Danfoss LPV Service guide

MAKING MODERN LIVING POSSIBLE

Service Manual

Closed Circuit Axial Piston Pumps

LPV

powersolutions.danfoss.com

Service Manual	LPV Closed Circuit Axial Piston Pumps

Revision history	Table of revisions
	Date	Changed	Rev
	July 2015	Danfoss layout	0100
	November 2006	First printing	A

2	11004904 • Rev 0100 • July 2015

Service Manual	LPV Closed Circuit Axial Piston Pumps
Contents
Introduction
	Overview..............................................................................................................................................................................................	4
	Warranty..............................................................................................................................................................................................	4
	General instructions........................................................................................................................................................................	4
	Safety Precautions............................................................................................................................................................................	5
	Symbols used in Danfoss literature............................................................................................................................................	6
	Design...................................................................................................................................................................................................	6
	Direct displacement drive system..............................................................................................................................................	8
	LPV Pump schematic diagram.....................................................................................................................................................	8
Operation
	HPRV (High pressure relief valve)...............................................................................................................................................	9
	Bypass function.................................................................................................................................................................................	9
	CPRV (Charge pressure relief valve)........................................................................................................................................	10
	Loop flushing valve.......................................................................................................................................................................	10
	Neutral return mechanism..........................................................................................................................................................	11
Technical specifications
	Specifications...................................................................................................................................................................................	12
Fluid and filter recommendations
	Fluid and filter recommendations...........................................................................................................................................	15
Startup procedures
	General ..............................................................................................................................................................................................	16
	Start-up procedure........................................................................................................................................................................	16
Pressure measurements
	Required tools.................................................................................................................................................................................	17
	Port locations and gauge installation.....................................................................................................................................	17
Troubleshooting
	Overview...........................................................................................................................................................................................	18
	System operating hot...................................................................................................................................................................	18
	Transmission operates normally in one direction only....................................................................................................	18
	System will not operate in either direction..........................................................................................................................	18
	System noise or vibration...........................................................................................................................................................	19
	Sluggish system response...........................................................................................................................................................	19
Adjustments
	Pump adjustment..........................................................................................................................................................................	20
	Standard procedures, inspections, and adjustments.......................................................................................................	20
	Charge pressure relief valve adjustments.............................................................................................................................	20
	System check and HPRV..............................................................................................................................................................	22
	Checking for proper HPRV valve operation....................................................................................................................	22
	Loop flushing valve.......................................................................................................................................................................	22
	Neutral return mechanism..........................................................................................................................................................	23
	Leveling swashplate with pump installed on machine....................................................................................................	24
Minor repair
	Input shaft and seal.......................................................................................................................................................................	25
	Trunion seal......................................................................................................................................................................................	29
	High Pressure Relief Valves.........................................................................................................................................................	30
	Charge pressure relief valve.......................................................................................................................................................	31
	Loop flushing valve.......................................................................................................................................................................	32
	Bypass valve.....................................................................................................................................................................................	33
	Coupling............................................................................................................................................................................................	34
Torque chart
	Fasteners and plugs......................................................................................................................................................................	35
	Fastener size and torque chart..................................................................................................................................................	35
	Plug size and torque chart..........................................................................................................................................................	35

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Service Manual	LPV Closed Circuit Axial Piston Pumps

Introduction

Overview

This manual includes information for the installation, maintenance, and minor repair of the LPV pump. It includes a description of the unit and its individual components, troubleshooting information, and minor repair procedures.

Performing minor repairs requires the unit to be removed from the vehicle/machine. Thoroughly clean the unit before beginning maintenance, or repair activities. Since dirt and contamination are the greatest enemies of any type of hydraulic equipment, follow cleanliness requirements strictly. This is especially important when changing the system filter and when removing hoses or plumbing.

A worldwide network of Danfoss Global Service Partners is available for major repairs. Danfoss Global Service Partners are trained by the factory and certified on a regular basis. You can locate your nearest Global Service Partner using the distributor locator at www.sauer-danfoss.com. Click on the Sales and Service link.

Warranty

Performing installation, maintenance, and minor repairs according to the procedures in this manual will not affect your warranty. Major repairs requiring the removal of a unit’s rear cover or front flange voids the warranty unless done by a Danfoss Global Service Partner.

General instructions

Follow these general procedures when repairing Series LPV variable displacement closed circuit pumps.

Remove the unit

Prior to performing major repairs, remove the unit from the vehicle/machine. Chock the wheels on the vehicle or lock the mechanism to inhibit movement. Be aware that hydraulic fluid may be under high pressure and / or hot. Inspect the outside of the pump and fittings for damage. Cap hoses after removal to prevent contamination.

Keep it clean

Cleanliness is a primary means of assuring satisfactory pump life, on either new or repaired units. Clean the outside of the pump thoroughly before disassembly. Take care to avoid contamination of the system ports. Cleaning parts by using a clean solvent wash and air drying is usually adequate.

As with any precision equipment, all parts must be kept free of foreign materials and chemicals. Protect all exposed sealing surfaces and open cavities from damage and foreign material. If left unattended, cover the pump with a protective layer of plastic.

Lubricate moving parts

During assembly, coat all moving parts with a film of clean hydraulic oil. This assures that these parts will be lubricated during start-up.

Replace all O-rings and gaskets

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Service Manual	LPV Closed Circuit Axial Piston Pumps

Introduction

It is recommended that all O-rings be replaced. Lightly lubricate all O-rings with clean petroleum jelly prior to assembly.

Secure the unit

For major repair, place the unit in a stable position with the shaft pointing downward. It will be necessary to secure the pump while removing and torquing the endcap bolts.

Safety Precautions

Always consider safety precautions before beginning a service procedure. Protect yourself and others from injury. Take the following general precautions whenever servicing a hydraulic system.

Unintended Machine Movement

W Warning

Unintended movement of the machine or mechanism may cause injury to the technician or bystanders. To protect against unintended movement, secure the machine or disable/disconnect the mechanism while servicing.

Flammable Cleaning Solvents

W Warning

Some cleaning solvents are flammable. To avoid possible fire, do not use cleaning solvents in an area where a source of ignition may be present.

Fluid Under Pressure

W Warning

Escaping hydraulic fluid under pressure can have sufficient force to penetrate your skin causing serious injury and/or infection. This fluid may also be hot enough to cause burns. Use caution when dealing with hydraulic fluid under pressure. Relieve pressure in the system before removing hoses, fittings, gauges, or components. Never use your hand or any other body part to check for leaks in a pressurized line. Seek medical attention immediately if you are cut by hydraulic fluid.

Personal Safety

W Warning

Protect yourself from injury. Use proper safety equipment, including safety glasses, at all times.

Hazardous Material

W Warning

Hydraulic fluid contains hazardous material. Avoid prolonged contact with hydraulic fluid. Always dispose of used hydraulic fluid according to state, and federal environmental regulations.

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Service Manual	LPV Closed Circuit Axial Piston Pumps

Introduction

Symbols used in Danfoss literature

WARNING may result in injury

CAUTION may result in damage to product or property

Reusable part

Non-reusable part, use a new part

Non-removable item

Option - either part may exist

Superseded - parts are not interchangeable Measurement required

Flatness specification

Parallelism specification

External hex head

Internal hex head

Torx head

O-ring boss port

Tip, helpful suggestion

Lubricate with hydraulic fluid

Apply grease / petroleum jelly

Apply locking compound

Inspect for wear or damage

Clean area or part

Be careful not to scratch or damage Note correct orientation

Mark orientation for reinstallation Torque specification

Press in - press fit

Pull out with tool – press fit

Cover splines with installation sleeve

Pressure measurement/gauge location or specification

The symbols above appear in the illustrations and text of this manual. They are intended to communicate helpful information at the point where it is most useful to the reader. In most instances, the appearance of the symbol itself denotes its meaning. The legend above defines each symbol and explains its purpose.

Design

LPV represents a family of hydrostatic pumps for low to medium power applications with maximum pressures up to 345 bar [5000 psi]. These pumps can be applied 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 [2.32 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 are provided with an internal neutral return mechanism for ease of installation, and are available with optional loop flushing for circuit flexibility. LPV pumps are designed to 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.

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Service Manual	LPV Closed Circuit Axial Piston Pumps

Introduction

LPV cross section

Cylinder block

Valve plate

Trunion	Tapered roller bearing

Ball bearing

Input shaft

Needle bearing	Piston		Swashplate
Cylinder block spring		Slipper	P106 271E

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Service Manual	LPV Closed Circuit Axial Piston Pumps

Introduction

Direct displacement drive system

The direct displacement control varies the swashplate angle. Swashplate angle determines pump flow and motor speed.

Pictorial circuit diagram

Cylinder block assembly

Input

shaft Variable displacement pump

			OMS
			orbital
			motor
		valve
			Output
			shaft
	Charge pump
		Suction flow
HPRV valves	Loop flushing valves	Charge pressure
		Servo pressure
		High pressure
		Case flow	P100 586E

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

Charge pressure inlet

L2

Port A

Port B

L1

P106 287E

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Service Manual	LPV Closed Circuit Axial Piston Pumps

Operation

HPRV (High pressure relief valve)

LPV pumps are equipped with a combination high pressure relief and charge check valve. The highpressure relief function is a dissipative (with heat generation) pressure control valve for the purpose of limiting excessive system pressures. The charge check function acts to replenish the low-pressure side of the working loop with charge oil. Each side of the transmission loop has a dedicated HPRV valve that is non-adjustable with a factory set pressure. When system pressure exceeds the factory setting of the valve, oil is passed from the high pressure system loop, into the charge gallery, and into the low pressure system loop via the charge check.

HPRV valve

P106 273E

Bypass function

The LPV contains a dedicated bypass valve. The bypass function is activated when the bypass valve is mechanically backed out 3 full turns (maximum). The bypass function allows a machine or load to be moved without rotating the pump shaft or prime mover.

Bypass valve

P106 286E

C Caution

Excessive speeds and extended load/vehicle movement must be avoided. The load or vehicle should be moved not more than 20% of maximum speed and for a duration not exceeding 3 minutes. Damage to drive motor(s) is possible. When the bypass function is no longer needed care should be taken to reseat the bypass valves to the normal operating position.

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Service Manual	LPV Closed Circuit Axial Piston Pumps

Operation

CPRV (Charge pressure relief valve)

An internal charge relief valve regulates charge pressure. Charge pressure is supplied to maintain a minimum pressure in the low side of the transmission loop.

CPRV valve

Case pressure

Charge pressure

P106 274E

Minimum charge pressure is the lowest pressure allowed to maintain a safe working condition in the low side of the loop.

Maximum charge pressure is the highest charge pressure allowed by the charge relief adjustment, and which provides normal component life. The charge pressure setting listed in the order code is the set pressure of the charge relief valve with the pump in neutral, operating with 5 gpm of charge flow. The charge pressure setting is referenced to case pressure. Charge pressure is the differential pressure above case pressure.

Loop flushing valve

LPV pumps incorporate an optional integral loop flushing valve, which removes heat and contaminants from the main loop at an increased rate.

Loop flushing valve

P106 276E

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Service Manual	LPV Closed Circuit Axial Piston Pumps

Operation

Neutral return mechanism

The neutral return mechanism is designed to mechanically return the pump to zero displacement. A cam allows precise zero displacement adjustment.

Neutral return adjusting cam

Adjusting cam

Lock/seal nut

P106 277E

Neutral return mechanism

Swashplate

Shaft

Neutral return

arm

Adjusting cam

P106 278E

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