lubrication in automotive gears
TRANSCRIPT
Lubrication
in Automotive Gears
Presented by : RAJIV RANJAN
Presented by: RAJIV RANJAN
Automotive Gear Oils
Presented by: RAJIV RANJAN
Contents
Gears & Gear Box
Main Functions of Gear Lubricants
Classifications & Specifications
General Failure Mechanisms
Oil Related Common Gear Box Problems
Presented by: RAJIV RANJAN
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
Presented by: RAJIV RANJAN
Gear Box
Presented by: RAJIV RANJAN
• 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
Presented by: RAJIV RANJAN
• 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
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• 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
Presented by: RAJIV RANJAN
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
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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
Presented by: RAJIV RANJAN
OTHERS
• Dispersancy • Prevention of sludge & deposit
formation • Anti-corrosion • Anti-foaming • Compatibility with metals • Compatibility with oil seals
Automotive Gear Oils : Characteristics
Presented by: RAJIV RANJAN
Gear Oils
Classification & Specifications
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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
Presented by: RAJIV RANJAN
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
Presented by: RAJIV RANJAN
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 -
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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
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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
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Intended for non synchronised manual transmissions of buses & heavy duty trucks
Provides protection against
Thermal Degradation
Component Wear
Oil Seal Deterioration
API MT-1
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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
Presented by: RAJIV RANJAN
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
Presented by: RAJIV RANJAN
Scratching/Scoring (Scuffing)
Rough , matte appearance
Cause
Localized welding of sliding surfaces
Poor EP
Poor oil film thickness
Prevention
Higher viscosity oil
EP oil
Presented by: RAJIV RANJAN
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
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Spalling
Appearance
Flaking larger than pitting
Cause
Initiated as pitting, several pits grow to form a spall
Prevention
Same as pitting
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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
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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
Presented by: RAJIV RANJAN
Oil Related Common Gear Box Problems
Presented by: RAJIV RANJAN
• 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
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•Improper Design Or Hardness •Faulty Installation •Faulty Operation •Misalignment •Worn Gears •Inadequate Lubrication
Noisy Operation
Possible Causes
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•Contamination •Oxidation
- Overheating
- Extended Drain Interval •Top up with Oil of higher viscosity
Oil Thickening
Possible Causes
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Overheating
Poor maintenance
Oil level too high
Oil level too low
High ambient temperatures
Improper oil viscosity
- Too thin
- Too thick
Overloading
Possible Causes
Presented by: RAJIV RANJAN
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