Two-Hand Control Devices
The two-hand control requires constant, concurrent pressure by the operator to activate the machine as shown in the image.
Two-Hand Control Device
The control device requires a part-revolution clutch, brake, and a brake monitor if used on a power press.
With this type of device, the operator's hands must be at a safe location (on control buttons) and at a safe distance from the danger area while the machine completes its closing cycle.
Two-Hand Controls
Key Features of Two-Hand Control Devices
The key features of a two-hand control device include the following:
- Ensures operator safety: Both hands must press the controls simultaneously, preventing accidental activation when one hand is in the danger zone.
- Requires constant pressure: The machine only operates while both buttons are held down, stopping immediately if either hand releases the controls.
- Used with safety mechanisms: Requires part-revolution clutch, brake, and brake monitor for power presses to control machine movement precisely.
- Hands remain away from danger area: Keeps operator’s hands on controls and out of harm’s way during machine operation.
Examples
- Power presses in metal stamping plants where both hands must activate the press.
- Press brakes used in sheet metal bending operations requiring two-hand activation.
- Hydraulic shear machines with two-hand controls to ensure operator’s hands are clear.
- Injection molding machines that use two-hand devices to prevent accidental start-up.
- Punch presses that require simultaneous button presses to operate the punch cycle.
| Safeguarding Action | Advantages | Limitations |
|
Concurrent use of both hands is required, preventing the operator from entering the danger area |
Operator's hands are at a pre-determined location Operator's hands are free to pick up a new part after first half of the cycle is completed |
Requires a partial cycle machine with a brake Some two-hand controls can be rendered unsafe by holding with arm or blocking, thereby permitting one-hand operation Protects only the operator |
Knowledge Check Choose the best answer for the question.
3-7. Which safeguard device requires constant, concurrent pressure by the operator to activate the machine?
You forgot to answer the question!