Machinery Parts Co., Ltd.
Machinery Parts Co., Ltd.
DAIKIN Rotor Pump   NACHI Piston Pump   Rexroth POPPET DIRECTIONAL VALVE  
English
English
  • Home
  • Stock Categories
    • DAIKIN Rotor Pump
    • NACHI Piston Pump
    • Rexroth POPPET DIRECTIONAL VALVE
    • Rexroth PRESSURE RELIEF VALVE
    • Rexroth Pressure switch
    • Rexroth THROTTLE VALVE
    • Rexroth Vane Pump
    • AMI Bearing
    • AURORA Bearing
    • FAG Bearing
    • IKO Bearing
    • KOYO Bearing
    • NSK Bearing
    • NTN Bearing
    • SKF Bearing
    • TIMKEN Bearing
    • REXROTH HY-CHECK VALVE
    • REXROTH Directional spool valves
    • REXROTH Directional poppet valves
    • REXROTH Throttle check valve
    • REXROTH Throttle check valves
    • REXROTH Valves
    • REXROTH Check valves
    • REXROTH Pressure reducing valve
    • REXROTH Twin throttle check valve
    • REXROTH Pressure relief valve
    • REXROTH Throttle valves
    • Timken 3780 Bearing
    • Hm804810 Bearing
    • 15118 Bearing
    • H715311 Bearing
    • Large Slewing Bearings
    • Slewing Ring Bearings
    • Bearing Slewing Ring
    • Kaydon Slewing Bearing
    • THK Linear Guide
    • THK Miniature Linear Guide
    • THK Linear Guide Rails
    • High Temperature Linear Guide
    • Curved Linear Guide
    • THK Linear Bearings And Rails
    • THK Linear Motion
    • Wide Series Cylindrical Roller Bearings
    • Double-row Angular Contact Ball Bearings
    • Deep Groove Ball Bearings
    • Sealed Spherical Roller Bearings Continuous Casting Plants
    • Spherical Roller Bearings
  • Technical Articles
  • DAIKIN Rotor Pump
  • NACHI Piston Pump
  • Rexroth POPPET DIRECTIONAL VALVE
✖

Home

Stock Categories

Technical Articles

DAIKIN Rotor Pump

NACHI Piston Pump

Rexroth POPPET DIRECTIONAL VALVE

Home>Products>REXROTH Pressure relief valve>REXROTH Z2DB 10 VD2-4X/315 R900906773 Pressure relief valve

  • REXROTH Z2DB 10 VD2-4X/315 R900906773 Pressure relief valve
  • REXROTH Z2DB 10 VD2-4X/315 R900906773 Pressure relief valve
  • REXROTH Z2DB 10 VD2-4X/315 R900906773 Pressure relief valve
  • REXROTH Z2DB 10 VD2-4X/315 R900906773 Pressure relief valve

REXROTH Z2DB 10 VD2-4X/315 MODELS

Need a CAD or 3D Model?

Contact NowWhatsAppBe Our Agent

REXROTH Z2DB 10 VD2-4X/315 R900906773 Pressure relief valve

category

REXROTH Pressure relief valve

REXROTH Z2DB 10 VD2-4X/315 Bearing SPECIFICATIONS

  • REXROTH Z2DB 10 VD2-4X/315 R900906773 Pressure relief valve Warehouse offers car parts and car accessories. We sell discount REXROTH Pressure relief valve online Machinery Parts Co., Ltd. as well as cheap FAG BEARING Brand machinery parts. 8482.10.50.28 Harmonized Tariff Code

  • REXROTH

  • Z2DB 10 VD2-4X/315

  • M38500
  • M38549
  • M38510
  • Imperial
  • 0.30 Kg
  • Stamped Steel
  • 34.925 mm
  • 66.675 mm
Machinery Parts Co., Ltd.

Machinery Parts Co., Ltd.China

  • Machinery Parts Co., Ltd.2020-07-10 09:46:19
    Welcome to my shop! Glad to serve you! Please send your question!
Price Inspection Certificate Product Specifications Company Profile

Specifications for REXROTH Z2DB 10 VD2-4X/315 R900906773 Pressure relief valve

  • M38500
  • M38549
  • M38510
  • Imperial
  • 0.30 Kg
  • Stamped Steel
  • 34.925 mm
  • 66.675 mm
  • 20.638 mm
  • 16.670 mm
  • 20.638 mm
  • 3.560 mm
  • 2.29 mm
  • 39.88 mm
  • 46.48 mm
  • 62.00 mm
  • 57.91 mm
  • 3.3 mm
  • -0.3 mm
  • -5.6 mm
  • 3640 lbf
  • 14000 lbf
  • 16400 lbf
  • 2200 lbf
  • 1.66
  • 0.35
  • 1.7
  • 20.3
  • 11.8
  • 0.068

REXROTH Z2DB 10 VD2-4X/315 REXROTH Z2DB 10 VD2-4X/315 R900906773 Pressure relief valve Product Identifiers

REXROTH Z2DB 10 VD2-4X/315 R900906773 Pressure relief valve part number reviews

No.Brand
型号品牌
Z2DB 6 VC2-4X/100REXROTH
DB 30-2-5X/100REXROTH
Z2DB 10 VD2-4X/315VREXROTH
DB 30-1-5X/50REXROTH
ZDB 10 VP2-4X/100VREXROTH
Z2DB 6 VD2-4X/315REXROTH
DBDS 20 K1X/50REXROTH
ZDB 6 VP2-4X/200REXROTH
Z2DB 10 VD2-4X/50VREXROTH
Z2DB 10 VD2-4X/200REXROTH
ZDB 6 VP2-4X/50REXROTH
DB 30-1-5X/100REXROTH
DBW 20 B2-5X/50-6EG24N9K4REXROTH
DB 20-2-5X/350REXROTH
DB 10-1-5X/50REXROTH
Z2DB 10 VC2-4X/100REXROTH
DBW 20 B1-5X/315-6EG24N9K4REXROTH
DBDS 20 P1X/50REXROTH
DBW 30 B2-5X/315-6EG24N9K4REXROTH
DB 20-1-5X/100REXROTH
Z2DB 10 VD2-4X/315REXROTH
DBW 30 B1-5X/315-6EG24N9K4REXROTH

 

REXROTH Z2DB 6 VD2-4X/200 R900496390 Pressure relief valveSeries:M38500; Cone Part Number:M38549; Cup Part Number:M38510; Design Units:Imperial; Bearing Weight:0.30 Kg; Cage Type:Stamped Steel; d:34.925 mm; D:66.675 mm; B - Cone Width:20.638 mm; C - Cup Width:16.670 mm; B:20.638 mm; R - Cone Backface To Clear Radius1:3.560 mm; r - Cup Backface To Clear Radius2:2.29 mm; da - Cone Frontface Backing Diameter:39.88 mm; db - Cone Backface Backing Diameter:46.48 mm; Da - Cup Frontface Backing Diameter:62.00 mm; Db - Cup Backface Backing Diameter:57.91 mm; Ab - Cage-Cone Frontface Clearance:3.3 mm; Aa - Cage-Cone Backface Clearance:-0.3 mm; a - Effective Center Location3:-5.6 mm; C90 - Dynamic Radial Rating (90 million revolutions)4:3640 lbf; C1 - Dynamic Radial Rating (1 million revolutions)5:14000 lbf; C0 - Static Radial Rating:16400 lbf; Ca90 - Dynamic Thrust Rating (90 million revolutions)6:2200 lbf; K - Factor7:1.66; e - ISO Factor8:0.35; Y - ISO Factor9:1.7; G1 - Heat Generation Factor (Roller-Raceway):20.3; G2 - Heat Generation Factor (Rib-Roller End):11.8; Cg - Geometry Factor:0.068;
REXROTH Z2DB 10 VC2-4X/50V R900431164 Pressure relief valveSeries:M38500; Cone Part Number:M38549; Cup Part Number:M38510; Design Units:Imperial; Bearing Weight:0.30 Kg; Cage Type:Stamped Steel; d:34.925 mm; D:66.675 mm; B - Cone Width:20.638 mm; C - Cup Width:16.670 mm; B:20.638 mm; R - Cone Backface To Clear Radius1:3.560 mm; r - Cup Backface To Clear Radius2:2.29 mm; da - Cone Frontface Backing Diameter:39.88 mm; db - Cone Backface Backing Diameter:46.48 mm; Da - Cup Frontface Backing Diameter:62.00 mm; Db - Cup Backface Backing Diameter:57.91 mm; Ab - Cage-Cone Frontface Clearance:3.3 mm; Aa - Cage-Cone Backface Clearance:-0.3 mm; a - Effective Center Location3:-5.6 mm; C90 - Dynamic Radial Rating (90 million revolutions)4:3640 lbf; C1 - Dynamic Radial Rating (1 million revolutions)5:14000 lbf; C0 - Static Radial Rating:16400 lbf; Ca90 - Dynamic Thrust Rating (90 million revolutions)6:2200 lbf; K - Factor7:1.66; e - ISO Factor8:0.35; Y - ISO Factor9:1.7; G1 - Heat Generation Factor (Roller-Raceway):20.3; G2 - Heat Generation Factor (Rib-Roller End):11.8; Cg - Geometry Factor:0.068;
REXROTH DBW 20 B1-5X/50-6EG24N9K4 R900920863 Pressure relief valveSeries:M38500; Cone Part Number:M38549; Cup Part Number:M38510; Design Units:Imperial; Bearing Weight:0.30 Kg; Cage Type:Stamped Steel; d:34.925 mm; D:66.675 mm; B - Cone Width:20.638 mm; C - Cup Width:16.670 mm; B:20.638 mm; R - Cone Backface To Clear Radius1:3.560 mm; r - Cup Backface To Clear Radius2:2.29 mm; da - Cone Frontface Backing Diameter:39.88 mm; db - Cone Backface Backing Diameter:46.48 mm; Da - Cup Frontface Backing Diameter:62.00 mm; Db - Cup Backface Backing Diameter:57.91 mm; Ab - Cage-Cone Frontface Clearance:3.3 mm; Aa - Cage-Cone Backface Clearance:-0.3 mm; a - Effective Center Location3:-5.6 mm; C90 - Dynamic Radial Rating (90 million revolutions)4:3640 lbf; C1 - Dynamic Radial Rating (1 million revolutions)5:14000 lbf; C0 - Static Radial Rating:16400 lbf; Ca90 - Dynamic Thrust Rating (90 million revolutions)6:2200 lbf; K - Factor7:1.66; e - ISO Factor8:0.35; Y - ISO Factor9:1.7; G1 - Heat Generation Factor (Roller-Raceway):20.3; G2 - Heat Generation Factor (Rib-Roller End):11.8; Cg - Geometry Factor:0.068;
REXROTH DB 30-1-5X/200 R900590768 Pressure relief valveSeries:M38500; Cone Part Number:M38549; Cup Part Number:M38510; Design Units:Imperial; Bearing Weight:0.30 Kg; Cage Type:Stamped Steel; d:34.925 mm; D:66.675 mm; B - Cone Width:20.638 mm; C - Cup Width:16.670 mm; B:20.638 mm; R - Cone Backface To Clear Radius1:3.560 mm; r - Cup Backface To Clear Radius2:2.29 mm; da - Cone Frontface Backing Diameter:39.88 mm; db - Cone Backface Backing Diameter:46.48 mm; Da - Cup Frontface Backing Diameter:62.00 mm; Db - Cup Backface Backing Diameter:57.91 mm; Ab - Cage-Cone Frontface Clearance:3.3 mm; Aa - Cage-Cone Backface Clearance:-0.3 mm; a - Effective Center Location3:-5.6 mm; C90 - Dynamic Radial Rating (90 million revolutions)4:3640 lbf; C1 - Dynamic Radial Rating (1 million revolutions)5:14000 lbf; C0 - Static Radial Rating:16400 lbf; Ca90 - Dynamic Thrust Rating (90 million revolutions)6:2200 lbf; K - Factor7:1.66; e - ISO Factor8:0.35; Y - ISO Factor9:1.7; G1 - Heat Generation Factor (Roller-Raceway):20.3; G2 - Heat Generation Factor (Rib-Roller End):11.8; Cg - Geometry Factor:0.068;
REXROTH Z2DB 10 VC2-4X/200V R900463267 Pressure relief valveSeries:M38500; Cone Part Number:M38549; Cup Part Number:M38510; Design Units:Imperial; Bearing Weight:0.30 Kg; Cage Type:Stamped Steel; d:34.925 mm; D:66.675 mm; B - Cone Width:20.638 mm; C - Cup Width:16.670 mm; B:20.638 mm; R - Cone Backface To Clear Radius1:3.560 mm; r - Cup Backface To Clear Radius2:2.29 mm; da - Cone Frontface Backing Diameter:39.88 mm; db - Cone Backface Backing Diameter:46.48 mm; Da - Cup Frontface Backing Diameter:62.00 mm; Db - Cup Backface Backing Diameter:57.91 mm; Ab - Cage-Cone Frontface Clearance:3.3 mm; Aa - Cage-Cone Backface Clearance:-0.3 mm; a - Effective Center Location3:-5.6 mm; C90 - Dynamic Radial Rating (90 million revolutions)4:3640 lbf; C1 - Dynamic Radial Rating (1 million revolutions)5:14000 lbf; C0 - Static Radial Rating:16400 lbf; Ca90 - Dynamic Thrust Rating (90 million revolutions)6:2200 lbf; K - Factor7:1.66; e - ISO Factor8:0.35; Y - ISO Factor9:1.7; G1 - Heat Generation Factor (Roller-Raceway):20.3; G2 - Heat Generation Factor (Rib-Roller End):11.8; Cg - Geometry Factor:0.068;
REXROTH DBW 10 B1-5X/315-6EG24N9K4 R900422422 Pressure relief valveSeries:M38500; Cone Part Number:M38549; Cup Part Number:M38510; Design Units:Imperial; Bearing Weight:0.30 Kg; Cage Type:Stamped Steel; d:34.925 mm; D:66.675 mm; B - Cone Width:20.638 mm; C - Cup Width:16.670 mm; B:20.638 mm; R - Cone Backface To Clear Radius1:3.560 mm; r - Cup Backface To Clear Radius2:2.29 mm; da - Cone Frontface Backing Diameter:39.88 mm; db - Cone Backface Backing Diameter:46.48 mm; Da - Cup Frontface Backing Diameter:62.00 mm; Db - Cup Backface Backing Diameter:57.91 mm; Ab - Cage-Cone Frontface Clearance:3.3 mm; Aa - Cage-Cone Backface Clearance:-0.3 mm; a - Effective Center Location3:-5.6 mm; C90 - Dynamic Radial Rating (90 million revolutions)4:3640 lbf; C1 - Dynamic Radial Rating (1 million revolutions)5:14000 lbf; C0 - Static Radial Rating:16400 lbf; Ca90 - Dynamic Thrust Rating (90 million revolutions)6:2200 lbf; K - Factor7:1.66; e - ISO Factor8:0.35; Y - ISO Factor9:1.7; G1 - Heat Generation Factor (Roller-Raceway):20.3; G2 - Heat Generation Factor (Rib-Roller End):11.8; Cg - Geometry Factor:0.068;
REXROTH Z2DB 6 VC2-4X/200 R900503515 Pressure relief valveSeries:M38500; Cone Part Number:M38549; Cup Part Number:M38510; Design Units:Imperial; Bearing Weight:0.30 Kg; Cage Type:Stamped Steel; d:34.925 mm; D:66.675 mm; B - Cone Width:20.638 mm; C - Cup Width:16.670 mm; B:20.638 mm; R - Cone Backface To Clear Radius1:3.560 mm; r - Cup Backface To Clear Radius2:2.29 mm; da - Cone Frontface Backing Diameter:39.88 mm; db - Cone Backface Backing Diameter:46.48 mm; Da - Cup Frontface Backing Diameter:62.00 mm; Db - Cup Backface Backing Diameter:57.91 mm; Ab - Cage-Cone Frontface Clearance:3.3 mm; Aa - Cage-Cone Backface Clearance:-0.3 mm; a - Effective Center Location3:-5.6 mm; C90 - Dynamic Radial Rating (90 million revolutions)4:3640 lbf; C1 - Dynamic Radial Rating (1 million revolutions)5:14000 lbf; C0 - Static Radial Rating:16400 lbf; Ca90 - Dynamic Thrust Rating (90 million revolutions)6:2200 lbf; K - Factor7:1.66; e - ISO Factor8:0.35; Y - ISO Factor9:1.7; G1 - Heat Generation Factor (Roller-Raceway):20.3; G2 - Heat Generation Factor (Rib-Roller End):11.8; Cg - Geometry Factor:0.068;
REXROTH DB 20-2-5X/200 R900971728 Pressure relief valveSeries:M38500; Cone Part Number:M38549; Cup Part Number:M38510; Design Units:Imperial; Bearing Weight:0.30 Kg; Cage Type:Stamped Steel; d:34.925 mm; D:66.675 mm; B - Cone Width:20.638 mm; C - Cup Width:16.670 mm; B:20.638 mm; R - Cone Backface To Clear Radius1:3.560 mm; r - Cup Backface To Clear Radius2:2.29 mm; da - Cone Frontface Backing Diameter:39.88 mm; db - Cone Backface Backing Diameter:46.48 mm; Da - Cup Frontface Backing Diameter:62.00 mm; Db - Cup Backface Backing Diameter:57.91 mm; Ab - Cage-Cone Frontface Clearance:3.3 mm; Aa - Cage-Cone Backface Clearance:-0.3 mm; a - Effective Center Location3:-5.6 mm; C90 - Dynamic Radial Rating (90 million revolutions)4:3640 lbf; C1 - Dynamic Radial Rating (1 million revolutions)5:14000 lbf; C0 - Static Radial Rating:16400 lbf; Ca90 - Dynamic Thrust Rating (90 million revolutions)6:2200 lbf; K - Factor7:1.66; e - ISO Factor8:0.35; Y - ISO Factor9:1.7; G1 - Heat Generation Factor (Roller-Raceway):20.3; G2 - Heat Generation Factor (Rib-Roller End):11.8; Cg - Geometry Factor:0.068;

 

 

REXROTH Z2DB 10 VD2-4X/315 R900906773 Pressure relief valve Video

 

REXROTH Z2DB 10 VD2-4X/315 INTERCHANGE

REXROTH Pressure relief valve Part series Z2DB 10 VD2-4X/315 is a potential replacement for these common bearing part numbers:

  • Z2DB 10 VD2-4X/315

  • Z2DB 10 VD2-4X/315

  • Z2DB 10 VD2-4X/315

  • Z2DB 10 VD2-4X/315

  • Z2DB 10 VD2-4X/315

  • Z2DB 10 VD2-4X/315

  • Z2DB 10 VD2-4X/315

  • Z2DB 10 VD2-4X/315

Contact Us

Machinery Parts Co., Ltd.
Address2370 North Main Street, East Peoria, Illinois 68811, U.S.A.
Phone(Working Time)722-298-7405
Fax
  • Machinery Parts Co., Ltd.
    • 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

REXROTH Z2DB 10 VD2-4X/315 Technical Articles

Can you use Vaseline as lube for bearings?
Skateboarders! I need your help!!!!! - Ultimate GuitarApr 22, 2009 — If your bearings are at the point of which you need to lube them, it'd be do need lube. but i advise on not using Vaseline. it might have some  difference between...
Can you use Vaseline on bearings?
Vaseline - Bike ForumsApr 13, 2005 — The Vaseline worked pretty well, my bearings are now overhauled and the pedals are almost like new. I overhauled my bearings in my pedals, it worked great. White Lithium grease is the std product. Small tubs...
How do you polish ball bearings?
Cleaning ceramic bearings | clean the bearing | bearingIn brief, hybrid bearings use ceramic balls, paired with metal inner and outer rings, whereas full ceramic bearings are entirely made from ceramic material. Now  4 Ways to Clean Ball...

REXROTH Pressure relief valve CATEGORIES

  • DAIKIN Rotor Pump
  • NACHI Piston Pump
  • Rexroth POPPET DIRECTIONAL VALVE
  • Rexroth PRESSURE RELIEF VALVE
  • Rexroth Pressure switch
  • Rexroth THROTTLE VALVE
  • Rexroth Vane Pump
  • AMI Bearing
  • AURORA Bearing
  • FAG Bearing
  • IKO Bearing
  • KOYO Bearing
  • NSK Bearing
  • NTN Bearing
  • SKF Bearing
  • TIMKEN Bearing
  • REXROTH HY-CHECK VALVE
  • REXROTH Directional spool valves
  • REXROTH Directional poppet valves
  • REXROTH Throttle check valve
  • REXROTH Throttle check valves
  • REXROTH Valves
  • REXROTH Check valves
  • REXROTH Pressure reducing valve
  • REXROTH Twin throttle check valve
  • REXROTH Pressure relief valve
  • REXROTH Throttle valves
  • Timken 3780 Bearing
  • Hm804810 Bearing
  • 15118 Bearing
  • H715311 Bearing
  • Large Slewing Bearings
  • Slewing Ring Bearings
  • Bearing Slewing Ring
  • Kaydon Slewing Bearing
  • THK Linear Guide
  • THK Miniature Linear Guide
  • THK Linear Guide Rails
  • High Temperature Linear Guide
  • Curved Linear Guide
  • THK Linear Bearings And Rails
  • THK Linear Motion
  • Wide Series Cylindrical Roller Bearings
  • Double-row Angular Contact Ball Bearings
  • Deep Groove Ball Bearings
  • Sealed Spherical Roller Bearings Continuous Casting Plants
  • Spherical Roller Bearings
More

Customers Who Viewed REXROTH Z2DB 10 VD2-4X/315 Bearing Also Viewed

  • REXROTH Z2DB 10 VC2-4X/200V R900463267 Pressure relief valve
  • REXROTH Z2DB 6 VD2-4X/200 R900496390 Pressure relief valve
  • REXROTH DBW 10 B1-5X/315-6EG24N9K4 R900422422 Pressure relief valve
  • REXROTH DBW 20 B1-5X/50-6EG24N9K4 R900920863 Pressure relief valve
  • REXROTH DB 20-2-5X/200 R900971728 Pressure relief valve

Top Products

IKO CR32VB Cam Follower and Track Roller - Stud Type FAG B7032-E-T-P4S-UM Precision Ball Bearings DAIKIN RP23C13JB-37-30 Rotor Pump
NACHI ZS-5B Piston Pump Timken h715345 Bearing
 
  • About Us|
  • Contact Us|
  • Site Map
  • Sitemaps

Machinery Parts Co., Ltd.. Copyright © 2017 - 2024 All Rights Reserved.

  • Home
  • Stock Categories
    • DAIKIN Rotor Pump
    • NACHI Piston Pump
    • Rexroth POPPET DIRECTIONAL VALVE
    • Rexroth PRESSURE RELIEF VALVE
    • Rexroth Pressure switch
    • Rexroth THROTTLE VALVE
    • Rexroth Vane Pump
    • AMI Bearing
    • AURORA Bearing
    • FAG Bearing
    • IKO Bearing
    • KOYO Bearing
    • NSK Bearing
    • NTN Bearing
    • SKF Bearing
    • TIMKEN Bearing
    • REXROTH HY-CHECK VALVE
    • REXROTH Directional spool valves
    • REXROTH Directional poppet valves
    • REXROTH Throttle check valve
    • REXROTH Throttle check valves
    • REXROTH Valves
    • REXROTH Check valves
    • REXROTH Pressure reducing valve
    • REXROTH Twin throttle check valve
    • REXROTH Pressure relief valve
    • REXROTH Throttle valves
    • Timken 3780 Bearing
    • Hm804810 Bearing
    • 15118 Bearing
    • H715311 Bearing
    • Large Slewing Bearings
    • Slewing Ring Bearings
    • Bearing Slewing Ring
    • Kaydon Slewing Bearing
    • THK Linear Guide
    • THK Miniature Linear Guide
    • THK Linear Guide Rails
    • High Temperature Linear Guide
    • Curved Linear Guide
    • THK Linear Bearings And Rails
    • THK Linear Motion
    • Wide Series Cylindrical Roller Bearings
    • Double-row Angular Contact Ball Bearings
    • Deep Groove Ball Bearings
    • Sealed Spherical Roller Bearings Continuous Casting Plants
    • Spherical Roller Bearings
  • Technical Articles
  • DAIKIN Rotor Pump
  • NACHI Piston Pump
  • Rexroth POPPET DIRECTIONAL VALVE
✖

Home

Stock Categories

Technical Articles

DAIKIN Rotor Pump

NACHI Piston Pump

Rexroth POPPET DIRECTIONAL VALVE

Contact Us