Mechanical drives & power transmission

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Basic Mechanical Drives and Power Transmission Training

December 2007

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Mechanical Drives/Power Transmission Training

The purpose of this presentation is to

provide a overview of industrial drives and their maintenance.

Gear Drives Belt Drives V-Belt Maintenance Chain Drives Sprocket and Roller Chain Maintenance

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Gear Drives

December 2007

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Gear Boxes

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Types

Types Automotive transmissions Auxiliary transmissions Transfer cases Power takeoffs Marine gears Hydraulic drives Industrial transmissions Differentials

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Gear Boxes

Series trains Planetary gearing Speed reducers

Base mountedShaft mounted

Speed increasers

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Gears and Gear Boxes

A gear is a form of disc, or wheel, that has teeth around its periphery for the purpose of providing a positive drive by meshing the teeth with similar teeth on another gear or rack.

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Right Angle Gear Drive

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Spur Gears

http://science.howstuffworks.com/enlarge-image.htm?terms=gears&gallery=1&page=3

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Involute Curve

Cord

Base Circle

Circle involute

Circle

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Pressure Angle

Pressure Angle

Pressure angle

Pressure angle

RotationLine of action

14 ½ ° 20°

Direction of tooth to

tooth push

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Pitch Diameter and Center Distance

2

21 DDC

+= 221 DCD −=Center Distance C

Pitch Diameter D1

Pitch Diameter D2

122 DCD −=

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Circular/Diametrical Pitch

Circular Pitch

3.1416”

1 2 3 4 5 6 7 8 9 10

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Names of Gear Parts

Clearance

Pitch Circle

Addendum

Pitch Circle

DedendumWhole depth

Working depth

ThicknessCircular

pitchPitch Line

Addendum

Dedendum Whole depth

Thickness

Circular pitch

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Backlash

Backlash

Pitch Line

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Other Gear Types

Bevel and Miter Helical Worm Herringbone

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Bevel and Miter Gear

Shaft Angle

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Helical

Helix angle

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Worm Gear

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Herringbone Gear

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Gear Damage

Vibration Frequency Component – gear mesh Normal profile

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Troubleshooting

Inappropriate bidirectional operation Gear overload Misalignment Poor maintenance Induced misalignment Visual inspection

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Wear patterns

Normal

Abrasives in lubricating oil

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Pattern caused by corrosive attack on gear teeth

Pitting caused by gear overloading

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December 2007 Belt Drives

Belt Drives

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Introduction

DescriptionBasic Components

Load carrying sectionRubber compression sectionCover

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Belt Drives

Belt drives are used to transmit power between a drive unit and a driven unit

Drive Motor

Driven Unit

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Belts

The size of the belt must match the sheave size. if they do not match, then the belt will not make proper contact with the sheave and will decrease the amount of load it can transmit.

A

AB

B

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Belt Selection

Standard V-Belt Cogged Belt

Joined V-Belt Positive Drive Belt

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Sheaves

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Shaft Speed

erave_diametDriven_she

_rpmdriveshaftncheseDiameterIDriveSheavt_rpmDrivenShaf

×=

12 inch dia.

6 in dia.

1800 rpm

DriveDriven

rpm

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Driven Sheave Diameter

ft_rpmDriven_sha

_rpmdriveshaftncheseDiameterIDriveSheavveDiameterDrivenShea

×=

___ inch dia.

6 in dia.

1800 rpm

DriveDriven

900 rpm

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Belt Length

12 inch dia.

6 in dia.

DriveDriven

35 inches

2centercenter_to_2

3.14meterdriven_dia2

3.14eterdrive_diamhBelt_lengt ×+×+×=

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Belt Speed

12

14.3 rpmdiameterFPM

××=

12 inch dia.

6 in dia.

1800 rpm

DriveDriven

900 rpm

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December 2007

V-Belt Maintenance

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Belt Maintenance

Routine maintenance is essential if a belt drive is to operate properly

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Belt Maintenance

Never force belt onto sheave Belt should not ride on bottom of sheave. Check belt condition Belt alignment Tension Inspect sheaves and shafts Belt stretch

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How to Read V-belt Numbers

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Classic Cog V-belts AX-BX-CX-DX

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D-V Wedge Belts 3VX-5VX-8V

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Classic V-belts A-B-C-D-E

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V-belt Inspection

Slapping Squealing Check belt

condition Tightness Tension

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V-belt Sidewall Wear

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V-belt Worn Cover/soft or Swollen

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V-belt Slips, Squeals (Spin Burn)

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V-belt Underside Cracked

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V-Belt Cover Split / Missing Cogs

Belts pried upon Foreign objects Excessive heat Sheave too small Sheave misaligned Improper storage

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Sheave Inspection

Sheave groves must be

like this

not this

Dished out

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Sheave Inspection

5V

10.01-16.0O.D.

40 deg

Under 10.0O.D.

38 deg

Over 16.0O.D.

42 deg

Example sheave gauge

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Alignment

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Types of Misalignment

Angular Misalignment

Parallel Misalignment

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Shaft Alignment

Cord tied to shaft

Cord touching sheaves at points indicated by arrows

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Tensioning V-belts Drives

Too tight

Too loose

Slight bow

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Check Tension

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Preventative Maintenance

Check belt condition Check belt tension Identify sources of contamination Check sheave alignment Check sheave wear

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December 2007

Chain Drives

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Introduction

DescriptionTypes of links

Self forming teethExtended Pin

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Introduction

DRIVEN ROLL

DRIVE GEAR BOX

Chain Pitch

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Chain Drive

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Advantages No slippage More compact than belt Good for slow speeds Easier to install Not subject to deterioration Operates under wet conditions Less adjustment required Can drive several shafts Less costly than gear drives

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Disadvantages Cannot be used where drive must slip Cannot except misalignment Noisy Causes vibration Needs frequent lubrication Small load capacity Shorter Service Live

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Chain Drive Principles

Drive chain

Drive Sprocket

Sprocket

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Shaft Speed

teethcket_#DrivenSpro

_rpmdriveshaftteethket_#DriveSproct_rpmDrivenShaf

×=

12 T 6 T

1800 rpm

DriveDriven

rpm

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Chain Length Calculation

( )2nterCenterToCe2

PitchcketTeethDrivenSpro2

PitchketTeethDriveSprochChainLengt

×+×+×=

12 T 6 T

DriveDriven

35 inches

40 Chain

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Chain Speed

12

rpmpitchteethFPM

××=

12 T 6 T

1800 rpm

DriveDriven

900 rpm

40 Chain

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Some Chain Drive Examples

Fork Lift Roller Conveyor

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December 2007

Sprocket and Roller Chain Maintenance

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Roller Chain

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Pitch

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Large Pitch Conveyor Chain

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Chain Part Friction Areas

Major friction areas in red

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Lubrication Methods

Hand Oiling Drop Lubrication Oil Bath Rotating Plate Forced Circulation

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Example Application Large Roller Chain Multi-strand conveyor

Large Roller Chain

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Sprockets

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Sprocket Classifications

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Chain Drive Factors

Location of slack Chain wrap Vertical arrangement

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Installation – Parallel Shafts

Level

Level

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Installation

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Installation - Sprockets

Straight edge or Straight string

Gap

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Installation

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Chain LengthThe following information is needed for an equation to find the chain length:

1. Number of teeth on the drive sprocket. 2. Number of teeth on the driven sprocket. 3. Center-to-center distance between the shafts. 4. The chain pitch in inches.

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Chain Inspection Cleanliness Lubrication Signs of wear Flexibility Check chain stretch Physical damage

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Chain Wear

WORN CHAIN

NEW CHAIN

SPROCKET

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Sprocket Tooth Wear SPROCKETS INDICATE

WEAR HERE

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Preventive Maintenance

Inspect for wear Lubricate Check chain sag Set tension Inspect sprockets

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Summary and Quiz

Review Objectives Question and Answer Session

Mechanical drives & power transmission

Devices & Hardware

Transcript of Mechanical drives & power transmission