TowWorks trailer hitch lock pin 5/8" extra-long 3-1/4" span — keyed tubular, hardened steel for 2" & 2.5" receivers

The TowWorks 79631 is an extra-long, 5/8" diameter keyed hitch lock pin designed to secure Class III and IV trailers with 2" and 2.5" receiver tubes.

This rugged tow-hitch locking pin combines a hardened-steel shaft with a corrosion-resistant finish, rubber vibration dampers and a push-lock tubular key for convenient, secure towing. Its 3-1/4" active span gives extra reach for deeper or offset receivers, while the included spring clip lets you use the pin even without the locking cylinder installed. Read on to understand fit, operation, and whether this lock is right for your trailer setup.

How do I know this hitch lock will fit my receiver?

Measure the internal length of your hitch tube and compare it to the lock's maximum active span of 3-1/4". The 5/8" diameter pin is sized for standard Class III and IV receivers; compatibility depends on your trailer's specific tube thickness and any hitch-mounted accessories.

• Active length: 3-1/4" (extra long span for deeper receivers)
• Pin diameter: 5/8" (solid, hardened steel)
• Designed for 2" and 2.5" (2" and 2-1/2") receiver tubes
• Always verify your hitch dimensions before purchase

What materials and weather protection does the TowWorks 79631 offer?

The main shaft is solid hardened steel finished with a zinc plating and black e-coat to resist rust and abrasion. The push-lock mechanism includes a watertight rubber dust cap to reduce moisture entry and slow internal corrosion, helping the lock maintain smooth operation in outdoor conditions.

• Hardened steel pin for strength and cut resistance
• Zinc-plated base with black e-coating for corrosion resistance
• Rubber dust cap seals the lock core from the elements
• Rubber O-rings reduce rattle and protect the receiver finish

How is the lock operated and what security features are included?

The TowWorks 79631 uses a push-lock tubular key system that locks with a 1/4-turn action; two tubular keys are included for convenience. For added redundancy you can still use the separate spring clip (cotter-style pin) if you prefer a non-keyed backup or need to secure the hitch quickly.

• Push-lock tubular cylinder with 1/4-turn operation
• Two tubular keys included for easier access
• Separate spring clip (cotter pin) included as an alternative safety measure
• Rubber O-rings hold the pin steady and cut down on noise

Are the keys interchangeable or keyed alike with other TowWorks locks?

Each 79631 lock is shipped keyed unique, so its keys will not open other locks by default. TowWorks does offer keyed-alike options under different part numbers if you need multiple locks that operate with a single key.

• 79631 ships keyed unique (each lock has its own key code)
• Choose 79632 for two locks keyed alike, 79633 for three keyed alike
• For four or more keyed-alike locks, order part 79630 and specify quantity

Who is this product for? The TowWorks 79631 is intended for truck and trailer owners who need an extra-long, heavy-duty locking pin for Class III and IV receivers—especially when standard-length pins don't reach the hitch's pin hole or when a deeper, offset mount is used. It's a practical choice for boat trailers, campers, work trailers and anyone wanting a durable, weatherproof locking solution with the option to revert to a cotter pin for quick setups.