BOSCH REXROTH A2FO FIXED DISPLACEMENT PUMPS SUPPLIER
BOSCH REXROTH A2FO FIXED DISPLACEMENT PUMPS SUPPLIER
Bosch Rexroth A2fo Fixed Displacement Pumps   Bosch Rexroth A10vno Axial Piston Pumps   Kawasaki K3vg Variable Displacement Axial Piston Pump  
English
English
  • Home
  • Stock Categories
    • Bosch Rexroth A2fo Fixed Displacement Pumps
    • Bosch Rexroth A10vno Axial Piston Pumps
    • Kawasaki K3vg Variable Displacement Axial Piston Pump
    • Bosch Rexroth A8vo Variable Displacement Pumps
    • Kawasaki K3vl Axial Piston Pump
    • Bosch Rexroth A10vo Piston Pumps
    • Bosch Rexroth A15vso Axial Piston Pump
    • Bosch Rexroth A7vo Variable Displacement Pumps
    • Bosch Rexroth A10vso Variable Displacement Pumps
    • Kawasaki K3v Hydraulic Pump
    • Bosch Rexroth A11vg Hydraulic Pumps
    • Bosch Rexroth A10vg Axial Piston Variable Pump
    • Bosch Rexroth A4vg Variable Displacement Pumps
    • Bosch Rexroth A4vso Variable Displacement Pumps
    • Bosch Rexroth A2v Variable Displacement Pumps
    • Linde Hpr Hydraulic Pump
    • Bosch Rexroth A4vtg Axial Piston Variable Pump
    • Bosch Rexroth A4v Variable Pumps
    • Kawasaki K5v Hydraulic Pump
    • Bosch Rexroth A11vlo Axial Piston Variable Pump
    • Bosch Rexroth A11vo Axial Piston Pump
    • Bosch Rexroth A4vsg Axial Piston Variable Pump
  • Technical Articles
  • Bosch Rexroth A2fo Fixed Displacement Pumps
  • Bosch Rexroth A10vno Axial Piston Pumps
  • Kawasaki K3vg Variable Displacement Axial Piston Pump
✖

Home

Stock Categories

Technical Articles

Bosch Rexroth A2fo Fixed Displacement Pumps

Bosch Rexroth A10vno Axial Piston Pumps

Kawasaki K3vg Variable Displacement Axial Piston Pump

Home>Products>Bosch Rexroth A7vo Variable Displacement Pumps>A7VO55LRDH-60R-PZB01 BOSCH REXROTH A7VO VARIABLE DISPLACEMENT PUMPS

  • A7VO55LRDH-60R-PZB01 BOSCH REXROTH A7VO VARIABLE DISPLACEMENT PUMPS
  • A7VO55LRDH-60R-PZB01 BOSCH REXROTH A7VO VARIABLE DISPLACEMENT PUMPS

BOSCH REXROTH A7VO55LRDH-60R-PZB01 MODELS

Need a CAD or 3D Model?

What is A7VO55LRDH-60R-PZB01 bearing cross reference？
Contact NowWhatsAppBe Our Agent

A7VO55LRDH-60R-PZB01 BOSCH REXROTH A7VO VARIABLE DISPLACEMENT PUMPS

category

Bosch Rexroth A7vo Variable Displacement Pumps

BOSCH REXROTH A7VO55LRDH-60R-PZB01 Bearing SPECIFICATIONS

  • Find the discount A7VO55LRDH-60R-PZB01 BOSCH REXROTH A7VO VARIABLE DISPLACEMENT PUMPS 161 mm Da max. online you need . We offer 1.08 Calculation factor f2D ... If you check out our large selection of A7VO55LRDH-60R-PZB01 BOSCH REXROTH A7VO VARIABLE DISPLACEMENT PUMPS once .

  • BOSCH REXROTH

  • A7VO55LRDH-60R-PZB01

  • 161 mm
  • 128.5 mm
  • 1.08
  • 290 N/µm
  • 0.68
  • 1.02
  • 503 N/µm
  • 2600 N
BOSCH REXROTH A2FO FIXED DISPLACEMENT PUMPS SUPPLIER

BOSCH REXROTH A2FO FIXED DISPLACEMENT PUMPS SUPPLIERChina

  • BOSCH REXROTH A2FO FIXED DISPLACEMENT 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

A7VO55LRDH-60R-PZB01 BOSCH REXROTH A7VO VARIABLE DISPLACEMENT PUMPS specification

  • 161 mm
  • 128.5 mm
  • 1.08
  • 290 N/µm
  • 0.68
  • 1.02
  • 503 N/µm
  • 2600 N
  • 1 mm
  • 1.41
  • 0.99
  • 1.14
  • 128.5 mm
  • 379 N/µm
  • 2 mm
  • 165 mm
  • 19.05 mm
  • 119 mm
  • 155.15 mm
  • 1300 N

BOSCH REXROTH A7VO55LRDH-60R-PZB01 A7VO55LRDH-60R-PZB01 BOSCH REXROTH A7VO VARIABLE DISPLACEMENT PUMPS Codes and sizes

 

AA7VO250DR/63R-VPB02 BOSCH REXROTH A7VO VARIABLE DISPLACEMENT PUMPSLimiting speed:1500 r/min; r1,2 min.:1.1 mm; Basic dynamic load rating C:297 kN; D:225 mm; ra max.:1 mm; Calculation factor kr:0.2; b1:7 mm; d:180 mm; Mass bearing:4.2 kg; rb max.:1 mm; Reference speed:1200 r/min; r3,4 min.:1.1 mm; Fatigue load limit Pu:69.5 kN; Basic static load rating C0:695 kN; B:45 mm; K:4 mm; Da max.:219 mm; da min.:186 mm; d1 ≈:200 mm; D1 ≈:208.5 mm;
A7VO250DR-60L-PPB02 BOSCH REXROTH A7VO VARIABLE DISPLACEMENT PUMPSCenter Guidance:Floating Steel Ring; Roller Profile:Symmetric; Radial Clearance:0.080 to 0.110 mm; Configuration:Double Row; B:64 mm; Bore Type:Tapered Bore; D:190 mm; Nr. of Holes:6; Limiting Speed - Grease:2,600 rpm; Fillet Radius/Chamfer:3 mm; Static Load Rating:660,000 N; Limiting Speed - Oil:3,200 rpm; d:90 mm; da (min):104 mm; Hole Diameter (do):6 mm; Da (max):176 mm; Axial Load Factor Y2:2.98;
A7VO500DRG-63R-VPH02 BOSCH REXROTH A7VO VARIABLE DISPLACEMENT PUMPSCalculation factor e:0.21; D:85 mm; db min.:50 mm; Fatigue load limit Pu:0.4 kN; d3:65 mm; Basic dynamic load rating C:22.9 kN; Limiting speed:5300 r/min; Da max.:78 mm; d:40 mm; B:23 mm; Calculation factor Y2:4.6; Calculation factor kr:0.045; Ba min.:8 mm; Mass bearing + adapter sleeve:0.76 kg; Calculation factor Y0:3.2; Basic static load rating C0:7.8 kN; da max.:53 mm; Permissible angular misalignment α:1.5 °;
A7VO107DR/63L-NZB01 BOSCH REXROTH A7VO VARIABLE DISPLACEMENT PUMPSRG:3/8 NPT; ba:51.594 mm; R1:67.945 mm; R2:31.75 mm; Labyrinth ring:2 x LOR 118; h:42.862 mm; P180°:60.9 kN; J max.:368.3 mm; H:239.713 mm; P120°:55.6 kN; P90°:89 kN; Mass pillow block:32.2 kg; J min.:320.675 mm; Cap bolt:2 x 3/4-10 UNC; P60°:149 kN; A1:120.65 mm; Ca:62.789 mm; PG:1/4 NPT; P150°:50.7 kN; Bearing limiting speed:3600 r/min;
A7VO55LRDS/63R-NZB01-S BOSCH REXROTH A7VO VARIABLE DISPLACEMENT PUMPSrb max.:4 mm; Axial load factor Y:0.4; ra max.:4 mm; Calculation factor kr:0.3; Mass bearing:115 kg; D1 ≈:433 mm; db min.:331 mm; s max.:4.5 mm; F:333 mm; B:130 mm; Fatigue load limit Pu:320 kN; da min.:298 mm; Reference speed:1200 r/min; Limiting value e:0.3; Da max.:482 mm; da max.:328 mm; D:500 mm; r1,2 min.:5 mm; Basic dynamic load rating C:2330 kN;
A7VO80DRS/63R-NZB01 BOSCH REXROTH A7VO VARIABLE DISPLACEMENT PUMPSAttachment bolt diameter G:4 x 22.225; Limiting speed:2100 r/min; L:247.65 mm; N1:23.813 mm; J:196.85 mm; da:100.013 mm; Mass bearing unit:31.3 kg; A6:31.75 mm; a:5.556 mm; A5:46.831 mm; s:41.275 mm; S:0.794 mm; Basic dynamic load rating C:426 kN; A:88.9 mm;
A7VO160LR-60R-PPB01 BOSCH REXROTH A7VO VARIABLE DISPLACEMENT PUMPSCa min.:5 mm; db min.:87.5 mm; r3,4 min.:2.5 mm; Mass bearing:1.31 kg; Da max.:109.5 mm; Basic dynamic load rating C:170 kN; r1,2 min.:3 mm; Cb min.:6 mm; T:31 mm; Fatigue load limit Pu:25 kN; D:120 mm; ra max.:3 mm; da max.:84 mm; Da min.:104 mm; Dimension series:M 714200; Db min.:115 mm; Limiting speed:5300 r/min; Calculation factor Y0:0.8; d:75 mm; B:29.5 mm;
AA7VO250FR/63L-VPB01-SO24 BOSCH REXROTH A7VO VARIABLE DISPLACEMENT PUMPSd:170 mm; Outside Ring Inside Diameter:272 mm; B:52 mm; ra (max):3 mm; db (max):204 mm; Db (min):292 mm; Fillet Radius/Chamfer:4 mm; Bore Type:Cylindrical Bore; Enclosure:Open; dc (min):211 mm; ra1 (max):3 mm; Dynamic Load Rating:475,000 N; da (min):188 mm; Limiting Speed - Oil:2,400 rpm; Db (max):284 mm; Radial Clearance:0.075 to 0.125 mm; dd (min):223 mm; Da (max):292 mm; Configuration:Single Row;
A7VO250LRDH1-63L-PPB02 BOSCH REXROTH A7VO VARIABLE DISPLACEMENT PUMPSC:7.5 mm; s:23 mm; r1,2 min.:1 mm; R:56 mm; B:9 mm; Da max.:60 mm; da:45 mm; Minimum load factor A:0.038; Mass bearing (including seat washer where applicable):0.78 kg; Basic dynamic load rating C:39 kN; Basic static load rating C0:86.5 kN; ra max.:1 mm; Fatigue load limit Pu:3.2 kN; D:73 mm; r3,4 min.:0.6 mm; Limiting speed:3600 r/min; Reference speed:2600 r/min; rb max.:0.6 mm; D2:60 mm; H1:45 mm;
A7VO160LRD/63R-NPB01 BOSCH REXROTH A7VO VARIABLE DISPLACEMENT PUMPSFatigue load limit Pu:4.65 kN; Fw:38 mm; Ew:43 mm; Reference speed:11000 r/min; Mass needle roller and cage assembly:0.029 kg; Limiting speed:12000 r/min; Basic dynamic load rating C:19.8 kN; U:17 mm; Basic static load rating C0:39 kN;
A7VO28LRD/63L-NZB01 BOSCH REXROTH A7VO VARIABLE DISPLACEMENT PUMPSCalculation factor Y2:0.87; r3,4 min.:1 mm; Reference speed:7500 r/min; Calculation factor Y0:0.76; Da max.:109 mm; Calculation factor Y1:0.92; Calculation factor e:0.68; da min.:66 mm; D1 ≈:96.13 mm; Calculation factor A:0.0234; ra max.:2 mm; Fatigue load limit Pu:2.85 kN; r1,2 min.:2 mm; Limiting speed:11000 r/min; Basic dynamic load rating C:96.5 kN; Calculation factor X:0.67; a:34 mm; Db max.:114 mm;
A7VO160DR-61R-PPB01 BOSCH REXROTH A7VO VARIABLE DISPLACEMENT PUMPSra (max):4 mm; Fillet Radius/Chamfer:5 mm; Dynamic Load Rating:1,200,000 N; dd (min):307 mm; r1:5 mm; ra1 (max):4 mm; dc (min):287 mm; Static Load Rating:1,570,000 N; Configuration:Single Row; Enclosure:Open; db (min):242 mm; Da (max):438 mm; Limiting Speed - Grease:1,200 rpm; D:460 mm; db (max):279 mm; d:220 mm; B:88 mm; Radial Clearance:0.105 to 0.165 mm; Weight:73.600 kg; Bore Type:Cylindrical Bore;
A7VO80LR-61L-PZB01 BOSCH REXROTH A7VO VARIABLE DISPLACEMENT PUMPSBearing Bore Shape:Round; d:1.9375 in; Ball Grade:Class 10; Bearing Series:211 Series; Base to Center Height:Standard; Expansion Type:Non-Expansion; Bearing Family:Setscrew Ball Bearin; UPC:782475908271; Bearing Insert Material:Steel; Housing Material:Cast Iron; Anti-Rotation Pin:Yes; Self Aligning:Self Centering; Max Bearing Speed:4000 rpm; Shaft Attachment (2):Set Screw; Flinger Material:Steel; Seal Type:Shield;
A7VO55LRDS/61R-PZB01 BOSCH REXROTH A7VO VARIABLE DISPLACEMENT PUMPSJ:105 mm; Mass bearing unit:0.31 kg; J min.:100 mm; H2:16 mm; A5:18 mm; Basic static load rating C0:7.8 kN; Limiting speed:1500 r/min; d:25 mm; s1:21 mm; B1:33 mm; A1:22 mm; Fatigue load limit Pu:0.335 kN; J max.:110 mm; Hexagonal key size for grub screw N:2.5 mm; Thread grub screw G2:M5; Housing material:Composite; Recommended diameter for attachment bolts, mm G:10 mm; H1:36.5 mm; N1:12.5 mm; Recommended diameter for attachment bolts, inch G:0.375 in;

 

 

No.BrandwGJMUasL
A7VO107LRH5-61R-PZB01BOSCH REXROTH - - - - - - - -
A7VO107LRH1-63L-NZB01BOSCH REXROTH - - - - - - - -
A7VO355LRD-63R-VPH02BOSCH REXROTH - - - - - - - -
A7VO28DR-63L-NZB01BOSCH REXROTH - - - - - - - -
V-PUMPEA7VO107DRS/60R-PPB01*G*BOSCH REXROTH - - - - - - - -
A7VO28DRG-63R-NZB01BOSCH REXROTH - - - - - - - -
A7VO107LRDH1-63R-NZB01BOSCH REXROTH - - - - - - - -
A7VO107HD1D-61R-PZB01BOSCH REXROTH - - - - - - - -
A7VO250DRG-63L-V02BOSCH REXROTH - - - - - - - -
A7VO80LRDH1/63R-NZB01BOSCH REXROTH60 mmM 45x3 - - - - - -
A7VO107LRDH1/63R-NZB01BOSCH REXROTH - Tr 420x5 - - - - - -
A7VO107LR3H1/63R-NZB01-SBOSCH REXROTH - M 64x4 - - - - - -
A7VO160LRDH1-63L-NZB01BOSCH REXROTH - - - - - - - -
A7VO28DR/63L-NZB01BOSCH REXROTH - - - - - - - -
A7VO80LR-61L-PZB01BOSCH REXROTH - - - - - - - -
A7VO160LRE-61L-MPB01-SBOSCH REXROTH55 mmM 45x3 - - - - - -
A7VO160EP-61R-PZB01BOSCH REXROTH - - - - - - - -
A7VO55DR-61L-DPB01BOSCH REXROTH - - - - - - - -
A7VO250-63R-PPBBOSCH REXROTH - - - - - - - -
A7VO80LRD-61L-PZB01BOSCH REXROTH - - - - - - - -
A7VO80LRD-63R-NZB01BOSCH REXROTH - 139.624 mm - - - - - -
A7VO80HD1-63L-NZB01BOSCH REXROTH - - - - - - - -
A7VO107LR-61R-DPB01BOSCH REXROTH - - - - - - - -
A7VO80LRDH1-63R-NPB01BOSCH REXROTH - - - - - - - -
A7VO80LRH1-63R-VZB01BOSCH REXROTH - - - - - 77.613 mm - -
A7VO80LRH1-61L-PZB01BOSCH REXROTH - - - - - - - -
A7VO107DRS-61R-PZB01BOSCH REXROTH - - - - - - - -
A7VO107LRH1/61R-PPB01BOSCH REXROTH - - - - - - - -
A7VO28DRG/63L-NZB01-YBOSCH REXROTH - - - - - - - -

 

A7VO55LRDH-60R-PZB01 BOSCH REXROTH A7VO VARIABLE DISPLACEMENT PUMPS Video

 

Variable displacement pump A7VO

RE 92 203/05.99 | A7VO. Mobile Hydraulics | Bosch Rexroth AG. 3/24. Fluid. Axial piston unit. Drive shaft bearings. Operating mode. Size. Control devices.

Axial piston variable pump | Bosch Rexroth AG

Axial piston variable pump. A7VO series 63. Robust high pressure pump for universal use; Size 28 … 500; Nominal pressure 350 bar; Maximum pressure 400 bar ...

Rexroth Axial Piston Variable Pump A7VO

The A7VO is a variable displacement pump with a bent tapered axial piston transmission for open-circuit hydrostatic drives. Flow is proportional to drive speed ...

Axial piston variable pump A7VO Series 63

Bosch Rexroth AG, RE 92202/02.2015. 4. A7VO Series 63 | Axial piston variable pump. Hydraulic fluids. Hydraulic fluids. The A7VO variable pump is designed ...

Axial piston variable pump A7VO

and Controls. Axial piston variable pump. A7VO. Data sheet. Series 63 ... ment and steplessly variable from qv max to qv min = 0 ... Bosch Rexroth AG. A7VO ...52 pages

Axial Piston Variable Displacement Pump A7VO Series 63

Axial Piston Variable Displacement Pump A7VO Series 63. Axial Piston Pumps ... Bosch Rexroth Axial Piston Variable Pump R902197657 / A4VG90DGD1/32R.

BOSCH REXROTH A7VO55LRDH-60R-PZB01 INTERCHANGE

Bosch Rexroth A7vo Variable Displacement Pumps Part series A7VO55LRDH-60R-PZB01 is a potential replacement for these common bearing part numbers:

  • A7VO55LRDH-60R-PZB01

  • A7VO55LRDH-60R-PZB01

  • A7VO55LRDH-60R-PZB01

  • A7VO55LRDH-60R-PZB01

  • A7VO55LRDH-60R-PZB01

  • A7VO55LRDH-60R-PZB01

  • A7VO55LRDH-60R-PZB01

  • A7VO55LRDH-60R-PZB01

Contact Us

BOSCH REXROTH A2FO FIXED DISPLACEMENT PUMPS SUPPLIER
Address
Phone(Working Time)
Fax
  • BOSCH REXROTH A2FO FIXED DISPLACEMENT 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 A7VO55LRDH-60R-PZB01 Technical Articles

How does a variable pump work?
Understanding Variable Displacement Pumps - WHYPSMay 4, 2019 — The variable displacement pump converts mechanical energy(rotation of motor or engine) to hydraulic energy. But, some variable piston pumps will  10 Things to Know About Variable Speed...
How does a variable-displacement motor work?
Variable Displacement Hydraulic Piston Pump/MotorThe variable displacement piston pump (also known as an axial piston pump or a bent-axis piston pump) is used to convert hydraulic flow in to mechanical energy Jun 14, 2018 · Uploaded by Predictive...
How does a variable-displacement pump change output flow?
Variable displacement pump - WikipediaA variable displacement pump is a device that converts mechanical energy to hydraulic (fluid) energy. The displacement, or amount of fluid pumped per  Variable Displacement Piston Pump Technical Information An...

Bosch Rexroth A7vo Variable Displacement Pumps CATEGORIES

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

Customers Who Viewed BOSCH REXROTH A7VO55LRDH-60R-PZB01 Bearing Also Viewed

  • A7VO160EPD-61R-DPB01 BOSCH REXROTH A7VO VARIABLE DISPLACEMENT PUMPS
  • A7VO160LRD-61L-NZB01 BOSCH REXROTH A7VO VARIABLE DISPLACEMENT PUMPS
  • A7VO80DRS-61L-PZB01 BOSCH REXROTH A7VO VARIABLE DISPLACEMENT PUMPS
  • A7VO250-63R-PPB BOSCH REXROTH A7VO VARIABLE DISPLACEMENT PUMPS
  • A7VO107LR-63R-NZB01 BOSCH REXROTH A7VO VARIABLE DISPLACEMENT PUMPS
 
  • About Us|
  • Contact Us|
  • Site Map
  • Sitemaps

BOSCH REXROTH A2FO FIXED DISPLACEMENT PUMPS SUPPLIER. Copyright © 2017 - 2022 All Rights Reserved.

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

Home

Stock Categories

Technical Articles

Bosch Rexroth A2fo Fixed Displacement Pumps

Bosch Rexroth A10vno Axial Piston Pumps

Kawasaki K3vg Variable Displacement Axial Piston Pump

Contact Us