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Summary of Contents for Danfoss LDU 20
- Page 1 Service Manual LDU 20 Closed Circuit Axial Piston Transmission powersolutions.danfoss.com...
- Page 2 Service Manual LDU 20 Closed Circuit Axial Piston Transmission Revision history Table of revisions Date Changed July 2017 Updated to Engineering Tomorrow 0202 March 2014 Danfoss layout January 2011 First edition 11071687 | AX00000049en-US0202 © Danfoss | July 2017...
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Page 3: Table Of Contents
Service Manual LDU 20 Closed Circuit Axial Piston Transmission Contents Introduction Overview......................................5 Warranty......................................5 General Instructions..................................5 Remove the unit..................................5 Keep it clean....................................5 Lubricate moving parts................................5 Replace all O-rings and gaskets............................. 5 Secure the unit..................................... 6 Safety Precautions....................................6 Unintended machine movement............................6 Flammable cleaning solvents.............................. - Page 4 Service Manual LDU 20 Closed Circuit Axial Piston Transmission Contents System Noise or Vibration................................21 Sluggish System Response................................. 21 Required Tools and Standard Procedures Required Tools....................................22 Standard Procedures..................................22 Charge Check/HPRV Adjustments............................22 Checking for proper charge check/HPRV operation....................22 Minor Repair Shaft Seals......................................23...
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Page 5: Overview
LDU 20 Closed Circuit Axial Piston Transmission Introduction Overview This manual includes information on the installation, maintenance, and minor repair of LDU 20 pumps. It includes a description of the unit and its individual components, troubleshooting information, and minor repair procedures. -
Page 6: Secure The Unit
Service Manual LDU 20 Closed Circuit Axial Piston Transmission Introduction Secure the unit For major repair, place the unit in a stable position with the shaft pointing downward. It is necessary to secure the pump while removing and torquing components and fasteners. - Page 7 Service Manual LDU 20 Closed Circuit Axial Piston Transmission Introduction Non-reusable part, use a new part External hex head Internal hex head Lubricate with hydraulic fluid Apply grease / petroleum jelly Inspect for wear or damage Clean area or part...
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Page 8: General Description
Service Manual LDU 20 Closed Circuit Axial Piston Transmission General Description Basic Design LDU20 is a U-style HST transmission, including a closed circuit variable displacement piston pump with DDC (Direct displacement control) and a fixed motor. LDU20 is specially designed with optimized performance, size, and cost, in order to fulfill the demand of the mobile applications marketplace. -
Page 9: System Diagram
Service Manual LDU 20 Closed Circuit Axial Piston Transmission General Description System Diagram Heat exchanger bypass Charge Reservoir pump Heat exchanger Cylinder block Filter assembly Cylinder block assembly Charge relief valve Input Output shaft shaft Fixed Variable displacement displacement motor... -
Page 10: Operation
Service Manual LDU 20 Closed Circuit Axial Piston Transmission Operation HPRV (High Pressure Relief Valve) LDU20 is equipped with a combination high pressure relief and charge check valve. The high-pressure relief function is a dissipative (with heat generation) pressure control valve for the purpose of limiting excessive system pressures. -
Page 11: Cprv (Charge Pressure Relief Valve)
Service Manual LDU 20 Closed Circuit Axial Piston Transmission Operation For example; an inoperable vehicle may need to be moved to the service or the repair location, or winched onto a trailer without operating the prime mover. Caution Excessive speed or extended movement will damage the transmission. -
Page 12: Control
Service Manual LDU 20 Closed Circuit Axial Piston Transmission Operation Control Direct Displacement Control The LDU20 features Direct Displacement Control (DDC) .The swashplate angle is set directly by a control lever or linkage attached directly to the swashplate trunnion. Control lever movement changes the speed and rotating direction of the motor by increasing or decreasing the swashplate angle. -
Page 13: Operating Parameters
Service Manual LDU 20 Closed Circuit Axial Piston Transmission Operating Parameters Overview This section defines the operating parameters and limitations for LDU20 with regard to input speeds and pressures. For actual parameters, refer to Operating Parameters in the Technical Specifications section. -
Page 14: Case Pressure
Service Manual LDU 20 Closed Circuit Axial Piston Transmission Operating Parameters Case Pressure Do not exceed rated case pressure under normal operating conditions. During cold start, keep case pressure below maximum intermittent case pressure. Size drain plumbing accordingly. Caution Possible component damage or leakage Operation with case pressure in excess of stated limits may damage seals, gaskets, and/or housings, causing external leakage. -
Page 15: Technical Specifications
Service Manual LDU 20 Closed Circuit Axial Piston Transmission Technical Specifications General Specifications Design U-style HST with variable displacement piston pump and fixed motor Direction of Rotation Clockwise Counterclockwise Pipe Connections Main Pressure Ports: SAE O-ring Boss Recommended Installation Position... - Page 16 Service Manual LDU 20 Closed Circuit Axial Piston Transmission Technical Specifications Features Units LDU20 Temperature Minimum Degrees C [Degrees F] -40 [-40] Recommended range +82 [+180] Maximum +104 [+220] Filtration (recommended minimum) Cleanliness per ISO 4406 22/18/13 Efficiency (charge pressure filtration) b - ratio b 15-20=75(b 10≥10)
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Page 17: Fluid And Filter Maintenance
Service Manual LDU 20 Closed Circuit Axial Piston Transmission Fluid and Filter Maintenance Fluid and Filter Recommendations To ensure optimum life, perform regular maintenance of the fluid and filter. Contaminated fluid is the main cause of unit failure. Take care to maintain fluid cleanliness when servicing. -
Page 18: Pressure Measurements
Service Manual LDU 20 Closed Circuit Axial Piston Transmission Pressure Measurements Port Locations and Gauge Installation The following table and drawing show the port locations and gauge sizes needed. Port Information Port Identifier Port Size Wrench Size Pressure Obtained Gauge Size, bar [psi]... -
Page 19: Initial Startup Procedure
Service Manual LDU 20 Closed Circuit Axial Piston Transmission Initial Startup Procedure Startup Procedure Always follow this procedure when starting up a new LDU20 installation or when the transmission has been removed. Warning This service procedure may require disabling a vehicle/machine (raising the wheels off the ground, or disconnecting the work function) to prevent injury to the technician and bystanders. -
Page 20: Troubleshooting
Service Manual LDU 20 Closed Circuit Axial Piston Transmission Troubleshooting Overview This section provides general steps to follow if you observe undesirable system conditions. Follow the steps listed until you solve the problem. Some of the items are system specific. We reference the section in this manual of more information is available. -
Page 21: System Noise Or Vibration
Service Manual LDU 20 Closed Circuit Axial Piston Transmission Troubleshooting System Noise or Vibration Item Description Action Reservoir oil level Low oil level leads to cavitation. Fill reservoir. Aeration of the oil/pump Air in the system decreases efficiency of units and controls. -
Page 22: Required Tools And Standard Procedures
Service Manual LDU 20 Closed Circuit Axial Piston Transmission Required Tools and Standard Procedures Required Tools The service procedures described in this manual can be performed using common mechanic's hand tools. Special tools, if required, are shown. When testing system pressure, calibrate pressure gauges frequently to ensure accuracy. -
Page 23: Minor Repair
Service Manual LDU 20 Closed Circuit Axial Piston Transmission Minor Repair Shaft Seals Removal 1. Using a snap ring pliers, remove retaining ring (F125, F215, H125, H215). 2. Use a slide-hammer style puller to remove seal (F115, F210, H115, H210). Be careful not to damage the shaft or seal bore when removing the seal. -
Page 24: Charge Check/Hprv
Service Manual LDU 20 Closed Circuit Axial Piston Transmission Minor Repair 3. Using a snap ring pliers, install retaining ring (F125, F215, H125, H215). Shaft Seals F115 F125 H115 P108 483E H125 F210 F215 H210 P108 165E H215 Charge Check/HPRV The high pressure relief and charge check valve assembly may be removed for cleaning and replacement of the O-rings. -
Page 25: Removal
Service Manual LDU 20 Closed Circuit Axial Piston Transmission Minor Repair Removal 1. Using an 24 mm hex wrench, remove the valve seat plugs (N120, P120). 2. Carefully lift the valve (N110, P110) and spring (N100, P100) assemblies from the center section using a magnet. - Page 26 Service Manual LDU 20 Closed Circuit Axial Piston Transmission Minor Repair 2. Install the bypass valve cartridge using a 17mm hex wrench. Torque to 12 N•m [9lbf•ft]. Bypass Valve M130 M110 M120 M100 17 mm P108 166E 12 Nm [9 lbf-ft]...
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Page 27: Torque Chart
Service Manual LDU 20 Closed Circuit Axial Piston Transmission Torque Chart Plug Size and Torque Chart Item O-ring Plug Wrench Size Torque N•m [lbf•ft] J200, J250, J300, J350 3/4-16 UNF 7/8 hex wrench 78.4 [57.8] J400 9/16-18 UNF 1/4 internal hex 35 [25.8]... - Page 28 Phone: +86 21 3418 5200 Danfoss can accept no responsibility for possible errors in catalogues, brochures and other printed material. Danfoss reserves the right to alter its products without notice. This also applies to products already on order provided that such alterations can be made without changes being necessary in specifications already agreed.
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