Mechanical Drives and Power Transmission Training

Basic Mechanical Drives and Power Transmission Training

December 2007

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

Gear Drives

December 2007


Gear Boxes


Types 

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


Gear Boxes Series trains  Planetary gearing  Speed reducers 

Base mounted  Shaft mounted 



Speed increasers


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.


Right Angle Gear Drive


Spur Gears


Involute Curve Cord Base Circle

Circle involute

Circle


Pressure Angle Direction of tooth to tooth push Pressure Angle

14 ½

Pressure angle

Pressure angle 20 Rotation Line of action


Pitch Diameter and Center Distance Pitch Diameter D2

Pitch Diameter D1

Center Distance C

C 

D1  D 2 2

D1  2C  D 2

D 2



2C  D1


Circular/Diametrical Pitch Circular Pitch

3.1416”

1

2

3

4

5

6

7

8

9

10


Names of Gear Parts

Pitch Circle

Clearance Addendum

Addendum

Pitch Circle Working Thickness Dedendum Whole depth Circular depth pitch Thickness Pitch Line

Dedendum Whole Circular pitch depth


Backlash Backlash

Pitch Line


Other Gear Types Bevel and Miter  Helical  Worm  Herringbone 


Bevel and Miter Gear

Shaft Angle


Helical

Helix angle


Worm Gear


Herringbone Gear


Gear Damage Vibration  Frequency Component – gear mesh  Normal profile 


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


Wear patterns 

Normal



Abrasives in lubricating oil




Pattern caused by corrosive attack on gear teeth



Pitting caused by gear overloading

Belt Drives

Belt Drives

December 2007


Introduction Description Basic Components 

Load carrying section  Rubber compression section  Cover 


Belt Drives 

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

Driven Unit

Drive Motor


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 B load it can transmit. A

B

A


Belt Selection

Standard V-Belt

Joined V-Belt

Cogged Belt

Positive Drive Belt


Sheaves


Shaft Speed Driven

12 inch dia. rpm

DrivenShaf t_rpm



Drive

6 in dia.

1800 rpm

DriveSheaveDiameterInches  driveshaft _rp _rpm m Driven_she ave_diameter


Driven Sheave Diameter Drive

Driven

___ inch dia.

6 in dia.

1800 rpm

900 rpm

DrivenShea veDiameter



DriveSheaveDiameterInches  driveshaft _rpm _rpm Driven_sha ft_rpm


Belt Length Driven

Drive

6 in

12 inch dia.

dia.

35 inches

Belt_length 

drive_diameter 3.14 driven_diameter 3.14   center_to_ center  2 2 2


Belt Speed Drive

Driven

12 inch dia.

6 in dia.

1800 rpm

900 rpm

FPM FP M 

diameter  3.14  rpm 12

V-Belt Maintenance

December 2007


Belt Maintenance 

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


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 


How to Read V-belt Numbers


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


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


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


V-belt Inspection Slapping  Squealing  Check belt condition  Tightness  Tension 


V-belt Sidewall Wear


V-belt Worn Cover/soft or Swollen


V-belt Slips, Squeals (Spin Burn)


V-belt Underside Cracked


V-Belt Cover Split / Missing Cogs Belts pried upon  Foreign objects  Excessive heat  Sheave too small  Sheave misaligned  Improper storage 


Sheave Inspection Sheave groves must be like this

not this

Dished out


Sheave Inspection

O 4 v 2 O e . r d D e . 1 6 g . 0

5V

0 . 0 . g 1 e r D . d e 8 d O n 3 U

10.01-16.0 O.D. 40 deg

Example sheave gauge


Alignment


Types of Misalignment 

Angular Misalignment



Parallel Misalignment


Shaft Alignment Cord tied to shaft

Cord touching sheaves at points indicated by arrows


Tensioning V-belts Drives

Too tight

Slight bow

Too loose


Check Tension


Preventative Maintenance Check belt condition  Check belt tension  Identify sources of contamination  Check sheave alignment  Check sheave wear 

Chain Drives

December 2007


Introduction Description Types of links 

Self forming teeth  Extended Pin 


Introduction DRIVE GEAR BOX

DRIVEN ROLL

Chain Pitch


Chain Drive


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


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


Chain Drive Principles Drive chain Drive Sprocket

Sprocket


Shaft Speed Driven

12 T

rpm

Drive

6T

1800 rpm

DriveSproc ket_# teeth  driveshaft _rp _rpm m DrivenShaf t_rpm  DrivenSpro cket_# teeth


Chain Length Calculation Driven

Drive

6T

12 T

35 inches

40 Chain DriveSproc ketTeeth  Pitch  2 DrivenSpro cketTeeth  Pitch  CenterToCe nter  2  2

ChainLengt h 


Chain Speed Driven

12 T

900 rpm

FPM 

Drive

6T

1800 40 Chain rpm

teeth pitch r pm 12


Some Chain Drive Examples

Fork Lift

Roller Conveyor

Sprocket and Roller Chain Maintenance

December 2007


Roller Chain


Pitch


Large Pitch Conveyor Chain


Chain Part Friction Areas

Major friction areas in red


Lubrication Methods Hand Oiling  Drop Lubrication Lubrication  Oil Bath  Rotating Plate  Forced Circulation 


Example Application Large Roller Chain 

Multi-strand Multi-strand conveyor

Large Roller Chain


Sprockets


Sprocket Classifications


Chain Drive Factors Location of slack  Chain wrap  Vertical arrangement 


Installation – Parallel Shafts Level

Level


Installation


Installation - Sprockets Straight edge or Straight string

Gap


Installation


Chain Length The 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. 


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


Chain Wear WORN CHAIN NEW CHAIN

SPROCKET


Sprocket Tooth Wear SPROCKETS INDICATE W EAR HERE HERE


Preventive Maintenance Inspect for wear  Lubricate  Check chain sag  Set tension  Inspect sprockets 


Summary and Quiz Review Objectives  Question and Answer Session 

Mechanical Drives and Power Transmission Training

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