TowWorks 5/8" Extra-Long Trailer Hitch Lock 4-1/2" Span for 3" Receivers — Keyed Unique, Weather-Resistant

TowWorks 79831 is a keyed-unique, extra-long 5/8" diameter trailer hitch pin lock with a 4-1/2" active span designed to secure adjustable channel hitches and pintle mounts on 3" receivers.

This heavy-duty locking pin gives you a longer reach than standard hitch pins so it can secure many adjustable channel-style hitches and pintle hooks that ordinary pins cannot. It combines a push-lock tubular key mechanism with weather protection, removable rubber O-rings to reduce rattle, and a separate spring (cotter) clip option for added backup safety. Each unit ships keyed unique for independent locking whenever you need separate keys for multiple trailers.

How does the extra-long 4-1/2" span improve hitch compatibility?

The extended active length allows the 79831 pin to pass through thicker adjustable channel hitches and larger pintle-style mounts that shorter pins cannot secure. This makes it compatible with many CURT-style adjustable hitches and specific pintle models listed by manufacturers.

• 5/8" diameter shaft fits standard heavy-duty hitch tubes.
• 4-1/2" maximum active length reaches through adjustable channels and pintle hooks.
• Designed to work with many CURT channel-style hitches (check model fits).
• Not compatible with FASTWAY adjustable hitches—verify dimensions before buying.

What security features prevent theft and wear?

The lock uses a tubular push-lock with two tubular keys and a watertight rubber dust cap to help keep moisture and grit out of the mechanism. The unit is keyed unique, so each lock has its own key to reduce the risk of duplicated access when managing different trailers.

• Push-lock mechanism with 1/4 turn operation for quick locking and unlocking.
• Two tubular keys included for immediate use or spare key storage.
• Watertight rubber cap protects internal components from corrosion and debris.
• Keyed-unique configuration prevents shared-key access across multiple locks.

How does the design reduce rattle and add backup safety?

Rubber O-rings slip onto the pin to hold it snug inside the receiver tube and damp vibrations that cause rattling. In addition to the lock body, a separate spring-style cotter clip is provided so you can secure the pin even when the lock is not used, offering a mechanical backup.

• Rubber O-rings included; add or remove rings to match receiver tube tolerances.
• O-rings reduce noise and movement while towing on rough roads.
• Separate R spring cotter clip included for additional mechanical restraint.
• Reminder: cotter clip must be used when operating without the lock in place.

Which hitches and situations should I check before ordering?

Measure the receiver and adjustable hitch channel to confirm the 4-1/2" active length and 5/8" diameter will fit your application. The 79831 is ideal for many CURT channel-style adjustable hitches and certain adjustable pintle hooks but explicitly does not fit FASTWAY adjustable hitches.

• Verify the inner width and total channel depth of your adjustable hitch or pintle hook.
• Compare the 5/8" pin diameter and 4-1/2" span to your hitch specifications.
• If you need multiple locks keyed alike, consider ordering model 79830 instead.
• Remove or adjust O-rings to accommodate slight receiver size variations.

Who is this for: TowWorks 79831 is built for truck owners, commercial haulers, fleet managers, and anyone who uses adjustable channel hitches or pintle mounts on 3" receivers and needs a longer, robust locking pin. It suits users who want a keyed-unique solution—where each lock has its own key—plus weather protection, rattle reduction, and a cotter-pin backup option. Always confirm your hitch dimensions against the lock’s 5/8" diameter and 4-1/2" span to ensure proper fit before purchase.