BOSCH REXROTH A11VG HYDRAULIC PUMPS SUPPLIER
BOSCH REXROTH A11VG HYDRAULIC PUMPS SUPPLIER
Bosch Rexroth A11VG Hydraulic Pumps   Bosch Rexroth A7VO Variable Displacement Pumps   Kawasaki K3V Hydraulic Pump  
English
English
  • Home
  • Stock Categories
    • Bosch Rexroth A11VG Hydraulic Pumps
    • Bosch Rexroth A7VO Variable Displacement Pumps
    • Kawasaki K3V Hydraulic Pump
    • Bosch Rexroth A2FO Fixed Displacement Pumps
    • Bosch Rexroth A15VSO Axial Piston Pump
    • Kawasaki K3VL Axial Piston Pump
    • Bosch Rexroth A4VSO Variable Displacement Pumps
    • Bosch Rexroth A10VSO Variable Displacement Pumps
    • Bosch Rexroth A11VLO Axial Piston Variable Pump
    • Bosch Rexroth A10VG Axial Piston Variable Pump
    • Bosch Rexroth A10VNO Axial Piston Pumps
    • Bosch Rexroth A11VO Axial Piston Pump
    • Bosch Rexroth A4V Variable Pumps
    • Linde HPR Hydraulic Pump
    • Bosch Rexroth A4VG Variable Displacement Pumps
    • Bosch Rexroth A4VSG Axial Piston Variable Pump
    • Bosch Rexroth A10VO Piston Pumps
    • Kawasaki K3VG Variable Displacement Axial Piston Pump
    • Bosch Rexroth A4VTG Axial Piston Variable Pump
    • Bosch Rexroth A2V Variable Displacement Pumps
    • Kawasaki K5V Hydraulic Pump
    • Bosch Rexroth A8VO Variable Displacement Pumps
  • Technical Articles
  • Bosch Rexroth A11VG Hydraulic Pumps
  • Bosch Rexroth A7VO Variable Displacement Pumps
  • Kawasaki K3V Hydraulic Pump
✖

Home

Stock Categories

Technical Articles

Bosch Rexroth A11VG Hydraulic Pumps

Bosch Rexroth A7VO Variable Displacement Pumps

Kawasaki K3V Hydraulic Pump

Home>Products>Bosch Rexroth A4VSO Variable Displacement Pumps>A4VSO250DFR1-30R-PZB13K34 BOSCH REXROTH A4VSO Variable Displacement Pumps

  • A4VSO250DFR1-30R-PZB13K34 BOSCH REXROTH A4VSO Variable Displacement Pumps
  • A4VSO250DFR1-30R-PZB13K34 BOSCH REXROTH A4VSO Variable Displacement Pumps

BOSCH REXROTH A4VSO250DFR1-30R-PZB13K34 MODELS

Need a CAD or 3D Model?

What is A4VSO250DFR1-30R-PZB13K34 bearing cross reference？
Contact NowWhatsAppBe Our Agent

A4VSO250DFR1-30R-PZB13K34 BOSCH REXROTH A4VSO Variable Displacement Pumps

category

Bosch Rexroth A4VSO Variable Displacement Pumps

BOSCH REXROTH A4VSO250DFR1-30R-PZB13K34 Bearing SPECIFICATIONS

  • Shop A4VSO250DFR1-30R-PZB13K34 BOSCH REXROTH A4VSO Variable Displacement Pumps BOSCH REXROTH A11VG HYDRAULIC PUMPS SUPPLIER huge online discount Bosch Rexroth A4VSO Variable Displacement Pumps inventory. Bosch Rexroth A4VSO Variable Displacement Pumps and 2.5 mm Chamfer Import machinery parts your car needs with Free Shipping and Free Extended Warranty.

  • BOSCH REXROTH

  • A4VSO250DFR1-30R-PZB13K34

  • 2.5 mm
  • 277 mm
  • 142 kN
  • 350 mm
  • 14 mm
  • 6 mm
  • 210 mm
  • 299 mm
BOSCH REXROTH A11VG HYDRAULIC PUMPS SUPPLIER

BOSCH REXROTH A11VG HYDRAULIC PUMPS SUPPLIERChina

  • BOSCH REXROTH A11VG HYDRAULIC PUMPS 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

Specifications for Bosch Rexroth A4VSO Variable Displacement Pumps

  • 2.5 mm
  • 277 mm
  • 142 kN
  • 350 mm
  • 14 mm
  • 6 mm
  • 210 mm
  • 299 mm
  • 380 mm
  • 286.2 kN
  • 20 mm
  • 40 mm
  • 240 mm
  • 16

BOSCH REXROTH A4VSO250DFR1-30R-PZB13K34 A4VSO250DFR1-30R-PZB13K34 BOSCH REXROTH A4VSO Variable Displacement Pumps Exchange Guide

 

A A4VSO 125 DFR1/30R-PZB25U68 -SO 86 BOSCH REXROTH A4VSO Variable Displacement PumpsTravel:6; Frame Accepts These Shaft Sizes (Bearing Bore):40 mm; Height G:3.938 in; Frame Size A:5 1/4 in; Bolt Pattern C:0.55 in; Shaft C/L Distance F:1 31/32 in; Bolt Pattern E:11 1/2 in; Bolt Pattern D:2 3/4 in; Frame Size B:13 in;
A4VSO40HS4/10R-PPB13N BOSCH REXROTH A4VSO Variable Displacement PumpsB:15.00 mm; Basic Dynamic Radial Load Rating C:14000 N; Grease Speed Rating Open/Shielded n1:12000 rpm; d:25.000 mm; Oil Speed Rating n2:15000 rpm; Sealed Speed Rating n3:8500 rpm; Grease Speed Rating n1:12000 rpm; Fillet Radius ra:1.00 mm; Basic Static Radial Load Rating Co:7800 N; D:52.0000 mm; Oil Speed Rating Open/Shielded n2:15000 rpm; Accessories:Two Seals;
A4VSO250HD1-30R-PPB13N BOSCH REXROTH A4VSO Variable Displacement PumpsBearing Bore Shape:Round; Max Bearing Speed:5250 rpm; Anti-Rotation Pin:Yes; Manufacturing Plant Location:Rogersville, TN; Bearing Inner Ring Material:Stainless Steel; End Cap Groove:Yes; Bearing Outer Ring Material:None; Flinger Type:INTERNAL RUBBER LIP; Housing Material:Polymer; Ball Material:440 STAINLESS STEEL; Bearing Family:Setscrew Ball Bearin; Housing Coating:No Coating; Grease Type:Mobilgrease FM222;
A4VSO125LR2H-30R-PPB13N BOSCH REXROTH A4VSO Variable Displacement PumpsBasic Static Radial Load Rating Co:32500 N; d:60.000 mm; B:22.00 mm; Grease Speed Rating n1:6000 rpm; Grease Speed Rating Open/Shielded n1:6000 rpm; Sealed Speed Rating n3:4000 rpm; Accessories:Two Shields; Oil Speed Rating Open/Shielded n2:7000 rpm; Oil Speed Rating n2:7000 rpm; Basic Dynamic Radial Load Rating C:47500 N; Fillet Radius ra:1.50 mm; D:110.0000 mm;
A4VSO125DFR1-30R-PZB13K33 BOSCH REXROTH A4VSO Variable Displacement PumpsEnd Cap Groove:Yes; Ball Bearing Housing Series:208 Series; Manufacturing Plant Location:Rogersville, TN; Self Aligning:Self Centering; Bearing Series:208 Series; Grease Type:Unirex N2; Expansion Type:Non-Expansion; Bearing Duty:Medium Duty; Bearing Inner Ring Material:Steel; UPC:782475115952; Retainer Material:Nylon; Housing Type:4 Bolt Flange; Housing Coating:Powder Coat; Bearing Bore Shape:Round;
A AA4VSE 250 HZ/10WX-VSM68B01 BOSCH REXROTH A4VSO Variable Displacement PumpsHousing Material:Cast Iron; Housing Type:2 Bolt Pillow Block; Seal Type:Single Lip; Retainer Material:Nylon; Ball Bearing Housing Series:207 Series; UPC:782477033445; Bearing Inner Ring Material:Steel; Flinger Material:None; Ball Material:Steel; Max Bearing Speed:5500 rpm; Bearing Locking Device:Eccentric Collar; Bearing Series:207 Series; Ship Weight:4.45 LB; Grease Type:Unirex N2; Base to Center Height:Standard;
A A4VSO 250 HS3/22R-PZB13N BOSCH REXROTH A4VSO Variable Displacement Pumpsd:50.000 mm; Fillet Radius ra:2.00 mm; B:27.00 mm; Basic Radial Load Rating-Static SCO:57000 N; Basic Radial Load Rating-Dynamic DC:80600 N; Fillet Radius rb:1.00 mm; D:110.0000 mm; Type:300-RDM Series (from; Speed Rating-Open and Shielded-Grease OSG:14500 rpm; Speed Rating-Open and Shielded-Oil OSO:21000 rpm;
A4VSO250LR2N 30R-PPB13K35 BOSCH REXROTH A4VSO Variable Displacement PumpsGrease Speed Rating n1:9000 rpm; Basic Dynamic Radial Load Rating C:24200 N; d:1.625 in; B:0.5625 in; Fillet Radius rb:0.024 in; Basic Static Radial Load Rating Co:18600 N; Oil Speed Rating n2:30000 rpm; Fillet Radius ra:0.04 in; D:2.8750 in;
A4VSO500HSK-10X-PPH13N BOSCH REXROTH A4VSO Variable Displacement Pumpsd:90.000 mm; D:190.0000 mm; Fillet Radius ra:2.50 mm; Basic Dynamic Radial Load Rating 40º C1:199000 N; Shielded or Sealed Co2:160000 N; Oil Speed Rating n2:4000 rpm; Basic Static Radial Load Rating 15º Co1:204000 N; Grease Speed Rating n1:3000 rpm; Width Plain C2:186000 N; B:86.00 mm; Fillet Radius rb:1.00 mm;
AA4VSO125HD1P/30R-PPB13N BOSCH REXROTH A4VSO Variable Displacement PumpsD:125.0000 mm; B:22.00 mm; Fillet Radius ra:1.00 mm; Basic Dynamic Radial Load Rating C:50700 N; Basic Static Radial Load Rating Co:41500 N; Sealed Speed Rating n3:3200 rpm; Accessories:Without Accessories; Oil Speed Rating Open/Shielded n2:6300 rpm; Grease Speed Rating Open/Shielded n1:5300 rpm; d:80.000 mm;
AHAA4VSO 250 DRG/30R-PSD63K18 -S1277 BOSCH REXROTH A4VSO Variable Displacement PumpsFillet Radius ra:1.50 mm; Grease Speed Rating n1:3800 rpm; Oil Speed Rating n2:5000 rpm; d:60.000 mm; Basic Static Radial Load Rating Co:58500 N; Sealed Speed Rating n3:3800 rpm; Basic Dynamic Radial Load Rating C:70200 N; B:36.50 mm; Accessories:No Shield, no Seal; D:110.0000 mm;
AA4VSO250FE1-30R-PSD63K78-SO859 BOSCH REXROTH A4VSO Variable Displacement PumpsEnd Cap Groove:Yes; Ship Weight:4.3 LB; Manufacturing Plant Location:Rogersville, TN; Bearing Series:210 Series; d:1.9375 in; Self Aligning:Self Centering; Retainer Material:Polymer; Flinger Material:Stainless Steel; Bearing Duty:Normal Duty; Bearing Bore Shape:Round; Ball Bearing Housing Series:210 Series; Max Bearing Speed:3600 rpm; Housing Type:Narrow Slot Take-Up; Seal Type:Triple Lip; UPC:782476478995;
A4VSO500 OV-30R-PZH13K07 BOSCH REXROTH A4VSO Variable Displacement PumpsRetainer Type:Max Life Cage; Bearing Insert Material:Nickel-Coated Steel; Flinger Type:INTERNAL RUBBER LIP; Ship Weight:1.7 LB; Grease Type:Mobilgrease FM222; Housing Coating:No Coating; Ball Bearing Housing Series:207 Series; Max Bearing Speed:5040 rpm; Self Aligning:Self Centering; Bearing Outer Ring Material:Steel; Expansion Type:Non-Expansion; Bearing Locking Device:Tapered Adapter Slee; Ball Grade:Class 24;
A A4VSO 125 LR2DF/30R-PPB13N BOSCH REXROTH A4VSO Variable Displacement PumpsMax Bearing Speed:2000 rpm; Bearing Family:Setscrew Ball Bearin; Housing Material:Cast Iron; Bearing Insert Material:Steel; Retainer Material:Nylon; Retainer Type:Std Retainer; Bearing Duty:Medium Duty; Shaft Attachment (2):Set Screw; UPC:782476044893; Bearing Bore Shape:Round; Bearing Locking Device:Setscrew; Self Aligning:Self Centering; Housing Type:4 Bolt Flange; d:3.4375 in; Flinger Type:Standard;

 

 

No.BrandBDddaDaUPCTypeTravel
AA4VSO125DR/30R-VPB13N00-SO527BOSCH REXROTH25 mm210 mm90 mm139 mm157 mm - - -
AH A4VSO 500 DP/30R-PPH25N00 -S1068BOSCH REXROTH63.00 mm460.0000 mm280.000 mm - - - - -
ALAA4VSO 180 DRG/30R-PSD63K07 -S136BOSCH REXROTH16.00 mm105.0000 mm75.000 mm - - - - -
A4VSO125LR2-30R-PPB13N00 -SO13BOSCH REXROTH17.46 mm40.0000 mm17.000 mm - - - - -
A4VSH71MA-10X-PPB02N000NBOSCH REXROTH0.7500 in4.5000 in3.000 in - - - - -
A4VSO500 OV-22R-PZH13NBOSCH REXROTH43.00 mm190.0000 mm90.000 mm - - - - -
A A4VSO 125 FRG/30R-PPB13NBOSCH REXROTH18.00 mm80.0000 mm40.000 mm - - - - -
A4VSO250DRG-10X-PPB13NBOSCH REXROTH14.00 mm47.0000 mm20.000 mm - - - - -
A4VSO125LR2G-30R-PPB13NBOSCH REXROTH42.00 mm180.0000 mm70.000 mm - - - - -
A4VSO750HD1T-30R-PPH25NBOSCH REXROTH9.00 mm30.0000 mm10.000 mm - - - - -
AP A4VSO 520 LR3DN/30L-VZH25K00-S1638BOSCH REXROTH - - 30.0000 mm - - 782476477042 - -
A AA4VSO 180 FE1/22R-PSD63K07-SO859BOSCH REXROTH15.00 mm52.0000 mm25.000 mm - - - - -
A4VSO125LR2G-10R-PPB13NBOSCH REXROTH - - 1.4375 in - - 782476479671 - -
A A4VSO 250 HS3/22R-PZB13NBOSCH REXROTH27.00 mm110.0000 mm50.000 mm - - - 300-RDM Series (from -
A4VSO250DFR1-30R-PZB13K34BOSCH REXROTH40 mm380 mm210 mm277 mm299 mm - - -
AA4VSO250FE1-30R-PSD63K78-SO859BOSCH REXROTH - - 1.9375 in - - 782476478995 - -
A A4VSO 180 EM2069/30R-PPB13NBOSCH REXROTH - - 2.9375 in - - 782475697540 - -
A4VSO71DR-10R-VZB13NBOSCH REXROTH - - - - - - - -
AA4VSO250LR2GN/30R-PPB13NBOSCH REXROTH - - - - - - - -
A4VSO250LR2N/30R-PPB13NBOSCH REXROTH35 mm295 mm160 mm218 mm238 mm - - -
A4VSO250LR2H-10R-PPB13NBOSCH REXROTH70.00 mm320.0000 mm110.000 mm - - - - -
A4VSO180LR2H-30R-PPB13N00-SO134BOSCH REXROTH - - 1.0000 in - - 782475139910 - -
AL A4VSO 71 LR2Z /10R-PPB13HBOSCH REXROTH - - 0.7500 in - - 782476483388 - -
A A4VSO 71 HD1/11R-PPB13K01BOSCH REXROTH24.00 mm42.0000 mm20.000 mm - - - - -
A4VSO250HS-30R-PPB25NBOSCH REXROTH - - 1.0000 in - - 782475986514 - -
A A4VSO 250 LR2S/30R-PPB13NBOSCH REXROTH - - - - - - - -

 

A4VSO250DFR1-30R-PZB13K34 BOSCH REXROTH A4VSO Variable Displacement Pumps Video

 

Axial piston variable pump A4VSO Series 10, 11 and 30

Features. Variable displacement pump with axial piston rotary group of swashplate design for hydrostatic drives in open circuit.

Axial piston variable pump A4VSO

S to B. Page 7. RE 92050/04.09 | A4VSO Series 10, 11 and 30. Bosch Rexroth AG.68 pages

Axial piston variable pump - A4VSO - Bosch Rexroth

Robust high pressure pump for industrial applications; Size 500 … 1000; Nominal pressure 5100 psi; Maximum pressure 5800 psi; Open circuit; Metric version ...

Industrial Hydraulics - Pumps - Bosch Rexroth

Axial piston variable pump. A4VSO. Robust high pressure pump for industrial applications; Size 40 … 1000; Nominal pressure 350 bar; Maximum pressure 400 bar ...

Axial piston variable pump (A)A4VSO Series 1X and 30

(A)A4VSO Serie 1X and 30 | Axial piston variable pump. Type code. Hydraulic fluid ... Bosch Rexroth evaluates hydraulic fluids using the Fluid.

Buy BOSCH REXROTH Variable pumps: A4VSO 250cm?/U

BOSCH REXROTH AHAA4VSO250DR/30R-VKD75U99E R902445975 Axial Piston Pumps · Variable pumps: A4VSO 250cm?/U · Table of values ...

PUMPS A4VSO BOSCH REXROTH - Parmafluid srl

Axial piston variable pump. Description. Component Series 10, 11 and 30. Size 40...1000. Nominal pressure 350 bar. Max pressure 400 bar. Open circuit ...

AA4VSO - Axial piston variable pump | Bosch Rexroth AG

Robust high pressure pump for industrial applications; Size 40 … 355; Nominal pressure 350 bar; Maximum pressure 400 bar; Open circuit; SAE version (for the ...

A4VSO- the continuous operator | Bosch Rexroth AG

A4VSO provides variable volume flow adjustment and very good priming properties with low noise level and rapid control response.

BOSCH REXROTH A4VSO250DFR1-30R-PZB13K34 INTERCHANGE

Bosch Rexroth A4VSO Variable Displacement Pumps Part series A4VSO250DFR1-30R-PZB13K34 is a potential replacement for these common bearing part numbers:

  • A4VSO250DFR1-30R-PZB13K34

  • A4VSO250DFR1-30R-PZB13K34

  • A4VSO250DFR1-30R-PZB13K34

  • A4VSO250DFR1-30R-PZB13K34

  • A4VSO250DFR1-30R-PZB13K34

  • A4VSO250DFR1-30R-PZB13K34

  • A4VSO250DFR1-30R-PZB13K34

  • A4VSO250DFR1-30R-PZB13K34

Contact Us

BOSCH REXROTH A11VG HYDRAULIC PUMPS SUPPLIER
Address
Phone(Working Time)
Fax
  • BOSCH REXROTH A11VG HYDRAULIC PUMPS 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 A4VSO250DFR1-30R-PZB13K34 Technical Articles

How do variable displacement piston pumps adjust output flow?
When and How to Adjust a Load-sensing Hydraulic PumpVariable-displacement pumps are used in hydraulic systems where the flow The compensator is adjusted to a pressure somewhat higher than that required to  Engineering Essentials: Fundamentals of...
How is displacement determined by piston pumps?
Gear and Piston Pumps | Quality HydraulicsThe hydraulic positive displacement pump is the heart of the hydraulic system. While it's true that pumps don't create pressure, they do create flow. It's also  What is the difference between fixed and variable...
What type of pump is a hydraulic pump?
Engineering Essentials: Fundamentals of Hydraulic PumpsJan 1, 2012 — A hydraulic pump is a mechanical device that converts mechanical power into hydraulic energy. It generates flow with enough power to overcome  Types of Hydraulic Pumps and How They...

Bosch Rexroth A4VSO Variable Displacement Pumps CATEGORIES

  • Bosch Rexroth A11VG Hydraulic Pumps
  • Bosch Rexroth A7VO Variable Displacement Pumps
  • Kawasaki K3V Hydraulic Pump
  • Bosch Rexroth A2FO Fixed Displacement Pumps
  • Bosch Rexroth A15VSO Axial Piston Pump
  • Kawasaki K3VL Axial Piston Pump
  • Bosch Rexroth A4VSO Variable Displacement Pumps
  • Bosch Rexroth A10VSO Variable Displacement Pumps
  • Bosch Rexroth A11VLO Axial Piston Variable Pump
  • Bosch Rexroth A10VG Axial Piston Variable Pump
  • Bosch Rexroth A10VNO Axial Piston Pumps
  • Bosch Rexroth A11VO Axial Piston Pump
  • Bosch Rexroth A4V Variable Pumps
  • Linde HPR Hydraulic Pump
  • Bosch Rexroth A4VG Variable Displacement Pumps
  • Bosch Rexroth A4VSG Axial Piston Variable Pump
  • Bosch Rexroth A10VO Piston Pumps
  • Kawasaki K3VG Variable Displacement Axial Piston Pump
  • Bosch Rexroth A4VTG Axial Piston Variable Pump
  • Bosch Rexroth A2V Variable Displacement Pumps
  • Kawasaki K5V Hydraulic Pump
  • Bosch Rexroth A8VO Variable Displacement Pumps
More

Customers Who Viewed BOSCH REXROTH A4VSO250DFR1-30R-PZB13K34 Bearing Also Viewed

  • A4VSO250DR-30R-PPB13N BOSCH REXROTH A4VSO Variable Displacement Pumps
  • AA4VSO125HD1P/30R-PPB13N BOSCH REXROTH A4VSO Variable Displacement Pumps
  • A4VSO125DFR-10X-PZB13N BOSCH REXROTH A4VSO Variable Displacement Pumps
  • A A4VSO 250 LR2GF/10R-PPB13N BOSCH REXROTH A4VSO Variable Displacement Pumps
  • A4VSO180EO2-22R-PPB13K51 BOSCH REXROTH A4VSO Variable Displacement Pumps
 
  • About Us|
  • Contact Us|
  • Site Map
  • Sitemaps

BOSCH REXROTH A11VG HYDRAULIC PUMPS SUPPLIER. Copyright © 2017 - 2024 All Rights Reserved.

  • Home
  • Stock Categories
    • Bosch Rexroth A11VG Hydraulic Pumps
    • Bosch Rexroth A7VO Variable Displacement Pumps
    • Kawasaki K3V Hydraulic Pump
    • Bosch Rexroth A2FO Fixed Displacement Pumps
    • Bosch Rexroth A15VSO Axial Piston Pump
    • Kawasaki K3VL Axial Piston Pump
    • Bosch Rexroth A4VSO Variable Displacement Pumps
    • Bosch Rexroth A10VSO Variable Displacement Pumps
    • Bosch Rexroth A11VLO Axial Piston Variable Pump
    • Bosch Rexroth A10VG Axial Piston Variable Pump
    • Bosch Rexroth A10VNO Axial Piston Pumps
    • Bosch Rexroth A11VO Axial Piston Pump
    • Bosch Rexroth A4V Variable Pumps
    • Linde HPR Hydraulic Pump
    • Bosch Rexroth A4VG Variable Displacement Pumps
    • Bosch Rexroth A4VSG Axial Piston Variable Pump
    • Bosch Rexroth A10VO Piston Pumps
    • Kawasaki K3VG Variable Displacement Axial Piston Pump
    • Bosch Rexroth A4VTG Axial Piston Variable Pump
    • Bosch Rexroth A2V Variable Displacement Pumps
    • Kawasaki K5V Hydraulic Pump
    • Bosch Rexroth A8VO Variable Displacement Pumps
  • Technical Articles
  • Bosch Rexroth A11VG Hydraulic Pumps
  • Bosch Rexroth A7VO Variable Displacement Pumps
  • Kawasaki K3V Hydraulic Pump
✖

Home

Stock Categories

Technical Articles

Bosch Rexroth A11VG Hydraulic Pumps

Bosch Rexroth A7VO Variable Displacement Pumps

Kawasaki K3V Hydraulic Pump

Contact Us