-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
1/60
Capabili ty & Improvement Dept.2004For Internal Use Only
PETRO NA S
G A S
TRAINING MODULE
ELECTRICAL
TITLE : ELECTRICAL DRIVEN HAND TOOLS AND
WORKSHOP EQUIPMENT
MODULE NO : E18
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
2/60
Power Tools and Workshop Equipment Page 2 of 60
ELECTRIC DRIVEN HAND TOOLS AND WORKSHOP EQUIPMENT,
ENGINE-DRIVEN WELDING MACHINE,
ELECTRICAL OVERHEAD CRANE
OBJECTIVES
Upon completion of this module, the electrical multitask technician will be able to :
1. Demonstrate understanding on the hazards of hand and power tools.
2. Know the basic requirements before operating hand and power tools.
3. Understand and explain the safety rules to follow to prevent hazards.
4. Recognize obvious defects during the conduct of physical inspection on electric driven hand
tools, workshop equipment, engine-driven welding machine and electrical overhead crane.
5. Identify and understand the major items to be observed during the conduct of periodic
maintenance.
6. Understand and recognize the importance of routine electrical testing.
7. Understand and explain welding process and its application in the maintenance work.
6. Understand and explain the principle of operation of engine driven welding machine.
7. Demonstrate understanding and identify the major component parts of engine-driven weldingmachine and electrical overhead crane.
8. Explain the function and operation of the major component parts.
9. Explain the periodic maintenance to be conducted and the troubleshooting and repair to be
performed on the equipment.
10. Demonstrate knowledge and understanding on the safety precautions to be observed when
working on welding machines and electrical overhead crane.
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
3/60
Power Tools and Workshop Equipment Page 3 of 60
TABLE OF CONTENTS
Description Page No.
PART 1 -Electric Driven Hand Tools and Workshop Equipment................................................. 6
1.0.0 Introduction............................................................................................................................ 6
2.0.0 Typical Electric Power Tools and Workshop Equipment...................................................... 7
3.0.0 Hazards of Hand and Power tools.......................................................................................... 8
3.1.0 Serious Hazards and Dangers in using Electric Tools........................................................ 8
3.1.1 Injuries brought about by electrical shocks ................................................................... 8
4.0.0 Requirements before Operating Hand and Power tools......................................................... 9
4.1.0 Basic safety rules:............................................................................................................... 9
4.2.0 General precautions to be observed:................................................................................... 95.0.0 Physical inspection on Electric driven tools and Equipment............................................... 11
6.0.0 Care and Periodic maintenance of Electric Power Tools..................................................... 12
6.1.0 Maintenance: Main point of attention for Power tools..................................................... 12
7.0.0 Routine Electrical Testing.................................................................................................... 15
8.0.0 Troubleshooting and Repair................................................................................................. 16
PART 2:- Welding Machine Engine Driven.............................................................................. 19
1.0.0 Fundamentals of Welding .................................................................................................... 192.0.0 Applications of Welding in the Maintenance Work ............................................................ 20
3.0.0 Most Common Types of Welding Processes....................................................................... 21
3.1.0 Gas Welding ..................................................................................................................... 21
3.2.0 Arc Welding ..................................................................................................................... 21
4.0.0 Arc-Welding Equipment ...................................................................................................... 22
4.1.0 Power Source for Arc Welding ........................................................................................ 22
4.2.0 Motor-generator welding machines.................................................................................. 22
4.2.1 Principle Of Operation Of Engine Driven Welding Generator.................................... 23
4.3.0 Alternating Current Transformer Welding Machines ...................................................... 24
4.4.0 Rectifier Welding Machines............................................................................................. 25
5.0.0 Procedures of Manual Arc Welding. ................................................................................... 26
6.0.0 Typical Engine Driven Welding Machine Nameplate Rating ............................................. 27
7.0.0 Major Component Parts ....................................................................................................... 28
7.1.0 Description of Component Parts....................................................................................... 28
8.0.0 Preparation for Startup and Hookup at Site ......................................................................... 29
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
4/60
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
5/60
Power Tools and Workshop Equipment Page 5 of 60
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
6/60
Power Tools and Workshop Equipment Page 6 of 60
PART 1 -Electric Driven Hand Tools and Workshop Equipment
1.0.0 Introduction
As the need for mechanization and use of power tools increases, dependable performance
and long service life of power tools are very important. A plants entire inventory of portable
tools can be kept in top operating condition for maximum production quality and cost efficiency
with a planned routine and periodic inspection.
There are many and varied causes of power tool failure. Variations will exist and will
depend upon the type of tool and the particular conditions of use. It is therefore of strong
importance that the recommended use and maintenance given in the manufacturers operation
and maintenance manual, supplied with each tool, be carefully followed.
An important part of preventive maintenance is technician training in the proper care and
use of portable power tools, basic safety procedures and safeguards associated with hand and
portable power tools.
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
7/60
Power Tools and Workshop Equipment Page 7 of 60
2.0.0 Typical Electric Power Tools and Workshop Equipment
There are many and varied types of electrical driven hand tools and workshop equipment.
Good examples are:
Compact threading machine,
Drilling machine,
Hydraulic press,
Lapping machine,
Grinders,
Milling machine,
Hacksaw machine,
Lathe machine,
Sanders,
Shears,
Tapers ,
Electric drills,
Power and impact wrenches,
Jigsaws,
Power screwdrivers,
Air compressors and many others.
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
8/60
Power Tools and Workshop Equipment Page 8 of 60
3.0.0 Hazards of Hand and Power tools
Tools are such a common part of our lives that it is difficult to remember that they may
pose hazards. Tragically, a serious incident can occur before steps are taken to identify and avoid
or eliminate tool-related hazards.
Technicians and workers who use hand and power tools are exposed to the following
hazards :
1. Falling, flying, abrasive, and splashing objects
2. Harmful dusts, fumes, mists, vapors, or gases
3. Electric shock
3.1.0 Serious Hazards and Dangers in using Electric Tools
1. Electrical burns
2. Electrical shocks
3.1.1 Injuries brought about by electrical shocks
1. Injury due to a fall
2. Fibrillation of the heart
3. Death
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
9/60
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
10/60
Power Tools and Workshop Equipment Page 10 of 60
4.3.0 Protection against Electric Shock and Burns
A few of the basic protection that can be utilized to protect user against electric shock and
burns are as follows:
1. The electric tools must have a three-wire cord with a ground and be plugged into a grounded
receptacle
2. Electric tools should be double insulated. On double-insulated tools, an internal layer of
protective insulation completely isolates the external housing of the tool.
3. Electric tools should be powered by a low-voltage transformer
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
11/60
Power Tools and Workshop Equipment Page 11 of 60
5.0.0 Physical inspection on Electric driven tools and Equipment
1. Perform visual inspection and be able to recognize obvious defects such as:
Cut, frayed, spliced or broken cords, conduits and boxes
Cracked or broken attachment plugs and
Missing or deformed grounding prongs.
2. Examine tools causing shocks and repair it before further use.
3. Check circuit breaker, fuses, local control switches for sign of overheating
4. Ensure power distribution board is free from dust, moisture, dirt or spider web.
5. Inspect wire termination for loose connection and overheating
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
12/60
Power Tools and Workshop Equipment Page 12 of 60
6.0.0 Care and Periodic maintenance of Electric Power Tools
Whenever maintenance is taking place on a machine the greatest care must be taken to
ensure that the machine is completely isolated electrically against any possibility of inadvertent
startup or electric shock. Before any work on the machine is undertaken, the fuses must be
removed and a lockout and tag out device is attached to the supply.
1. Operation and functions of the equipment should be clearly understood. Refer to the tool or
equipment operation manual.
2. Power tools must be given an initial safety inspection by a competent electrician.
3. Service the power tools regularly, can be at six-monthly intervals.
4. Conduct visual inspection on plugs, leads and associated equipment.
5. Defective tools must be withdrawn promptly for repair or replacement.
6. Machines must be used only within their design capacity and no accessories larger than those
recommended by the manufacturer may be used.
7. Keep record of inspection and testing of electric power tools.
6.1.0 Maintenance: Main point o f attention for Power tools
Maintenance main point of attention should be given to the following:
1. Periodic inspection of crucial wear points
2. Excessive dirt accumulation.
3. Insufficient or improper lubrication.
4. Care of cord and attachment plug.
5. Integrity of the grounding circuit.
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
13/60
Power Tools and Workshop Equipment Page 13 of 60
1. Periodic inspection of Crucial Wear Points
Parts like, brushes and commutators should be inspected periodically. This is done by
removal of brush holder plugs or inspection plates. Brushes worn down to 50% of their original
size should be replaced.
2. Excessive dirt accumulation.
Power tools are commonly fitted with universal motors. Universal motors are fan
ventilated to prevent excessive heat. Even if many tools have filters and deflectors to prevent
destructive material from damaging the motor, a small amount of dust and dirt will pass through.
dirt affects the brush operation and reduces the volume necessary to cool the motor. When
required, the tool should be blown out with low pressure, dry compressed air.
3. Insufficient or Improper Lubrication.
Lubricant inspection is needed at frequent intervals to insure sufficient lubricant to
prevent wear to mechanical parts. Dirty lubricant should be removed and replaced. Since
lubricant varies from tool to tool, it is proper to follow the recommended lubricant by the
manufacturer. The wrong amount of lubricant can cause serious problems. Too little, of course,
means that surfaces are not adequately covered and excess wear will result. Too much lubricant
can cause excess pressure in the gear case and eventually ruin seals.
4. Care of cord and attachment plug.
The cord of an electric power tool is the life line. It should be kept free of oil, grease and
other material that may ruin the rubber cover.
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
14/60
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
15/60
Power Tools and Workshop Equipment Page 15 of 60
7.0.0 Routine Electrical Testing
Periodic electrical testing will uncover many operating defects and their immediate correction
will insure safe operation and prevent breakdown and more costly repairs. Testing and the
related maintenance should be systematic. A visual inspection before and after each use when
issued and when returned to the tool crib should be required.
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
16/60
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
17/60
Power Tools and Workshop Equipment Page 17 of 60
References:
Electrical Equipment Maintenance
Hand and Power Tools Booklet, OSHA
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
18/60
Power Tools and Workshop Equipment Page 18 of 60
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
19/60
Power Tools and Workshop Equipment Page 19 of 60
PART 2:- Welding Machine Engine Driven
1.0.0 Fundamentals of Welding
Welding is a process of joining together two metal parts by heating them to melting
point. Welding arcs are produced by electric current from a welding machines which in turn
produces heat to cause melting of metal parts. The amount of current is adjusted depending on
the size of electrode being used and the position in which the welding work is being performed.
The welding circuits require higher amperage at low voltage
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
20/60
Power Tools and Workshop Equipment Page 20 of 60
2.0.0 Applications of Welding in the Maintenance Work
Welding machine is an essential tool available in maintenance workshop and at site for a
variety of repair, construction, fabrication, strengthening, modification, erection works including
the following:
Fabrication of structures
Plugging old holes and making new ones
Fabricating broken parts, replacing castings by welded machined parts
Supports, jigs, fixtures
Joining two plates, bars
Strengthening weak parts
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
21/60
Power Tools and Workshop Equipment Page 21 of 60
3.0.0 Most Common Types of Welding Processes
1. Oxyfuel gas welding (OFW)
2. Arc welding (AW)
3. Resistance welding (RW)
3.1.0 Gas Welding
One of the most popular welding methods uses a gas flame as a source of heat. In the
oxyfuel gas welding process, heat is produced by burning a combustible gas, such as MAPP
(methylacetylene-propadiene) or acetylene, mixed with oxygen. Gas welding is widely used in
maintenance and repair work because of the ease in transporting oxygen and fuel cylinders.
3.2.0 Arc Welding
Arc welding is a process that uses an electric arc to join the metals being welded. A
distinct advantage of arc welding over gas welding is the concentration of heat. In gas welding
the flame spreads over a large area, sometimes causing heat distortion. The concentration of heat,
characteristic of arc welding, is an advantage because less heat spread reduces buckling and
warping. This heat concentration also increases the depth of penetration and speeds up the
welding operations. Arc welding is often more practical and economical than gas welding.
Arc welding provides the user the ability to join two metals by melting them with an arc
generated between a coated-metal electrode and the base metal. The temperatures developed by
the arc can reach as high as 10,000 OF. The arc energy is provided by a power source that
generates either direct or alternating current. The electrodes that carry the current produce a gas
that shields the arc from the atmosphere and supplies filler metal to develop the weld shape.
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
22/60
Power Tools and Workshop Equipment Page 22 of 60
4.0.0 Arc-Welding Equipment
All types of arc-welding equipment are similar in their basic function of producing the
high-amperage, low-voltge electric power required for the welding arc.
The basic parts of a typical shielded metal-arc welding outfit include the following:
Welding machine
Cables
Electrode holder (stinger)
Electrodes
Accessories such as combination chipping hammer and wire brush, welding
table (for shop work), C-clamps and protective apparel
4.1.0 Power Source for Arc Welding
The power source used in arc welding is called a welding machine or welder. The basic
types of welding machines presently in use are:
Motor-generator welding machines
Alternating current transformer welding machines
Rectifier welding machine
4.2.0 Motor-generator welding machines
Motor-generator welding machines are types of welding machines powered by electrical,
gasoline, or diesel motors, the diesel and gasoline motors are ideal for use in areas whereelectricity is not available. These machines have the capability of generating alternating or direct
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
23/60
Power Tools and Workshop Equipment Page 23 of 60
current. Typical example of this type is as shown on the figure which consists of a heavy-duty,
ac/dc generator powered by a diesel engine.
For general purposes, standardized ratings of welding machines are as follows:
1. Machines rated 150 and 200 amperes - 30 volts. For light welding jobs or shop work.
2. Machines rated 200, 300, and 400 amperes - 40 volts. For general welding purposes.
3. Machines rated 600 amperes - 40 volts. For submerged-arc welding.
4.2.1 Principle Of Operation Of Engine Driven Welding Generator
The generator is required to run and turn at a required number of revolutions per minute
(rpm) in order to produce the required welding current. The engine of the welding unit is
provided with governor which control the speed of the engine. Welding speed switch is provided
and can be set to idle the engine when no welding job is taking place. The welding speed switch
can also be set to run the engine continuously.
After the engine come to speed and the electrode is made to touch the work piece, the
engine governor will automatically increase the engine speed to the required number of turns
(rpm) required for welding.
Welding current control is done by moving or setting the selector knobs or switches toamount of current required for welding.
Engine controls and welding current controls are provided on the welding generator set.
Normally, engine controls include the following:
Starter
Voltmeter
Fuel gauge
Temperature gauge
Running hour meter
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
24/60
Power Tools and Workshop Equipment Page 24 of 60
4.3.0 Alternating Current Transformer Welding Machines
Practically all the alternating current arc-welding machines in use are the static-
transformer type as shown in figure.
These types of machines are the smallest, least expensive, and the lightest type of welders
made. Industrial applications for manual operation use machines having 200, 300, and 400
ampere ratings. Machines with a 150-ampere rating are used in light, garage and job/shop
welding.
The transformers are usually equipped with arc stabilizing capacitors. Current control is
provided in several ways. One such method is an adjustable reactor that is set by turning a crank
until the appropriate setting is found. Another method is by plugging the electrode cable into
different sockets located on the front of the machine.
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
25/60
Power Tools and Workshop Equipment Page 25 of 60
4.4.0 Recti fier Welding Machines
Rectifier welders are single-phase or three-phase transformers that have selenium or
silicon rectifiers added to rectify (change) the output current from alternating to direct current.
Most of these machines have the capability of producing either ac or dc straight or reverse
polarity. By flickering a switch, the welder can select the current that best suits the job.
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
26/60
Power Tools and Workshop Equipment Page 26 of 60
5.0.0 Procedures of Manual Arc Welding.
Electrodes with coating of shielding material are commercially available in standard
lengths (250 or 500 mm). Consumable electrode is fixed in electrode holder held in hand. The
two cables from AC welding transformer or DC welding generator are connected to electrode
holder and the work piece. (Normally positive is connected to the electrode holder and the
negative connected to the work piece)
Welding is begun by touching the electrode tip to the work piece near the location of the
joint and establishing electric circuit. Arc is initiated by withdrawing the electrode slightly
manually.
The electrode holder is lowered gradually as the welding continues, thereby maintaining
a steady arc length. Electrode is moved forward manually along the desired weld contour.
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
27/60
Power Tools and Workshop Equipment Page 27 of 60
6.0.0 Typical Engine Driven Welding Machine Nameplate Rating
Nameplate
Serial No.
Phase 1
Volt 120/240 Amp 26/13
Hz. 50/60 PF 1.0
Max. rpm 1,850
Rated weld output
Max. OCV 95 95
Volts 40 40
Ampere 400 250
Duty cycle 40% 100%
Max. rpm No load 1850 1850
Welding Range 40 to 400 A
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
28/60
Power Tools and Workshop Equipment Page 28 of 60
7.0.0 Major Component Parts
Engine
DC welding generator
Control circuitry
Metering system
Welding cable, welding cable lugs or connectors, quick disconnects, ground clamps,
electrode holders, cable terminals
7.1.0 Descript ion of Component Parts
Engine -The size and type of the engine varies and it depends on the capacity of the welding
generator.
Arc welding generator- Its size is determined by the ampere rating output at a given duty cycle.
Duty cycle refers to the amount of time in a 10-minute period the welding machine can
continuously produce its rated amperage without undue overheating. A welding machine can
have a 10%, 20%,30%,40%,60% up to 100% duty cycle, i.e. 400A at 40% duty cycle (250A at
100%)
Welding cable -Large diameter cable can carry more welding current. Welding cable sizes vary
from No. 8 AWG to No. 4/0 AWG. The size of the cable depends on the amperage load as well
as the distance the current will travel. In measuring the distance, add the lengths of the electrode
lead and the ground lead. Cable amperage requirement is determine by the rated capacity of the
welding machine.
Lugs They are used to connect the welding cable to the welding current terminals.
Quick disconnects They serve as cable extensions for connecting two lengths of welding
cable.
Ground clamps They are mechanically connected to the end of the welding cable (ground
cable) and provides connection to the work piece.Electrode holders They are mechanically connected to the end of the welding cable and
provides electrical contact between the electrode and the welding cable.
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
29/60
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
30/60
Power Tools and Workshop Equipment Page 30 of 60
9.0.0 Inspections for Component Parts (Prior To Start Up)
Engine driven welding machines require regular inspection prior to its use. In most cases
an operator will be required to fill up and turn in an inspection form before starting the engine.
After all the required information have been checked and completed, welding works can
commence. Common information required involved results of the following checks and
inspection:
Check before and after use the condition of the following: Engine oil and filter, fuel oil and
filter, cooling system, batteries, belts, exhaust system, air filter, injectors, meters, enclosure,
any visible leaks.
Verify that welding cable is long enough to reach the work area. Welding cable should be
inspected for cuts or breaks before use. Breaks in the welding cable insulation when comes in
contact with metallic surfaces could result an arc which will damage the surface and the
cable itself.
Check that cable lugs are tightly crimped onto welding cable to ensure good attachment.
Ensure quick disconnects are tightly connected to prevent arcing and overheating.
Ensure the size of the ground clamps is at least the same as the rated capacity of the welding
set to prevent overheating. Position the ground clamp so that welding current will not pass
through any contacting surface. Never connect the ground clamps to pipes carryingflammable or corrosive materials. Make sure there is a good electrical contact on the
connections to avoid overheating and sparks.
Ensure the size of the holder is big enough to carry the rated amperage to avoid overheating.
Ensure that termination points are free from dirt and corrosion and welding cables are tightly
terminated
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
31/60
Power Tools and Workshop Equipment Page 31 of 60
10.0.0 Preventive Maintenance Program
Good maintenance habits are especially important on more advanced welding systems
that use robotics and automation. Proper upkeep includes an appropriately administered
preventive maintenance program.
Appropriately administered preventive maintenance program can be started by performing the
following:
1. By compiling a complete equipment list
2. Prepare equipment inspection schedule
3. Catalogue all maintenance performed and chart based on inspection analysis
4. As maintenance is performed, create a thorough record and history of inspections,
analysis and repairs
Along with preventive maintenance, a maintenance schedule should include clearly
defined areas of inspection and procedures. Critical areas of inspection include:
1) Lubrication
2) Bearings
3) Fasteners, brackets and bolts
4) Commutators
5) Condensers6) Brushes and holders
7) Controls, programmable logic controllers and master panels
8) Motor stators
9) Generator frame
10) Armature
11) Relays
12) Exciter generator
13) Engine
14) Manipulators, feed rolls and positioners
15) Cords, cables, nozzles and guns
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
32/60
Power Tools and Workshop Equipment Page 32 of 60
10.1.0 A General Schedule for Routine Maintenance
The following is a general routine
maintenance schedule, but should
be modified according to a
companys specific
conditions: (Operating hours)
Description of tasks
8 hours Wipe oil and fuel spills immediately
Check fluid levels (oil & fuel)
Service the air filter (refer to engine manual for specifics)
50 hours Service air filter element (refer to engine manual for
specifics)
Clean and tighten weld terminals
100 hours Change oil
Change oil filter (refer to engine manual for specifics)
Clean and tighten battery connections
Clean cooling system (refer to engine manual for
specifics)
200 hours Replace unreadable labels
Replace fuel filter
Check valve clearance (refer to engine manual for
specifics)
250 hours Check and clean spark arrestor
500 hours Tape or replace cracked cables
Clean/Set injectors (refer to engine manual for specifics)
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
33/60
Power Tools and Workshop Equipment Page 33 of 60
11.0.0 Troubleshooting and Repair
TROUBLESHOOTING CHART FOR ARC WELDING
TROUBLE CAUSES REMEDIES
Power supply dead Check voltage
Power lead broken Repair or replace
Supply voltage wrong for welding set Check nameplate rating
Main switch or set switch open Close
Starter button has open circuit Repair
Welding does not start,
starter does not operate
Contactor stuck open Release, maintain or replace
Brushes worn-out/missing Replace
Brush connections loose Tighten
Welding start, but
welding current does not
pickup Open field Correct
Electrode connection loose Correct it
Ground connection loose Correct it
Poor ground Correct it
Brush fitting improper Correct it
Current falls during
welding
Connections loose Tighten
Check relay setting Set as per required current,
time
Defective relay ReplaceWelder set stops
Ventilation poor due to blocking Clear it
Arc makes sputtering
noise
Current high
Polarity wrong
Check setting
Correct the polarity
Touching the set gives a
shock feelingFrame not grounded Ground the frame solidly
Current controller of
generator failsCheck field circuit
Correct the defective
contactor
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
34/60
Power Tools and Workshop Equipment Page 34 of 60
12.0.0 Safety Precautions
1. Electric shock can kill
Always wear dry insulating gloves
Insulate yourself from work and ground
Do not touch live electrical parts
Stop engine before installing or servicing
Keep all panels and covers securely in place
2. Welding can cause fire or explosion
Do not weld near flammable material
Watch for fire, keep fire extinguisher nearby
Do not locate unit over combustible surfaces
Do not weld on closed containers
3. Arc rays can burn eyes and skin; noise can damage hearing
Wear welding helmet with correct filter
Wear correct eye, ear, and body protection
4. Fumes and gases can be hazardous
Keep head out of the fumes
Ventilate the area or use breathing device
5. Engine exhaust can kill
Use in open, well ventilated area or vent exhaust outside
6. Engine fuel can cause fire or explosion
Stop engine before fueling
Do not fuel while smoking
Do not overfill tank; clean up any spilled fuel
7. Moving parts
Keep away from moving parts
Keep doors, panels, covers, and guards closed and securely in place
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
35/60
Power Tools and Workshop Equipment Page 35 of 60
References :National Electrical Code
Testing, Commissioning, Operation & Maintenance of Electrical
Equipment by S. Rao
Miller Electric Mfg. Co. Technical Articles
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
36/60
Power Tools and Workshop Equipment Page 36 of 60
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
37/60
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
38/60
Power Tools and Workshop Equipment Page 38 of 60
2.0.0 General Requirements
All overhead cranes must meet the specifications of American National Standard Safety
Code for Overhead and Gantry Cranes, ANSI B30.2
The rated load of the crane shall be plainly marked on each side of the crane.
Clearance must be maintained above and to the side of cranes. Walkways cannot be
placed in a crane operating zone that would compromise employee safety when the crane
is in operation.
Only designated personnel will be permitted to operate a crane
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
39/60
Power Tools and Workshop Equipment Page 39 of 60
3.0.0 Major component parts of Hoists System
Overhead crane is a crane with a movable bridge carrying a movable or fixed hoisting
mechanism and traveling on an overhead fixed runway structure. Major component parts are as
follows:
Hoist motor
Brake motor
Gearbox
Hoist
Rope drum
Runway
Bridge
Trolley
Load detectors
Geared limit switches
Power supply disconnecting means
Multi-button pendant control switch
Electrical controls
Cables,
Wiring , contacting devices
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
40/60
Power Tools and Workshop Equipment Page 40 of 60
3.1.0 Typical Bridge Crane Installation and Specification
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
41/60
Power Tools and Workshop Equipment Page 41 of 60
4.0.0 Typical sectional drawing of Crane Hoist Mechanism
Parts description is as shown:
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
42/60
Power Tools and Workshop Equipment Page 42 of 60
5.0.0 Description of Major Parts
1. Hoist motor:
Commonly, motor is a combination of electric motor and brake which operates on the
sliding rotor principle. The motors are equipped with Positive Temperature Coefficient (PTC)
thermistors to protect against overheating. The PTC thermistor triggering devices are
electronically interlocked in order to prevent the motors being switched back on. It is possible to
continue operation after the motors have cooled down by briefly switching off the mains switch
or crane isolator.
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
43/60
Power Tools and Workshop Equipment Page 43 of 60
2. Brake motor:
Brake motors are asynchronous motors with cylindrical squirrel-cage rotor and integrated
brake. The brake mainly consists of
Brake disc with bonded brake linings
Armature disc
Housing with coil
Brake springs
Opposing brake surfaces
Operation :
The brake disc with toothed plastic hub can move axially on the shaft. The armature disc
can slide axially guided by two pins.
When no current flows, the brake springs press the armature disc against the brake disc
and consequently press this against the opposing brake surface. The frictional force applied on
both sides of the brake disc causes the braking torque to build up and this is held by the fixing
pins on the housing.
If there is a loss of voltage at the solenoid, the brake is applied.
When a voltage is applied to the solenoid, the magnetic field builds up, pulls the armature
disc away from the brake disc in opposition to the spring forces, and the brake is released.
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
44/60
Power Tools and Workshop Equipment Page 44 of 60
3. Gearbox
The torque of the motor is transmitted to the planetary gearbox by a roller coupling which
is flexible in both radial and axial directions. The 2 or 3-stage planetary gearbox inside the drum
houses all gear stages.
4. Hoist
A hoist is an apparatus which is a part of a crane, exerting a
force for lifting or lowering. Main hoist is the hoist mechanism
provided for lifting the maximum rated load. Auxiliary hoist is a
supplemental hoisting unit of lighter capacity and usually higher
speed than provided for the main hoist.
The size of the hoist is determined by the load spectrum (light,
medium, heavy, very heavy), average operating time per working
day, safe working load and reeving.
5. Rope drum
The drum is the cylindrical member around which the ropes are wound for raising or
lowering the load.
6. Load block
The load block is the assembly of hook or shackle, swivel, bearing sheaves, pins, and
frame suspended by the hoisting rope.
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
45/60
Power Tools and Workshop Equipment Page 45 of 60
7. Geared limit switches:
Limitation of motion at the upper and lower end positions is effected by the geared limit
switch. Geared limit switches are mounted in the electrical equipment casing. It switches off the
hoist motor when the top or bottom hook position is reached. The direction of movement can be
reversed. Operating limit switches are required where the end positions are approached regularly
during normal operation.
Normally, there are four switching element contacts, each with different functions:
S1 - Emergency limit switch for top hook position
S2 - Main lifting limit switch. Operating limit switch for top hook position
S3 - Emergency limit switch for bottom hook position
S4 - Operating limit switch for bottom hook position
The emergency limit switch must not be actuated during normal operation.
8. Control Pendant
Normally a multi-button pendant control switches are used to
control the hoist unit. The control pendants are available in different
sizes with openings for switching elements, so that they can be adapted
according to the given drive combination requirements.
Pendant switches house the operating and emergency limit
switch switches.
The strainer wire for the control cable should be secured by the
clamps which are fixed to the sides of the electrical equipment enclosure. The multi-button
pendants should be suspended so that the bottom edge is approximately 1 meter above the floor
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
46/60
Power Tools and Workshop Equipment Page 46 of 60
level. The arrow symbols on the buttons must indicate the correct direction of the respective
movement.
Every hoist unit is fitted with an emergency-stop equipment which can stop the entire
hoist unit in the event of a hazard. The emergency-stop button is arranged on the control
pendant.
To actuate the emergency-stop button, press the button until it reaches the end stop. It
then locks automatically. To unlock the actuated emergency-stop button, turn the push button in
the direction of the arrows and release.
9. Electrical Control
It is a master switch which dominates the operation of contactors, relays, or other
remotely operated device. For standard controls, electrical switch gear is installed in the
electrical enclosure of the hoist unit. The enclosure casing is protected to IP 55, that is protected
against harmful dust deposits and is hose-proof in all directions.
10. Load detectors:
Load detectors are used to protect hoist units and supporting structures against excessive
stresses. Load detectors can either be electronic type or mechanical type.
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
47/60
Power Tools and Workshop Equipment Page 47 of 60
11. Bridge
Bridge is that part of a crane consisting of girders, trucks, end ties, foot walk, and drive
mechanism which carries the trolleys.
12. Runway
Runway is an assembly of rails, beams, girders, brackets, and framework on which the
crane or trolley travels. Hoist travel on track beams must in no way be obstructed by protruding
suspension bolts, screw heads, butt straps, clamping plates, etc. End stops must be fitted at both
ends of the runway.
The running surfaces of rails or track beams must not be painted as this would impair
hoist travel. Rails and track beams should be kept clean; oil, grease, and dirt on the running
surfaces will cause travel wheel to skid.
13. Trolley
The trolley is the unit which travels on the bridge rails and carries the hoisting
mechanism
14. Power supply disconnecting switch (Isolation and De-isolation switch)
It is the main switch controlling the entire power supply to the crane.
Disconnecting means for cranes and monorail hoists should have a continuous ampere
rating not less than the motor nameplate rating and to be provided between the runway contact
conductors and the power supply.
Such disconnecting means shall consist of a
1) motor-circuit switch,
2) circuit breaker, or
3) molded case switch.
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
48/60
Power Tools and Workshop Equipment Page 48 of 60
The disconnecting switch should be installed to meet the following requirements:
(1) Readily accessible and operable from the ground or floor level
(2) Capable of being locked in the open position
(3) Open all ungrounded conductors simultaneously
(4) Placed within view of the runway contact conductors
The runway supply conductors and main contact conductors of a crane or monorail shall be
protected by an over current device that shall not be greater than the largest rating or setting of
any branch circuit protective device plus the sum of the nameplate ratings of all the other loads.
Crane, hoist, and monorail hoist motor branch circuits shall be protected by fuses or inverse-time
circuit breakers.
Runwa Conductor
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
49/60
Power Tools and Workshop Equipment Page 49 of 60
6.0.0 Typical Technical Specification for a Bridge Crane
Item Description
1 Manufacturer:
2 Installation: Outdoor, Indoor, Under Roof
3 Service:Erection, Maintenance, Storehouse
4 Type: Single girder bridge, single girder gantry
Double girder bridge, double girder gantry
5 Class of bridge crane
6 Control system:Manual, Electrical by cab
Electrical with push button station sliding along the bridge
Electrical with fixed push button station on the trolley
Electrical with fixed push button on the bridge side
7 Control Station: with push button , with spring recovery levers
8 Electrical equipment protection:IP 55, 56, 65,...
9 Electrical power supply:415 V, 50 Hz., 3 phase10 Ambient conditions:minimum temperature, maximum temperature
11 Hook capacity: ______ton
12 Vertical traverse: ______meter
13 Normal lifting speed: ______m/min
14 Slow lifting speed: _______m/min
15 Lifting motor power (main/creep hoist): ______kW
16 Normal traverse speed: _______m/min
17 Slow traverse speed: _______m/min
18 Traverse motor power (travel motor): _______kW
19 Bridge sliding speed _______
20 Bridge sliding motor power (travel motor): _______kW
21 Electric motor manufacturer
22 Bridge sliding:drive on both sides with 2 motors, in short circuit, slip-ring
23 Runway substructure: in masonry, in steel
24 Winch trolley (cm): gauge, wheel diameter, wheel pitch
25 Transmission pulley pitch diameter: lifting
26 Brake type:
27 Mechanical stop device
28 Auto electric limit stop
29 Hook capacity: kg
30 Anti release device (safety latch)
31 Gears
32 Electric feeding line trolley/winch
33 Electric feeding line along the runway.Festoon type normal, festoon type
explosion proof, armor-plate type, junction boxes, isolators
34 Mechanical limit stop
35 Lubricants
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
50/60
Power Tools and Workshop Equipment Page 50 of 60
7.0.0 Operation of the Hoist units
The manufacturers instruction must be followed when operating the crane system. Basic
procedures are as follows:
1. Attach the load to the block hook by means of slings or other approved devices,
making sure the sling is clear of obstacles.
2. Once the load is properly secured and balanced in the untwisted sling, slowly raise the
load.
3. Horizontal movement must also begin slowly to prevent the load from swinging or
coming into contact with other obstacles.
4. The crane warning signal or horn must be sounded when the load or hook comes near
or over personnel. Carrying loads over personnel is not recommended.
5. A load should not be left suspended.
6. Audible and discernible voice communication should be kept with the operator at all
times. If this cannot be accomplished, a signal system should be used.
7.1.0 Guidelines and safety instruct ion in operating hoist system
Hoist units are systems used for lifting and moving loads, such as cranes, crabs, traveling
hoist units, rail systems.
Hoist units are only intended for lifting and moving loads and may be used both as stationary
or traveling units.
Hoist units may only be operated when in perfect working order by trained operating
personnel in accordance with the relevant safety and accident prevention regulations. This
also includes compliance with the operating and maintenance conditions specified in the
operating instructions.
Hoist units are industrial equipment designed to be used with a rated voltage between 50 and
690 V AC. Power feed is via power supply lines (mobile cables, open or enclosed powerconductor systems). These systems are live up to the terminals of the isolating switch. During
operation or when the main switch is not switched off, electrical components inside
enclosures, motors, switch gear cabinets, terminal boxes, etc., carry dangerous voltages.
Before starting the work using the hoist units, the operator must first check the function of
the hoist unit brakes and emergency limit stop devices. Only operate hoist units when all
protective devices and safety-related equipment, i.e. movable protective devices and
emergency-stop devices, are fitted and fully functioning. The operator must be satisfied that
the installation is safe and in correct operating condition.
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
51/60
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
52/60
Power Tools and Workshop Equipment Page 52 of 60
8.0.0 Taking Hoist Unit Out of Service
The hoist unit is considered out of service during the following conditions and
appropriate action should be taken at the said state:
At the end of the shift
During emergency or hazard
During maintenance work
8.1.0 At the end of the shift
When the work has been completed, raise the hook assembly or bottom block to the
upper limit position. Switch off the power supply at the mains connection or isolating switch.
8.2.0 During emergency or hazard
Emergency-stop equipment is fitted in the hoist to stop the entire hoist unit in the event of
a hazard. The emergency-stop button is arranged on the control pendant. To actuate the
emergency-stop button, turn the push button until it reaches the end stop. It then locks
automatically. To unlock the actuated emergency-stop button, turn the push button in the
direction of the arrows and release. The emergency-stop equipment must only be reset after the
hazard and its cause have been eliminated.
8.3.0 During maintenance work
Maintenance work on the hoist system must not commence before the load has been
removed and the main switch/isolator switched off.
Tests and inspections required in addition to those outlined in the maintenance schedule
should be carried out.
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
53/60
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
54/60
Power Tools and Workshop Equipment Page 54 of 60
9.3.0 Periodic inspections (Monthly to yearly intervals)
Items to be inspected are:
Deformed, cracked or corroded members
Loose bolts or rivets Cracked or worn sheaves and drums
Worn, cracked or distorted parts such as bearings, gears, rollers, etc.
Excessive wear on brake system parts
Inaccuracies in load, wind and other indicators
Electric motors
Excessive wear of chain drive sprockets and chain
Deteriorated electrical components such as circuit breakers, fuses, pushbuttons,
limit switches or contactors
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
55/60
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
56/60
Power Tools and Workshop Equipment Page 56 of 60
Item
no.Description of task Frequency
15
Check adhesive grease in bearings of return sheaves,
crossheads, compensating sheaves and pins of rope
anchorage and re-grease, as required
Every 4 years
16Change oil in following gearboxes: hoist reduction gear,
cross travel unit gearboxEvery 4 years
17Change grease in the protective caps of the last stage of the
gearbox on monorail hoist carriagesEvery 4 years
18 Check corrosion protection, improve or supplement Every 12 months
19
Check suspension of rope anchorage. Check play of the set
bolt/pin in the counter bore hole of the retaining plate.
Check retaining ring for correct fitting in the groove of the
set bolt/pin
Every 12 months
20 Check the coupling of the creep speed hoist motor Every 12 months21 Overhaul hoist unit completely
After 8-10 years
operation
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
57/60
Power Tools and Workshop Equipment Page 57 of 60
11.0.0 Troubleshooting and Repair
Simple repair work such as replacing of original parts like relays, terminals, can be
generally carried out in electrical workshops. Major repair works should be carried out by
suitably experienced technicians.
When troubleshooting and repair work is to be performed on the electrical equipment, a
circuit diagram showing all the details of the control system must be secured and referred to
prior to the commencement of the work. Follow the procedures as recommended in the
equipment manufacturers operation and maintenance manual.
Safety guidelines during the conduct of troubleshooting and repair are as follows:
1. Before work is started, the equipment must be disconnected from the supply.
2. Electrical equipment must be earthed or connected to protective earth conductor.
3. It must be secured against accidental or unauthorized switching on, install locks.
4. A warning sign must be placed at the disconnecting point prohibiting switching on of
the installation while maintenance work is being performed.
5. Faults in electrical installations can originate from the electrical equipment or from the
cables. Defective cables must be replaced.
6. Fuses must not be replaced by others of higher capacity, as otherwise short circuit
protection for the contactors and cables would not be ensured.
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
58/60
Power Tools and Workshop Equipment Page 58 of 60
References :
National Electrical Code
Operating Instructions for Demag hoist units
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
59/60
-
8/10/2019 Module No E18 PowerTools and Wkshop Equipment
60/60