Negative Flow Control (NFC) Hydraulic Systems . . . 477
Proportional Solenoids in NFC Circuits . . . . . . . . . . . . . . 479
Pump Outlet Pressure. . . . . . . . . . . . . . . . . . . . . 480
Cross Sensing Pressure . . . . . . . . . . . . . . . . . . . . 481
Pilot-Controlled DCV . . . . . . . . . . . . . . . . . . . . . 482
Flow Limit Solenoid. . . . . . . . . . . . . . . . . . . . . . 484
ECM Logic . . . . . . . . . . . . . . . . . . . . . . . . . 484
Case Excavators. . . . . . . . . . . . . . . . . . . . . . . 486
Kobelco Dynamic Acera SK210-290 Excavators . . . . . . . . . . 487
Positive Flow Control (PFC) Hydraulic Systems . . . 487
Pilot System . . . . . . . . . . . . . . . . . . . . . . . . 488
Deere G-Series and Hitachi Zaxis
Excavator PFC Pump Regulator Assemblies . . . . . . . . . . . 492
Electro-Hydraulic (EH) PFC Systems . . . 495
Standby Mode. . . . . . . . . . . . . . . . . . . . . . . . 496
Upstroked . . . . . . . . . . . . . . . . . . . . . . . . . 497
Controlling the Proportional Solenoid Valve (PSV) . . . . . . . . . . 497
Chapter 21
Hydraulic Test Equipment 503
Introduction to Test Equipment . . . 503
Flowmeters . . . 504
Mechanical Flowmeters . . . . . . . . . . . . . . . . . . . . 504
Electronic Flowmeters. . . . . . . . . . . . . . . . . . . . . 506
Flowmeter Features . . . . . . . . . . . . . . . . . . . . . 508
Installation of a Flowmeter . . . . . . . . . . . . . . . . . . . 510
PQ Curve . . . . . . . . . . . . . . . . . . . . . . . . . 511
Pressure Testing Equipment . . . 512
Diagnostic Pressure Taps . . . . . . . . . . . . . . . . . . . 512
Traditional Pressure Gauge. . . . . . . . . . . . . . . . . . . 513
Differential Pressure Gauge . . . . . . . . . . . . . . . . . . 517
Quadrigage. . . . . . . . . . . . . . . . . . . . . . . . . 517
Electronic Digital Pressure Meter . . . . . . . . . . . . . . . . 520
Snubbers . . . . . . . . . . . . . . . . . . . . . . . . . 523
Selecting a Pressure Gauge . . . 523
Pressure Gauge Accuracy . . . . . . . . . . . . . . . . . . . 524
Measuring Pump Inlet Pressure . . . . . . . . . . . . . . . . . 524
Miscellaneous Service Equipment . . . 526
Infrared Temperature Meter . . . . . . . . . . . . . . . . . . 526
Photocell Tachometer . . . . . . . . . . . . . . . . . . . . . 527
Stopwatch . . . . . . . . . . . . . . . . . . . . . . . . . 527
Pump and Motor Test Stand . . . . . . . . . . . . . . . . . . 528
Data Logger . . . . . . . . . . . . . . . . . . . . . . . . 528
Portable Particle Counter . . . . . . . . . . . . . . . . . . . 529
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