Danfoss LPV User guide
Technical Information
Axial Piston Pumps
LPV
www.danfoss.com
Technical Information
LPV Axial Piston Pumps
Revision history Table of revisions
Date Changed Rev
April 2021 Changed document number from 'BC00000044' and '520L0954' to 'BC152886483590' and
removed obsolete end cap options
May 2018 add straight keyed shaft 0103
September 2017 update model code 0102
July 2015 Danfoss Layout 0100
January 2009 neutral assist return mechanism - changes AF
October 2008 added serial number plate drawing AE
April 2008 changes to auxilliary mounting dimensions AD
August 2007 revised endcap and loop flusing options in model code AC
May 2007 correct displacement errors AB
July 2006 First edition A-0
0301
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Technical Information
LPV Axial Piston Pumps
Contents
General description
Operating parameters
System design parameters
Operation
Technical specifications
Product coding
Features and options
Installation drawings
Overview..............................................................................................................................................................................................4
Design...................................................................................................................................................................................................4
Typical applications.........................................................................................................................................................................4
LPV product specifications............................................................................................................................................................4
Design...................................................................................................................................................................................................6
Direct displacement drive system..............................................................................................................................................7
LPV Pump schematic diagram.....................................................................................................................................................7
Overview..............................................................................................................................................................................................8
Input speed.........................................................................................................................................................................................8
System pressure................................................................................................................................................................................8
Pressure Ratings................................................................................................................................................................................8
Viscosity............................................................................................................................................................................................... 8
Temperature.......................................................................................................................................................................................9
Case pressure.....................................................................................................................................................................................9
Independent braking system.......................................................................................................................................................9
Reservoir.............................................................................................................................................................................................. 9
Case drain......................................................................................................................................................................................... 10
Charge flow requirements..........................................................................................................................................................10
Loop flushing...................................................................................................................................................................................10
Bearing loads and life................................................................................................................................................................... 10
Applications with external shaft loads..............................................................................................................................10
Hydraulic unit life...........................................................................................................................................................................12
Mounting flange loads.................................................................................................................................................................12
Estimating overhung load moments.................................................................................................................................12
Input shaft torque rating and spline lubrication................................................................................................................ 13
Understanding and minimizing system noise.....................................................................................................................13
Sizing equations.............................................................................................................................................................................14
Fluids.................................................................................................................................................................................................. 14
Filtration system.............................................................................................................................................................................15
Charge filtration........................................................................................................................................................................ 15
Suction filtration....................................................................................................................................................................... 16
HPRV (High pressure relief valve).............................................................................................................................................17
Bypass function...............................................................................................................................................................................17
CPRV (Charge pressure relief valve)........................................................................................................................................ 17
Loop flushing valve.......................................................................................................................................................................18
Neutral return mechanism..........................................................................................................................................................18
Specifications...................................................................................................................................................................................20
LPV Model Code............................................................................................................................................................................. 23
Controls............................................................................................................................................................................................. 26
Direct displacement control.................................................................................................................................................26
Features and benefits..............................................................................................................................................................26
Control handle requirements...............................................................................................................................................26
Input shafts.......................................................................................................................................................................................26
Auxiliary mounting pads.............................................................................................................................................................27
SAE-A Auxiliary mounting..................................................................................................................................................... 27
LPV Installation drawings............................................................................................................................................................29
LPV Schematic.................................................................................................................................................................................30
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Technical Information
LPV Axial Piston Pumps
General description
Overview
Design
LPV is a family of variable displacement, axial piston pumps for closed circuit applications. The LPV family
is uniquely designed to optimize performance, size, and cost, matching the work requirements of the
demanding turf care and utility vehicle marketplace. This document gives the detailed specifications and
features for LPV pumps.
High performance
Displacements 25 cm³/rev [1.53 in3/rev], 30 cm³/rev [1.83 in3/rev], 35 cm³/rev [2.14 in3/rev]
•
Speeds up to 3600 rpm
•
Pressures up to 210 bar [3045 psi] continuous, and 345 bar [5000 psi] peak
•
Direct displacement control
•
Latest technology
Customer-driven using quality function deployment (QFD) and design for manufacturability (DFM)
•
techniques
Optimized valve plates for quiet operation
•
Compact package size minimizing installation space requirements
•
Single piece rigid housing to reduce noise and leak paths
•
Integrated neutral return mechanism for simplified installation
•
Optional loop flushing for circuit flexibility
•
Typical applications
LPV product specifications
Reliability
Designed to rigorous standards
•
Proven in both laboratory and field
•
Manufactured to rigid quality standards
•
Long service life
•
Turf care
•
Utility vehicles
•
Basic units
The LPV pumps provide an infinitely variable speed range between zero and maximum in both forward
and reverse modes of operation.
LPV pumps are compact, high power density units. All models use the parallel axial piston/slipper
concept in conjunction with a tiltable swashplate to vary the pump's displacement. Reversing the angle
of the swashplate reverses the flow of fluid from the pump, reversing the direction of rotation of the
output motor.
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Made in USA
Place of Manufac tur
e
Part Number
Serial
Number
Model
Code
LPVAAADAEACCABDDD
P107852
83002847
A084012345
RAFFBNNN***
Technical Information
LPV Axial Piston Pumps
General description
LPV pump
Serial number plate
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P106271
Input shaft
Ball bearing
Needle bearing
Tapered roller bearing
Cylinder block
Valve plate
Cylinder block spring
Piston
Slipper
Swashplate
Trunion
Technical Information
LPV Axial Piston Pumps
General description
Design
LPV is a family of hydrostatic pumps for low to medium power applications with maximum loads of 345
bar [5000 psi]. You can apply these pumps with other products in a system to transfer and control
hydraulic power.
LPV pumps provide an infinitely variable speed range between zero and maximum in both forward and
reverse modes of operation. LPV pumps come in three displacements (25 cm3 [1.53 in3], 30 cm3 [1.83 in3],
and 35 cm3 [2.14 in3]).
LPV pumps are compact, high power density units. All models use the parallel axial piston / slipper
concept in conjunction with a tiltable swashplate to vary the pump's displacement. Reversing the angle
of the swashplate reverses the flow of fluid from the pump, reversing the direction of rotation of the
motor output.
LPV pumps have an internal neutral return mechanism for ease of installation, and are available with
optional loop flushing for circuit flexibility. LPV pumps can receive charge flow from an auxiliary circuit or
from a gear pump mounted on the auxiliary mounting pad. LPV pumps feature an SAE A auxiliary
mounting pad to accept auxiliary hydraulic pumps for use in complementary hydraulic systems.
LPV pumps include a trunnion style direct displacement control.
LPV cross section
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Variable
displacement
pump
Input
shaft
Cylinder
block
assembl y
HPRV valves
Loop flushing valves
OMR
orbital
motor
Suction flow
Servo pressur e
High pressur e
Case flow
Charge pressur e
Output
shaft
Filter
Charge
pump
Reservoir
Heat
exchanger
Heat exchanger
bypass
Charge relief
valve
Bypass
valve
P100586
Charge pressure
inlet
Port A
Port B
P106287
L2
L1
Technical Information
LPV Axial Piston Pumps
General description
Direct displacement drive system
The direct displacement control varies the swashplate angle. Swashplate angle determines pump flow
and motor speed.
Pictorial circuit diagram
The diagram shows an LPV pump driving an OMR motor. The system shown uses an external charge pump and external filter. Charge
pressure relief valves, high pressure relief valves, and loop flushing valves are shown separated from the pump to provide clarity to the
hydraulic system.
LPV Pump schematic diagram
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W
Technical Information
LPV Axial Piston Pumps
Operating parameters
Overview
Input speed
This section defines the operating parameters and limitations for LPV pumps with regard to input speeds
and pressures. For actual parameters, refer to Technical specifications on page 20.
The table in Technical specifications on page 20, gives rated and maximum speeds for each
displacement. Not all displacements operate under the same speed limits. Definitions of these speed
limits appear below.
Continuous speed is the maximum recommended operating speed at full power condition. Operating at
or below this speed should yield satisfactory product life. Do not exceed maximum pump speed during
unloaded, on-road travel over level ground.
Maximum speed is the highest operating speed permitted. Exceeding maximum speed reduces pump
life and can cause loss of hydrostatic power and braking capacity. Never exceed the maximum speed
limit under any operating conditions.
Warning
Unintended vehicle or machine movement hazard.
The loss of hydrostatic drive line power, in any mode of operation (forward, neutral, or reverse) may cause
the system to lose hydrostatic 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.
System pressure
Pressure Ratings
The table in Technical specifications on page 20, gives maximum and maximum working pressure
ratings for each displacement. Not all displacements operate under the same pressure limits. Definitions
of the operating pressure limits appear below.
System pressure is the differential pressure between high pressure system ports. 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 or pressure limiter 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.
Minimum low loop pressure must be maintained under all operating conditions to avoid cavitation.
All pressure limits are differential pressures referenced to low loop (charge) pressure. Subtract low loop
pressure from gauge readings to compute the differential.
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
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C
W
Technical Information
LPV Axial Piston Pumps
Operating parameters
Temperature
Case pressure
severe duty cycle operation. Maximum viscosity should only occur at cold start. Limit speeds until the
system warms up. Refer to Specifications on page 20, for specifications.
Maintain fluid temperature within the limits shown in the table. Technical specifications on page 20.
Minimum temperature relates to the physical properties of the component materials. Cold oil will not
affect the durability of the pump components, however, it may affect the ability of the pump to provide
flow and transmit power. Maximum temperature is based on material properties. Don't exceed it.
Measure maximum temperature at the hottest point in the system. This is usually the case drain. Refer to
Specifications on page 20, for specifications.
Ensure fluid temperature and viscosity limits are concurrently satisfied.
Do not allow case pressure to exceed ratings under normal operating conditions. During cold start, keep
case pressure below maximum intermittent case pressure. Size drain plumbing accordingly.
Caution
Independent braking system
Reservoir
Possible component damage or leakage.
Operation with case pressure in excess of stated limits may damage seals, gaskets, and/or housings,
causing external leakage. Performance may also be affected since charge and system pressure are
additive to case pressure.
Warning
Unintended vehicle or machine movement hazard.
The loss of hydrostatic drive line power, in any mode of operation (forward, neutral, or reverse) may cause
the system to lose hydrostatic 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 reservoir provides clean fluid, dissipates heat, and removes trapped 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 5/8 of the charge pump flow (per minute) is satisfactory for a closed reservoir. Open circuit
systems sharing a common reservoir require greater fluid capacity.
Locate the reservoir outlet (suction line) near the bottom, allowing clearance for settling foreign particles.
Use a 100 - 125 µm screen covering the outlet port.
Place the reservoir inlet (return lines) below the lowest expected fluid level, as far away from the outlet as
possible. Use a baffle (or baffles) between the reservoir inlet and outlet ports to promote de-aeration and
reduce fluid surging.
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Technical Information
LPV Axial Piston Pumps
System design parameters
Case drain
Charge flow requirements
Connect the case drain line to one of the case outlets to return internal leakage to the system reservoir.
Use the higher of the outlets to promote complete filling of the case. Case drain fluid is typically the
hottest fluid in the system. Return case drain flow through the heat exchanger to the reservoir.
All LPV pumps applied in closed circuit installations require charge flow. The charge pump provides flow
to make up internal leakage, maintain a positive pressure in the main circuit, provide flow for cooling and
filtration, replace any leakage losses from external valving or auxiliary systems, and to provide flow and
pressure for the control system.
Many factors influence the charge flow requirements and charge pump size selection. These factors
include system pressure, pump speed, pump swashplate angle, type of fluid, temperature, size of heat
exchanger, length and size of hydraulic lines, control response characteristics, auxiliary flow
requirements, hydrostatic motor type, etc. When sizing and selecting hydrostatic units for an application,
it is frequently not possible to have all the information necessary to accurately evaluate all aspects of
charge pump size selection.
Maintain charge pressure at the level specified in the table Technical specifications on page 20 under all
operating conditions to prevent damage to the transmission. Danfoss recommends testing under actual
operating conditions to verify this.
Charge pump displacement should be at least 10% of the total displacement of all axial piston
components in the system. However, unusual application conditions may require a more detailed review
of charge pump sizing. Refer to Selection of Drive line Components, BLN-9985, for a more detailed
selection procedure, or contact your Danfoss representative for assistance.
Loop flushing
Bearing loads and life
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.
LPV utilizes a special loop flushing spool design. On dual path systems, take special care to verify
acceptable performance.
Bearing life is a function of speed, system pressure, charge pressure, and swashplate angle, plus any
external side or thrust loads. The influence of swashplate angle includes displacement as well as
direction. External loads are found in applications where the pump is driven with a side/thrust load (belt
or gear) as well as in installations with misalignment and improper concentricity between the pump and
drive coupling. All external side loads will act to reduce the normal bearing life of a pump. Other life
factors include oil type and viscosity.
In vehicle propel drives with no external shaft loads and where the system pressure and swashplate angle
are changing direction and magnitude regularly, the normal L20 bearing life (80 % survival) will exceed
the hydraulic load-life of the unit.
In non propel drives such as vibratory drives, conveyor drives, or fan drives, the operating speed and
pressure are often nearly constant and the swashplate angle is predominantly at maximum. These drives
have a distinctive duty cycle compared to a propulsion drive. In these types of applications a bearing life
review is recommended.
Applications with external shaft loads
LPV pumps have bearings that can accept some external radial and thrust loads. When external loads are
present, the allowable radial shaft loads are a function of the load position relative to the mounting
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