Technical Information
L and K Frame Variable Motors
www.danfoss.com
Technical Information
L and K Frame Variable Motors
Revision history |
Table of revisions |
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Date |
Changed |
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February 2020 |
Changed document number from BC00000330 and increased version |
0307 |
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November 2019 |
Added shaft option H drawing |
0206 |
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July 2018 |
Model code - add minimum displacement angles |
0205 |
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April 2018 |
Model code minimum angle update |
0204 |
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November 2016 |
Minor updates |
0203 |
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June 2015 |
new cartridge endcap dimension drawings |
0202 |
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November 2014 |
add new cartridge dimension drawings |
CB |
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January 2014 |
Danfoss layout |
CA |
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July 2013 |
corrections to the schematics |
BI |
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June 2013 |
add HIC and anticavitation options |
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October 2012 |
edits to various pages |
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September 2009 |
L35 Max. pressure 300 bar [4350 psi], and speed ring pulses L = 41, K = 44 |
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April 2008 |
corrected the schematic drawings |
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January 2008 |
removed displacement limiter setting F12 - 65.3% |
BD |
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April 2007 |
LV (41 pulses/rev) KV (44 pulses/rev) |
BC |
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March 2007 |
changed 41 pulses/rev to 44 pulses/rev |
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October 2006 |
Added Loop flushing valve and 5 bolt endcap |
B |
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February 2004 |
First edition |
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2 | © Danfoss | February 2020 |
BC161386484850en-000307 |
Technical Information |
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L and K Frame Variable Motors |
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Contents |
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General Information |
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Basic Design........................................................................................................................................................................................ |
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Key Features....................................................................................................................................................................................... |
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System Circuit Diagram.................................................................................................................................................................. |
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Schematic Diagrams........................................................................................................................................................................ |
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Technical Specifications |
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Overview.............................................................................................................................................................................................. |
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Features and Options...................................................................................................................................................................... |
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Specifications..................................................................................................................................................................................... |
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Operating Parameters..................................................................................................................................................................... |
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Fluid Specifications.......................................................................................................................................................................... |
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Operating Parameters |
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Fluids..................................................................................................................................................................................................... |
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Viscosity............................................................................................................................................................................................... |
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Temperature....................................................................................................................................................................................... |
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Charge Pressure/Open Circuit Operation................................................................................................................................ |
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Case Pressure................................................................................................................................................................................... |
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Shift Pressure................................................................................................................................................................................... |
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System Pressure.............................................................................................................................................................................. |
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Input Speed...................................................................................................................................................................................... |
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System Design Parameters |
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Installation........................................................................................................................................................................................ |
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Filtration............................................................................................................................................................................................ |
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Reservoir............................................................................................................................................................................................ |
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Overpressure Protection............................................................................................................................................................. |
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Loop Flushing.................................................................................................................................................................................. |
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Charge Flow..................................................................................................................................................................................... |
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Charge Pressure / Open Circuit Operation........................................................................................................................... |
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Redundant Braking System Requirement............................................................................................................................. |
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Series Operation............................................................................................................................................................................. |
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Shaft Loads....................................................................................................................................................................................... |
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Radial load formula.................................................................................................................................................................. |
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Duty Cycle and Bearing Life....................................................................................................................................................... |
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Hydraulic Equations Helpful for Motor Selection............................................................................................................... |
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Name Plate....................................................................................................................................................................................... |
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Product Coding |
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Model Code...................................................................................................................................................................................... |
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Features and Options |
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Speed Sensor................................................................................................................................................................................... |
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Shaft Torque..................................................................................................................................................................................... |
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Output Shafts.................................................................................................................................................................................. |
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Loop Flushing.................................................................................................................................................................................. |
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Anti-Cavitation Valve Option..................................................................................................................................................... |
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Dust Seal Option............................................................................................................................................................................. |
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Displacement Limiters................................................................................................................................................................. |
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Motor Rotation................................................................................................................................................................................ |
28 |
Controls............................................................................................................................................................................................. |
28 |
Brake Release Port (cartridge motors).................................................................................................................................... |
28 |
Installation Drawings |
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SAE-B Mount (LV/KV).................................................................................................................................................................... |
29 |
Cartridge (LC/KC)............................................................................................................................................................................ |
34 |
© Danfoss | February 2020 |
BC161386484850en-000307 | 3 |
Technical Information
L and K Frame Variable Motors
The L and K Frame variable motors are light to medium power two-position axial piston motors incorporating an integral servo piston. They are designed for operation in closed and open circuit applications. The L and K Frame motors consist of five unique rotating groups (displacements) and two housing (mounting) configurations. An SAE-B, two-bolt, and a cartridge style (for space-optimized gearbox mounting) configurations are available for each frame. Maximum speeds and maximum applied pressures for each displacement vary. The standard control is a direct acting single line hydraulic control. For SAE-B mount motors a two line control is also available. 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. Two standard porting configurations are available: twin radial (side) or axial (end) O-ring boss main ports.
Cross section, SAE-B mount |
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Bias spring |
Servo piston |
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Minimum |
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Swashplate |
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angle |
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stop |
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Output |
Cylinder |
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shaft |
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block |
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Shaft seal
Endcap |
Piston |
Slipper Bearing |
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Valve plate |
P101109E |
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Cross section, cartridge mount
Servo piston |
Bias spring |
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Swashplat e
Output
shaft
Cylinder block
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Shaft |
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Endcap |
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seal |
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Bearing |
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Valve plate |
Piston |
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Slipper |
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P104161E |
4 | © Danfoss | February 2020 |
BC161386484850en-000307 |
Technical Information
L and K Frame Variable Motors
General Information
•Five displacements allow the optimum selection of hydraulic motor for the lowest possible installed cost.
•SAE-B, two-bolt, and cartridge mounting configurations available.
•Short and compact; fits into existing installation with improved porting.
•Three clean sides with superior clearance and access to mounting bolts.
•High Efficiency - nine piston rotating groups with 18 degree maximum angle.
•Versatility - working displacement range of 3.4:1 with a minimum angle option to one degree overcenter (-1°).
•Reliability - uses existing and proven technology.
•Worldwide service and technical support.
Pictorial system diagram
Control handle
contro valve
Cylinder block assembly
Input
shaft
Variable displacement pump
Motor displacement control valve
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Motor |
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servo |
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piston |
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Bypass |
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valve |
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Output |
Charge |
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shaft |
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pump |
Loop flushing |
Cylinder |
Motor |
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module |
block |
swashplate |
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assembly |
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High loop pressure |
Loop flushing |
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Check valves |
Case pressure |
relief valve |
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w/ high pressure |
Charge/low loop pressure |
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relief valve |
Inlet pressure |
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The circuit above shows the LV/KV motor in a simple closed-loop hydrostatic propel application. The motor is driven by a Series 40 M46 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.
© Danfoss | February 2020 |
BC161386484850en-000307 | 5 |
Technical Information
L and K Frame Variable Motors
General Information
SAE motor - single or two line control
X2 X1
A
L2
B
L1
P107 785
Cartridge motor - single line control
X1
A
L2
B
L1
P107 784
6 | © Danfoss | February 2020 |
BC161386484850en-000307 |
Technical Information
L and K Frame Variable Motors
Specifications and operating parameters for L and K Frame motors are given here for quick reference. For additional information, seeFeatures and Options, Operating Parameters on page 7, and Product Coding.
Mount |
SAE-B (LV/KV) |
Cartridge (LC/KC) |
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Motor type |
Inline, axial piston, positive displacement, two-speed variable motors |
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Displacement |
L: 25, 30, or 35 cm3 [1.50, 1.83, or 2.14 in3] K: 38 or 45 cm3 [2.32 or 2.75 in3] |
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Rotation |
Bidirectional |
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Installation position |
Discretionary: Housing must always be filled with hydraulic fluid |
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Porting |
SAE O-ring boss, axial or twin radial |
SAE O-ring boss, twin radial |
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Output shafts |
Splined 13 or 15 tooth 16/32 pitch, 0.875 inch straight |
Splined 13 or 15 tooth 16/32 pitch |
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keyed, and 1:8 taper |
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Control options |
Single or dual line hydraulic control |
Single line hydraulic control |
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Displacement limiter |
Fixed maximum and minimum displacement limiters available |
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Speed sensor |
Available - refer to Features and options section |
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Loop Flushing Valve |
Available - refer to Features and options section |
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Specifications
Parameter |
Unit |
L25 |
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L30 |
L35 |
K38 |
K45 |
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Displacement (maximum) |
cm3 [in3] |
25 [1.50] |
30 [1.83] |
35 [2.14] |
38 [2.32] |
45 [2.75] |
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Weight (cartridge and SAE-B) |
kg [lb] |
15.4 |
[34] |
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Mass moment of inertia of rotating components |
kg•m2[slug•ft2] |
0.0017 [0.0012] |
0.0016 [0.0012] |
0.0015 [0.0011] |
0.0023 [0.0017] |
0.0023 [0.0017] |
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Theoretical torque |
N•m/bar |
0.40 |
[244] |
0.48 [293] |
0.56 [347] |
0.60 [366] |
0.72 [439] |
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[lbf•in/1000psi] |
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Operating parameters
Parameter |
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Unit |
L25 |
L30 |
L35 |
K38 |
K45 |
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System pressure |
maximum working |
bar [psi] |
400 [5800] |
350 [5075] |
300 [4350] |
350 [5075] |
300 [4350] |
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maximum |
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420 [6090] |
375 [5440] |
325 [4715] |
415 [6020] |
350 [5075] |
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Speed limit (at max. disp.) |
rated |
min-1 (rpm) |
3400 |
3500 |
3600 |
3600 |
3500 |
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maximum |
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3950 |
4150 |
4300 |
4000 |
3900 |
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Speed limit (at min. disp., including |
rated |
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4400 |
4450 |
4500 |
4650 |
4500 |
Zero degrees) |
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maximum |
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5000 |
5150 |
5300 |
5200 |
5050 |
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Case pressure |
maximum working |
bar [psi] |
2 [29] |
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maximum |
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6 [87] |
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© Danfoss | February 2020 |
BC161386484850en-000307 | 7 |
Technical Information
L and K Frame Variable Motors
Technical Specifications
Parameter |
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Unit |
Minimum |
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Continuous |
Maximum |
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Viscosity |
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mm2/sec (cSt) [SUS] |
7 [47] |
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12-60 [70-278] |
1600 [7500] |
Temperature |
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°C [°F] |
-40 [-40] |
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82 [180] |
104 [220] |
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Cleanliness |
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ISO 4406 Class 18/13 or better |
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Filtration efficiency |
suction filtration |
β35-44=75 (β10≥1.5) |
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Ratings and data are based on operation with premium petroleum-based hydraulic fluids containing oxidation, rust, and foam inhibitors.
8 | © Danfoss | February 2020 |
BC161386484850en-000307 |
Technical Information
L and K Frame Variable Motors
Ratings and performance data for these motors are based on operating with premium hydraulic fluids containing oxidation, rust, and foam inhibitors. These include premium turbine oils, API CD engine oils per SAE J183, M2C33F or G automatic transmission fluids (ATF), Dexron II (ATF) meeting Allison C-3 or Caterpillar T0 2 requirements, and certain specialty agricultural tractor fluids. For more information on hydraulic fluid selection, see Danfoss publications:
Hydraulic Fluids and Lubricants, Technical Information, 520L0463,
Experience with Biodegradable Hydraulic Fluids, Technical Information, 520L465.
Maintain fluid viscosity within the recommended range for maximum efficiency and bearing life. Minimum viscosity should only occur during brief occasions of maximum ambient temperature and severe duty cycle operation. Maximum viscosity should only occur at cold start. Limit speeds until the system warms up.
Fluid viscosity limits
Condition |
mm2/s (cSt) |
SUS |
Minimum |
7 |
47 |
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Continuous |
12-60 |
70-278 |
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Maximum |
1600 |
7500 |
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Maintain fluid temperature within the limits shown in the table. Minimum temperature relates to the physical properties of the component materials. Cold oil will not affect the durability of the motor components. However, it may affect the ability of the motor to transmit power. Maximum temperature is based on material properties. Exceeding the maximum temperature may result in damage to the unit. Measure maximum temperature at the hottest point in the system. This is usually the case drain.
Temperature limits
Minimum |
- 40° C [- 40° F] |
(intermittent, cold start) |
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Continuous |
85° C [185° F] |
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Maximum |
105° C [221° F] |
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Ensure fluid temperature and viscosity limits are concurrently satisfied.
L and K Frame motors can be operated in closed and open circuit applications. For a propel motor open circuit, the motor must have a direct line (no combining flows) from the motor case to the reservoir to prevent pressure spikes. When the motor is being operated with zero backpressure, the maximum limit for case pressure is 2 bar.
© Danfoss | February 2020 |
BC161386484850en-000307 | 9 |
Technical Information
L and K Frame Variable Motors
Operating Parameters
Maintain case pressure within the limits shown in the table. The housing must always be filled with hydraulic fluid.
C Caution
Operating outside of case pressure limits will damage the motor. To minimize this risk, use full size inlet and case drain plumbing, and limit line lengths.
Case pressure limits
Maximum (continuous) |
0.5 [7] above outlet pressure |
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2 |
[29] maximum pressure |
Intermittent (cold start) |
2 |
[29] above outlet pressure |
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6 |
[87] maximum pressure |
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Minimum shift pressure required to keep motor swashplate at minimum angle is 14 bar [203 psi].
Control input pressure limits
LV/KV with single line control |
14 to 240 bar |
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[200 to 3500 psi] |
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LV/KV with dual line control |
14 to 35 bar |
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[200 to 500 psi] |
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LC/KC with single line control |
14 to 69 bar |
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[200 to 1000 psi] |
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System pressure is the differential pressure between system ports A and B. It is the dominant operating variable affecting hydraulic unit life. High system pressure, which results from high load, reduces expected life. Hydraulic unit life depends on the speed and normal operating, or weighted average, pressure that can only be determined from a duty cycle analysis.
Application pressure is the high pressure relief setting normally defined within the order code of the pump. This is the applied system pressure at which the driveline generates the maximum calculated pull or torque in the application.
Maximum working pressure is the highest recommended Application pressure. Maximum working pressure is not intended to be a continuous pressure. Propel systems with Application pressures at, or below, this pressure should yield satisfactory unit life given proper component sizing.
Maximum pressure is the highest allowable Application pressure under any circumstance. Application pressures above Maximum Working Pressure will only be considered with duty cycle analysis and factory approval. Pressure spikes are normal and must be considered when reviewing maximum working pressure.
All pressure limits are differential pressures referenced to low loop (charge) pressure. Subtract low loop pressure from gauge readings to compute the differential.
Minimum low loop pressure (above case pressure) is the lowest pressure allowed to maintain a safe working condition in the low side of the loop.
10 | © Danfoss | February 2020 |
BC161386484850en-000307 |
Technical Information
L and K Frame Variable Motors
Operating Parameters
Minimum speed is the lowest input speed recommended during engine idle condition. Operating below minimum speed limits the pump's ability to maintain adequate flow for lubrication and power transmission.
Rated speed is the highest input speed recommended at full power condition. Operating at or below this speed should yield satisfactory product life.
Maximum speed is the highest operating speed permitted. Exceeding maximum speed reduces product life and can cause loss of hydrostatic power and braking capacity. Never exceed the maximum speed limit under any operating conditions.
Operating conditions between rated speed and maximum speed should be restricted to less than full power and to limited periods of time. For most drive systems, maximum unit speed occurs during downhill braking or negative power conditions.
For more information consult Pressure and Speed Limits, BLN-9884, when determining speed limits for a particular application.
During hydraulic braking and downhill conditions, the prime mover must be capable of providing sufficient braking torque in order to avoid pump over speed. This is especially important to consider for turbocharged and Tier 4 engines.
W Warning
Unintended vehicle or machine movement hazard
Exceeding maximum speed may cause a loss of hydrostatic drive line power and braking capacity. You must provide a braking system, redundant to the hydrostatic transmission, sufficient to stop and hold the vehicle or machine in the event of hydrostatic drive power loss. The braking system must also be sufficient to hold the machine in place when full power is applied.
© Danfoss | February 2020 |
BC161386484850en-000307 | 11 |
Technical Information
L and K Frame Variable Motors
L and K motors may be installed in any position. The motor housing must always remain full of hydraulic fluid.
Fill the motor housing and system lines with clean fluid during installation. Connect the case drain line to the uppermost drain port (L1 or L2) to keep the housing full during operation.
To allow unrestricted flow to the reservoir, use a dedicated drain line. Connect it below the minimum reservoir fluid level and as far away from the reservoir outlet as possible. Use plumbing adequate to maintain case pressure within prescribed limits (see Case Pressure on page 10).
To prevent damage to the motor, including premature wear, fluid entering the motor must be free of contaminants. L and K motors require system filtration capable of maintaining fluid cleanliness at ISO 4406-1999 class 22/18/13 or better.
Consider these factors when selecting a system filter:
•Cleanliness specifications
•Contaminant ingression rates
•Flow capacity
•Desired maintenance interval
Typically, a filter with a beta ratio of β10 = 1.5 to 2.0 is adequate. However, open circuit systems supplied from a common reservoir may have considerably higher requirements. Because each system is unique, only a thorough testing and evaluation program can fully validate the filtration system. For more information, see Danfoss publication Design Guidelines for Hydraulic Fluid Cleanliness, 520L0467.
The reservoir provides clean fluid, dissipates heat, and removes entrained air from the hydraulic fluid. It allows for fluid volume changes associated with fluid expansion and cylinder differential volumes. Minimum reservoir capacity depends on the volume needed to perform these functions. Typically, a capacity of one half the charge pump flow (per minute) is satisfactory for a closed circuit system reservoir. Open circuit systems sharing a common reservoir will require greater fluid capacity.
Locate the reservoir outlet (suction line) near the bottom, allowing clearance for settling foreign particles. Place the reservoir inlet (return lines) below the lowest expected fluid level, as far away from the outlet as possible.
L and K Frame motors have no internal overpressure protection. Therefore, relief valves or pressure limiters are required to maintain system pressure within prescribed limits. Relief valves are adequate to protect against transient or unusually rapid load application, but excessive or continuous flow through them adds heat to the system and can damage the fluid. In applications operating at or near pressure, use a pressure compensating variable pump.
Closed circuit systems may require loop flushing to meet temperature and cleanliness requirements. A loop flushing valve removes hot fluid from the low pressure side of the system loop for additional cooling and filtering. Ensure the charge pump provides adequate flow for loop flushing and the loop flushing valve does not cause charge pressure to drop below recommended limits.
12 | © Danfoss | February 2020 |
BC161386484850en-000307 |