R900911869 Directional spool valves Video
Contact Us
- Piston Pump INC
- AddressWorld Trade Center Panamá, Floor 16. Oficina 1601, Urbanización Marbella, Calle 53 Este, Apartado Po
- Phone(Working Time)264-3269
REXROTH 4WE 10 E3X/CW230N9K4 Technical Articles
280x380x75 bearing size catalogue |
50x90x30.2 bearing cad model |
55x90x36 bearing price list |
REXROTH Directional spool valves CATEGORIES
- Vickers PVXS series Piston Pump
- Vickers Piston Pump PV Series
- Vickers Piston pump PVH
- Vickers Piston Pump PVQ
- Vickers Piston Pump PVB
- Vickers Vane Pump
- SKF Bearing
- Timken Bearing
- AMI Bearing
- CONSOLIDATED BEARING
- DODGE Bearing
- LINK BELT Bearing
- QM INDUSTRIES Bearing
- SEALMASTER Bearing
- REXROTH Pressure reducing valve
- REXROTH HY-CHECK VALVE
- REXROTH Check valves
- REXROTH Pressure relief valve
- REXROTH Twin throttle check valve
- REXROTH Throttle check valves
- REXROTH Directional poppet valves
- REXROTH Throttle valves
- REXROTH Valves
- REXROTH Directional spool valves
- REXROTH Throttle check valve
- 32306 Bearing
- 32013x Bearing
- 32026 Bearing
- hk1010 needle Bearings
- Eaton Vickers ydraulic Pump
- For Komatsu
- For Rexroth
- Gear Pump
- Hydraulic Motor
- Kawasaki ydraulic Pump
- Original Hydraulic Pump
- Parker Denison ydraulic Pump
- Piston Pump
- Replacement for CAT
- Sauer ydraulic Pump
- Vane Pump
- Water Pump
- Yuken Hydraulic Pump
Customers Who Viewed REXROTH 4WE 10 E3X/CW230N9K4 Also Viewed
- REXROTH 4WE 10 U5X/EG24N9K4/M R901278778 Directional spool valves
- REXROTH 4WE 6 QA6X/EG24N9K4 R900906009 Directional spool valves
- REXROTH 4WE 6 E6X/EW230N9K4/B10 R901130020 Directional spool valves
- REXROTH 4WE 6 G6X/EG24N9K4/B10 R900945896 Directional spool valves
- REXROTH 4WE 10 E5X/EG24N9K4/M R901278761 Directional spool valves