Danfoss K Frame Series, L Frame Series Service Manual
Service Manual
K and L Frame
Variable Motors, Cartridge Mount
powersolutions.danfoss.com
Revision history Table of revisions
Date Changed Rev
July 2017 Updated to Engineering Tomorrow 0402
April 2014 Danfoss layout DA
July 2013 add anti-cavitation valve CB
October 2010 new back page CA
November 2006 Added loop flushing valve B
July 2004 First edition A
Service Manual
K and L Frame Variable Motors, Cartridge Mount
2 | © Danfoss | July 2017 520L0631 | AX00000042en-US0402
Introduction
Overview..............................................................................................................................................................................................4
Safety precautions............................................................................................................................................................................4
Symbols used in Danfoss literature............................................................................................................................................4
Design...................................................................................................................................................................................................6
The System circuit............................................................................................................................................................................ 6
Technical specifications
Overview..............................................................................................................................................................................................8
Features and options...................................................................................................................................................................... 8
Specifications.....................................................................................................................................................................................8
Operating parameters.................................................................................................................................................................... 8
Fluid specifications.......................................................................................................................................................................... 8
Features
Output shafts...................................................................................................................................................................................10
Controls............................................................................................................................................................................................. 10
Control orificing........................................................................................................................................................................ 10
Brake release port.......................................................................................................................................................................... 10
Pressure measurements
Required tools.................................................................................................................................................................................11
Port locations and gauge installation.....................................................................................................................................11
Initial start-up procedures
General ..............................................................................................................................................................................................12
Start-up procedure........................................................................................................................................................................12
Fluid and filter maintenance
Recommendations........................................................................................................................................................................ 13
Troubleshooting
Excessive noise and/or vibration..............................................................................................................................................14
System operating hot...................................................................................................................................................................14
Motor shifting irregularities....................................................................................................................................................... 14
Minor repair
Shaft seal replacement.................................................................................................................................................................15
Remove the shaft seal.............................................................................................................................................................15
Inspect the components........................................................................................................................................................15
Install the new shaft seal........................................................................................................................................................15
Loop flushing valve.......................................................................................................................................................................15
Remove the loop flushing valve..........................................................................................................................................15
Inspect the components........................................................................................................................................................16
Install the loop flushing valve.............................................................................................................................................. 16
Anti-Cavitation Valve....................................................................................................................................................................16
Remove the anti-cavitation valve.......................................................................................................................................16
Inspect the components........................................................................................................................................................17
Install the anti-cavitation valve............................................................................................................................................17
Notes
Service Manual
K and L Frame Variable Motors, Cartridge Mount
Contents
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Danfoss | July 2017 520L0631 | AX00000042en-US0402 | 3
Overview
This manual includes information for the installation, maintenance, and minor repair of the K and L Frame
Cartridge Mount Variable Motors. The manual includes a description of the units and their individual
components, troubleshooting information, and minor repair procedures. Performing installation,
maintenance, and minor repair of K and L Frame Variable Motors according to the procedures in this
manual will not affect your warranty.
Performing minor repairs requires the unit to be removed from the vehicle/machine. Thoroughly clean
the unit before beginning maintenance, or repair activities. Since dirt and contamination are the greatest
enemies of any type of hydraulic equipment, follow cleanliness requirements strictly. This is especially
important when changing the system filter and when removing hoses or plumbing.
A worldwide network of Danfoss Authorized Service Centers (ASCs) is available for major repairs. Major
repairs require the removal of the unit's endcap, which voids the warranty unless done by an ASC.
Danfoss ASCs are trained by the factory and certified on a regular basis. You can locate your nearest ASC
using the distributor locator at www.powersolutions.danfoss.com.
Safety precautions
Always consider safety precautions before beginning a service procedure. Protect yourself and others
from injury. Take the following general precautions whenever servicing a hydraulic system.
W
Warning
Unintended machine movement
Unintended movement of the machine or mechanism may cause injury to the technician or bystanders.
To protect against unintended movement, secure the machine or disable / disconnect the mechanism
while servicing.
W
Warning
Flammable cleaning solvents
Some cleaning solvents are flammable. To avoid possible fire, do not use cleaning solvents in an area
where a source of ignition may be present.
W
Warning
Fluid under pressure
Escaping hydraulic fluid under pressure can have sufficient force to penetrate your skin causing serious
injury and/or infection. This fluid may also be hot enough to cause burns. Use caution when dealing with
hydraulic fluid under pressure. Relieve pressure in the system before removing hoses, fittings, gauges, or
components. Never use your hand or any other body part to check for leaks in a pressurized line. Seek
medical attention immediately if you are cut by hydraulic fluid.
W
Warning
Personal safety
Protect yourself from injury. Use proper safety equipment, including safety glasses, at all times.
Symbols used in Danfoss literature
WARNING may result in injury
CAUTION may result in damage to product or property
Reusable part
Service Manual
K and L Frame Variable Motors, Cartridge Mount
Introduction
4 | © Danfoss | July 2017 520L0631 | AX00000042en-US0402
Non-reusable part, use a new part
Non-removable item
Option – either part may exist
Superseded – parts are not interchangeable
Measurement required
Flatness specification
Parallelism specification
External hex head
Internal hex head
Torx head
O-ring boss port
Tip, helpful suggestion
Lubricate with hydraulic fluid
Apply grease / petroleum jelly
Apply locking compound
Inspect for wear or damage
Clean area or part
Be careful not to scratch or damage
Note correct orientation
Mark orientation for reinstallation
Torque specification
Press in – press fit
Pull out with tool – press fit
Cover splines with installation sleeve
Service Manual
K and L Frame Variable Motors, Cartridge Mount
Introduction
©
Danfoss | July 2017 520L0631 | AX00000042en-US0402 | 5
Pressure measurement / gauge location or specification
The symbols above appear in the illustrations and text of this manual. They are intended to communicate
helpful information at the point where it is most useful to the reader. In most instances, the appearance
of the symbol itself denotes its meaning. The legend above defines each symbol and explains its purpose.
Design
K and L Frame Variable Motors (KC/LC) are low to medium power, two-position axial piston motors
incorporating an integral servo piston. They are designed for operation in both open and closed circuit
applications. KC/LC motors have a cartridge style mounting configuration. The standard control is a direct
acting single line hydraulic control. The integral servo piston controls motor displacement.
The motor is spring biased to maximum displacement and hydraulically shifted to minimum
displacement. Minimum and maximum displacement can be set with fixed internal stops. The large
diameter servo piston allows smooth acceleration and deceleration with relatively large circuit orificing.
The motor is ideally configured for installations requiring compact packaging and optimized plumbing,
such as wheel ends. One face of the motor contains all hydraulic porting.
KC/LC cross section
Bias spring
Servo piston
Swashplate
Output
shaft
Piston
Slipper
Cylinder
block
Endcap
Shaft
seal
Bearing
P104 161E
Valve plate
The System circuit
The circuit below shows the KC/LC motor in a simple closed-loop hydrostatic propel application. The
motor is driven by a Series 42 medium power axial piston pump with manual displacement control.
Control pressure applied through an external control valve shifts the motor to minimum displacement;
spring force returns the motor to maximum displacement in the absence of control input.
Service Manual
K and L Frame Variable Motors, Cartridge Mount
Introduction
6 | © Danfoss | July 2017 520L0631 | AX00000042en-US0402
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