Manitowoc National Crane NBT30H-2 Service Manual

2
National Crane 03-20-2019 Control # 613-06 2-1
NBT30H-2 SERVICE MANUAL HYDRAULIC SYSTEM
SECTION 2
HYDRAULIC SYSTEM
SECTION CONTENTS
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
Hydraulic System General Overview . . . . . . . . . . 2-1
Hydraulic Symbols . . . . . . . . . . . . . . . . . . . . . . . . . 2-3
Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5
Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5
Hydraulic System Maintenance Precautions . . . . 2-5
Label Parts when Disassembling . . . . . . . . . . . . . 2-5
Hydraulic Oil Recommendations. . . . . . . . . . . . . . 2-5
Parts Replacement . . . . . . . . . . . . . . . . . . . . . . . . 2-5
Visual Inspection of Hoses and Fittings . . . . . . . . 2-5
Troubleshooting Aids . . . . . . . . . . . . . . . . . . . . . . 2-6
Troubleshooting Procedures. . . . . . . . . . . . . . . . . 2-6
General Hydraulic System Troubleshooting . . . . . 2-7
Parts Replacement . . . . . . . . . . . . . . . . . . . . . . . . . 2-8
Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-9
Hydraulic Oil Recommendations. . . . . . . . . . . . . . 2-9
Draining and Flushing. . . . . . . . . . . . . . . . . . . . . . 2-9
Removing Air from the Hydraulic System . . . . . . 2-10
Hydraulic Pump . . . . . . . . . . . . . . . . . . . . . . . . . . 2-11
Load Sense Control . . . . . . . . . . . . . . . . . . . . . . 2-11
System Circuit Flow . . . . . . . . . . . . . . . . . . . . . . 2-11
Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-12
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-12
Directional Control Valve . . . . . . . . . . . . . . . . . . . 2-14
Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-14
Pilot Manifold Valve . . . . . . . . . . . . . . . . . . . . . . 2-14
Radio Remote Control - (Optional) . . . . . . . . . . . 2-14
Relief Pressures . . . . . . . . . . . . . . . . . . . . . . . . . . 2-15
Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-15
Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-15
Checking Relief Pressure . . . . . . . . . . . . . . . . . . . 2-15
Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-15
Telescope In and Telescope Out Reliefs. . . . . . . 2-16
Swing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-16
Outriggers Maximum Pressure . . . . . . . . . . . . . . 2-16
Outriggers Beam Extend . . . . . . . . . . . . . . . . . . . 2-17
Center Front Outrigger. . . . . . . . . . . . . . . . . . . . . 2-17
Supply Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-19
Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-19
Hydraulic Reservoir and Filter . . . . . . . . . . . . . . . 2-19
Hydraulic Filter Replacement. . . . . . . . . . . . . . . . 2-19
Hydraulic Oil Cooler (Option). . . . . . . . . . . . . . . . 2-19
Hydraulic Valves . . . . . . . . . . . . . . . . . . . . . . . . . 2-20
Directional Control Valve Manifold. . . . . . . . . . . . 2-21
Pilot Manifold Valve . . . . . . . . . . . . . . . . . . . . . . . 2-21
Outrigger Manifolds . . . . . . . . . . . . . . . . . . . . . . . 2-21
Holding Valves. . . . . . . . . . . . . . . . . . . . . . . . . . . 2-21
Swing Gearbox . . . . . . . . . . . . . . . . . . . . . . . . . . 2-21
Hydraulic Pump Service . . . . . . . . . . . . . . . . . . . 2-22
Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-22
Removal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-22
Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-22
Pump Startup. . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-22
Pump Margin Pressure . . . . . . . . . . . . . . . . . . . . 2-23
Maximum Pump Pressure . . . . . . . . . . . . . . . . . . 2-23
Directional Control Valve . . . . . . . . . . . . . . . . . . . 2-24
Lockout Pressure Adjustment . . . . . . . . . . . . . . . 2-24
Telescope Extend Pressure. . . . . . . . . . . . . . . . . 2-24
Trouble Diagnosis . . . . . . . . . . . . . . . . . . . . . . . . 2-24
INTRODUCTION
This section describes the hydraulic system, the
components which make up the hydraulic system, and the
components dependent upon the hydraulic system for their
operation. This includes descriptions of the supply pressure
and return hydraulic circuit, hydraulic pumps, all hydraulic
valves, and all hydraulic cylinders. Detailed descriptions and
operation of individual hydraulic circuits are discussed within
their individual sections as applicable. A complete hydraulic
system schematic showing all options is at the back of this
manual.
Hydraulic System General Overview
A hydraulic system uses liquid to make a transfer of force.
Any force on a confined liquid is applied to any point in the
system that the liquid reaches. Oil is used as the hydraulic
liquid for this system because the liquid must be a lubricant
for the components of the system.
There are several main components in a hydraulic system.
Each component has a specific function in the system.
The pump moves the oil through the system. It is important
to remember that the pump causes the flow, not the pressure

Manitowoc National Crane NBT30H-2 Specifications

General

Brand	Manitowoc
Model	National Crane NBT30H-2
Category	Construction Equipment
Language	English