Push Button Switches
ALX-HB4-BC21 Mushroom Head Push Button Switch | 22mm 40mm 1NO
22 mm mushroom head push button switch with 40 mm cap and 1 NO contact, momentary spring return, black / green / yellow cap, zinc alloy chrome bezel, screw terminals, 600 V AC 10 A.
The HB4-BC21 group is the normally-open version of the 40 mm mushroom button. It is used where the large cap is wanted for a start, cycle-initiate or acknowledgement function rather than a stop: the contact closes only while the cap is held down, and the spring returns it as soon as the operator lets go.
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 |
Operation | Momentary, spring return |
Actuator | Mushroom head, 40 mm dia. |
Actuator colour | Black, green, yellow |
Illumination | None |
Rated voltage / current | 600 V AC, 10 A (AC-15 duty) as marked on the contact block |
Termination | Screw terminals |
Colour is fixed by the suffix: BC21 black, BC31 green, BC51 yellow. The red 1 NC version is HB4-BC42.
Design Features
- Normally-open contact closes only while the cap is held, so a start or cycle-initiate command cannot latch by itself
- 40 mm cap gives a large, glove-friendly target on panels that are operated in a hurry
- Three cap colours (black, green, yellow) let a panel separate start, acknowledge and jog functions
- Chrome-plated zinc alloy bezel and metal clamping ring hold the switch square against the panel
- Contact block is a separate clip-on part, replaceable without disturbing the bezel or the panel wiring loom
Model Options
Model | Colour | Contact |
HB4-BC21 | Black | 1 NO |
HB4-BC31 | Green | 1 NO |
HB4-BC51 | Yellow | 1 NO |
For the red normally-closed version order HB4-BC42; both share the same 40 mm cap and bezel.
Applications
Conveyor start stations, packaging machines, pump control panels, access and gate control, and general machinery where a large positive push target is preferred.