956-3124 Littelfuse Cole Hersee 956-3124 Heavy-Duty 3-Position Ignition Switch (Short Lever)

Littelfuse 956-3124 Switch Overview – SW ROT IGN & START | 3-Position Lever | 956 Heavy Duty Series Toggle Switch

The Littelfuse Cole Hersee 956-3124 Switch on Toggle is a rugged, heavy-duty ignition switch purpose-built for universal 12 V DC vehicle applications operating in harsh environments. It features a clear three-position logic—OFF → IGN/ACC → START—with a positive spring return from START to IGN/ACC to protect the starter drive and simplify operator workflow. An integrated start-lockout requires the switch to return to OFF before the start circuit can be re-energized, helping prevent accidental re-starts and ring-gear damage.

Mechanically, the 956-3124 combines a plated-steel housing, bronze contacts, and a 1″-24 mounting bushing for secure panel installation. Environmental sealing is comprehensive: an O-ring in the stem, a gasketed face, and a shuttered lock seal guard against dust and moisture ingress, extending service life under vibration, washdown, or outdoor duty. The short-lever actuator with a crisp 40° indexing provides gloved-hand ergonomics and tactile detents.

For fleet security and power-down discipline, the coded tumbler lock accepts two keys and permits key removal in the OFF position only. Wiring is straightforward via five screw terminals (including a dedicated ground), enabling quick service and reliable terminations. Electrical ratings at 12 V DC are tailored for common vehicle loads: 10 A Accessory, 10 A Ignition, 5 A Start, plus 1 A Ground for reference. The design meets SAE J259 ignition-proof guidelines, making it suitable where ignitable vapor may be present.

Whether you are outfitting construction equipment, ag machinery, municipal fleets, generators, or marine auxiliaries, the 956-3124 delivers the durability, safety interlocks, and operator familiarity that reduce downtime and total cost of ownership across demanding duty cycles.

Specifications

• Series / Model: Littelfuse Cole Hersee 956 Heavy Duty / 956-3124

• Positions / Function: 3-position (OFF – IGN/ACC – START), spring return to IGN/ACC; start-lockout

• Voltage Rating: 12 V DC

• Current Ratings (12 V DC): 10 A Accessory; 10 A Ignition; 5 A Start; 1 A Ground

• Contacts / Terminals: Bronze; 5× screw (with ground)

• Actuator: Short lever; coded tumbler lock with 2 keys; key removable at OFF

• Indexing: 40°

• Housing: Plated steel; O-ring in stem, gasket-sealed, shutter lock seal

• Mounting: 1″-24 bushing (panel mount)

• Illumination: Non-illuminated

• Unit Weight: ~236.17 g

• Compliance: Ignition-proof to SAE J259

Key Features

• Heavy-Duty, Sealed Construction:
  Designed for extreme environments, featuring O-ring stem seal, gasket-sealed face, and a shuttered lock mechanism to block dust, moisture, and debris—ideal for off-road and outdoor equipment.

• Operator-Safe Logic:
  Built-in spring return from START to IGN/ACC and start-lockout ensure that the starter motor can’t be accidentally re-engaged, protecting both electrical and mechanical systems.

• Service-Friendly Wiring:
  Equipped with five screw terminals, including a dedicated ground, allowing straightforward installation, secure connections, and simplified field maintenance.

• Ignition-Proof to SAE J259:
  Certified ignition-proof design prevents ignition of surrounding flammable vapors, making it safe for use in fuel-handling, marine, and confined-space environments.

• Coded Lock Cylinder with Two Keys:
  Key removable only in the OFF position, preventing unauthorized use and ensuring the vehicle or equipment is fully powered down before the operator leaves.

• Durable Plated Steel Housing:
  The plated steel body provides corrosion resistance and structural strength against vibration, shock, and heavy-duty wear.

• Bronze Contacts for Long Life:
  High-conductivity bronze contacts offer low resistance and consistent electrical performance over extended operational cycles.

• Ergonomic Short-Lever Actuator:
  Compact, die-cast short lever with 40° indexing offers precise tactile feedback and easy operation—even while wearing gloves.

• Universal 12V DC Compatibility:
  Optimized for 12V electrical systems, supporting typical load circuits such as ignition, accessories, and start motor applications (10A/10A/5A rated).

• Secure 1″-24 Mounting Bushing:
  Provides strong panel retention and vibration resistance in both OEM and retrofit installations.

• Non-Illuminated, Compact Form Factor:
  Designed for rugged simplicity—no internal illumination means fewer failure points, ensuring maximum reliability in high-duty cycles.

• Proven 956 Heavy-Duty Platform:
  Part of Littelfuse’s trusted 956 Heavy Duty Series, ensuring part interchangeability, consistent quality, and long-term parts availability.

These combined features make the Littelfuse Cole Hersee 956-3124 an ideal ignition solution for heavy machinery, fleet vehicles, marine applications, and industrial systems that demand maximum durability, safety, and ease of maintenance.

Applications

The Littelfuse Cole Hersee 956-3124 Heavy-Duty Ignition Switch is engineered for reliability across a wide spectrum of industrial, commercial, and specialty vehicle platforms where dependable ignition control is essential. Its rugged build, sealed design, and universal 12 V compatibility make it a preferred choice for OEM and aftermarket integration in demanding environments.

• Construction & Material-Handling Equipment
  Ideal for loaders, excavators, bulldozers, cranes, pavers, rollers, and concrete mixers, where exposure to dust, vibration, and moisture demands robust performance. The spring-return feature ensures smooth restarts and operator safety on job sites.

• Agricultural Machinery
  Used in tractors, harvesters, sprayers, seeders, balers, and irrigation pumps requiring consistent electrical connection under field vibration and extreme temperature cycles. Its sealed contacts prevent contamination from dirt or chemicals during agricultural operations.

• Municipal & Specialty Vehicles
  Commonly installed in refuse trucks, snowplows, fire engines, street sweepers, airport ground support equipment (GSE), and mining support vehicles, where ignition proofing and safety lockout functions enhance reliability and operator protection.

• Marine & Power Equipment
  Excellent for small craft, workboats, auxiliary marine engines, and 12 V generator sets, as its SAE J259 ignition-proof certification minimizes ignition risk in vapor-laden environments such as bilges or fuel-handling zones.

• Light/Medium-Duty Commercial Vehicles
  Compatible with delivery trucks, service vans, fleet pickups, and vocational upfit vehicles. The switch provides a standardized ignition interface suitable for body builders and electrical upfitters seeking durable key-switch integration.

• Industrial & Stationary Equipment
  Reliable for portable generators, hydraulic power units, mobile compressors, and lighting towers, where operator panels require a compact, easy-to-service ignition switch with tactile feedback and mechanical reliability.

Overall, the 956-3124 provides a universal, long-life ignition control solution adaptable to both mobile and stationary platforms operating in harsh, high-duty environments.

About Littelfuse & Replacement Options

Littelfuse is a global leader in circuit protection and commercial-vehicle electrical systems. Through its Cole Hersee line, the company offers a century of field-proven switches, relays, breakers, and power distribution components optimized for severe-duty fleets. The 956 Heavy Duty ignition family embodies that approach: robust metals, proven sealing methods, intuitive actuation, and compliance with automotive and off-highway standards. These traits translate to fewer field failures, predictable service intervals, and consistent operator experience across mixed equipment.

If your panel layout, key policy, or wiring style calls for a close substitute, consider these specific 956-series alternatives that maintain similar electrical behavior while varying mechanics or lifecycle status:

• 956-3125 — Heavy-duty 3-position ignition & start with anti-restart logic in the same 12 V/10 A/5 A envelope. Ideal where enforced restart interlock is required.

• 956-3127 — 3-position ignition & start with short-lever actuator (boxed variant). Often selected when a lever operator is preferred over a key cylinder style.

• 956-3122 — 3-position SW IGN & ST variant (note: listed as obsolete on Littelfuse’s site). Useful for legacy equipment documentation or replacements via distributor stock.

When selecting a drop-in replacement, verify: position logic and spring-return direction, panel hole and 1″-24 thread engagement, terminal numbering against your harness, key-withdrawal position, and required certification (e.g., SAE J259 ignition-proof). For fleets standardizing on a single operator feel, staying within the 956 Heavy Duty family helps preserve tactile indexing and wiring conventions while simplifying spares.