Hamilton · Railroad

Strap for Railroad 40 Auto Stainless Steel / Black / Bracelet

Takes 20 mm straps. Verified lug width, the straps that fit this model, and answers to the most common questions.

Lug width20 mm
Case diameter40 mm
ReferenceH40555131
FamilyRailroad
MovementHamilton caliber H-10 Hours, Minutes, Seconds | Date
CaseStainless Steel

Spring bar

Swiss Standard universal spring bars

The right category for this model · 316L steel, all lug widths 13–26 mm

Straps for the Railroad H40555131

Selected for the 20 mm lug width · workshop selection

All 20 mm straps →

The Railroad H40555131, seen from the bench

The Hamilton Railroad represents the brand's railway tradition with a classic dial and hour, minute, second and date indications. It is equipped with the automatic caliber H-10 which offers an extended power reserve. The strap features 20mm lugs for wide compatibility of replacement.

Frequently asked questions

What is the lug width of the Hamilton Railroad H40555131?

The Hamilton Railroad H40555131 features a lug width of 20mm. This specification falls outside the more common 18mm or 22mm standards, making it essential to verify compatibility before purchasing a strap. The lug width is measured by calculating the distance between the internal shoulders of the case, at the point where the spring bars attach.

Which strap is best suited to the Hamilton Railroad H40555131?

For the H40555131, we recommend straps in alligator, vegetable-tanned calf, military-tone NATO, or FKM rubber. Alligator enriches the steel with organic texture; vegetable-tanned calf ensures elegant natural ageing; NATO echoes the model's railroad-instrument vocation; rubber offers contemporary practicality. Your choice depends on intended use and wearing context.

How do you change the strap on the Hamilton Railroad H40555131?

To change the strap, remove the spring bars (the small metal pins protruding from the case lugs). Use a spring bar tool (with a small flat spatula) to compress the spring and slide the pin out of the current strap. Align the new strap openings with the lugs, then reinsert the spring bar until it clicks into position. The operation is straightforward but requires care to avoid scratching the case.

Is an aftermarket strap compatible with the Hamilton Railroad H40555131?

Yes, provided they have internal openings of exactly 20mm. Not all aftermarket brands offer this specific width, so it is crucial to verify dimensions before ordering. Specialist strap makers guarantee construction precision superior to generic production, avoiding lateral play and instability during wear.

How long does a leather strap last on the Hamilton Railroad H40555131?

The lifespan of a leather strap varies depending on material, use, and maintenance. A quality alligator or calf strap, used in contexts not exposed to constant humidity or intense abrasion, maintains structural integrity for 5–7 years. Regular exposure to perspiration, rain, or friction shortens this period. Water staining, cracking, or edge thinning are signs that the strap has reached end-of-life and should be replaced for stability and safety reasons.

The next step

The right strap isn't chosen. It is built, together.

From the atelier appointment to delivery, every step is made for those who know that things done well take time. Rare leathers, one piece at a time, eighteen months of warranty.

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Casati Milano · Via XX Settembre 15, Milan · by appointment only