Limit Switches

Limit switches are a contact proximity sensor device that consists of an actuator mechanically linked to a set of output contacts. When an object comes into contact with the actuator, the device operates the contacts to make or break an electrical connection.

Limit Switch Makeup
Limit switches are made up of three key components:

  • Actuator Head - The actuator is the part of the switch that makes physical contact with the object. In some limit switches, the actuator is attached to an operating head which translates a rotary, linear, or perpendicular motion to open or close the electrical contacts of the switch.
  • Switch Body – The switch body is the component containing the electrical contact mechanism, the contacts within the body open or close the electrical circuit when the actuator is activated.
  • Receptacle/Terminals - The component containing the terminal screws or screw/clamp assembly necessary for wiring purposes.

Actuator Types
Limit switches are available with a wide range of actuator types. The type of actuator used can be determined by the mounting position, force required and objects to be detected.

  • Rotary Lever - with lever actuators, a cam or plate hits the end of the lever arm which in turn rotates a shaft and operates the contacts in the switch. The rotation may be spring returned (momentary) or maintained.
  • Plunger - Plunger types are best where short controlled machine movements are present or where mounting space does not permit a lever type.
  • Cat Whisker or Coil Spring – Longer actuators with a coil wire that can be moved/bent in multiple directions. Typically used in conveying applications to count objects as they pass by.
  • Forked – Used with maintained contacts, consisting of two roller levers. One roller will trip the switch and when the second is moved to the opposite direction it will reset the switch.

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Description Price Actuator Type Pole and Throw Configuration Normal State Configuration IP Rating Maximum Current Housing Material Maximum AC Voltage Maximum DC Voltage Connection Type Series Contact Type Terminal Type Length Width
RS Stock No. 386-0423
Mfr. Part No.Z-15GW2BOMI
BrandOmron
£7.64
Each
Units
Roller Lever SPDT NO/NC IP00 15 A - 500V 250V - - Snap Action Screw 39.4mm 49.2mm
RS Stock No. 386-0366
Mfr. Part No.Z-15GQ22B
BrandOmron
£12.64
Each
Units
Plunger SPDT NO/NC IP00 15 A - 500V 250V - - Snap Action Screw 58.9mm 49.2mm
RS Stock No. 435-0343
Mfr. Part No.ZC-Q2255
BrandOmron
£28.80
Each
Units
Plunger SPDT NO/NC IP67 10 A - 250V 250V - - Snap Action Screw 69.4mm 70mm
RS Stock No. 621-1521
Mfr. Part No.D4N-112G
BrandOmron
£25.60
Each
Units
Roller Lever SPDT NO/NC IP67 - - - - Screw D4N - - 73mm 31mm
RS Stock No. 621-1515
Mfr. Part No.D4N-1120
BrandOmron
£20.64
Each
Units
Roller Lever SPDT NO/NC IP67 - - - - Screw D4N - - 73mm 31mm
RS Stock No. 908-3284
Mfr. Part No.WLNJ-G-N
BrandOmron
£40.38
Each
Units
Coil Spring SPST NO/NC IP67 10 A - 500V 250V PG 13.5 WL Snap Action Screw 40mm 42mm
RS Stock No. 757-9140
Mfr. Part No.D4B4111N
BrandOmron
£45.44
Each
Units
Roller Lever DPST NO/NC - - Metal - - Screw D4B-N - - 99.5mm 40mm
RS Stock No. 828-1027
Mfr. Part No.WL-CA12-GN
BrandOmron
£49.97
Each
Units
Adjustable Roller Lever DPST NO/NC IP67 2 A Aluminium Alloy, Stainless Steel 250V 48V G1/2 Conduit WL Double Break Screw 94.1mm 40mm
RS Stock No. 757-9159
Mfr. Part No.D4B4116N
BrandOmron
£54.65
Each
Units
Roller Lever DPST NO/NC - - Metal - - Screw D4B-N - - 99.5mm 40mm
RS Stock No. 386-0372
Mfr. Part No.Z-15GQB
BrandOmron
£10.50
Each
Units
Plunger SPDT NO/NC IP00 15 A - 500V 250V - - Snap Action Screw 47.3mm 49.2mm
RS Stock No. 386-0417
Mfr. Part No.Z-15GW22B
BrandOmron
£8.09
Each
Units
Roller Lever SPDT NO/NC IP00 15 A - 500V 250V - - Snap Action Screw 39.4mm 49.2mm
RS Stock No. 746-7261
Mfr. Part No.D4N-4180
BrandOmron
£24.15
Each
Units
Cat's Whisker DPST NO/NC - - - - - Screw D4N - - 64mm 31mm
RS Stock No. 621-1559
Mfr. Part No.D4N-1162
BrandOmron
£22.57
Each
Units
Roller Plunger SPDT NO/NC IP67 - - - - Screw D4N - - 83.6mm 31mm
RS Stock No. 621-1543
Mfr. Part No.D4N-1132
BrandOmron
£18.44
Each
Units
Roller Plunger SPDT NO/NC IP67 - - - - Screw D4N - - 83.6mm 31mm
RS Stock No. 435-0337
Mfr. Part No.ZC-Q2155
BrandOmron
£29.03
Each
Units
Plunger SPDT NO/NC IP67 10 A - 250V 250V - - Snap Action Screw 69.4mm 70mm
RS Stock No. 757-9231
Mfr. Part No.D4NS-1BF
BrandOmron
£26.92
Each
Units
- - 2NC IP67 10 A Plastic 240V 250V Screw D4NS - - 96mm 31mm
RS Stock No. 757-9156
Mfr. Part No.D4B-4171N
BrandOmron
£34.34
Each
Units
Roller Plunger DPST NO/NC - - Metal - - Screw D4B-N - - 97mm 40mm
RS Stock No. 435-0387
Mfr. Part No.ZE-Q22-2G
BrandOmron
£30.57
Each
Units
Plunger SPDT NO/NC IP65 15 A - 480V 250V - - Snap Action Screw 75.2mm 86mm
RS Stock No. 436-0182
Mfr. Part No.Z-15GQ21-B
BrandOmron
£11.80
Each
Units
Plunger SPDT NO/NC IP00 15 A - 500V 250V - - Snap Action Screw 58.9mm 49.2mm
RS Stock No. 748-2926
Mfr. Part No.SHL-Q2255
BrandOmron
£32.09
Each
Units
Roller Plunger SPDT NO/NC IP67 2 A ac, 200 mA dc - 480V 250V Screw - Snap Action Screw 73.5mm 35.9mm