BOSCH REXROTH A4VSG AXIAL PISTON VARIABLE PUMP SUPPLIER
BOSCH REXROTH A4VSG AXIAL PISTON VARIABLE PUMP SUPPLIER
Bosch Rexroth A4vsg Axial Piston Variable Pump   Bosch Rexroth A4vg Variable Displacement Pumps   Bosch Rexroth A10vso Variable Displacement Pumps  
English
English
  • Home
  • Stock Categories
    • Bosch Rexroth A4vsg Axial Piston Variable Pump
    • Bosch Rexroth A4vg Variable Displacement Pumps
    • Bosch Rexroth A10vso Variable Displacement Pumps
    • Bosch Rexroth A2fo Fixed Displacement Pumps
    • Bosch Rexroth A4v Variable Pumps
    • Kawasaki K3vg Variable Displacement Axial Piston Pump
    • Kawasaki K3v Hydraulic Pump
    • Bosch Rexroth A4vso Variable Displacement Pumps
    • Kawasaki K5v Hydraulic Pump
    • Kawasaki K3vl Axial Piston Pump
    • Bosch Rexroth A10vo Piston Pumps
    • Bosch Rexroth A11vg Hydraulic Pumps
    • Bosch Rexroth A10vg Axial Piston Variable Pump
    • Bosch Rexroth A10vno Axial Piston Pumps
    • Bosch Rexroth A2v Variable Displacement Pumps
    • Bosch Rexroth A11vlo Axial Piston Variable Pump
    • Bosch Rexroth A8vo Variable Displacement Pumps
    • Linde Hpr Hydraulic Pump
    • Bosch Rexroth A4vtg Axial Piston Variable Pump
    • Bosch Rexroth A15vso Axial Piston Pump
    • Bosch Rexroth A11vo Axial Piston Pump
    • Bosch Rexroth A7vo Variable Displacement Pumps
  • Technical Articles
  • Bosch Rexroth A4vsg Axial Piston Variable Pump
  • Bosch Rexroth A4vg Variable Displacement Pumps
  • Bosch Rexroth A10vso Variable Displacement Pumps
✖

Home

Stock Categories

Technical Articles

Bosch Rexroth A4vsg Axial Piston Variable Pump

Bosch Rexroth A4vg Variable Displacement Pumps

Bosch Rexroth A10vso Variable Displacement Pumps

Home>Products>Bosch Rexroth A15vso Axial Piston Pump>AA20VG45DGM2/10R-NTC66F023D-S BOSCH REXROTH A20VG VARIABLE PUMPS

  • AA20VG45DGM2/10R-NTC66F023D-S BOSCH REXROTH A20VG VARIABLE PUMPS
  • AA20VG45DGM2/10R-NTC66F023D-S BOSCH REXROTH A20VG VARIABLE PUMPS

BOSCH REXROTH AA20VG45DGM2/10R-NTC66F023D-S MODELS

Need a CAD or 3D Model?

What is AA20VG45DGM2/10R-NTC66F023D-S bearing interchange？
Contact NowWhatsAppBe Our Agent

AA20VG45DGM2/10R-NTC66F023D-S BOSCH REXROTH A20VG VARIABLE PUMPS

category

Bosch Rexroth A15vso Axial Piston Pump

BOSCH REXROTH AA20VG45DGM2/10R-NTC66F023D-S Bearing SPECIFICATIONS

  • Enjoy High Margins on 73.5 mm Da max Competitive Bosch Rexroth A15vso Axial Piston Pump Pricing.Great Wholesale Products at 40x80x56 Low Costs.

  • BOSCH REXROTH

  • AA20VG45DGM2/10R-NTC66F023D-S

  • 4.5
  • 18 mm
  • 73.5 mm
  • 54 mm
  • 19.2 kN
  • 40x80x56
  • 7.28 Hz
  • 56 mm
BOSCH REXROTH A4VSG AXIAL PISTON VARIABLE PUMP SUPPLIER

BOSCH REXROTH A4VSG AXIAL PISTON VARIABLE PUMP SUPPLIERChina

  • BOSCH REXROTH A4VSG AXIAL PISTON VARIABLE PUMP SUPPLIER2020-07-10 09:46:19
    Welcome to my shop! Glad to serve you! Please send your question!
Price Inspection Certificate Product Specifications Company Profile

Information techniques AA20VG45DGM2/10R-NTC66F023D-S BOSCH REXROTH A20VG VARIABLE PUMPS

  • 4.5
  • 18 mm
  • 73.5 mm
  • 54 mm
  • 19.2 kN
  • 40x80x56
  • 7.28 Hz
  • 56 mm
  • 46.5 mm
  • 80,000
  • 0.72 kg
  • 2.9
  • 40,000
  • 56
  • 120 °C
  • 11208G15
  • 3.04
  • 1.1 mm
  • 0.22
  • P0

BOSCH REXROTH AA20VG45DGM2/10R-NTC66F023D-S AA20VG45DGM2/10R-NTC66F023D-S BOSCH REXROTH A20VG VARIABLE PUMPS Code system

 

AA20VO95DRG-10L-VSD74N00-ES BOSCH REXROTH A20VO HYDRAULIC AXIAL PISTON PUMP(Grease) Lubrication Speed:3200 r/min; Oil rpm:4300; outer rb:3.3; BETA_:1; Prod_Type3:TRBSR_ID_A; LangID:1; DA_:16.605; KBRG:3161; Bore Diameter (mm):53,975; inner r:3.5; D_:127; da:74 mm; DA1:17.849; D:127 mm; ALP21:22; C0:300; CUP:1.22; D_b:117; ALP22:30; Db:117 mm;
A17VO107DRS00/ BOSCH REXROTH A17VO AXIAL PISTON VARIABLE PUMPMinimum Buy Quantity:N/A; Limiting speed:32000 r/min; Fw:10 mm; ra max.:0.3 mm; series:NK; Inventory:0.0; Bore Diameter (mm):17; r1,2 - min.:0.3 mm; Da max.:15 mm; overall width:16 mm; dynamic load capacity:5.94 kN; outside diameter:17 mm; Basic dynamic load rating - C:5.9 kN; Basic static load rating - C0:8 kN; static load capacity:8 kN; Fatigue load limit - Pu:0.9 kN; Product Group:B04144; bore diameter:10 mm;
A15VSO210LRDRE2AHV/10MRVE4A21EU0000- BOSCH REXROTH A15VSO AXIAL PISTON PUMPd1:171 mm; Width (mm):65; r2 min.:4 mm; Bearing number:NJ422-M+HJ422; r4 min.:4 mm; S:3,3 mm; D:280 mm; r1 min.:4 mm; d:110 mm; Bore Diameter (mm):110; Outer Diameter (mm):280; Basic static load rating (C0):626 kN; F:155 mm; B:65 mm; B3:29,5 mm; Basic dynamic load rating (C):551 kN; Size (mm):110x280x65; D1:220,5 mm; r3 min.:4 mm; B2:17 mm;
A22VG045HT1003M1/40BRNB2S73UB2S5A-S BOSCH REXROTH A22VG PISTON PUMPWidth (mm):64,000; Bore Diameter (mm):90,000; H:64,000 mm; Bearing number:22318EKF800; Outer Diameter (mm):190,000; D:190,000 mm; Size (mm):90x190x64; d:90,000 mm;
A18VO107DRS00/ BOSCH REXROTH A18VO AXIAL PISTON PUMPA1:20 mm; Basic dynamic load rating (C):43,55 kN; Thread (G):M6x1; J:184 mm; s:11,8 mm; D1:69 mm; Bearing number:USFA211; A2:58,5 mm; J1:86 mm; Bore Diameter (mm):55; A:43 mm; d:55 mm; Weight:3,5 Kg; L1:104 mm; N:16 mm; L:130 mm; H:219 mm; B1:45,3 mm; e:25 mm;
A20VLO190 LRDH1/10R-NZD24K02 BOSCH REXROTH A20VLO HYDRAULIC PUMPY0:0.78; Mass:0.7 kg; Nlim (oil):4,700 rpm; ra max:3.5 mm; Characteristic cage frequency, FTF:0.45 Hz; Rating life coefficient, A2:1.4; Minimum Buy Quantity:N/A; Weight / Kilogram:0.738; T:25,4 mm; r1s min:3.3 mm; Product Group:B04334; Manufacturer Name:NTN; e:0.43; d:62,738 mm; a:22.9 mm; Characteristic rolling element frequency, BSF:9.15 Hz; Bearing number:4T-28995/28921; Category:Bearings; r1a max:3.3 mm;
A A20VO60DFR1/10R-VSD24K01-S2106 BOSCH REXROTH A20VO HYDRAULIC AXIAL PISTON PUMPC:25,4 mm; Basic static load rating (C0):188 kN; Outer Diameter (mm):123,825; B:32,791 mm; Bearing number:72225C/72487; D:123,825 mm; Size (mm):57.15x123.825x36.512; d:57,15 mm; T:36,512 mm; Basic dynamic load rating (C):154 kN; Weight:1,96 Kg; (Grease) Lubrication Speed:2900 r/min; Width (mm):36,512; Bore Diameter (mm):57,15;
A2FM28 BOSCH REXROTH A2F PISTON PUMPSOuter Diameter (mm):12,7; C:11,13 mm; Fw:7,938 mm; Weight:0,0043 Kg; Width (mm):11,13; Basic static load rating (C0):3,22 kN; Bearing number:BA 57 Z; D:12,7 mm; Size (mm):7.938x12.7x11.13; Basic dynamic load rating (C):3,31 kN; Bore Diameter (mm):7,938;
A20VLO260LE2S2/10R-NZD24N00T-S BOSCH REXROTH A20VLO HYDRAULIC PUMPdb:214 mm; Width (mm):88,9; Da:300,5 mm; Aa:11,5 mm; Factor (Cg):0,0349; a -:22,4 mm; Basic static load rating (C0):1580 kN; Db:293 mm; C:65,088 mm; Bearing number:H239649/H239610; Basic dynamic load rating (C1):1030 kN; B:85,725 mm; Calculation factor (e):0,32; Factor (G1):905,7; Factor (G2):90,3; Size (mm):187.325x319.964x88.9; d:187,325 mm; Ab:2,8 mm; R:5,6 mm; Weight:26,5 Kg;
A A20VO 520 LR3DN /10L-VZH26K00-S1858 BOSCH REXROTH A20VO HYDRAULIC AXIAL PISTON PUMPFw:7,938 mm; Size (mm):7.938x12.7x7.94; Bearing number:B55; D:12,7 mm; C:7,94 mm; Weight:0,0035 Kg; Outer Diameter (mm):12,7; Bore Diameter (mm):7,938; Width (mm):7,94; Basic dynamic load rating (C):3,55 kN; Basic static load rating (C0):4,5 kN;
AL A20VO60DFR1/10R-VSD24K01-S2279 BOSCH REXROTH A20VO HYDRAULIC AXIAL PISTON PUMPB1:3,5 mm; Basic dynamic load rating (C):36 kN; Basic static load rating (C0):240 kN; Eb:78,5 mm; Outer Diameter (mm):100; Size (mm):75x100x3.5; Width (mm):3,5; Bore Diameter (mm):75; d:75 mm; D:100 mm; Ea:94,2 mm; Bearing number:AX 3,5 75 100; Weight:0,065 Kg;
A20VO95EP2D-10R-NSD24N00H BOSCH REXROTH A20VO HYDRAULIC AXIAL PISTON PUMPOuter Diameter (mm):170; Size (mm):95x170x32; Basic dynamic load rating (C):165 kN; Fw:113.5 mm; r min.:2.1 mm; Weight:2.80 Kg; Width (mm):32; Category:Bearings; Product Group:B04144; B:32 mm; Bearing number:NJ219; Basic static load rating (C0):195 kN; r1 min.:2.1 mm; C:32 mm; Manufacturer Name:KOYO; d:95 mm; Bore Diameter (mm):95; D:170 mm; Minimum Buy Quantity:N/A; (Grease) Lubrication Speed:3700 r/min;
A2F225 BOSCH REXROTH A2F PISTON PUMPSBore Diameter (mm):25; D:35 mm; Bearing number:KH25; JL4:8 mm; L:40 mm; Weight:0,066 Kg; N2:2,5 mm; Fw:25 mm; Basic dynamic load rating (C):2,42 kN; Outer Diameter (mm):35;
A20VLO190LRDH1/10R-NZD24K79 BOSCH REXROTH A20VLO HYDRAULIC PUMPD:7,938 mm; Width (mm):3,175; Basic dynamic load rating (C):0,359 kN; d:4,763 mm; (Grease) Lubrication Speed:53000 r/min; Basic static load rating (C0):0,15 kN; Size (mm):4.763x7.938x3.175; C:3,175 mm; B:3,175 mm; Bearing number:R156-2TS; Outer Diameter (mm):7,938; Bore Diameter (mm):4,763;
AA20VG45DGM2-10R-NSC66F023D-S BOSCH REXROTH A20VG VARIABLE PUMPST:15 mm; Size (mm):35x41x15; d:35 mm; (Grease) Lubrication Speed:7500 r/min; Basic static load rating (C0):33,5 kN; Width (mm):15; Weight:0,027 Kg; Bearing number:K35X41X15; Basic dynamic load rating (C):20,9 kN; Bore Diameter (mm):35; D:41 mm; Outer Diameter (mm):41;
AA20VG45DGM2/10R-NTC66F023D-S BOSCH REXROTH A20VG VARIABLE PUMPSD:72 mm; Bore Diameter (mm):30; Bearing number:6306ZZ; Size (mm):30x72x19; C:19 mm; d:30 mm; Outer Diameter (mm):72; B:19 mm; Width (mm):19;

 

 

No.BrandMKJ1mFXS
A20VO95 LRCU2+A10VO45DR-SKBOSCH REXROTH - - - - - - - -
A2FF5L-63XX-SBOSCH REXROTH - - - - - - - -
A20VO 60 DFR/10R-VSD24K68-SO969BOSCH REXROTH - - - - - - - -
A20VG045HT1001M1/11BRNB2S73FB2S4A-SBOSCH REXROTH - - - - - - - -
A15VSO280LRDRA0V/10MRVE4A41EU0000-BOSCH REXROTH - - - - - - - -
A2F500W5P1BOSCH REXROTH - - - - - - - -
A A20VO 520 LR3DN /10L-VZH26K00-S1858BOSCH REXROTH - - - - - - - -
A20VLO190LE2DH2+A10VO28DR-KBOSCH REXROTH - - - - - - - -
A18VO107DRS00/11NRWK0E810-BOSCH REXROTH - - - - - - - 1,5 mm
A18VO107DRS00/11NLWK0E820-Y 77725.3116BOSCH REXROTH - - - - - - - -
AA20VG45DGM2/10R-NTC66F023D-SBOSCH REXROTH - - - - - - - -
AL A20VO 520 LR3DN /10L-VZH26K00-S2096BOSCH REXROTH - - - - - - - -
A15VSO175LRDRE2AHV/10MRVE4A21EU0000-BOSCH REXROTH - - - - - - - -
A22VG045EP1P0403/40BRNB2S73UB2S5A-SBOSCH REXROTH - - - - - - - -
A2F45W1Z6BOSCH REXROTH - - - - - - - -
A18VO080DRS00/BOSCH REXROTH - - - - - - - -
AA20VLO190EP4D/10L-NXDXXN00T-SBOSCH REXROTH - - - - - - - -
A A20VO60DFR1/10R-VSD24K01-S2106BOSCH REXROTH - - - - - - - -
A20VLO190EP2D/10L-NZD24K02P-SBOSCH REXROTH - - - - - 72 mm - 1,6 mm
A20VLO190LRDH1/10R-NZD24K79BOSCH REXROTH - - - - - - - -
AA20VG45DGM2/10R-NTC66K043E-SBOSCH REXROTH - - - - - - - -
AA20VLO260LG2S-10R-NXD74N00X-SBOSCH REXROTH - - - - - - - -
A2F107W1P6BOSCH REXROTH - - - - - - - -
A A2F355 W5Z1-SOBOSCH REXROTH - - - - - - - -
A18VLO080DRS0E/11NRWK0E810-0 77722.4115BOSCH REXROTH - - - - - - - -
AA20VLO260LG2S/10R-NXDXXN00X-SBOSCH REXROTH - - - - - - - -
A17FO032/10NLWK0E81-BOSCH REXROTH - - - - - - - -
A20VG045HT1003M1/11ARNB2S53FB2S4A-OBOSCH REXROTH - - - - - - - -

 

AA20VG45DGM2/10R-NTC66F023D-S BOSCH REXROTH A20VG VARIABLE PUMPS Video

 

Axial piston variable pump A15VSO, A15VLO series 10

Bosch Rexroth AG, RE 92800/10.2013. 2. A15VSO, A15VLO series 10 | Axial piston variable pump. Ordering code. Axial piston unit.

Bosch Rexroth A15VSO Axial Piston Pump - Series 10

The Bosch Rexroth A15VSO pump is a high pressure, variable displacement axial piston pump with through drive. It has a swashplate design for use in open ...

Rexroth Axial Piston Variable Pump A15VSO

HEASH TECH, who is very know Rexroth hydraulics, supply hydraulic valves, pumps and motors to meet with your demand on industrial and mobile hydraulics.

Axial piston variable pump | Bosch Rexroth AG

A15VSO series 1x · All-purpose high pressure pump with through drive · Size 110 … 280 · Nominal pressure 350 bar · Maximum pressure 420 bar · Open circuit.

Axial Piston Variable Displacement Pump A15VSO series 10

Axial Piston Variable Displacement Pump A15VSO series 10. Axial Piston Pumps ... Bosch Rexroth Axial Piston Variable Pump R902197657 / A4VG90DGD1/32R.

Rexroth releases A15VSO hydraulic axial-piston pump

March 26, 2014 - Rexroth releases A15VSO hydraulic axial-piston pump for stationary applications in open circuit operation. It can meet pressure requirements to ...

Bosch Rexroth A15VSO Catalog, Page 1 - SP-SpareParts

Rexroth - A15VSO. Rexroth · Industrial Hydraulics · Pumps · Axial piston pumps · Variable pumps, open circuit · A15VSO. Rexroth catalog for A15VSO.

A15VSO high-pressure axial piston unit from Rexroth with ...

Jan 12, 2015 — Bosch Rexroth Corporation, Corporate Communications ... improved efficiency in the A15VSO axial piston hydraulic pump for.

BOSCH REXROTH AA20VG45DGM2/10R-NTC66F023D-S INTERCHANGE

Bosch Rexroth A15vso Axial Piston Pump Part series AA20VG45DGM2/10R-NTC66F023D-S is a potential replacement for these common bearing part numbers:

  • AA20VG45DGM2/10R-NTC66F023D-S

  • AA20VG45DGM2/10R-NTC66F023D-S

  • AA20VG45DGM2/10R-NTC66F023D-S

  • AA20VG45DGM2/10R-NTC66F023D-S

  • AA20VG45DGM2/10R-NTC66F023D-S

  • AA20VG45DGM2/10R-NTC66F023D-S

  • AA20VG45DGM2/10R-NTC66F023D-S

  • AA20VG45DGM2/10R-NTC66F023D-S

Contact Us

BOSCH REXROTH A4VSG AXIAL PISTON VARIABLE PUMP SUPPLIER
Address
Phone(Working Time)
Fax
  • BOSCH REXROTH A4VSG AXIAL PISTON VARIABLE PUMP SUPPLIER
    • Quick question Quick question I'm very interested in your products; could you send me some detail reference information? Please send me detail product specification, thank you! May I be an agency of your products,and what's yourterms? We intend to purchase this product, would you please send me the quotation and minimum order quantity?
     This feature is Quick question function, select the corresponding question types, automatically enter the corresponding problem, remove your trouble of typing
Send Now

BOSCH REXROTH AA20VG45DGM2/10R-NTC66F023D-S Technical Articles

How do hydraulic systems work?
How Do Hydraulic Systems Work?Dec 11, 2019 — Imagine you have two pistons connected by hydraulic fluid. One piston has one inch of surface area, and the other has 10 inches. Now, if you  How do hydraulics work? - Hydroline OyHydraulic fluid creates...
How do variable displacement pumps work?
What is the difference between fixed and variable pumps?May 9, 2019 — Variable displacement axial piston pumps use a swashplate to guide the pistons as they reciprocate while rotating about the shaft's axis. Hydraulic Pump Working Principles |...
How do you increase the flow of a hydraulic pump?
Pumps don't create pressure, they generate flow. A - LinkedInOct 28, 2016 — The same is true for any fixed displacement pump in a hydraulic system. When the engine or motor turns the pump, flow is produced. Pressure  Engineering Essentials:...

Bosch Rexroth A15vso Axial Piston Pump CATEGORIES

  • Bosch Rexroth A4vsg Axial Piston Variable Pump
  • Bosch Rexroth A4vg Variable Displacement Pumps
  • Bosch Rexroth A10vso Variable Displacement Pumps
  • Bosch Rexroth A2fo Fixed Displacement Pumps
  • Bosch Rexroth A4v Variable Pumps
  • Kawasaki K3vg Variable Displacement Axial Piston Pump
  • Kawasaki K3v Hydraulic Pump
  • Bosch Rexroth A4vso Variable Displacement Pumps
  • Kawasaki K5v Hydraulic Pump
  • Kawasaki K3vl Axial Piston Pump
  • Bosch Rexroth A10vo Piston Pumps
  • Bosch Rexroth A11vg Hydraulic Pumps
  • Bosch Rexroth A10vg Axial Piston Variable Pump
  • Bosch Rexroth A10vno Axial Piston Pumps
  • Bosch Rexroth A2v Variable Displacement Pumps
  • Bosch Rexroth A11vlo Axial Piston Variable Pump
  • Bosch Rexroth A8vo Variable Displacement Pumps
  • Linde Hpr Hydraulic Pump
  • Bosch Rexroth A4vtg Axial Piston Variable Pump
  • Bosch Rexroth A15vso Axial Piston Pump
  • Bosch Rexroth A11vo Axial Piston Pump
  • Bosch Rexroth A7vo Variable Displacement Pumps
More

Customers Who Viewed BOSCH REXROTH AA20VG45DGM2/10R-NTC66F023D-S Bearing Also Viewed

  • A20VLO190EP2D/10L-NZD24K02P-S BOSCH REXROTH A20VLO HYDRAULIC PUMP
  • A20VO60DFR1-10R-NSD24K01 BOSCH REXROTH A20VO HYDRAULIC AXIAL PISTON PUMP
  • A20VO60DRG-10R-NSD24K68 BOSCH REXROTH A20VO HYDRAULIC AXIAL PISTON PUMP
  • A2F87L1Z3-S BOSCH REXROTH A2F PISTON PUMPS
  • AA20VLO190EPXD/10R-NXDXXN00XP-S BOSCH REXROTH A20VLO HYDRAULIC PUMP
 
  • About Us|
  • Contact Us|
  • Site Map
  • Sitemaps

BOSCH REXROTH A4VSG AXIAL PISTON VARIABLE PUMP SUPPLIER. Copyright © 2017 - 2022 All Rights Reserved.

  • Home
  • Stock Categories
    • Bosch Rexroth A4vsg Axial Piston Variable Pump
    • Bosch Rexroth A4vg Variable Displacement Pumps
    • Bosch Rexroth A10vso Variable Displacement Pumps
    • Bosch Rexroth A2fo Fixed Displacement Pumps
    • Bosch Rexroth A4v Variable Pumps
    • Kawasaki K3vg Variable Displacement Axial Piston Pump
    • Kawasaki K3v Hydraulic Pump
    • Bosch Rexroth A4vso Variable Displacement Pumps
    • Kawasaki K5v Hydraulic Pump
    • Kawasaki K3vl Axial Piston Pump
    • Bosch Rexroth A10vo Piston Pumps
    • Bosch Rexroth A11vg Hydraulic Pumps
    • Bosch Rexroth A10vg Axial Piston Variable Pump
    • Bosch Rexroth A10vno Axial Piston Pumps
    • Bosch Rexroth A2v Variable Displacement Pumps
    • Bosch Rexroth A11vlo Axial Piston Variable Pump
    • Bosch Rexroth A8vo Variable Displacement Pumps
    • Linde Hpr Hydraulic Pump
    • Bosch Rexroth A4vtg Axial Piston Variable Pump
    • Bosch Rexroth A15vso Axial Piston Pump
    • Bosch Rexroth A11vo Axial Piston Pump
    • Bosch Rexroth A7vo Variable Displacement Pumps
  • Technical Articles
  • Bosch Rexroth A4vsg Axial Piston Variable Pump
  • Bosch Rexroth A4vg Variable Displacement Pumps
  • Bosch Rexroth A10vso Variable Displacement Pumps
✖

Home

Stock Categories

Technical Articles

Bosch Rexroth A4vsg Axial Piston Variable Pump

Bosch Rexroth A4vg Variable Displacement Pumps

Bosch Rexroth A10vso Variable Displacement Pumps

Contact Us