Lecture 5 - Biomechanics 2 Flashcards
traditional methods of classifying and evaluating manual work
We take a historical perspective
- > describing manual activities with reference to standard categories of effort was traditionally used to classify and evaluate manual work
- > based on improving efficiency without major concern for safety
Taylorism
in the 1800s, taylorism is a scientific way to measure and control industrial workers
- > “how” and “how fast” a task should be done
- > labour leaders reaction: eliminate “personality, intelligence, even the very desires of the worker”
Frederic Winslow Taylor
Taylorism
To determine the best way to do a job, he broke each activity down into very small motions and timed each motion with a stopwatch. He would then analyze the action to eliminate unnecessary motion, which created the most efficient method of performing an assigned task. Each worker was trained to perform the task in exactly the same way, leading to an efficient operation that resulted in consistent quality and output.
Frank Gilbreth
- > applied taylorism later in history
- > study and streamline industrial activities
Contemporary approach to classifying and evaluating manual work
*Worker is of critical importance
- > labour costs are a significant portion of payroll and injury costs are a potential source of saving (reduction not less treatment)
*Fit worker into ideal task
*Consider environmental effects
* Physical stress checklists and surveys
* Risk assessment and intervention
Physical stress checklist and surveys look into what information
- > reactive (usually brought in after the fact)
- will it be considered valid, reliable, objective
- will employees open; are there consequences
- > injury history throughout workplace
- > indicates where in-depth study s warranted
- > initiates discussion between employee-employer
Risk assessments and interventions consider what
- > they’re proactive (done before the fact
- > identifying at risk individuals
- > reported/observed violations of principles
relate unstructured jobs and robotics to manual labour
- > robotics has decreased manual labour
- mainly the repetitive and structure jobs
- > unstructured jobs are still manual labour
- constructions, assembly, nursing, police
Results of the 1981 NIOSH Study
- > overexertion claimed to have caused ~60% of low back pain
- > if the hurt person lost significant time <33% will return to previous work still with back pain
- > overexertion injuries account for ~25% of all reported occupational injuries in the US
*66% lifting and 20% from push/pulling
Factors affecting manual material handling system
- > Worker characteristics (individual)
- physical, sensory, motor, training, health status, ect.
- > Material/Container Characteristics (Task and Environment)
- load, dimension, distribution of load, coupling (handles)
- > Task and Workplace characteristics (environment)
- workplace geometry, frequency/duration/pace, temp/noise
- > Work practice characteristics
- individual, organization and administrative concerns
3 strategies to prevent overexertion injury
- Design the task for all workers
- Select workers believed to be at low risk
- Train workers to reduce personal risk levels
things to consider when setting lifting limits in manual handling
- > setting “safe” limits for employees
- > epidemiology/etiology of MS injury
- > biomechanics concepts
- > physiological principles
- > psychophysical lifting limits
objective of NIOSH equation to evaluate plane lifting
to determine a safe lifting load by determining
- > location of CoM of object in hor direction (H)
- > location of COM in vertical direction (V)
- > vertical travel distance of the hands (D)
- > frequency of lifting (lifts/minute) averaged over a period (F)
what factors were added to NIOSH equation to evaluate plane lifting after it was revized
- > angle of asymetry from sagital plane
- > quality of coupling (C) in 3 classes
according to NIOSH where is the site of greatest stress and what is the safe number they found
- > L5/S1
- > 3.4 kN (3400N)
- safe for most but not all employees
- cadaver study
