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

The TowWorks 79831 is an extra-long, keyed-unique 5/8" trailer hitch locking pin engineered to secure 3" receiver and adjustable channel-style hitches with a 4-1/2" active span.

The TowWorks 79831 hitch lock combines a long locking pin, watertight push-lock cylinder, rubber O-rings to reduce noise, and a backup spring clip so you can secure adjustable hitches used for towing or hauling. Its 4-1/2" active length and 5/8" diameter are designed to work with many adjustable channel-style hitches and pintle hooks; note this model is keyed unique (each lock has its own key) and is not compatible with FASTWAY adjustable hitches. Check your hitch dimensions before ordering to ensure a proper fit.

Will this lock fit my adjustable hitch or pintle hook?

The 79831 features a 5/8" diameter pin and a maximum active length of 4-1/2", making it suitable for most adjustable channel-style hitches and many adjustable pintle hooks. It is explicitly compatible with several CURT-style adjustable models but will not fit FASTWAY adjustable hitches.

• Pin diameter: 5/8" (0.625 in)
• Active pin length (span): 4-1/2"
• Compatible examples: CURT channel-style adjustable hitches 45900, 45901, 45902
• Not compatible with: FASTWAY adjustable hitches

How does the lock resist rattles and weather over time?

TowWorks uses rubber O-rings around the pin to dampen vibration and eliminate clanking between the pin and receiver tube. The push-lock mechanism includes a watertight dust cap that helps keep moisture and dirt from reaching the cylinder, reducing corrosion risk.

• Rubber O-rings reduce vibration and noise
• Adjustable O-ring quantity to fit different tube tolerances
• Watertight dust rubber cap protects the lock cylinder
• Stainless/treated metal finish resists outdoor exposure (follow maintenance guidance)

What safety and convenience features does this hitch lock include?

The 79831 includes a backup spring clip (cotter pin) you must insert during use for additional retention, and a push-lock design operated with tubular keys for straightforward locking and unlocking. Two tubular keys are supplied, and the model is sold keyed unique by default, so each unit has its own distinct key.

• Push-lock cylinder with 1/4-turn operation for quick use
• Includes two tubular keys for each lock
• Separate spring clip (cotter pin) for redundant safety—must be used
• Sold keyed unique; select model 79830 for keyed-alike sets

How should I prepare and install the TowWorks 79831 for best performance?

Measure the inside width of your receiver and the span required by your adjustable hitch before purchasing to confirm compatibility. Install rubber O-rings as needed to eliminate play; maintain the lock by keeping the dust cap closed and applying light lubrication to the keyway periodically.

• Confirm receiver diameter and required pin span first
• Adjust O-ring count to prevent slop or remove if too tight
• Insert spring clip after pin placement for added security
• Keep the dust cap closed and use lock lubricant as part of maintenance

Who is this for: The TowWorks 79831 is for trailer owners, contractors, and fleet operators who use adjustable channel-style hitches or compatible pintle hooks and need a longer locking pin to secure heavy towing connections. Choose this model if you require a keyed-unique lock with vibration-dampening O-rings and a watertight push-lock design; if you want multiple locks to operate on the same key, opt for the keyed-alike 79830 instead.