Program and Schedule of Preventive Maintenance in Mechanical Equipment

1. Program and Schedule of preventive maintenance
in Mechanical equipment
Presented By,
Pavithra S
Avinashilingam University

2. NAME SOME SIMPLE MECHANICAL EQUIPMENT
2

3. PRE REQUISITES
 Bearings
 Grooves
 Housing
 Crankcase
 Crankshaft
 Shafts
 Torsion
 Torque
 Sprockets
3

4. PARTS IN A MECHANICAL EQUIPMENT
 Plain Bearings
 Rolling-Element Bearings
 Flexible Couplings for Power Transmission
 Chains for Power Transmission
 Cranes : Overhead and Gantry
 Chain Hoists
 Belt Drives
 Mechanical Variable Speed Drives
 Gear Drives and Speed Reducers
 Reciprocating Air Compressors
 Valves
 Pumps: Centrifugal and Positive Displacement
4

5. Plain Bearings
 Plain or sleeve bearings are designed to support shafts that
rotate, oscillate, or reciprocate.
 One of the least expensive of mechanical parts, sleeve
bearings are highly engineered components
PREVENTIVE MAINTAINENCE:
 Lubricant Supply
 Cleanliness
 Lubricant Type
 Inspection and Reconditioning
5

6.  Bearings – to be replaced not because they wear not but
do not perform intended function
 Dirt
 Fatigue
 Excessive wear
 Foreign material
 Hot short phenomenon
 Crankshaft and Crankcase distortion
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7. Bearing Nomenclature
A sample of bearings, bushings,
and thrust washers
Bearing damaged by scoring
7

8. Foreign Particles on bearing
Skewed wear pattern caused by
bent connecting rod
Fatigue of bearing lining
Bearing with severe dirt
embedment
8

9. WHY BEARINGS FAIL?
 Heavier loading than original
 Seals and mountings are too tight
 Poor lubrication
 Liquid or solid contaminants
Specific to industries
 Pulp and paper industry
 Poor lubrication and contamination
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10. Rolling-Element Bearings
• Radial-Radial loads
• Thrust-Axial Loads
• Ball bearing-Light to moderate loads
• Roller – Heavy loads
Radial ball bearing types
Radial roller bearing types
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11. 11
Thrust Bearings
Determining internal bearing clearance
for a spherical roller bearing
 ISO and Anti Friction Bearing
Manufacturers Association –
Maintenance procedure
 Roller Bearing – Series of 2,3 and 4 –
depending on the boundary plan.
 Basic Rating Life
 Service Life
 Mounting of bearings
 Mounted on shaft
 Provision for thermal expansion
 Located and held axially
 Locking device – tight fit the shaft
 Grease Lubrication is used.

12. FLEXIBLE COUPLINGS FOR POWER
TRANSMISSION
 To connect two axially oriented shafts
 Purpose: Transmit torque or rotary motion without slip
 Functions: Minimize/Eliminate heat, electricity, sound.
 Torsional dampening & Torsional tuning.
 Flexible Couplings
 Mechanical – Flexibility- components to slide/ move relative to
each other. Ex: Chain, Gear, Grid, Oldham flexible couplings
 Material – Designed to flex. Metal, Rubber, Plastic or
Composite. Ex: Laminated disk, Spring, Elastomer
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13. TYPES
Chain couplings
Gear couplings
Floating shaft gear couplings
Spindle couplings
Metallic grid couplings
Oldham couplings
Laminated Disk ring couplings 13

14. 14
a
b
e
d
c
a. Roller chain coupling
b. Gear tooth coupling
c. Metallic grid coupling
d. Oldham coupling
e. Laminated disc-ring coupling

15.  Failures occur due to
 Improper/Poor Machining
 Improper Product design
Diaphragm coupling
High speed, high horsepower applications
Elastomeric couplings
Placed in shear and in compression
15
Diaphragm coupling Elastomeric couplings

16. CHAINS FOR POWER TRANSMISSION
 Roller Chains
 Roller links
 Pin links
 Favorable service Factors for chain life:
 Slow speeds, smooth steady load
 Long centers, on adjustable center distance drives
 Exceptionally good lubrication
 Unfavorable
 Small sprocket having fewer teeth
 Impulse, load reversals, or shock loading
 Three or more sprockets in the drive
 Poor lubrication
 Dirty or dusty conditions
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17. METHODS OF LUBRICATION
 Type A: Manual or Drip
Lubrication
 When manual lubrication is used,
oil is applied periodically with a
brush or spout can, preferably
once every 8 hours of operation.
 When drip lubrication is used, oil
drops are directed between the
link plate edges by a drip
lubricator.
 Precaution must be taken against
misdirection of the drops by wind
age.
 Drops on the center of the chain
will not effectively lubricate the
joint areas.
 The lubricant should be directed
at the inside of the pin and roller
side plate surfaces.
 Type B: Bath or Disk Lubrication
 With bath lubrication, the lower
strand of the chain runs through a
sump of oil in the drive housing
 With disk lubrication, the chain
operates above oil level.
 The disk picks up oil from the sump
and deposits it on the chain, usually
by means of a trough.
 Type C: Oil-Stream Lubrication
 The lubrication is usually supplied in
a continuous stream to each chain
drive.
 Oil should be applied inside the chain
loop, evenly across the chain width,
and directed, preferably, at the slack
strand.
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18. CRANES: OVERHEAD AND GANTRY
 Maintenance – to avoid premature
breakdowns or accidents
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19. CRANE
MAINTENANCE
Recommended spares
 Brake solenoids, coils, disks
linings
 Hoist-limit switches
 Contactors
 Contact kits
 Timing relays
 Push-button stations or parts
 Crane wheels and guide rollers
 Motor couplings and brushes
 Current collectors or collector
shoes
 Bearings
 Load hooks, nuts, and thrust bearings
 Hoisting ropes
 Load brake parts 19

20. CHAIN HOISTS
Manually Lever Operated chain hoists – For
Pulling horizontally, vertically or at any angle.
Hand Chain manually operated chain hoists –
For overhead lifting application, Brake provided,
lower cost, lighter duty, spur geared hand chain
Powered Chain hoists – High speed applications,
Powered units
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21. 21
Light weight electric
chain hoist with push
button
Pulley/ratchet
level hoist
Spur geared
hoist
Screw geared
hoist
Differential
hoist
Twin-hook hoist
with link chain

22. 22
Hoist parts to be inspected and
serviced
Comparison of hand hoists.

23. BELT DRIVES
 Gives dependable power transmission with minimum
maintenance.
 V BELT can be
 Heavy duty
 Light duty
 Wrapped/Molded notch
23
Typical narrow cross-sectional
V-belt, banded construction.
Typical narrow cross-sectional V-
belt, molded notch construction

24. SYNCHRONOUS BELT
24
 Toothed belts --- positive
engagement between belt
tooth and pulley or sprocket
groove
 Trapezoid - most commonly
used
 Curvilinear – increased
capacity over trapezoid,
higher horsepower
 Modified curvilinear –
refinement in tooth shape,
depth
 Sprocket – higher capacity
drive systems pulleys

25. MAINTENANCE
 On critical drives, 1 to 2 weeks.
 On normal drives, once per month.
 A drive shutdown to thoroughly inspect belts, pulleys,
and other components should be performed every 3 to 6
months.
 A visual and hearing inspection consists of the following
three items:
 Look and listen for unusual noise and vibration while
observing the drive.
 Inspect the guard for looseness and damage
 Look for oil and grease dripping from the guard
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26. MECHANICAL VARIABLE-SPEED DRIVES
 MAS – Mechanical Adjustable Speed - method of power
transmission for both accessory drives and main engine-
to-wheel drives
 MAS Drive includes
 sliding cone-face pulley with a wide V-belt
 Types of friction drives
 Adjustable While in Motion (Non-enclosed)
 Static-Adjustment Types
 Belt Transmissions
 Packaged Belt Drives
 Friction-Disk-Type Drives
 Traction-Type Drives
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27. 27
Spring-loaded split pulley,
adjustable with drive-in operation
Fixed-center-distance compound-pulley
arrangement
Use of
compounded
variable-pitch
sheave to obtain
wide speed range

28. 28
Trouble Cause Correction Prevention
Short belt life Inherent slippage; contact
surface
speed varies across face of
belt
None
Slipping belt Overloaded; remember belts
are necessarily narrow to
approach
theoretically ideal line
contact
Reduce loading Do not overload
Slipping belt Belt has stretched Extend center
distance between
pulleys or use idler
roll
Slipping belt Pulley faces greasy Clean with solvent Keep clean

29. GEAR DRIVES AND SPEED REDUCERS
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 Gear drives and speed
reducers
 changes of speed, torque,
shaft direction, or
direction of rotation are
required between a prime
mover and the driven
machinery.
Basic types of gears

30. 30
Double helical drives.

31. LUBRICATION
 Lubricating oils –
 high-grade,
 high-quality,
 well refined,
 straight mineral petroleum oils, within the recommended viscosity ranges
 They must not be corrosive to gears or ball or roller bearings.
 They must be neutral in reaction.
 They should have good de-foaming properties.
 No grit or abrasives should be present.
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32. GOOD MAINTENANCE PRACTICE
 During normal periods of operation, gear-drive units should
be given daily routine inspection, consisting of visual
inspection and observation for oil leaks or unusual noises.
 If oil leaks are evident, the unit should be shut down, the
cause of the leakage corrected, and the oil level checked.
 If any unusual noises occur, the unit should be shut down until
the cause of the noise has been determined and corrected.
 Check all oil levels at least once a week. The operating
temperature of the gear-drive unit is the temperature of the oil
inside the case.
 Under normal conditions, the maximum operating
temperature should not exceed 180°F. Generally, pressure-
lubricated units are equipped with a filter which should be
cleaned periodically.
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33. RECIPROCATING AIR COMPRESSORS
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The suction inlet must be
 tight,
 free of dirt,
 chips, and scale,
 corrosion-resistant, and
 of adequate size for the length
necessary to connect the air filter to
compressor suction

34. LUBRICATION
 compressor well lubricated; check the oil level at least once
every 8 hour of operation
 only oil and greases - low carbon-forming tendency and sulfur
content and contain an oxidation inhibitor
 Non Lubricating Cylinders – avoids metal to metal contact
between piston and cylinder boxes
 They have extended length piston rods
 Equipped with baffle ring to prevent creepage of lubrication
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35. VALVES
35
Butterfly
Iron Bronze
Ball

36. RECOMMENDED PIPING
 valve be closed tightly by hand only, not use a wrench or
persuader
 A valve that is cracked open is subject to the most severe
wire-drawing or throttling conditions possible,
decreasing valve life and increasing maintenance
 Check valves should be installed as far as possible from
the pump discharge
 Clean the inside of the pipe before installing or repairing
a valve
 Remove rust, scale, welding beads, and dirt
 Apply pipe dope or Teflon tape to male threads only
when making up a threaded joint.
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37. PUMPS: CENTRIFUGAL AND POSITIVE DISPLACEMENT
37
A positive-displacement pump makes a fluid
move by trapping a fixed amount and forcing
(displacing) that trapped volume into the
discharge pipe
• Centrifugal pumps are used to induce flow
or raise a liquid from a low level to a high
level.
• A centrifugal pump converts rotational
energy, often from a motor, to energy in a
moving fluid

38. PERFORMANCE
 Determined by,
 Viscosity
 Rotating Speed
 Suction supply
 Poor piping practices in hydraulic-system applications
are primary sources of positive-displacement pump
problems, particularly in parallel pump applications.
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39. SUMMARY
 Different type of mechanical equipment
 How they can be maintained to increase the performance
 Safety issues
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