精品人妻av区二区三区-尤物在线观看视频免费-亚洲国产一区二区三区四-亚洲成人免费av一区二区

力士樂壓力閥ZDB 6, Z2DB 6

博世力士樂作為德國博世集團的全資子公司，是工業技術市場的供應商。在傳動和控制領域聲譽*。2006年銷售額超過49億歐元，擁有專業員工29,831名。早在1978年，博世力士樂就開始了在中國的業務，現已成立了四家公司。憑借*的產品和豐富的應用經驗，博世力士樂為中國客戶提供現代高效和靈活完整的解決方案。 從標準解決方案到大型工程項目，博世力士樂幾乎為所有的工業領域提供專業服務。從機床、塑料機械、食品和包裝機械、冶金、汽車工業、印刷和造紙工業，到電子工業、半導體工業、海事工程、建筑與農業機械、鉆探設備，博世力士樂的服務領域在不斷延伸。得益于在工業及工廠自動化的諸多領域和行走機械應用方面積累的豐富經驗，博世力士樂總能準確把握客戶對機械制造及工廠建設與維護的各種需求，這就是其廣受客戶青睞的原因。

Pressure valves of type ZDB and Z2DB are pilot-operated pressure relief valves in sandwich plate design.

They are used for limiting a system pressure.

The valves basically consist of the housing (7) and one or two pressure valve cartridges.

The system pressure can be set via the adjustment type (4).

Example version "VA":

In the initial position the valves are closed. The pressure in channel A acts on the spool (1). At the same time, pressure is applied to the spring-loaded side of the spool (1) via nozzle (2) and to the pilot poppet (6) via nozzle (3). If the pressure in channel A exceeds the value set at the spring (5), the pilot poppet (6) opens.

Hydraulic fluid flows from the spring-loaded side of the spool (1), nozzle (3), channel (8) into channel T. The resulting pressure drop moves the spool (1) and thus opens the connection from A to T while maintaining the pressure set at spring (5).

Die pilot oil drain from the two spring chambers is effected externally, via channel T.

Type ZDB 6 VA2-...

? = component side

? = plate side

力士樂壓力閥ZDB 6, Z2DB 6

力士樂部分產品型號：

4WP-6D60/N

4WH6D-5X

4WMM6E5X

4WMM6J5X

4WMM6G5X/F

4WMM6D50/F

4WMM6J53/F

4WMM10C31

4WMM10E31

4WMM10E-3X/F

4WMM10D-3X

4WMU10Y31/B10

4WMU 10 D3X/

4 WE 6 D6X/EG24N9K4

4WE6C6X/EG24N9K4,

4WE10D3X/CG24N9K4

4WE10J31/CW230N9K4+Z5L

4WE10E33/CG24N9K4,

4WE10D3X/CG24N9K4+Z4

4WE10D3X/CG24N9K4+Z5L

4WEH16E7X/6EG24N9ES2K4

5-4WE10D33/CG24N9K4/C

4WE10E3X/CG24N9K4+00057292

4WE10E33/CG24N9K4=CSA

4WE10D33/CG220N9K4/B10

4WE10HA31/CG24N9K4+Z4

4WE10J3X/CG24N9K4+Z4

4WE10Y73-3X/CG24N9K4A12

4WE6H73A62/EG24N9K4/A12

4WE6H73A62/EG24N9K4/A12

4WE6J73-6X/EG24N9K33L/A12

4WE6J73-62/EG24N9K33L/A12

4WE6E67-62/EG24N9K4/T06貨號R900572738*1

4WE4D20/EG24N9K4

4WE4E20/EG24N9K4 

4WE6C73-6X/EG24N9K4 

4WE6J6X/EG24N9Z4

4WE6E60/EG24N9K4/62

4WE6Q62/EG24NPK33L

4WE6D6X/EW110N9K4

4WE6D6X/OFEG24N9K4

4WE6D6X/OFEG220N9K4  帶燈插頭

4WE6D46-62/OFEG24N9K33L.SO407

4WE10D33/OFCG220N9K4/B10

4WS2EM10-51/60B11T315K31CV-114

4WS2EM10-51/90B11T315K31CV-114

4WEH32M6X/6EG24N9K4

4WEH10J4X/6EG24N9EK4/10B8S0269

4WEH10J4X/6EG24N9EK4/B10

4WEH32J6X/6EG24N9K4

4WEH16EB70/6EG24N9EK4/B10D3

4WEH10J45/6EG205N9ETS2K4

4WEH10D45/6EG205N9ETS2K4/B10

4WEH10E45/6EG205N9ETS2K4

4WEH16HD7X/OF6EG24N9ETK4/B10

4WRAP 6 W7-04-30/G 24K4/M

4WEZ16E150-7X/6EG24N9EK31F1D3M+插頭021267

4WRZ10W6-85-70/6EG24N9ETK4/D3M

4WRZ16E150-70/6EG24N9ETK4/D3M

4WRE6V16-21/G24K4/V

4WRE6E16-2X/G24K4/V

4WREE6V08-20/G24K31/A1V

4WREE6V16-22/G24K31/AIV

4WREE6V16-2X/G24K31/A1V

4WREE6WA32-22/G24K31/A1V

4WREE6W1-08-2X/G24K31/F1V+插頭

4WREE10W3-75-2X/G24K31/F1V

4WREE10W75-2X/G24K31/A1V

4WREE10W3-50-2X/G24K31/AIV

4WREE6E-32-2X/G24K31/F1V+00021267

4WREE10E75-22/G24K31/A1V

4WREE10E75-2X-G24K31/F1V

4WREE6E1-32-22/G24K31/A1R

4WRZ10E85-7X/6EG24N9EK4M

4WRZ10W6-85-70/6EG24N9ETK4/D3M

4WRZ16W8-150-7X/6EG24N9ETK4/M

4WRZ16W6-150-7X/6EG24N9K4V

4WRZ25W8-220-7X/6EG24N9K4V

4WRZ25W9-220-7X/6EG24N9ETK4/M

4WRZ25W8-325-7X/6EG24N9ETK4/M

4WRZ32W1-520-5X/6A24N9ETZ4D3M

4WRZ32W8-520-7X/6EG24N9ETK4D3M+Z4

4WRZ32W9-520-7X/6EG24N9ETK4/M

4WRZE10E85-7X/6EG24N9ETK31/F1D3M

4WRZE10E85-7X/6EG24EK31/A1M

4WRZE16EA100-70/6EG24N9K31/A1M

4WRZE25-W8-220-7X/6E-G24-N9-E-K31/F1-D3M

4WRZE25W5-325-7X/6EG24N9ETK31/F1/D3/V

4WRZE16W6-150-7X/6EG24K31/A1M

4WRZE10W6-85-7X/6EG24N9ETK31/F1D3M 

4WRZE10W8-50-7X/6EG24N9ETK31/F1D3M

4WRZE10W8-85-7X/6EG24EK31/A1M

4WRZE16W8-150-7X/6EG24N9K31/F1D3M 

4WRZE16W8-100-70/6EG24N9TK31/A1D3M

4WRZE10W8-50-7X/6EG24N9ETK31/F1D3M 

4WRZE10W8-50-70/6EG24N9ETK31/F1D3M

4WRZE10W8-85-7X/6EG24EK31/A1M

4WRZE16W8-150-7X/6EG24N9K31/A1D3M

4 WRZE 10 W6-85-7X/6EG24N9ETK31/F1D3M

4WRZE10W8-85-7X/6EG24EK31/A1M

4WRZE25W6-325-70/6EG24N9ETK31/A1D3M

4WRZE25W8-220-7X/6E-G24-N9-E-K31/F1-D3M

4WRZE25W8-220-70/6EG24N9TK31/A1D3M

4WRZE25W8-220-7X/6EG24N9ETK31F1/D3V

4WRZE32W8-520-70/6EG24N9K31/F1D3M

4WRZE32W8-520-70/6EG24EK31/A1D3M

4WRKE10E-100L-3X/6EG24TK31/A1D3M 

4WRKE10E-100L-3X/6EG24ETK31/F1D3M

4WRKE25E220L-3X/6EG24K31/A1D3M

4WRKE35E3-1000L-3X/6EG24TK31/A1D3M

4WRKE10W8-100L-3X/6EG24K31/F1D3M

4WRKE 16 W8-200L-31/6EG24ETK31/A1D3M

4WRKE16W6-125P-32/6EG24EK31/A1D3M

4WRKE16W6-125P-32/6EG24K31/F1D3M

4WRKE25W8-220L-3X/6EG24K31/F1D3M

4WRKE27W8-500L-3X/6EG24ETK31/F1D3V

4WRTE10E-100L-4X/6EG24TK31/A1M

4WRTE25E1-350L-4X/6EG24K31/A1WB15M

4WRTE25E220L-4X/6EG24K31/A1M

4WRTE25E1-350L-4X/6EG24K31/A1WB15M RD29083

4WRTE35V1000P-42/6EG24K31/A1M-650

4WRDE10W1-100L-5X/6L24EK9/V

4WRDE16W1-125L-5X/6L24K9/V

4WRDE16V-200L-5X/6L24K9/V

4WRL25V-370M-3X/G24Z4/M

4WRA6V30-22/G24N9K4/V

4WRA10W60-22/ G24N9K4/V

4WRAE10E60-2X/G24N9K31/A1V

4WRAE10E60-2X/G24K31/A1V

4WRAEB6W30-2X/G24N9K31/A1V

4WRAE6W30-21/G24N9K31/A1V

4WRSE6V10-3X/G24K0/A1V-SO644 

4WRSEH6V24LD-3X/G24KO/A1V

4WRPEH6C40L-2X/G24KO/F1M

4WSE3EE16-1X/200-B8-315-K9-D-V-S0122

4WSE3EE16-1X/300B8-315K9EV

4WSE2ED10-5X/90B9210 K31EV

4WRPE10EA50SJ-2X/G24K0/A1M

4WRPH6C4B40L-2X/G24Z4/M

4WRPH6C3B24L-2X/G24Z4M

4WRPEH6C3B04L-2X/G24K0/F1M-885

4WRBA10EA75-2X/G24K4/M-828

4TH6E06-14/VT23M01  訂貨號:R900230498

3 WE 6 A6X/EG24N9K4

3WH6A5X

3WH6B53

3WE6B62/EG24N9K4

3WE6B9-62/EG24N9K4

3WE10B33/CG24N9K4

3DR10P5-6X/200Y/00M 

3DREME10P62/200YG24K31V

3DREME16P6X/200YG24K31V +R900021267

3DREE16P6X/XXXYG24K31V

3DREE16P6X/200YG24K31V

3DREP6B-2X/25EG24N9K4/M

3DREP6C-20-25EG24N9K4M-00即為:3DREP6C-2X/25EG24N9K4/M

DBT1-52/315

DKCO1.3-100-7KW(R911279429)

DA10-2-56/315-280-17

DA6VA2-4X/100-17M

DA6VA2-4X/100-10M

DA6VP2-41/200-10V

DZ10-2-5X/200XYM

DZ30-2-5X/315

DR10-5-5X/200YM

DR10DP2-4X/25YM

DR10DP2-4X/75YM

DR10DP3-4X/75Y

DRC5-52/200Y

DR10-5-5X/315YM

DR20G5-5X/200YM

DR20-5-52/200YM

DR20-5-5X/100YM

DR30-5-52/200YM

DRE6-10/100MG24K4M

DRE6-10/100MG24K4M

DRE6-10/100MG24K4V

DRE10-51-315YG24K4M

DRE20-5X/200YG24K4M

DREE10-5X/315YMG24K31M+插頭

DREE20-5X/315YMG24NK31M+插頭

DBDA6G1X/200V

DB10-2.5X/315XY

DBDS6K1X/100

DBDS10P1X/315V

DBDS10P1X/315

DBDS10P1X/200

DBDS20P10/25

DBDS30P18/315

DBDS30P1X/315V

DBDS30P1X/315

DBDS6G1X/315V

DBDS10G1X/100

DBDS10G1X/200

DBDS15G1A/25

DBDS20G18/200

DBDS20G18/315V

DBDS20K1X/100

DBDS30K-18/315

DBT-XP2-1X/160

DBW10A1-5X/31.5-6EW220RNZ5L由以下型號替DBW10B1-5X/315-6EW230N9K4+RZ5L

DBW10B1-5X/31.5-6EW220RNZ5L由以下型號替代DBW10B1-5X/31.5-6EW220RNZ5L

DBW20B1-52/315-6EW230N9K4

DBW30B1-52/315-6EW230N9K4

DBW10B2-5X/200-6EG24N9Z4

DBW20B2-5X/315-6EG24N9K4SO160

DBW20B-3-5X/200-6EG24N9K4+Z4

DBW30B2-52/315-6EG24N9K4

DBAW15BH2-2X/350Z6EG24N9K4A08

DBAW30BH1-21/200-6EG24N9K4A10

DBAW30BH2-21/315  6EG24N9K4A08

DBAW30BH2-21/315Z6EGG24N9K4A08

DBAWR30BH2N12/315-190-6EG24N9K4

 DBAWR40BH2N11/315-315-6EG24N9K4

DBE30-3X/315YG24K4M

DBEE6-1X/200-G24-K31-M

DBEE6-1X/200G24K31M

DBET61/315G24K4V

DBET6X/350YG24K4V

DBETE61/200G24K31F1V

DBETE6X/200G24K31F1V

DBETE6X/315YG24K31A1V

DBETE6X/420YG24K31A1V

DBEM10-5X/315YG24K4M

DBEM20-5X/315YG24NK4M

DBEM20-5X/315YG24K4M

DBEM30-37/200YG24K4M

DBEME10-5X/315YG24K31M+21267

DBEM10-5X/200XYG24K4M-1

DBEME10-5X/315YG24K31M

DBEME10-5X/350YG24K31M

M-SR10KE02-1X

M-SR10KE05-1X

M-SR15KE05-1X

M-SR20KE05-1X

M-SR20KE02-1X

M-SR30KE05-1X/V

M-2SEW6N36/420MG24N9K4

M-2SEW6P3X/420MG24N9K4

M-2SEW6P36/420MG125N9K4/V

M-3SEW6C3X/420MG24N9K4

M-3SEW6U3X/420MG24N9K4

M-3SEW6U3X/420MG24N9K4/V

M-3SEW6C3X/420MG24N9K4/V

M-3SEW6C36/420MG24N9K4/B06

M-3SEW6C36/420MG25N9Z2/B08/V SO214

M-3SEW6C36/420MG24N9K4/B12 

M-3SEW6U36/630MG24K4/P

M-3SEW10U14/420MG24N9K4

M-2SEH10C6X/420-6MG24NS3K4/B08Z5L

M-2SEH10U6X/420-6MG24NS3K4/B08Z5L

M-2SEH10U60/420-6MG24N9S3K4/B08

M-2SEH10C60/420-6MG24N9S3K4/B08

M-3SED6CK1X/350CG24N9K4

M-4 SED 6D1X/350CG24N9K4

M-3SED6CK13/350CG24N9K4V

M-3SED6UK13/350CG24N9K4V

M-3SED6UK1X/350CG24N9K4

M-3SED6CK1X/350CG2205N9K4

M-3SED10CK13/350CG24N9K4

M-3SED10CK1X/350CG24N9K4

M-4SEW6D3X/420MG24N9K4

M-4SED6D1X/350CG24N9K4

M-4SED10D1X/350CG24N9K4

M-Z4SEH10E2X/3CG24ETK4

MHD112B-024-PG1-BN

MHD112C-024-PGO-BN(R911276332)

MG10G1.2/

MK30G1XV

MKE098B-047-KPO-BENNMKE098-00374

MKE071B-061-KGO-KNR911260467

MKM11AZ1X/M2AON01

MTS-R02.2-M2-B1-S4-NN-FM(R911285088)

MSA30EP250

A2FM 32/61W VBB010

A2FM10/61W-VPB040

A2F032/61RPBB05

A2FO160/61R-PPB05

A2FO160/61RVPB05

A2FO250/60R-VPB05

A2FO250/60RVPB11

A2FO355/60RVPB11

A4VSO71EO2/10R-PPB13NOO

A4VSO40DR/10R-PPB13N00

A4VSO125DR/30R-PPB13N00

A4VSO125DR/30R-PB13N00-SO127

A4VSO180DRG/30R-PZB1+A4VSO40DRG/10R-PZB13

A4VSO180DR/30R-PPB13N00

A4VSO250DFR/30R-PPB13N00

A4VSO500HS4/30R-PZH25N00

A4VSO500E02/30R-PPH13N00

A10VS018DR/31R-PPA12N00

A10VS018DR/31R-PPA12NOO

A10VSO28DFLR/31R-PPA12NOO

A10VS071DR/31R-PPA12N00

A10VSO100DR/31R-PPA12NOO

A10VSO45DFR/31R-PPA12K68

A10VSO140DR/31R-PPB12N00

A10VSO140DFR/31R-PPB12K26

A10VSO140DFR1/31R-PPB12N00

AA10VS045DFR/31R-PKC62N00

AA10VSO100DFR/31L-PKC62K03

AA10VSO140DRG/31R-PKD62N00

A10VSO100DFLR/31R-PPA12K26+A10VSO45DFR1/31R-PPA12N00

A10VSO140DFLR/31R-PPB12N00 

E-A10VSO45DR/31R-PPA12N00

E-A10VSO100DR/31R-PPA12N00

E-A10VSO140DR/31R-PPB12NOO

E-A4VSO125DR/30R-PPB13N00

E-A4VSO180DR/30R-PPB13N00

A4VSO250E01/30R-PPB13N00-S0368

E-A10VSO140DR/31R-PPB12NOO

A4FO500/30R-PZH25N00

A4VG180EP2MT1/32RNZD02F0215+A10V028DR/31R-PSC12N00

A4VSG250EO1/22R-PPB10N000N 

A4VG250HD1D1/32R-NSD10F001D 由以下型號替代：A4VG250HD3D1/32R-NSD10F001D

A4FM71/10W-PPB01

A2VK28MAOR1GOPE2-S02  2028554

A2VK12MAOR4GOPE1-S02  9447172

ABZMS-36-1X/0370M-K24插頭（K24-POLES）

R900027088 AB31-21/127 FT200V

ABZAS-065-016-G-K-1X/M

AB31-32 R900020588

AB20-11/1000

AB21-23/G1 1/4G24K4+Z5L

AB22-31/065-16NM

AB31-13/063-0060BAR/Mpa

AB31-15/100-R2.5-22

AB31-21/127 FT200V

AB31-32  R900020588

AB32-10/2D380-50

ABZMM 63-400BAR/MPA-R/B-G替代AB31-13/063-0400BAR/MPA

AB21-22/10-25

AB21-20 G 1/4-500

AB22-31/065-16NM

AMP-TYCO MT2/JPT 52 POLIG R902602414

AB20-11/K1 G1/4 R900009090

AB20-11/1000 R900011191

ABZAS-065-016-G-K-1X/M

ABZMS-36-1X/037M-k24+插頭

ABZMS-36-1X/0800M-K24

ABZFV-E1SP-M12X1-1X/-DIN

ABZFV-E2SP-M12X1-1X/DIN

ABZFV-RE2-1X/M-A

ABZFV-RV2-1X/M-A

ABZFR-S0450-10-1X/M-A

AZPF-1X-008RQR20MB

AZPF-11-022LAB1MB

SLEEVE AB31-22 NBR R900067516

LT06-A06-3X/150B18/02M

1PF2G2-4X/022LA01MB 由以下型號替代：AZPF-11-022LAB1MB

AZPN-11-032RDC7KB-S0023

04POL Z14 M SW R901017012

03POL Z5L1 M 24V R901017026

PGF1-21/4.1RA01VP1

PGF1-2X/4.1RA01VP1

PGF2-2X/008RJ20VU2

PGF2-2X/013RL20VM

PGF3-31/032RH07VE4替代PGF3-31/032RE07VE4

PGF3-31/032RH07VM替代PGF3-31/032RN07VM

PGH3-22/011RE07VU2

PGF3-3X/025RE07VE4

PR4-3X/1,60-700RA01M01

PGF3-31/040RE07VE4

PGH4-21/032RE11VE4-A437

PGH4-21/040RE11VE4

PGH5-2X/250RE07VE4-A388

PGH5-21/100RE11VU2

PVV21-1X/060-018RA15DLMB

PVV5-1X/193RA15DMC

PVV1-1X/018RA15UMB

PVV4-1X/082RA15DMC

PVV4-1X/082RA15DMC

PVV4-1X-098RB15DMC

PVV4-1X/122RA15DMC

PVV5-1X/193RA15UMC

PV7-1X/10-14RE01MCO-16

PV7-17/10-14RE01MC3-16

PV7-1X/16-30RE01MCO-08

PV7-17/16-20RE01MC0-16

PV7-17/10-20RE01MC0-10

PV7-1X/25-30RE01MCO-16

PV7-1X/25-45RE01MCO-08

PV7-1X/06-10RA01MAO-10

PV7-2X/20-20RA01MA0-10

PV7-20/20 25RA01MAO-05+PV7-18/63-71RE07MCO-16

P55556-3

VT11006-12,DC24/±15V

VT11011-1X

VT11131-1X

VT-11013-12

VT-2000-5X

VT-3002-2X/32D

VT5035-1X

VT-11118-10

VT-VSPA1-1-1X

VT-VSPA1-1-1X

VT-VSPA1-1-1X

VT-VSPA2-1-1X/T1

VT-VSPA2-1-1X/T5

VT-VSPA2-50-1X/T1

VT-VSPA2-50-1X/T5

VT-VSPA2-1-2X/V0/T1

VT-VSPA2-1-2X/V0/T5

VT-VSPA2-50-1X/T1

VT-VSPA2-50-1X/T5

VT-VRPA2-1-1X/VO/T1

VT-VRPA1-151-1X/V0/0

VT-MRPA2-2-1X/ V0/0

VT-MSPA2-1-1X/ V0/ 0

VT-HNC100-1-2X/W-08P0

VT-DFPE-A-2X/G24K0/0B1C/V

VT-HNC100-1-2X/W-08P0

VT-MAC8-10/S1- PM4

HY30622EG-3

HY30569EG

HM12-1X/315

HM14-10/315

HED20A2X/400

HED80A10/50K14S /12

HED8OA-2X/100K14

HED80A-2X/200K14S

HED 8 OA-2X/200K14S

HED80A20/200K14S

HED80A-2X/350K14S/12

HED80A-2X/350K14KS

HED8OH2X/100K14

HEDE10A1-2X/100K41G24/1/V

HSE05G06A001-3X/VOO

HSZ06A608-3X/M00

HCS02.1E-W0012-A-03-NNNN

HCS02.1E-W0028-A-03-NNNN

S10A1。0

S25A1.0

S20A5.0

S30A5.O

SCA16CZ2X/M

SL6PB2-6X1

SL10PB3-4X

SL10PA1-4X/V

SL52PA3-12

SL62PA3-12"

SL10PA1-4X/

SL20PA1-4X

SL30PA1-4X

SL30APA1-42/6SMG24N9K4

SV10PA1-4X

SV10PA1-4X

SV30PB1-4X

SV30PA1-4X

SV10PA1-4X

SV20PA2-30升級SV20PA2-4X/

STW0070-14/D32

SYDFE1-20/071R-PPA12NOO-OOOO-A010PX

L10VO28DR/31R-PPA12NOO 

LC16A05E7X

LFA16D-7X/F

LFA16H2-7X/F

LFA16G-7X

LFA16DB2-7X/100

LFA16D-7X/F

LC16A05E7X

LC25AO5E7X

LC25A10E7X

LC16A20E7X/

LC25A20E7X/

LC32A05D7X

LC40A05D-7X/

LC40A20E7X/

LC16A40E7X/V

LC40B20E7X/

LC16DB2OE7X

LC40DB20D7X/

LC63A05E-7X/

LT06-A06-3X/150B18/02M

LFA25DB2-7X/100

LFA25WEA7X/A10P10T10

LFA25G-7X

LFA25D7X/FX10

LFA25DB2-71/315

LFA32DB2-7X/420

LFA32H2-7X/F

LFA50DB2-71/200

LFA50H2-7X/FX18

LFA40D-71/FX15

LFA40H2-71/FX15

LFA32DR2-7X/150

LFA32DBWD2-71/315

LFA63E7X/CA10DQMG24F/V

LFR32WEA105-1X/

LFR32DBE49-1X

Z2SRK10-1-11/V

Z1S10P1-3X/V

Z1S6E05-4X/V

Z2S6-3-6X

Z2FSK10-2-1X/2QV

Z2S22-1-5X

Z2SRK611XV

ZS 332-11Y-M20

Z2FS10-5-3X/V

Z2FS6-2-4X/1Q由以下型號替代:Z2FS6-2-4X/1QV

Z2FS10-5-3X由以下型號替代：Z2FS10-5-3X/V

Z2FS6-2-4X/2QV

Z2FS10-5-3X/V

Z2FS16-30/S2

Z2FS16-3X/S2