Danfoss L and K Frame Variable Motors Technical Information
Technical Information
L and K Frame Variable Motors
www.danfoss.com
Technical Information
L and K Frame Variable Motors
Revision history Table of revisions
Date Changed Rev
February 2020 Changed document number from BC00000330 and increased version 0307
November 2019 Added shaft option H drawing 0206
July 2018 Model code - add minimum displacement angles 0205
April 2018 Model code minimum angle update 0204
November 2016 Minor updates 0203
June 2015 new cartridge endcap dimension drawings 0202
November 2014 add new cartridge dimension drawings CB
January 2014 Danfoss layout CA
July 2013 corrections to the schematics BI
June 2013 add HIC and anticavitation options BH
October 2012 edits to various pages BG
September 2009 L35 Max. pressure 300 bar [4350 psi], and speed ring pulses L = 41, K = 44 BF
April 2008 corrected the schematic drawings BE
January 2008 removed displacement limiter setting F12 - 65.3% BD
April 2007 LV (41 pulses/rev) KV (44 pulses/rev) BC
March 2007 changed 41 pulses/rev to 44 pulses/rev BB
October 2006 Added Loop flushing valve and 5 bolt endcap B
February 2004 First edition A
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Technical Information
L and K Frame Variable Motors
Contents
General Information
Basic Design........................................................................................................................................................................................4
Key Features....................................................................................................................................................................................... 5
System Circuit Diagram..................................................................................................................................................................5
Schematic Diagrams........................................................................................................................................................................6
Technical Specifications
Overview..............................................................................................................................................................................................7
Features and Options......................................................................................................................................................................7
Specifications.....................................................................................................................................................................................7
Operating Parameters.....................................................................................................................................................................7
Fluid Specifications..........................................................................................................................................................................8
Operating Parameters
Fluids.....................................................................................................................................................................................................9
Viscosity............................................................................................................................................................................................... 9
Temperature.......................................................................................................................................................................................9
Charge Pressure/Open Circuit Operation................................................................................................................................9
Case Pressure...................................................................................................................................................................................10
Shift Pressure...................................................................................................................................................................................10
System Pressure..............................................................................................................................................................................10
Input Speed......................................................................................................................................................................................11
System Design Parameters
Installation........................................................................................................................................................................................12
Filtration............................................................................................................................................................................................ 12
Reservoir............................................................................................................................................................................................12
Overpressure Protection............................................................................................................................................................. 12
Loop Flushing..................................................................................................................................................................................12
Charge Flow.....................................................................................................................................................................................13
Charge Pressure / Open Circuit Operation........................................................................................................................... 13
Redundant Braking System Requirement.............................................................................................................................13
Series Operation.............................................................................................................................................................................13
Shaft Loads.......................................................................................................................................................................................13
Radial load formula..................................................................................................................................................................14
Duty Cycle and Bearing Life....................................................................................................................................................... 14
Hydraulic Equations Helpful for Motor Selection...............................................................................................................14
Name Plate....................................................................................................................................................................................... 15
Product Coding
Model Code......................................................................................................................................................................................17
Features and Options
Speed Sensor...................................................................................................................................................................................20
Shaft Torque.....................................................................................................................................................................................20
Output Shafts.................................................................................................................................................................................. 21
Loop Flushing..................................................................................................................................................................................25
Anti-Cavitation Valve Option.....................................................................................................................................................26
Dust Seal Option.............................................................................................................................................................................27
Displacement Limiters................................................................................................................................................................. 27
Motor Rotation................................................................................................................................................................................28
Controls............................................................................................................................................................................................. 28
Brake Release Port (cartridge motors)....................................................................................................................................28
Installation Drawings
SAE-B Mount (LV/KV).................................................................................................................................................................... 29
Cartridge (LC/KC)............................................................................................................................................................................34
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Bias spring
Servo piston
Swashplate
Output
shaft
Piston
Slipper
Cylinder
block
Endcap
Shaft
seal
Bearing
Minimum
angle
stop
P101109E
Valve plate
Bias spring
Servo piston
Swashplat e
Output
shaft
Piston
Slipper
Cylinder
block
Endcap
Shaft
seal
Bearing
P104161E
Valve plate
Technical Information
L and K Frame Variable Motors
General Information
Basic Design
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
Cross section, cartridge mount
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Output
shaft
Cylinder
block
assembly
Motor
swashplate
Motor
displacement
control valve
Motor
servo
piston
Displacement
limiter
Input
shaft
Filter
Charge
pump
Reservoir
Cylinder
block
assembly
Heat
exchanger
Check valves
w/ high pressure
relief valve
Variable
displacement
pump
Heat exchanger
bypass
Charge relief
valve
Displacement
control
valve
Control
handle
Bypass
valve
Loop flushing
module
High loop pressure
Case pressure
Charge/low loop pressure
Inlet pressure
Loop flushing
relief valve
Technical Information
L and K Frame Variable Motors
General Information
Key Features
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.
•
System Circuit Diagram
Pictorial system diagram
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.
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P107 785
A
B
Optional
X1
X2
L1
L2
Min.
Disp.
P107 784
A
B
Optional
X1
L1
L2
Technical Information
L and K Frame Variable Motors
General Information
Schematic Diagrams
SAE motor - single or two line control
Cartridge motor - single line control
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Technical Information
L and K Frame Variable Motors
Technical Specifications
Overview
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.
Features and Options
Mount SAE-B (LV/KV) Cartridge (LC/KC)
Motor type Inline, axial piston, positive displacement, two-speed variable motors
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]
Rotation Bidirectional
Installation position Discretionary: Housing must always be filled with hydraulic fluid
Porting SAE O-ring boss, axial or twin radial SAE O-ring boss, twin radial
Output shafts Splined 13 or 15 tooth 16/32 pitch, 0.875 inch straight
keyed, and 1:8 taper
Control options Single or dual line hydraulic control Single line hydraulic control
Displacement limiter Fixed maximum and minimum displacement limiters available
Speed sensor Available - refer to Features and options section
Loop Flushing Valve Available - refer to Features and options section
Splined 13 or 15 tooth 16/32 pitch
Specifications
Specifications
Parameter Unit L25 L30 L35 K38 K45
Displacement (maximum) cm3 [in3] 25 [1.50] 30 [1.83] 35 [2.14] 38 [2.32] 45 [2.75]
Weight (cartridge and SAE-B) kg [lb] 15.4 [34]
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]
Theoretical torque N•m/bar
[lbf•in/1000psi]
0.40 [244] 0.48 [293] 0.56 [347] 0.60 [366] 0.72 [439]
Operating Parameters
Operating parameters
Parameter Unit L25 L30 L35 K38 K45
System pressure maximum working bar [psi] 400 [5800] 350 [5075] 300 [4350] 350 [5075] 300 [4350]
maximum 420 [6090] 375 [5440] 325 [4715] 415 [6020] 350 [5075]
Speed limit (at max. disp.) rated min-1 (rpm) 3400 3500 3600 3600 3500
maximum 3950 4150 4300 4000 3900
Speed limit (at min. disp., including
Zero degrees)
Case pressure maximum working bar [psi] 2 [29]
rated 4400 4450 4500 4650 4500
maximum 5000 5150 5300 5200 5050
maximum 6 [87]
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Technical Information
L and K Frame Variable Motors
Technical Specifications
Fluid Specifications
Parameter Unit Minimum Continuous Maximum
Viscosity mm2/sec (cSt) [SUS] 7 [47] 12-60 [70-278] 1600 [7500]
Temperature °C [°F] -40 [-40] 82 [180] 104 [220]
Cleanliness ISO 4406 Class 18/13 or better
Filtration efficiency suction filtration β
Ratings and data are based on operation with premium petroleum-based hydraulic fluids containing
oxidation, rust, and foam inhibitors.
=75 (β10≥1.5)
35-44
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Technical Information
L and K Frame Variable Motors
Operating Parameters
Fluids
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.
Viscosity
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
Continuous 12-60 70-278
Maximum 1600 7500
Temperature
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
(intermittent, cold start)
Continuous
Maximum
Ensure fluid temperature and viscosity limits are concurrently satisfied.
Charge Pressure/Open Circuit Operation
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.
- 40° C [- 40° F]
85° C [185° F]
105° C [221° F]
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C
Technical Information
L and K Frame Variable Motors
Operating Parameters
Case Pressure
Maintain case pressure within the limits shown in the table. The housing must always be filled with
hydraulic fluid.
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)
Intermittent (cold start)
Shift Pressure
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
LV/KV with dual line control 14 to 35 bar
LC/KC with single line control 14 to 69 bar
0.5 [7] above outlet pressure
2 [29] maximum pressure
2 [29] above outlet pressure
6 [87] maximum pressure
[200 to 3500 psi]
[200 to 500 psi]
[200 to 1000 psi]
System Pressure
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.
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Technical Information
L and K Frame Variable Motors
Operating Parameters
Input Speed
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.
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.
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Technical Information
L and K Frame Variable Motors
System Design Parameters
Installation
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).
Filtration
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
•
Reservoir
Overpressure Protection
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.
Loop Flushing
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.
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