CM-1 Phenolic Horizontal Limit Switches

Horizontal switches with phenolic housings

CM-1 limit switches use a phenolic molding compound body and snap-action 1NO+1NC contacts. Twenty-one actuator configurations cover long and short levers, wire and curved levers, panel-mount plungers, leaf springs and one-way roller mechanisms. Select by approach direction, available movement and operating force; roller material and lever geometry remain model-specific.

Model-code selection

CM-1703M consists of the fixed series identifier CM-1 followed by actuator code 703M. No housing suffix denotes the phenolic version. Keep M and X within their complete actuator codes. All models in the following table use the same snap-action 1NO+1NC contact form, with COM, NC and NO terminal functions.

General characteristics

Each endurance figure retains its own load condition. Validate life with the selected model at the actual operating speed, frequency and load. Standard CM-1 switches are not waterproof sealed devices; use suitable external protection against direct oil or water splash and debris.

Switching and inrush ratings

Current values are amperes. Shared NC/NO cells retain the same value for both contacts. The inrush limits apply across all eight voltage rows. The 30VDC resistive entry is designated 6(2)A; confirm the applicability of its parenthetical rating before selecting that duty.

Operating force and travel by model

OF is maximum operating force, RF minimum release force, PT maximum pretravel, OT minimum overtravel, MD maximum differential travel and FP maximum free position. OP is the operating-position datum. A dash means the value is not specified. One-way roller models switch only in their intended approach direction.

Other motion-diagram symbols are TF total-travel force, RP release position, TTP total-travel position and TT total travel. Set the movement beyond the operating point to 70-100% of the specified OT, without exceeding the allowable overtravel. Avoid impact, excessively slow contact transfer and excessive operating frequency.

Dimensions, covers and mounting

The standard body drawings show 49.6mm length and 25.4±0.1mm mounting centers. Width and hole geometry vary by actuator construction; check the exact outline before machining. Long lever CM-1701 uses R63.5mm, short lever CM-1702 R28.2mm, roller levers CM-1703/1703M R48.5mm and short roller levers CM-1704/1704M R26.6mm. Their rollers are Ø9.5×4mm. CM-1713 has a Ø20×4mm plastic roller; CM-1705 has a Ø1mm wire lever with R155mm geometry.

Panel plungers use M12×1 threads. CM-1308 and CM-1309 have Ø12.7×3.8mm rollers in different orientations; CM-1308X is the small vertical roller configuration. The slim spring plunger is Ø4mm, the short spring plunger Ø7.3mm and the pin plunger Ø2.3mm. Use the full dimension drawings for clearance and operating-position tolerances.

Accessories are separate selection items and do not establish an ingress-protection rating. Secure the switch with M4 screws, flat washers and spring washers at 1.18-1.47N·m. For panel mounting, tighten the actuator hexagonal nut to 2.94-4.9N·m. The panel-plunger cutout is Ø12.5mm with +0.2/0 tolerance; the roller-plunger cutout has the additional 13mm by 5mm keyed geometry shown in the attachment. For side-screw mounting of CM-1307/1308/1309, remove the actuator hex nut and avoid excessive cam angle, speed or shocks above 1000m/s².

Wiring and contact protection

Isolate power before mounting, wiring or maintenance. Keep wire fragments out of the switch. Use insulated M3.5 crimp terminals with AWG20-AWG18 or 0.5-0.75mm² conductors, fitted flat without interfering with the casing or cover. Terminal thickness must not exceed 0.5mm.

Where solder connections are used, use an iron no greater than 60W and limit heating to 5 seconds at 350°C or 3 seconds at 380°C. Avoid incomplete joints and prolonged heating. Keep silicone oils and volatile silicone materials away from the contacts. For loads below 24VDC/10mA or prolonged low-frequency service, specify a suitable low-load contact version. Contacts already used on general loads must not be reused for small signals. Apply suitable RC suppression and contact protection for bounce, noise and impulse currents.

Standards and application limits

Protect the switch from chips, dust accumulation, direct splash, corrosive gases and resonance. Avoid steam, hot water above 60°C, rapid thermal changes and outdoor exposure beyond the specified conditions. Add guards where accidental actuation is possible. Personnel protection, nuclear or utility infrastructure, fire or explosion hazards, harsh chemical service, military and aerospace applications require a separately specified design and application approval.