CHAPTER 1 : Introduction to maintenance management

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Mechanical drives

mechanical drives are used to provide a variable output speed from constant speed power source or to provide torque increase for a variable speed power source as in an automobile

Types Of Mechanical Drive

a) Geared Transmission - Provides specific fixed type ratios.

b) Belt drives - Provide flexibility in the positioning of the motor .

c) Chain Drives - Provide infinitely variable speeds.

d) Traction Drives - Provides adjustabe speed with relatively high speed.

Advantages

a) Mechanical drives are less costly than competing electrical drives and their control is much simpler.

b) They are used in industries ranging from aerospace to mining and heavy industry.

c) With the advanced technology, the working of mechanical drive has become more efficient.

Disadvantages

The disadvantage of these drives is that they are not durable and cannot be controlled as precisely as electrical drives. They cannot transmit as much power as electrical drives when variable speed is essential.

Maintenance

Mechanical drives have internal spaces that have void spaces where residues can be deposited. The system should be cleaned at regular intervals. Clean-in place (CIP) is a method designed automatically to clean pipes and drives. This method is used to clean the void spaces in the drives.

Pump

Most common pumps

a) external gear pump

b) internal gear pump

c) lobe pump

d) vane pump

Two identical gears rotating against each other. One driving gear and one driven gear

Advantages

High Speed

High Pressure

Relatively quiet operation

Can use variety of materials

Disadvantages

No solids allowed
Fixed End Clearances

Applications

Low volume transfer or application

Acids and caustic (stainless steel or composite construction)

Industrial and mobile hydraulic

Various fuel oils and lube oils

Chemical mixing and blending (double pump)

Chemical additive and polymer metering

One interior gear and one exterior gear. Interior gear drives the Interior gear drives the

Advantages

Disadvantages

Applications

Excellent for high-viscosity liquids

Operates well in either direction

Single adjustable end clearance

Easy to maintain

Requires moderate speeds
Medium pressure limitations

All varieties of fuel oil and lube oil

Resins and Polymers

Alcohols and solvents

Asphalt, Bitumen, and Tar

Polyurethane foam (Isocyanate and polyol)

Food products such as corn syrup,chocolate, and peanut butter

Paint, inks, and pigments

Soaps and surfactants

Glycol

Similar with external gear pump, but the lobes do not make contact.
Timing gears drive both lobes.

Advantages

Disadvantages

Applications

No metal-to-metal contact

Non-pulsating discharge

Pass medium solids

Long term dry run

Requires timing gears
Reduced lift with thin liquids

Polymers

Paper coatings

Soaps and surfactants

Paints and dyes

Rubber and adhesives

Pharmaceuticals

Food applications

Rotor with spring-equipped vanes. Single motor drives rotor.

Advantages

Disadvantages

Applications

Handles thin liquids at relatively higher pressures

Develops good vacuum

Compensates for wear through vane extension

Can run dry for short periods

Complex housing and many parts
Not suitable for high pressures

Aerosol and Propellants

Aviation Service - Fuel Transfer, Deicing

Auto Industry - Fuels, Lubes,

Refrigeration Coolants

Bulk Transfer of LPG and NH3

LPG Cylinder Filling

Alcohols

Refrigeration - Freons, Ammonia

Solvents

Aqueous solutions

Common Failure

Cavitations

Air in Fluid

Coupling Misaligned

Pump worn or damaged

Excessive load

Damage caused by metal object

Excessive heat

Overpressure

Incorrect Installation

Pump Failures

Pumping machinery and pumping station are
very important components in a water supply system.

Pumping machinery is subjected to wear, tear, erosion and corrosion due to their nature of functioning and therefore are vulnerable for failures.

Sudden failures can be avoided by timely inspection, follow up actions on observations of inspection and planned periodical maintenance.