Push Button Switches
ALX-HB4-BD21 Two Position Selector Switch | 22mm
22 mm two position rotary selector switch, 1 NO or 1 NO + 1 NC contact, maintained (stay put) and spring return versions, black knob, zinc alloy chrome bezel, screw terminals, 600 V AC 10 A.
The HB4-BD21 is a two position selector on the 22 mm HB4 bezel. Turning the knob through 60 degrees switches the contact; a detent holds the knob where it is left on the maintained version, while the spring return version snaps back to the rest position when the operator lets go. Selectors like this are used for mode selection, auto/manual changeover and isolating functions where a rotary position is clearer than a push.
Technical Specifications
Item | Specification |
Mounting hole | 22 mm (22.3 mm cutout) |
Bezel / head material | Zinc alloy, chrome plated |
Contact housing | Plastic |
Contact configuration | 1 NO, or 1 NO + 1 NC (by model) |
Operation | Two position, 60 deg. throw, maintained or spring return |
Actuator | Rotary knob, black |
Actuator colour | Black |
Illumination | None |
Rated voltage / current | 600 V AC, 10 A (AC-15 duty) as marked on the contact block |
Termination | Screw terminals |
Positions | 2 (left / right) |
Mounting | 22 mm single hole, anti-rotation key |
BD21 and BD25 are maintained (stay put); BD41 and BD45 are spring return. The digit after BD sets the contact combination.
Design Features
- Two position selector with a 60 degree throw and a positive detent at each position
- Maintained versions hold the selected position; spring return versions snap back to rest
- Black knob with a moulded pointer, readable against a legend engraved on the panel
- Anti-rotation key on the mounting collar stops the whole switch turning when the knob is operated
- Contact blocks clip on from the rear, so the contact combination can be changed without a new bezel
Model Options
Model | Action | Contact |
HB4-BD21 | Maintained (stay put) | 1 NO |
HB4-BD25 | Maintained (stay put) | 1 NO + 1 NC |
HB4-BD41 | Spring return | 1 NO |
HB4-BD45 | Spring return | 1 NO + 1 NC |
The short-lever equivalent is the HB4-BJ group; the illuminated equivalent is HB4-BK12.
Applications
Auto/manual and local/remote changeover, mode selection on machine tools, pump duty selection and isolator functions on control cabinets.