上海交通大学：《工程学导论》课程教学资源（讲义）Technical knowledge_4bearings

Machine Components Introduction to Engineering

1 Introduction to Engineering Machine Components

Bearings 2 Introduction to Engineering

2 Introduction to Engineering Bearings Bearings Bearings

"Bearing"-Definitions A device that >Supports >Guides >Reduces the friction of motion between fixed and moving machine parts Introduction to Engineering

3 Introduction to Engineering “Bearing” –Definitions A device that Supports Guides Reduces the friction of motion between fixed and moving machine parts

Bearing Types Journal bearings >Rolling-element bearings Introduction to Engineering

4 Introduction to Engineering Bearing Types Journal bearings Rolling-element bearings

Lubrication & Journal Bearings 0 5 Introduction to Engineering

5 Introduction to Engineering Lubrication & Journal Bearings Lubrication & Lubrication & Journal Bearings Journal Bearings

Lubricant Purposes Prevent metal-to-metal contact Remove or help dissipate heat Protect metal surfaces from corrosion Protect parts from contamination Any interposed substance that reduces friction and wear is a lubricant Lubricants are usually liquid but can be a solid,such as graphite,or a gas,such as pressurized air 6 Introduction to Engineering

6 Introduction to Engineering Lubricant Purposes Prevent metal-to-metal contact Remove or help dissipate heat Protect metal surfaces from corrosion Protect parts from contamination Any interposed substance that reduces friction and wear is a lubricant Lubricants are usually liquid but can be a solid, such as graphite, or a gas, such as pressurized air

Liquid Lubricants ·Generally oils Characterized by their viscosity Introduction to Engineering

7 Introduction to Engineering Liquid Lubricants • Generally oils • Characterized by their viscosity

Modern oil lubricants usually contain one or more additives designed to > Cause the oil to flow at lower temperatures Have less variation of viscosity with temperature Resist foaming when agitated by high-speed machinery Resist oxidation at high temperatures Prevent corrosion of metal surfaces > Reduce friction and wear when full lubricating films cannot be maintained 8 Introduction to Engineering

8 Introduction to Engineering Modern oil lubricants usually contain one or more additives designed to  Cause the oil to flow at lower temperatures  Have less variation of viscosity with temperature  Resist foaming when agitated by high-speed machinery  Resist oxidation at high temperatures  Prevent corrosion of metal surfaces  Reduce friction and wear when full lubricating films cannot be maintained

Greases Thickened liguid lubricants Can stay in position Prevent harmful contaminants from entering between the bearing surfaces Cannot circulate 9 Introduction to Engineering

9 Introduction to Engineering Greases  Thickened liquid lubricants  Can stay in position  Prevent harmful contaminants from entering between the bearing surfaces  Cannot circulate

Journal Bearings Oil inlet bearing D Beart oil Oil journal journal >A shaft rotates inside a bearing bore slightly larger than the shaft diameter >A lubricant is supplied to the annular gap >The portion of the shaft within the bearing is called the journal 10 Introduction to Engineering

10 Introduction to Engineering Journal Bearings A shaft rotates inside a bearing bore slightly larger than the shaft diameter journal A lubricant is supplied to the annular gap The portion of the shaft within the bearing is called the journal