KELEMEN'S KREATIONS - Impact Eliminator - Shock Absorbing Shovel handle.

DETAILED INFORMATION
Patent Information: US Patent Number: 6,145,899 CDN Patent Number: 2298150

THE IMPACT ELIMINATOR
Invented by
Michael Kelemen

Manual labor has always been a physically stressful job. One of the most painful aspects of manual labor comes from shoveling. There are many different types of shovels and many different uses for them, but all shovels create the same problem. No matter what the task, regular shovels cause undo stress to the wrist, elbow, and shoulder joints.

Michael Kelemen has come up with a solution to this problem by creating a shovel with a shock-absorbing handle. Designed by a worker for a worker, Impact Eliminator™ absorbs the shock that would be ordinarily transferred to the users wrist, elbow, and shoulder joints during repetitive movements. Utilizing a unique rubber disc design which produces an instant rebound, this shovel prevents the shock from traveling up the entire arm without affecting efficiency. The shock-absorbing handle can be easily removed from one shovel to another allowing the user to benefit from the shock-absorbing handle. After a hard day's work, one may feel less joint pain in the areas specified above.

Michael Kelemen's shovel can improve all kinds of tasks. The Impact Eliminator™ is designed to be sturdy for all types of jobs and has been tested to withstand considerable force. This innovation will work with sand, gravel, snow and virtually any type of matter that must be shoveled. The Impact Eliminator™ can save the consumer valuable time and therefore valuable money!

Click to Enlarge Photo

Evaluation of the revised design of shock absorbent D-handle (the Impact Eliminator™)

James B Morrison, PhD, C Eng
Shearwater Human Engineering
North Vancouver, B.C.

CURRICULUM VITAE: JAMES B. MORRISON – March 2009
Introduction

In the use of shovels, impacts transmitted to the hand-arm in the form of shock and vibrations are a major concern for musculoskeletal injury. This can result in chronic fatigue type injury from repeated impacts, or acute injury from a single high-force impact.
Unexpectedly high forces can be generated at the hand when the tool strikes hidden roots or rocks.

Impact force transmitted from handle to hand-arm.

In order for the blade to penetrate the soil, it is necessary to generate a driving force at the handle. This is perceived by the user as an impact transmitted through the hand-arm.
It is not possible to eliminate the impact necessary to drive the blade into the soil. However, it is possible to limit unwanted shock and vibrations generated when striking an unexpected object such as a rock, tree root, or concrete edge. This can be achieved by the use of a shock absorber built into the tool (see Fig.1) or a vibration absorbent material (e.g. a handle wrap - see Fig. 3). It is also possible to reduce the effect of the impact on soft tissues by spreading the load over a greater surface area of the hand by using a more malleable material in the handle.

Vibration absorbent materials and shock absorbers

Vibration absorbent materials and shock absorbers can reduce risk of injury and improve performance in several ways:

- Absorb the higher frequencies of vibration that accompany impacts;
- Reduce lateral and fore-aft vibrations transmitted to the hand;
- Reduce contact stress at the handle by deforming to the shape of the hand. This spreads the load and lowers soft tissue stress (pressure) for the same force.
- Add compliance to the system, thereby reducing the peak deceleration (impact) at the handle when striking a solid object such as a rock.
- Provide greater comfort.

In general, vibration absorbent materials are more suited to absorbing high frequency vibrations (often associated with power tools). Shock absorbers are more suited to absorbing isolated impacts.

Evaluation of shock absorbent D-handle

The revised design of shock absorbent D-handle (Impact Eliminator) was reviewed for ergonomic design and some provisional testing was carried out in a gardening environment consisting of different earth conditions.

Figure 1: Revised design of Shock absorbent D-handle (Impact Eliminator, 2nd generation)
Testing

The revised design of shock absorbent D-handle was tested in a range of gardening and clearing conditions.

I have tested in:

Soft ground, bare earth, flower bed;
Earth with turf, small stones/roots;
Earth with large buried tree roots hidden (buried 2-4 cm) below surface earth;
Large rocks and tarmac driveway surface hidden (buried 2-4 cm) below earth covering.

Four different handles were tested:

Original shock absorbent design
New revised shock absorbent design (Impact Eliminator)
Hard plastic D-handle (Fig. 2)
Rubber (resilient, synthetic rubber) D-handle

Each handle was tested without a glove;
Each handle was tested with an ordinary work glove.

Summary of results:

Soft ground bare earth, flower bed:

There were no appreciable differences (advantage) among handles when digging in soft earth. All handles were comfortable to use due to the relatively low force at impact.

Earth with turf, small stones and roots:

The shock absorbent handle was more comfortable than the hard plastic handle. Wearing a work glove provided a small improvement in some cases, but had no notable effect with the new shock absorbent handle.

Soil with large buried tree root 2-4 cm below surface earth:

There were incidences of moderate-severe discomfort when using the hard plastic handle and striking large buried tree roots, both with and without a work glove. There were no comparable incidents of severe discomfort when using the shock absorbent handles.
The shock absorbent handle appeared to mitigate the shock to the hand when striking large tree roots hidden beneath the surface.

Large rock or tarmac surface hidden (buried 2-4 cm) below earth covering:

There were some incidences of moderate to severe discomfort when using the hard plastic handle and striking a rock or tarmac, both with and without a work glove. When using the shock absorbent handle, the impact forces generated at the hand appeared to be lower and there was less feeling of vibration at the handle.

The shock absorbent handle appeared to mitigate the shock to the hand when striking a solid surface (rock or tarmac) hidden beneath a cover of earth. When compared to a hard plastic handle, the difference in impact sensed by the user was substantial. Ergonomics

The handgrip surface consists of a semi-compliant material that is more likely to avoid high tissue stresses at the palm of the hand than a hard plastic or wooden handle. The handgrip also provides superior grip (friction) characteristics than a hard plastic handle.
The handle is compact and close to a standard D-handle in size and weight. It provides adequate spacing for the hand grip without being unnecessarily bulky. The weight has been reduced to 290 gm (10 oz) compared to 230 to 260 gm (8 to 9 oz) for a selection of hard plastic D-handles handles and 315 gm (11 oz) a for D-Handle wrapped with absorbent material.
With an effective “built-in” absorbent, the user will always be protected from the adverse effects of striking hard objects. In other words it transfers the role of protection from the user to the supplier
Building effective shock absorbent characteristics into the tool will eliminate the need for the user to select, maintain and replace a vibration absorbent material as an “add-on” to the tool.
In its present configuration, the design characteristics of the shock absorbent handle (Impact Eliminator) is suited to household activities such as gardening, earth moving and snow clearing.

Conclusions

When digging in rough ground, the new design of shock absorbent handle (Impact Eliminator) appeared to mitigate shocks to the hand/arm. This was particularly noticeable when striking a solid object such as a large tree root or buried tarmac or rock with sufficient force to cause severe discomfort and a jarring action when using a hard plastic handle. The discomfort and jarring sensation was not present when the shock absorbent handle was used under the same conditions. It is concluded that when digging in rough ground (for example, earth containing hidden roots or rocks), the new shock absorbent D-Handle has superior absorbent characteristics to a regular D-handle consisting of a hard plastic material, and is more comfortable to use.

Limitation of evaluation

The evaluation of the new design of shock absorbent handle is based on my views and experience and does not include a statistical sample of users, or direct measurements of force, impact or vibration

Figure 2: Hard Plastic D-Handle

Figure 3: Wrapped D-Handle with accelerometer for measuring vibration and shock

U.S. Occupational Safety and Health Administration (OSHA):

According to OSHA, "work-related musculoskeletal disorders [MSDs] currently account for one-third of all occupational injuries and illnesses reported to the Bureau of Labor Statistics (BLS) by employers every year. These disorders constitute the largest job-related injury and illness problem in the U.S. today. In 1997, employers reported a total of 626,000 lost workday MSDs to the BLS, and these disorders accounted for $1 of every $3 spent for workers' compensation in that year. Employers pay more than $15-$20 billion in workers' compensation costs for these disorders every year, and other expenses associated with MSDs may increase this total to $45-$54 billion a year. Workers with severe MSDs can face permanent disability that prevents them from returning to their jobs or handling simple, everyday tasks like combing their hair, picking up a baby, or pushing a shopping cart."

For more information check on their website: Ergonomics in the Workplace

Workers Compensation Board Statistics: CLAIMS STATISTICS FOR REPETITIVE MOTION INJURIES DUE TO THE USE OF A SHOVEL, RESULTING IN AN ARM INJURY, ALL INDUSTRIES, 1992-2005 PERIOD
YEAR 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 TOTALS	DISABILITY CLAIMS ACCEPTED IN YEAR 88 101 82 63 82 73 55 58 55 45 36 33 31 23 825	DISABILITY, FATAL BENEFITS CHARGED IN YR $188,071 $254,387 $173,256 $154,674 $324,335 $217,562 $606,158 $264,510 $211,156 $181,788 $71,468 $95,028 $367,687 $195,524 $3,305,604	DAYS LOST IN THE YEAR 2203 3032 2497 1915 1926 2589 2276 2639 1465 1657 706 948 1740 1,394 26987

Further Information:
	Mike Kelemen Kelemen's Kreations Inc. 17786 Palling Rd Burns Lake BC Canada VOJ 1E1 Phone: 250-698-7507 Cell: 250-692-9408 E-mail: