Hand, Arm & Tool Safety

D. Rhodes, MSPH, CIH

Tool Grip Body Grip Style Tools

• The grip is simply the tool body.

• Diameter of grip may be too large for best grip

• There is often no protection from the moving parts

• Poor at resisting high torque forces on hand/arm

Tool Grip Body Grip Style Tools

• Some tool designs provide slender parts of tool bodies to grip or a combination with attached in-line handle.

• A longer tool and spread out grips helps with resisting torque

• But, length puts the center of gravity father from the workers body causing more torso strain and increases reaching

Tool Grip Body Grip Style Tools

A B

C D

What are the safety advantages or disadvantages of these pneumatic ratchets?

Tool Grip Handle Size and Cross Sectional Shape

• Handle size affects grasping force required

• High force increases muscle fatigue and can contribute to:– tendonitis – carpal tunnel syndrome– accidents from loss of or

weak grip– blisters, calluses and

hand soreness

Tool Grip – Power ToolsHandle Size and Cross Sectional Shape

Tool handle length is important for a comfortable safe grip. • Select tools with handles a bit

longer than your bare hand – about 4.5 inches.

• When gloves are to be worn the handle needs to be about 0.75 inches longer.

• For angled handles add an additional 0.75 inches to either of the above to a maximum of about 6 inches.

Tool Grip –Handle Size and Cross Sectional Shape

Handle girth is also important;

• For round handles, a diameter of about 1.5 inches causes the fewest problems

• For handles that are not round, the perimeter measurement should be about 4.75 inches.

When gloves are to be used both these measurements should be slightly smaller.

Tool Handles – Surface and Texture

A basic rule for handle design is that they NOT be fluted as in this example.

The flutes rarely fit individual users.

When they don’t fit, the high spots create pressure points that can injure hands.

Tool Handles – Surface and Texture

Other guidelines require a tradeoff because they are contradictory.

When selecting tools, the work conditions need to be considered and the best tool for MOST conditions should be chosen.– A knurled or rough surface helps reduce

gripping force especially when using gloves.– BUT, deeply grooved or rough surfaces can

collect grime, chemicals, chips and particles which can irritate or injure skin.

– A rubbery or soft handle can increase comfort of grasp and improve grip but can absorb chemicals or trap sharp particles.