By Dr. Jody Muelaner
There are many types of handles, but they are all designed to transmit a force between a person’s hand and an object. Handles are installed on many types of tools, packages, furniture and machinery. Buildings and vehicles may also be fitted with safety handles which a person can hold to prevent themself from falling.
An appropriate handle should:
- Be strong enough to support the required force
- Have sufficient area and an ergonimic shape to comfortably transfer the required surface normal forces into the hand
- Have sufficient friction to transfer any required surface tangent forces into the hand
- Be ergonomically arranged so that it remains comfortable over the range of required movement
Many types of handles are used in machinery. Examples of uses include:
- Moving slideways and lead screws
- Tightening clamps
- Opening of covers and guards
- Operating electrical switches
Some standard types of handles used for building machinery include:
- Lever arms: A simple bar with a rounded handle at one end and a screw thread for installation at the other end.
- Clamping levers: These are effectively a machine screw with an attached spanner. A threaded bar with a serrated head is attached to a handle, which can engage with the serrated head. Sliding the handle axially allows the serrated head to be engaged and disengaged to tighten the screw within confined spaces.
- Ratchet handles: These are similar to clamping levers, but use a ratchet to make tightening easier.
- Knobs: These are rounded handles used to provide a means of firmly holding on to a piece of machinery. They may be approximately spherical or T-shaped.
- Crank Handles: These are often a detachable part which can be temporarily fitted to a shaft to enable actuation or tightening of a screw. They often have a square hole to enable a high torque to be transferred into the shaft.
- Hand Wheels: These provide a means of continuously rotating a shaft by hand. They are often used to actuate lead screws, for example on lathes and milling machines.
Building fixtures and furniture
Both building fixtures, such as doors and windows, and furniture, such as cabinets and draws, use handles. Some handles are fixed and are simply used to pull these items open or closed. Other handles can be moved, actuating a latch which locks the door or window in a closed positon. Handles which are elongated bars are typically referred to simply as handles while handles which are approximately spherical are called knobs.
A handle is an integral part of any hand tool, providing the interface through which the tool is held and operated. Ergonomics are often of very high importance in ensuring that tools can be operated with comfort and precision over prolonged periods. Tool handles often differ from other types of handles in that they are frequently an integral part of a tool’s structure. Most other handles are discrete parts, which are fastened to some other object.
Packages and carrying handles
Packages often include handles to make them easier to carry. These may be integral to the structure, such as cut-outs in the sides of a cardboard box, or they may be additional parts added to the packaging. Standard hardware carrying handles are available, which can be fitted to cases and machinery.