LIFT ASSIST VEST FOR PEOPLE WITH LOSS OF AN UPPER LIMB William Askins Jr. [1], Darin Cook, Dan Folz, Chris Hedrick, Jared Leininger, David O’Dell, Kirk Payne, Mike Starkey and Dane Turk Ohio University ABSTRACT Many people with physical disabilities are turned away from certain jobs because of their inability to perform manual labor efficiently. One of the major requirements for many jobs is the ability to lift objects. For someone suffering from the loss of an upper limb, lifting a small object poses little problem; however, other jobs require a person to be able to lift objects much larger than a single arm can handle. Since a person missing an upper limb cannot complete this task, their employment is limited in any job market requiring physical labor. Therefore, we have created a lift assist vest which is simple, inexpensive, and universal. It allows a person with an upper limb loss to be able to lift large and/or heavy objects in the workplace taking away physical adversities that limit employment opportunities. BACKGROUND Roughly 100,000 people in the United States are missing an upper limb [2]. Of those people, 30-50% do not use a prosthetic on a regular basis. One of the tasks which prevent people with an upper limb loss [3] from being able to work is the obstacle of lifting objects in the workplace. Lifting relies heavily on the cooperation between two arms to enable a person to lift an object. Without the second arm, the object is not fully supported and is unable to be lifted. There is a need for a device that is easily operated and inexpensive, which allows for someone missing an upper limb to lift large and/or heavy objects. There are lift assist devices available on the market [4], but none were found that would allow someone missing an upper limb to lift a heavy or large object. Our lift assist vest is specifically made for the task of one-handed lifting of boxes or other square objects. It is important to note that this project was done in conjunction with a year-long capstone design course for mechanical engineers at Ohio University. The capstone course focused on all the aspects of project design as well as valuable professional skills that engineers need in the workplace. The course focused heavily on seeking outside feedback on the work we completed. Throughout the year, we have been helped tremendously by the comments and suggestions of other groups in the class, our professors, teaching assistant, and most importantly, our customer. STATEMENT OF PROBLEM As stated by our customer, “lifting large boxes is difficult because I don’t have another arm to support or pin the box (on opposite sides) to lift it” – Dan Bohner. Dan, 21, has been missing his left arm, from the shoulder down, since birth. He has worked two retail jobs; one with Polo Ralph Lauren, where he was an assistant manager, and one with Carter’s Kids. Shipments would arrive weekly and he would be unable to assist the other employees in unloading and distributing the boxes. Dan’s job responsibilities would be expanded and he could be more productive if he had a device which aided him in lifting and transporting the boxes that came in with each shipment.

LIFT ASSIST VEST This problem of lifting can be applied to a wide range of objects covering many different types of jobs; retail/department stores, mail delivery, grocery stores, warehouse jobs, and movers, just to name a few. In each of these jobs, people with an upper limb loss will be less suited for the job because of their disability, and may be restricted from the job. RATIONALE Based on our background research and customer feedback, providing an easily usable, inexpensive, and universal lifting aid to people with an upper limb loss would open many new job opportunities for people with disabilities, generating income for those people and boosting their self-esteem. Designing a device that would be inexpensive and universal for all users would give a wide range of companies the option to provide their own units for employees whose job description required such a vest, while still permitting individuals to obtain their own personal unit if they so desired. DESIGN Our design, shown in Figure 1, is a lift assist vest which allows users of a wide range of sizes and shapes to use it. The simplicity of the design provides ease of use while still maintaining a low cost. For explanation purposes, the vest can be broken up into three components: the support belt, the shoulder strap, and the lifting strap (shown in red, Figure 1). The support belt is a foam-padded, nyloncovered weight lifting belt that was purchased from an outside vendor. It is secured around the waist by a single Velcro strap that can be adjusted easily with one hand. The belt size for the vest in Figure 1 is a medium, and it was determined based on the customer’s waist size of 28 inches. Twenty-eight inches is towards the smaller end of this weight belt’s size range, and it has been found to fit other members of the group who have waist sizes up to 35 inches. If Figure 1- System Overview this vest were to be mass produced, different sized support belts could be purchased that would accommodate an even wider range of waist sizes. The shoulder strap attaches to the support belt in the back and front as shown in Figures 2 and 3 of the appendix. The lifting force is transmitted from the shoulder strap to the support belt by a metal “D” shaped ring (D-ring) sewn to the center and back of the support belt as shown in Figure 2. The D-ring allows the shoulder strap to be placed over either shoulder, depending on which limb the user is missing. In the front, a loop in the shoulder strap is placed around the support belt and held in place by a Velcro strap located on either side of the support belt. The shoulder strap is therefore easily switched from one side to the other depending on which limb is missing. A close-up of the front of the support belt and shoulder strap is shown in Figure 4. The width of the support belt transmits the force developed by the load across 2

LIFT ASSIST VEST a large area on the lower back permitting the user to lift large objects without straining back muscles. This is one of the safety features designed into the vest. Based on customer feedback, little to no discomfort was encountered when lifting up to 60 pounds. The shoulder strap is made of a tubular nylon strap commonly used in tie-down applications and climbing harnesses. The strap is two inches wide, which allows the load force to be distributed across a large area on the body. A foam shoulder pad was placed under the shoulder strap to further distribute the load and provide even more comfort during lifting. Three D-rings, shown in Figure 5, were added to the top of the shoulder pad to provide locations for the connection of the lifting strap. The three locations were chosen to allow the user to select the connection point that is most comfortable and beneficial to them, depending on their body size and current application. The shoulder strap was fed through the D-rings and sewn to the shoulder pad, causing the rings to stand up and away from the shoulder strap, allowing easy attachment of the lifting strap to the rings. To continue to allow for wide ranges of users, an adjustment point was implemented into the shoulder strap using a metal slide (shown right above the support belt in Figure 4) so the user can select the most comfortable fit. The lifting strap, which compensates for the missing limb, is made from the same type of tubular nylon as the shoulder strap, but it is only one inch wide. The two ends of the lifting strap are attached to an angled stainless steel corner piece, which can be seen in Figures 6 and 7. The angled corner piece was specifically designed for lifting boxes or objects with square corners. The corner piece is placed under the opposite edge of the box and prevents the strap from slipping off when the object is lifted. A steel bolt snap, similar to a clip on a dog leash, secures the lifting strap to the D-rings on the shoulder strap. Like the shoulder strap, there is a metal slide incorporated into the lifting strap to allow for length adjustments when needed. It was found from testing, however, that it was only necessary to adjust the lifting strap for extremely large or small objects. Since we were dealing with someone who has only one upper limb, ease of use was very important to us. To put the vest on, the user simply has to lift the shoulder strap over their head and onto their shoulder with their functioning limb. After the shoulder strap has been placed, the user then has to feed the loop in the front of the shoulder strap over the opposite side of the support belt and secure it with the Velcro strap. Once that is complete, the support belt can be easily tightened around the waist using its Velcro strap. Every component of the system can be adjusted using one hand. If one assumes that the user has worn the vest before, the front of the shoulder strap would already be in place and the user would only need to tighten the support belt, making it even easier to put on. The lifting strap is then clipped onto one of the D-rings on the shoulder strap. To pick up a box, the user places the angled steel piece on the corner of the box opposite the functioning arm. While supporting the object with the functional hand, the user can lift and transport the box to its intended location. View the attached video file Dan Lifting.wmv to view our customer using the vest. The video is attached to the original submitted email. This video shows Dan lifting 30 and 45 pound boxes of different size and shape. If for some reason there is a technical problem with the video, a YouTube link is supplied in the References and Acknowledgments section of this report.

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LIFT ASSIST VEST DEVELOPMENT The vest development went through numerous revisions to improve and simplify the vest making it easier to use and lowering the cost of its production. The original design consisted of two shoulder straps and a lifting strap that did not have a stainless steel angled piece. This was refined down to a single shoulder strap version based on observations of wasted material and customer feedback regarding comfort and ease of use. The drawback of our first single shoulder strap design was that we would have to manufacture two styles of vest, one each for left and right limb loss. The ability to choose which side of the body the shoulder strap went over was then built into the vest, allowing for a more universal design that would be much cheaper to manufacture. The angled metal piece was added after most of the vest specifications had been established. The lifting strap without the metal corner piece had a tendency to slip from a standard size box, creating the need for the addition of the angled piece. The angled piece efficiently keeps the lifting strap snug against the box and prevents the strap from slipping off. For additional safety, the sharp edges of the metal corner piece were smoothed off and coated with a rubberizing agent, which further keeps the lifting strap from slipping off of the box and prevents any injuries due to cuts or abrasions from the lifting strap. Developmental Testing Safety is important in any design, and our group has tried to implement safety wherever possible. We did a variety of tensile tests on our strap, as received from the vendor, to simulate large loads being applied. Some tests were performed on the strap alone, and others used the strap with stitching. We did a slow tensile test to simulate steady loading and a faster tensile test to simulate impact loading, with very similar results; the straps and stitching were found to sustain loads reaching 3000-5000 pounds, far past the human lifting limit. When making our vest, two types of stitching were used, a straight pattern and an X-pattern; they are shown in Figures 8 and 9. The X-pattern was used whenever space allowed due to its ruggedness and its higher tensile strength. In tighter spaces, where the D-rings attach to the shoulder strap for instance, the straight pattern was used. We also performed tensile tests with straps that had cuts in them to simulate possible damage to the straps. In this case, the straps still held close to 900 pounds when the strap was cut three-quarters of the way through. This verified that the user would know the strap was damaged far before the vest would become a hazard to use. Cost The cost of the lifting device was of great concern to us, as well as the customer. Initially, our customer said that he would pay $75-100 for a lifting vest that met his specifications. As shown in Tables 1 and 2, the materials for our prototype vest had a cost of $53.80 and an overall manufacturing cost of $107.26. As is, with no profit margin, the vest would cost our customer slightly higher than what he originally said he would pay. With a typical mark-up for profitability, the vest would probably sell for around $150 dollars. We believe that if this vest were mass produced, we could probably sell it in the range of $70-75 dollars and still be able to make some profit. Most of the price drop would come from buying the sheet metal and support belts in bulk, and with more research, making the shoulder strap in house should be rather easy. Further, with more experience, the time it takes laborers to perform operation 2 (our highest labor rate), should come down (see table 2). 4

LIFT ASSIST VEST EVALUATION As stated earlier, all individual components of the system, including the stitching, were tensile tested for safety. The final prototype was constructed and tested for functionality and ease of use by the customer as well as group members. Through functional testing, it was found that boxes all the way up to 24x24x24 inches could be lifted comfortably. The weight that can be lifted depends on the build of the user, but as stated earlier, the customer lifted up to 60 pounds with very little discomfort. Rarely does he have to lift 60 pound boxes while at work. The customer determined that the vest improved his ability to lift objects quickly and safely, and he could now lift objects that were previously hard or impossible to lift. The vest was more than satisfactory for his specifications, and he stated that he would definitely use it in his workplace. DISCUSSION The inability to lift objects in the workplace causes numerous people with an upper limb loss to be assigned different tasks within a company or even passed over for those jobs. Providing a device which allows a person with an upper limb loss to perform tasks of lifting will give more people with disabilities the chance to be hired in jobs that require the lifting of objects. Our vest system provides an easy, low cost way for people with upper limb loss to accomplish this. The vest can be customized to many body types and is universal for left and right limb loss. The system is also reasonably priced for a prototype. As discussed, with further development and manufacturing, the price of the vest is projected to drop into a price range most people would be able to afford. Because the vest would be universal and cheap to buy, companies should be able to purchase a number of the vests and hire people with an upper limb loss who would otherwise not be suited for the positions they have to offer. In regards to our specific customer, the use of our vest will increase his productivity and sense of self-worth by allowing him to perform more tasks at his current job than he ever could do before. REFERENCES AND ACKNOWLEDGMENTS [1] William Askins Jr.; 12905 N Peach Ridge Rd.; Athens, OH 45701 [2] http://www.aboutonehandtyping.com/statistics.html [3] Throughout the report, upper limb loss refers to anyone who has lost an upper limb or has deformities in an upper limb. This may include, but is not limited to, the hand, forearm, upper arm, and shoulder. [4] Some examples are: U.S. Patents 4280645, 6257633; www.handi-straps.com; and www.teamstrap.com [5] Lifting video address: http://www.youtube.com/watch?v=tE31O0mVqYE

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LIFT ASSIST VEST APPENDIX

Figure 2- Back View

Figure 4- Front of Support Belt

Figure 3- Front View

Figure 5- Close-up of D-rings

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LIFT ASSIST VEST

Figure 6- Side of Metal Corner Piece

Figure 8- Straight Stitching

Figure 7- Top of Metal Corner Piece

Figure 9- X-pattern Stitching

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LIFT ASSIST VEST Table 1- Material Costs Material  1" Tubular Webbing  2" Tubular Webbing  2" Velcro  1" Metal D‐Ring  2" Metal D‐Ring  2" Metal Slide  1" Stainless Steel Slide  1" Metal Bolt Snap  2" Shoulder Pad  4" Weight Lifting Belt  12"x2"x1/8" Stainless Sheet Metal   

Cost  $0.35 /ft  $1.20 /ft  $0.70 /ft  $0.53  $0.47  $0.45  $1.25  $1.46  $7.19  $13.80  $16.04    

 

 

Qty.  Total  7 ft  $2.45   7 ft  $8.40   1 ft  $0.70   3  $1.59  1  $0.47  1  $0.45  1  $1.25  1  $1.46  1  $7.19  1  $13.80  1  $16.04    Total  Material  $53.80   Cost: 

Vendor  www.strapworks.com  www.strapworks.com  www.strapworks.com  www.strapworks.com  www.strapworks.com  www.strapworks.com  www.strapworks.com  www.strapworks.com  www.warrior‐gear.com  www.ultrahomestore.com  www.mcmaster.com       

Table 2- Overall Cost   

Operation 1:  Cut 12"  sheet metal in half.  Mill  out 1" slots at ends.  Bend  corners up.  Grind and  deburr edges.  Rubberize  slots to further reduce  sharp edges. Inspect and  cleanup. 

Operation 2:  Cut all webbing to  respective lengths.  Feed 2" webbing  through Metal Slides, D‐rings, and  Shoulder Pad.  Pin together first, then  stitch.  Feed 1" webbing through Metal  Slide, Bolt Snap, and Metal Corner Piece  from Operation 1.  Pin and stitch 1"  strap.  Inspect and cleanup. 

0.5 hour per vest  1 hour per vest  a. Total time to complete operation(s)   $15/hr  $28.14/hr  b. Labor rate for the operation  $7.50   $28.14   c. Labor cost = a x b  1  1  d. Basic overhead factor  0.5  0.5  e. Equipment factor  0  0  f. Special operation/tolerance factor  g. Labor/overhead/equipment cost = c x  $18.75  $70.35   (1+d+e+f)  $16.04   $38.00   h. Purchased materials/components cost        Total Vest Cost =  Σ(purchased materials/components cost) + Σ (labor/overhead/equipment costs) = $143.14 

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