lubrication in automotive gears

Lubrication

in Automotive Gears

Presented by : RAJIV RANJAN

Presented by: RAJIV RANJAN

Automotive Gear Oils


Contents

Gears & Gear Box

Main Functions of Gear Lubricants

Classifications & Specifications

General Failure Mechanisms

Oil Related Common Gear Box Problems


Main Functions Of Gears

Definition: A toothed wheel, cylinder,

or other machine element that meshes with another toothed element to transmit motion or to change speed or direction

Functions

Transmit Power

Increase or Decrease Speed

Increase or Decrease Torque

Change Axis/Direction of Motion

Synchronize Timing


Gear Box


• Reduce Friction

• Reduce Wear

• Protection against metal contact

• Dissipate Heat

• Reduce Friction, Shock, And Noise Between Gears

• Carrier For Additives

• Remove Contaminants From Metal Contact Areas

• Prevent Corrosion

• Protect Against Pitting

• Protect Against Metal Transfer

Major Functions Of Gear Lubricants

Bottom Line – Extend Gear Set Life


• Metallurgy • Surface Hardness • Surface Finish • Sliding And Rolling

Viscosity • Surface Coating • Tooth Contact Pressure

• Oil Viscosity • Temperature Of The

Gear Oil Interface • Lubricant Quality • Bulk Oil Temperature • Operating Conditions

Factors Affecting Gear Life


• Anti-wear agents

• Reduce the loss of metal from component surfaces by preventing

metal to metal contact under high loads

• Film forming compounds such as ZDDP, organic acids, fatty oils etc

protect surfaces by Reacting/adsorbing on metal surfaces

• EP agents

• Special type of anti-wear agents, which react with metals under

extreme loads

• Sulphur , Phosphorus compounds are used as EP agents

Anti-wear & EP Agents


How Do Gear Oils Protect Equipment ?

Metal Contact May Occur Under the Following Conditions

High Load/Extreme Pressure (EP)

High Temperature

Low Viscosity

Gear Oils contain EP and Antiwear Additives that form a protective film on metal surfaces

Major EP/Antiwear Technologies

Conventional Sulfur/Phosphorous

Borate

Metal

Oil

Motion

Metal Film

Additive


FRICTION AND WEAR

VISCOSITY AND TEMPERATURE

• Reduction of wear

• Anti-wear performance

• Control of friction characteristics

• Oil film stability

• Heat Conductance

• Thermal stability

• Oxidation stability

• High temperature viscosity

• Low temperature fluidity

• Viscosity vs Temperature characteristics

• Shear stability

Automotive Gear Oils : Characteristics


OTHERS

• Dispersancy • Prevention of sludge & deposit

formation • Anti-corrosion • Anti-foaming • Compatibility with metals • Compatibility with oil seals

Automotive Gear Oils : Characteristics


Gear Oils

Classification & Specifications


SAE Viscosity

Grade

Max Temperature for Viscosity of 150,000 cP (0C)

Kinematic Viscosity at 1000C (cSt)

min max

70W -55 4.1 -

75W -40 4.1 -

80W -26 7.0 -

85W -12 11.0 -

80 - 7.0 <11.0

85 - 11.0 <13.5

90 - 13.5 <24.0

140 - 24.0 <41.0

250 - 41.0 -

SAE J 306 – Automotive Gear Oils


Need for New Classification

• The existing viscosity ranges for SAE 90 & SAE 140 were too wide

• Lubricant of same viscosity (SAE 90 or SAE 140) perform

significantly differently in an intended application

• Lead to introduction of two new Viscosity grades

• SAE 110

• SAE 190

• In future, Indian OEMs may also recommend gear lubricants based

on the revised SAE J 306 classification


Revised SAE J 306 Classification

SAE Viscosity Grade

Max Temperature for Viscosity of 150,000 cP (0C)

Kinematic Viscosity at 1000C (cSt)

min max

70W -55 4.1 -

75W -40 4.1 -

80W -26 7.0 -

85W -12 11.0 -

80 - 7.0 <11.0

85 - 11.0 <13.5

90 - 13.5 <18.5

110 18.5 <24.0

140 - 24.0 <32.5

190 32.5 <41.0

250 - 41.0 -


API TYPE

GL-1 Mineral Oil

GL-2 Contains Antiwear or Minor EP agent

GL-3 Contains mild EP agent

GL-4 Contains EP Agent. Equivalent to MIL-L-2105

GL-5 Contains EP Agent. Equivalent to MIL-L-2105D

GL-6 Obsolete

API Classification – Automotive Gear Oils


Other Classifications

API MT-1 :

For non-synchronised manual transmissions – provides protection against thermal degradation, component wear & oil seal deterioration

MIL- PRF- 2105E

API GL- 5 + API MT-1

SAE J 2360

Non- Governmental standard of MIL- PRF- 2105E.

Oil companies can get their product listed in the approval list


Intended for non synchronised manual transmissions of buses & heavy duty trucks

Provides protection against

Thermal Degradation

Component Wear

Oil Seal Deterioration

API MT-1


Combines the requirements of :

MIL-L-2105 D & API MT-1

Maintains all test requirements Of MIL-L-2105 D

In addition, meets Oil Seal Compatibility & Thermal Durability requirement of API MT-1

SAE J 2360, an off shoot – Non Governmental Standards

– Additional Channel Point & Flash Point requirements

MIL-PRF-2105E/ SAE J 2360


General Gear Failure Mechanisms

Wear (Loss of Materials by Abrasive/Adhesive Contact)

Plastic Flow (Surface Yielding and Deformation Due to Heavy Loads)

Surface Fatigue (Failure Related to Repeated Contact)

Breakage

Associated Gear Failures (Lubricant Starvation, Etc.)

General Gear Failure mechanisms


Scratching/Scoring (Scuffing)

Rough , matte appearance

Cause

Localized welding of sliding surfaces

Poor EP

Poor oil film thickness

Prevention

Higher viscosity oil

EP oil


Pitting Appearance

Very small ( < 1sq mm) cavities on surface resulting from material breakout

Cause

Fatigue phenomena – initiation of cracks in sub surface which propagate outward and separate surface material

Prevention

High lube film thickness

Low contact stress – appropriate design

Heat treated contact material


Spalling

Appearance

Flaking larger than pitting

Cause

Initiated as pitting, several pits grow to form a spall

Prevention

Same as pitting


Ridging

Appearance

Series of parallel raised ridges on tooth surface in the direction of rotation

Cause

Plastic deformation

High stress from low sliding velocity

Prevention

High lube film thickness

Low contact stress – appropriate design

Heat treated contact material


Rippling

Appearance

Fish scales on tooth surface

Cause

Plastic deformation

Very slow speed operation

Poor lube supply

Prevention

Reduce contact stress

Improve oil film thickness

Improve steel hardness


Oil Related Common Gear Box Problems


• Excess Oil • Additive Type • Water • Design Features - Reservoir Too Small - Excessive Churning • Contamination - Preservative Left In Unit From Mfg. • Suction Leak On Circulating Pump

Foaming

Possible Causes


•Improper Design Or Hardness •Faulty Installation •Faulty Operation •Misalignment •Worn Gears •Inadequate Lubrication

Noisy Operation

Possible Causes


•Contamination •Oxidation

- Overheating

- Extended Drain Interval •Top up with Oil of higher viscosity

Oil Thickening

Possible Causes


Overheating

Poor maintenance

Oil level too high

Oil level too low

High ambient temperatures

Improper oil viscosity

- Too thin

- Too thick

Overloading

Possible Causes


Summary

• Gears are primarily used to transmit power

• Gear Lubricants reduce friction & wear and thereby extend

gear set life

• Revised SAE J 306 include two new viscosity grades

• API, Military & other specifications

• General Failure Mechanisms & Oil Related Problems

Thank You !

RAJIV RANJAN [email protected]

mailto:[email protected]