What is a Therblig?
Therbligs are the smallest units of work. They were developed by Frank Gilbreth, one of the fathers of ergonomics, the science of motion. Frank Gilbreth was a very interesting man, and if you read further, you'll learn more about both therbligs and Gilbreth. And you may discover you knew a little about therbligs, after all.
Therblig graphic by Zcademy
The image at left is available as a poster and other products at Zazzle.com
Have You Heard of Therbligs Before?
Gilbreth's original work
About Frank Gilbreth
Frank Bunker Gilbreth, Sr. was born on July 7, 1868 and died June 14, 1924. He was an early advocate of scientific management and a pioneer of motion study, a field in business that was just beginning in the early 1900s, and later changed into what we know as ergonomics today. He was accepted by MIT, but turned it down for economic reasons, and began work as a bricklayer, becoming a building contractor, inventor, and finally as a management engineer.
Mr. Gilbreth got his start in time and motion study when he invented a work platform for his fellow bricklayers to hold the bricks at a comfortable height, instead of reaching down to their feet for each brick. He later went on to develop ways to decrease unnecessary motion in a number of fields, and served as a consultant to many of the largest companies of his era. He invented the concept of therbligs to help quantify and explain his work.
Mr. Gilbreth married Lillian Evelyn Moller on October 19, 1904 in Oakland, California; they had 12 children, 11 lived to adulthood. Despite his ground-breaking work, he is far better known as an unconventional father, because two of his children wrote a book about their family life, Cheaper by the Dozen. A sequel, Belles on Their Toes, was written after Mr. Gilbreth's sudden death at 55, when most of his children were still young, and Mrs Gilbreth continued the management consulting business.
This biography was adapted from the Wikipedia article, with additional knowledge I gained from reading, and the photo also comes from Wikipedia.
Books By and About Frank Gilbreth - Click on any book or link to buy it
The books (and one video) shown in this hub are either about Frank Gilbreth and his family, or written by him. They range from light biography to serious research work. Clicking any picture or link will take you to Amazon.com, where you can buy the book, or anything else.
I read this book in 5th grade, and again as an adult. I loved it both times, though I saw very different material in it each time.
Cheaper by the Dozen
This is a delightful story about a highly intelligent offbeat family in the 1910s. The Gilbreths were truly geeks of their time.
I'm not sure what I enjoyed more: when Mr Gilbreth painted the Morse code on the dining room wall, when he played Learn a Foreign Language records as the kids used the bathrooms in the morning, or the scene where he marches in to the school principal's office, demanding that one kid or another be given a grade skip.
After reading this as an adult, I changed my parenting style a bit.
This is a sequel to Cheaper by the Dozen, about the Gilbreth family after Frank dies suddenly.
Mrs Gilbreth's Story
What do you do if it's 1923 and your husband and business partner dies suddenly, leaving you with 11 children?
This book, written by two of the Gilbreth kids, describes these years. Mrs Gilbreth had been a full partner in her husband's work, but could get very few consulting jobs because she was "just a woman."
She eventually became an expert on kitchen design, and wrote one of the mid century's best books on household management.
This book focuses on family life in a 1920s house full of teenagers. Prepare for a wild ride!
So, What Are Therbligs?
Aside from Gilbreth spelled sideways?
Therbligs are the smallest units of work motions
For example, if you need to check off a box on a form, you need to look for the pencil, reach for the pencil, pick it up, maybe change your grip, move it to the paper, make the check mark, then take the pencil to its resting place and put it down. Each of these tiny steps is a therblig.
Mr Gilbreth defined 17 different therbligs. Each therblig has its own symbol, and color, so one could produce motion charts for each task. Mr Gilbreth would time each therblig, and used early motion picture studies to find ways to eliminate unnecessary therbligs from work tasks.
It is useful for manufacturers to determine how workers can use as few therbligs as possible to do their work, both because the workers will be able to get more done, and because they will be less tired. This is often called "time and motion study," and is useful in preventing repetitive motion injuries as well as in improving worker efficiency.
For example, if you always put your pencil in a stand that lets you grab it using the same hand position you use for writing, you use fewer therbligs then if you keep it in a drawer or flat on the table. The task would take less time, and you would have more energy to do other things.
For a much more detailed essay, with detailed explanations of each therblig, visit the Therbligs page at The Gilbreth Network. This site also has other information about the Gilbreths.
The 17 Therbligs
Rest (to overcome fatigue)
Mr Gilbreth was an early adopter of motion picture technology in analyzing work habits. These films let him quantize work units into therbligs.
Other Therblig References
There are very few direct references to therbligs. One of the best known is from science fiction author, Robert Heinlein: Minimize your therbligs until it becomes automatic; this doubles your effective lifetime - and therby gives time to enjoy butterflies and kittens and rainbows." This quote is actually what led me to learn about therbligs.
Much of what we call ergonomic design involves minimizing therbligs. When Mr. Gilbreth worked as a bricklayer, he designed a platform for holding bricks at the ideal working height - an example of design to minimize therbligs.
Good kitchen design also involves thinking about therbligs. The trends toward open shelving, drawers instead of lower cabinets, and similar, are all rooted in the desire to get work done with few excess motions - therbligs in action.
Have you seen other references to Therbligs? Share them in the Comments section below.
Therbligs Mug from Zazzle
One side of this mug has the author's graphic showing the 17 therbligs, the other has the quote as shown.
You can find the therblig image on many other products by clicking on the link above.
What do you think about therbligs? Are you going to try to use fewer of them? Or is this silly early-20th century thinking? Share your ideas here!