Machine Safeguarding and Lock-out / Tag-out

Supplemental Resources 

Machine Safeguarding 

Lockout-Tagout (LOTO) 

PUBH 3310 

November 30, 2011 

• The Basics of Occupational Safety (course 

text) 

– Chapter 10 “Mechanical Hazards and Machine 

Safeguarding” 

• Pages 217-231, Safeguarding 

• Pages 231-238, Control of Hazardous Energy 

(Lockout/Tagout systems) 

• Selected Internet websites, as noted in this 

presentation 

1 

2 

Objectives 

• Understand basics of machine safeguarding 

– Recognize hazardous mechanical motions and 

actions 

– Know general safeguard requirements 

• Be familiar with methods of machine 

safeguarding 

– Guards, devices, distance, feeding & ejection 

methods 

• Know basics of "Control of Hazardous 

Energy" (LO/TO) 

– The four requirements for lockout/tagout devices, 

removal, etc. 

3 

Outline 

• Safeguarding introduction 

– Hazardous motions 

– Hazardous actions 

• Machine safeguarding 

– Requirements 

– Methods 

–Actions 

• Lockout/Tagout 

– Procedures 

– Devices 

4 

Introduction 

OSHA “Top 10” violations, 2011 

• Any machine part, function or process which 

may cause injury must be safeguarded 

• When machine a can injure, the hazards 

must be controlled or eliminated 

• OSHA issues 

– "Top 10" in citations 

– 1997 "National Emphasis Program" for power 

presses 

• Outreach, inspections targeted at 10 worst industries 

– OSHA standards: 

• 29 CFR 1910 Subpart O (general industry) 

• 29 CFR 1926 Subpart I (construction) 

5 

1. Scaffolding 

2. Fall protection 

3. Hazard communication 

4. Respiratory protection 

5. Lockout/Tagout 

6. Electrical, Wiring Methods 

7. Powered industrial trucks 

8. Ladders 

9. Electrical, General Requirements 

10. Machine guarding 

http://www.osha.gov/Top_Ten_Standards.html

Where Mechanical Hazards 

Occur 

• Point of operation 

– Cutting, punching, etc. 

• Power transmission apparatus - components 

which transmit energy 

– Belts, flywheels, pulleys, connecting rods, chains, 

gears, cams, cranks, etc. 

• Other moving parts 

– Feed mechanisms, auxiliary parts, etc. 

7 

• Rotating motion 

– Couplings, 

flywheels, gears, 

shafts 

– Nip points 

• Opposite rotation 

(gears) 

• Between rotating 

and tangentially 

moving (belts and 

pulley) 

• Between rotating 

and fixed parts 

Hazardous Motions 

Rotating couplings 

and shafts 

Nip points 

8 

Hazardous Motions 

• Reciprocating motion 

– Back-and-forth, up and 

down 

• Transverse motion 

• Point of Operation 

– Cutting 

– Punching 

Hazardous Actions 

9 

10 

• Point of 

Operation 

(cont.) 

– Shearing 

– Bending 

Hazardous Actions 

Safeguard Requirements 

• Prevent contact with the hazard 

• Secure 

– Durable, firmly attached, not easily defeated or 

removed 

• Protect moving parts from falling objects 

• Create no new hazards 

• Create no interference to impede workers 

• Allow safe lubrication of the machine 

11 

12


Methods 

• Guards 

–Fixed 

• No moving parts 

– Interlocked 

• Mechanism stops when guard 

is open 

Machine Safeguarding Methods 

• Guards 

– Adjustable 

• Accommodate different stock sizes 

– Self-adjusting 

• Stock moves the guard 

Fixed guard with inspection panel 

Guard 

Adjustable 

Guard 

Self-adjusting guard 

with interlock 

13 

14 


Methods 

• Devices 

– Presence sensing 

• Photoelectric, 

radiofrequency, 

electromechanical 

Presence sensing devices at USU library 

Pressure sensitive mats 

Robotic book retrieval system 

15 

Optical sensor 

16 


Methods 

• Devices 

– Restraint (passive) 

• Hand-feeding tools to 

position work 

– Pullback (active) 

Pullback 

device 

Pullback 

Adjustable 

wrist 

straps 

Passive restraint 

Safety tongs 

17 

18


Methods 

• Devices 

– Safety controls 

• Safety trip control 

– Shuts off machine if 

someone pushes or pulls 

the safety trip 

Safety trip rod 


Methods 

• Devices 

• Safety controls 

– Two-hand 

control, twohand 

trip 

– Obliges the 

operator to 

remove their 

hands from 

the point of 

operation 

Two-hand control 

Safety stop switch 19 

20 

http://www.youtube.com/watch?v=7_PfxZMLP6o 


Methods 

• Devices (cont.) 

–Gates 

• Movable barrier 

that must be 

closed for the 

machine to 

operate 

Safety gate 

(with interlock) 


Methods 

• Safeguarding by 

Location/Distance 

– Hazardous locations are 

inaccessible during operation 

• Feeding and ejection 

methods to improve safety 

– Avoid need for operator to 

place hands in danger area 

Safety gate and interlock at 

USU library 

21 

22 

Automatic feed 

Lockout/Tagout 


• NIOSH investigated 152 deaths (1982-1997) that 

occurred during installation, maintenance, service, or 

repair tasks on or near machines, equipment, 

processes, or systems: 

– 82% from failure to completely de-energize, isolate, block, 

and/or dissipate the energy source) 

– 11% from failure to lockout and tagout energy control devices 

and isolation points after de-energization 

– 7% from failure to verify that the energy source was deenergized 

before beginning work 

• 20% of deaths among UAW members (1973-1995) 

caused by inadequate hazardous lockout/tagout 

procedures 

23 

• OSHA Control of Hazardous Energy 

(Lockout/Tagout, or “LOTO”), 29 CFR 

1910.147 

– 1989 standard 

– 3 million workers at highest risk 

– 122 annual deaths, 28,400 lost time injuries 

– 2% of workplace deaths in affected industries 

– Applies where unexpected startup could injure 

24


Energy Control Program 

• Equipment must be de-energized and locked 

or tagged for servicing or maintenance 

operations 

– Guards or other safety devices are removed 

– Employee places any body part into point of 

operation, equipment, a danger zone associated 

with the machine cycle 

– Exception for cord-and-plug and "hot tap" 

operations 

– Not for minor servicing that is routine, repetitive 

and integral to production 

• New or modified equipment must be capable 

• Energy control program 

– Where unexpected energizing, startup or release 

of stored energy could cause injury 

– Includes: 

• Documented energy control procedures 

• Employee training 

• Periodic inspections of procedures 

of being locked out 25 

26 

Energy control procedures 

• Energy control procedures 

– How procedure will be used 

– Steps to isolate, block and secure equipment 

– Steps for lockout/tagout devices 

– Verify effectiveness of controls (test equipment) 

Lockout/Tagout Devices 

• Four requirements for lockout and tagout 

devices: 

1. Durable 

2. Standardized 

3. Substantial 

4. Identifiable 

27 

28 


• Four requirements for lockout and tagout 

devices (cont.): 

1. Durable 

• Withstand the environment 

• Tags must not deteriorate 

2. Standardized 

Standardized locks 

• Color, shape, or size 

• Tags with standard print and format 


• Four requirements for lockout and 

tagout devices (cont.): 

3. Substantial 

• Locks must withstand all but 

excessive force or unusual 

techniques, like bolt cutters or other 

metal cutting tools 

• Tags must withstand 50 pound force 

Standard format tag 

29 

Bolt cutters 

30


• Four requirements for lockout and 

tagout devices (cont.): 

4. Identifiable 

• Clearly identify employee 

• Tags must have a warning 

Energy-isolating devices 

• Tags 

– For equipment that cannot 

be locked out 

– Tags may be used for 

lockable equipment only if 

"at least as effective" as 

locks 

– Tags removed only by 

person that applied it 

– Legible and understandable 

– Securely attached 

Label for a padlock 

Tag with warning and 

employee name 

Tag with warning (employee name is on 

the other side) 

Using Lockout/Tagout Devices 

• Application 

– Shutdown equipment and apply device 

– “Render safe" stored or residual energy 

• Use blocks, discharge springs, bleed pressure, etc. 

– Verify isolation/deenergization 

• Try to operate the equipment 

• Test voltage, etc. 

Using Lockout/Tagout Devices 

• Removal of locks and tags 

– Inspect and work area, check around 

machine 

– Notify affected employees before 

starting equipment 

– Locks and tags removed by 

employees that attached them 

• Special procedures when this is not 

possible 

Electrical lock-out 

Valve lock-out 

Valve lock-out 

Other Lockout/Tagout 

Requirements 

• Procedures required for: 

– Testing or positioning machines 

– Outside personnel 

– Group lockout or tagout 

– Shift or personnel changes 

Group lock-out devices 

35 

For More Information 

• Safeguarding Equipment and Protecting Workers 

from Amputations, 

http://www.osha.gov/Publications/OSHA3170/osha31 

70.html or 

http://www.osha.gov/Publications/osha3170.pdf 

• OSHA machine guarding “e-tool”, 

http://www.osha.gov/SLTC/etools/machineguarding/in 

dex.html 

• Preventing Worker Deaths from Uncontrolled Release 

of Electrical, Mechanical, and Other Types of 

Hazardous Energy http://www.cdc.gov/niosh/docs/99- 

110/ 

• OSHA Lockout/Tagout “Expert Advisor”, 

http://www.osha.gov/dts/osta/oshasoft/lotoplus.html 

36

Machine Safeguarding and Lock-out / Tag-out

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