Danfoss SAE Mount Service guide
MAKING MODERN LIVING POSSIBLE
Service Manual
Closed Circuit Axial Piston
K and L Frame Variable Motors,
SAE Mount
powersolutions.danfoss.com
Service Manual K and L Frame Variable Motors, SAE Mount
Revision history Table of revisions
Date Changed Rev
November 2014 Danfoss layout DA
May 2013 Add Anti-Cavitation Valve CB
October 2010 Minor edits, new back page CA
November 2006 Added loop flushing valve B
July 2004 First edition A
2 520L0629 • Rev DA • November 2014
Service Manual
Contents
Introduction
Technical specifications
Features
Pressure measurements
Initial start-up procedures
Fluid and filter maintenance
Troubleshooting
Minor repair
K and L Frame Variable Motors, SAE Mount
Overview..............................................................................................................................................................................................4
Safety precautions............................................................................................................................................................................4
Unintended machine movement..........................................................................................................................................4
Flammable cleaning solvents.................................................................................................................................................4
Fluid under pressure..................................................................................................................................................................4
Personal safety............................................................................................................................................................................. 4
Symbols used in Danfoss literature............................................................................................................................................5
Design...................................................................................................................................................................................................5
The System circuit............................................................................................................................................................................ 6
Overview..............................................................................................................................................................................................7
Features and options...................................................................................................................................................................... 7
Specifications.....................................................................................................................................................................................7
Operating parameters.................................................................................................................................................................... 7
Fluid specifications.......................................................................................................................................................................... 7
Displacement limiter.......................................................................................................................................................................9
Output shafts..................................................................................................................................................................................... 9
Controls................................................................................................................................................................................................9
Control orificing...........................................................................................................................................................................9
Required tools.................................................................................................................................................................................10
Port locations and gauge installation.....................................................................................................................................10
General ..............................................................................................................................................................................................12
Start-up procedure........................................................................................................................................................................12
Recommendations........................................................................................................................................................................ 13
Excessive noise and / or vibration............................................................................................................................................14
System operating hot...................................................................................................................................................................14
Won’t shift or slow to shift..........................................................................................................................................................14
Shaft seal replacement.................................................................................................................................................................15
Remove the shaft seal.............................................................................................................................................................15
Inspect the components........................................................................................................................................................15
Install the new shaft seal........................................................................................................................................................15
Speed sensor replacement.........................................................................................................................................................15
Remove the speed sensor..................................................................................................................................................... 15
Install the new speed sensor................................................................................................................................................ 16
Speed sensor adjustment........................................................................................................................................................... 17
Adjustment and troubleshooting.......................................................................................................................................17
Loop flushing valve.......................................................................................................................................................................17
Remove the loop flushing valve..........................................................................................................................................17
Inspect the components........................................................................................................................................................18
Install the loop flushing valve.............................................................................................................................................. 18
Anti-Cavitation Valve....................................................................................................................................................................19
Remove the anti-cavitation valve.......................................................................................................................................19
Inspect the components........................................................................................................................................................19
Install the anti-cavitation valve............................................................................................................................................19
520L0629 • Rev DA • November 2014 3
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Service Manual
Introduction
Overview
Safety precautions
K and L Frame Variable Motors, SAE Mount
This manual includes information for the installation, maintenance, and minor repair of the K and L Frame
SAE 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.danfoss.com.
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.
Unintended machine movement
Warning
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.
Flammable cleaning solvents
Warning
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.
Fluid under pressure
Warning
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.
Personal safety
Warning
Protect yourself from injury. Use proper safety equipment, including safety glasses, at all times.
4 520L0629 • Rev DA • November 2014
Service Manual
K and L Frame Variable Motors, SAE Mount
Introduction
Symbols used in Danfoss literature
WARNING may result in injury Tip, helpful suggestion
CAUTION may result in damage to product or
property
Reusable part Apply grease / petroleum jelly
Non-reusable part, use a new part Apply locking compound
Non-removable item Inspect for wear or damage
Option - either part may exist Clean area or part
Superseded - parts are not interchangeable Be careful not to scratch or damage
Measurement required Note correct orientation
Flatness specification Mark orientation for reinstallation
Parallelism specification Torque specification
External hex head Press in - press fit
Internal hex head Pull out with tool – press fit
Torx head Cover splines with installation sleeve
Lubricate with hydraulic fluid
Design
O-ring boss port 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.
K and L Frame Variable Motors (KV/LV) 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. KV/LV motors have an SAE-B, two bolt mounting configuration. The standard control is a
direct acting single line hydraulic control. The integral servo piston controls motor displacement.
The motors are 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 motors are ideally configured for installations requiring compact packaging and optimized
plumbing, such as wheel ends. One face of the motor contains all hydraulic porting. Two standard
porting configurations are available: twin radial (side) or axial (end) O-ring boss main ports.
520L0629 • Rev DA • November 2014 5
Bias spring
Servo piston
Swashplate
Output
shaft
Piston
Slipper
Cylinder
block
Endcap
Shaft
seal
Bearing
Minimum
angle
stop
P101109
Valve plate
Reservior
Check valves
w/high pressure
relief valves and
bypass plunger
Charge
pump
Cylinder
block
assembly
Cylinder
block
assembly
Pump
swashplate
Motor
swashplate
Output
shaft
Input
shaft
Servo
piston
Displacement
control spool
Filter
High loop pressure
Case pressure
Charge/low loop pressure
Control pressure
Inlet pressure
Charge relief valve
Motor
displacement
control valve
Pump control handle
and feedback linkage
Motor
servo
piston
Displacement
limiter
P101 335E
Service Manual
Introduction
The System circuit
System circuit diagram
K and L Frame Variable Motors, SAE Mount
Cross section view
The circuit below shows the KV/LV 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. The
motor shown uses a single line hydraulic 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.
6 520L0629 • Rev DA • November 2014
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