Danfoss L and K Frame Variable Motors Technical Information

Technical Information

L and K Frame Variable Motors

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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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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
Bias spring	Servo piston
Minimum
		Swashplate
angle
stop
		Output
Cylinder		shaft
block

Shaft seal

Endcap	Piston	Slipper Bearing
	Valve plate	P101109E

Cross section, cartridge mount

Servo piston	Bias spring

Swashplat e

Output

shaft

Cylinder block

			Shaft
	Endcap		seal
			Bearing
	Valve plate	Piston
			Slipper
			P104161E

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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

Control handle

contro valve

Cylinder block assembly

Input

shaft

Variable displacement pump

Motor displacement control valve

			Motor
			servo
			piston
	Bypass
	valve
			Output
Charge			shaft
pump	Loop flushing	Cylinder	Motor
	module	block	swashplate
		assembly
	High loop pressure	Loop flushing
Check valves	Case pressure	relief valve
w/ high pressure	Charge/low loop pressure
relief valve	Inlet pressure

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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Technical Information

L and K Frame Variable Motors

General Information

Schematic Diagrams

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

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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	Splined 13 or 15 tooth 16/32 pitch
	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

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	0.40	[244]	0.48 [293]	0.56 [347]	0.60 [366]	0.72 [439]
	[lbf•in/1000psi]

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	rated		4400	4450	4500	4650	4500
Zero degrees)
	maximum		5000	5150	5300	5200	5050
Case pressure	maximum working	bar [psi]	2 [29]
	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			β35-44=75 (β10≥1.5)

Ratings and data are based on operation with premium petroleum-based hydraulic fluids containing oxidation, rust, and foam inhibitors.

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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	- 40° C [- 40° F]
(intermittent, cold start)
Continuous	85° C [185° F]
Maximum	105° C [221° F]

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.

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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.

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
	2	[29] maximum pressure
Intermittent (cold start)	2	[29] above outlet pressure
	6	[87] maximum pressure

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
	[200 to 3500 psi]
LV/KV with dual line control	14 to 35 bar
	[200 to 500 psi]
LC/KC with single line control	14 to 69 bar
	[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.

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.

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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

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.

Reservoir

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.

Overpressure Protection

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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