Part of the New Holland Repair Manuals.
A relief valve that will not hold pressure parks the whole crew. The New Holland EH50.B service manual PDF is the factory answer: 767 pages, OEM ID 6-78610NA, built for this hydraulic excavator alone. Hydraulic schematics trace the pilot control circuit from pump to spool, and wiring diagrams map each harness so you can run an electrical fault to its connector instead of swapping parts on a hunch. Rebuild coverage carries from the boom and arm cylinders through the upper slewing structure and travel system into the engine, fuel injection pump governor, and turbocharger. Set the main relief to gain 12.2 MPa (1770 psi) per full adjusting turn, then torque the lock nut to 19.6 N·m (14.5 lb·ft). Guessing that setting can cost a pump and a second teardown. This bookmarked, keyword-searchable PDF rides along wherever your excavator sits.
What's Inside This New Holland EH50.B Manual
| System | Pages | Key Topics |
|---|---|---|
| Standard Specifications and Maintenance | 4-103 | General Information and Safety, Specifications, Attachment Dimensions, Tools, Standard Maintenance Time Table, Maintenance Standards and Test Procedures |
| Hydraulic, Electrical, and Component Systems | 104-259 | Hydraulic System, Electrical System, Components System |
| Disassembly and Assembly | 260-495 | General Disassembly and Assembly, Attachments, Upper Slewing Structure, Travel System |
| Troubleshooting | 496-543 | Troubleshooting Hydraulic System, Troubleshooting Electrical System, Troubleshooting Engine |
| Engine | 544-767 | Engine Specifications, Inspection and Adjustment, Disassembly Inspection and Reassembly, Lubrication System, Cooling System, Fuel Injection Pump Governor, Turbocharger |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Main relief valve & Overload relief valve adjustment (one full turn) | 12.2 MPa (1770 psi) | p. 94 |
| Slewing motor relief valve adjustment (one full turn) | 9.8 MPa (1420 psi) | p. 94 |
| Sum of both clearances after shim adjustment | 0.5 mm to 0.9 mm | p. 282 |
| Starting motor output (12 V) | 2.3 kW | p. 26 |
| L dimension (pinion projection length) | 0.3-1.5 mm | p. 740 |
| Fuel Injection Nozzle Pressure (3TNV82A-TNV88 CL) | 19.6-20.6 MPa | p. 610 |
| Engine oil capacity, 4TNV88 CL (total / effective) | 9.8 L / 2.3 L | p. 575 |
| Coolant water capacity, 4TNV88 (engine only) | 2.7 L | p. 575 |
New Holland EH50.B Common Problems This Manual Covers
New Holland EH50.B hydraulic pump not building pressure, boom and arm dig weak under load
Check working pressure against the pump specification: piston pumps P1 + P2 work at 23.0 MPa (3340 psi) and deliver 38.4 L/min (10.1 gal/min) each, gear pump P3 at 20.0 MPa (2900 psi) and trochoid pump P4 at 3.5 MPa (508 psi) (page 174). On the main relief and overload relief valves, one full turn of the setscrew changes pressure by approximately 12.2 MPa (1770 psi), clockwise to increase; tighten lock nut (2) to 19.6 N·m (14.5 lb·ft) and recheck the setting (page 94).
Manual Section: Hydraulic System Troubleshooting p. 174Engine cranks slowly or won't start after sitting overnight, worse in cold weather
The EH50.B's Yanmar 4TNV88-XYB engine uses a 12 V x 2.3 kW starting motor and a 12 V x 55 A generator (page 26). Test the battery and clean the cable ends, then bench check the starter, including pinion projection length L of 0.3-1.5 mm (page 740).
Manual Section: Starting Motor Troubleshooting p. 26Swing feels weak and slow, upper structure hesitates before rotating under load
On the slewing motor relief valve, one full turn of the setscrew changes pressure by approximately 9.8 MPa (1420 psi), clockwise to increase; tighten lock nut (2) to 34.3 N·m (25.3 lb·ft) after adjusting (page 94). The hydraulic trouble diagnosis table on page 505 separates slewing operational failure, slow slewing speed and low slewing power by pump, valve and actuator causes.
Manual Section: Upper Slewing Structure Troubleshooting p. 94Travel weak or intermittent on one side, machine pulls to one track when driving straight
Measure pilot relief pressure with the engine at high idle and hydraulic oil at 50-60°C, using a 6.86 MPa (1000 psi) gauge on test port G4 (PF 1/4); after adjusting, tighten lock nut (2) to 7.8 N·m (5.8 lb·ft) (page 95). Each piston pump (P1, P2) delivers 38.4 L/min (10.1 gal/min) (page 174), and the trouble diagnosis table on page 505 covers slow travel speed and deviation in travel independent operation.
Manual Section: Travel System Troubleshooting p. 95Boom drifts down with controls in neutral, oil weeping past arm cylinder rod seal
Before loosening the cylinder head, pull out the piston rod by 100 ~ 200 mm (4 ~ 8 in), then pull the piston rod assembly straight out of the tube to prevent damage to the sliding surface (page 286). After reinstalling, bleed air by extending and retracting the cylinder 4 or 5 times at slow engine speed, stopping 100 mm (4 in) short of the stroke end (page 296).
Manual Section: Disassembly and Assembly p. 286Frequently Asked Questions
What is the hydraulic pressure specification for the main circuit of the New Holland EH50.B?
The main circuit pressure for the boom, bucket, and travel (LH) is 23.0 +0.5 to 0 MPa (3340 +73 to 0 psi). For the arm, swing, travel (RH), and service circuits, the pressure is also 23.0 +0.5 to 0 MPa (3340 +73 to 0 psi). p. 89
What is the torque specification for the track roller bolts on the New Holland EH50.B?
The tightening torque for the lower roller capscrews (M14x50) is 280 Nm (207 lb ft). p. 130
What is the standard valve clearance for the Yanmar engine in the New Holland EH50.B?
The EH50.B uses the Yanmar 4TNV88-XYB engine (page 26). The engine manual lists a standard valve clearance of 0.15~0.25 mm for the 3TNV82A~98 models, which covers the 4TNV88 (page 609). p. 609
What is the engine oil capacity of the New Holland EH50.B's 4TNV88 engine?
The Yanmar 4TNV88 engine data lists a lubricant capacity (oil pan) of 9.8 L total and 2.3 L effective for the CL specification, or 8.6 L total and 4.2 L effective for the VM specification; coolant water capacity for the engine only is 2.7 L (page 575). p. 575
How is the pilot circuit relief pressure checked and set on the New Holland EH50.B?
Measure with the engine at high idle and hydraulic oil at 50-60°C, using a 6.86 MPa (1000 psi) pressure gauge on test port G4 (PF 1/4). Adjust with setscrew (1), clockwise to increase, then tighten lock nut (2) to 7.8 N·m (5.8 lb·ft); relief valve PR1 is tightened to 44 N·m (32 lb·ft) (page 95). p. 95
Do I get instant access to this New Holland EH50.B Service Manual?
All 767 pages arrive as one searchable PDF at checkout. Read it at the desk, then take the phone out to the machine.
Is this New Holland EH50.B Service Manual printable?
Zero restrictions. The PDF is DRM-free. Print whatever sections you need to take out to the shop. Standard letter or A4 paper works.
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