Reference
Switch Key & Lock Glossary
A collector's reference guide to railroad switch key and padlock terminology — mechanisms, key types, railroad departments, manufacturing terms, and collector vocabulary.
83+ Terms Defined
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A
- Adlake
- Adams & Westlake Company, Chicago — one of the most prolific producers of railroad switch keys and padlocks in North America. Operating from the 1880s onward, Adlake supplied keys and hardware to hundreds of railroads. Keys bearing the Adlake name or logo are among the most commonly encountered in the collector market, with examples spanning the early brass era through mid-20th century steel production.
- Agent (Station Agent)
- A railroad employee stationed at a depot or freight house who managed local operations, handled freight, sold tickets, and operated the telegraph. Station agents held keys to freight houses, tool boxes, and sometimes switch locks within their territory. Keys marked with station initials or the agent's district are occasionally found.
- Amalgamated
- A railroad formed through the consolidation or merger of two or more predecessor lines. Keys from amalgamated roads frequently bear the markings of the predecessor company on one face and the successor on the reverse, or were continued in service after a merger without remarking — making them particularly important for establishing timeline provenance.
- Attribution
- The process of associating a key with a specific railroad, manufacturer, or time period based on physical characteristics, markings, historical records, or collector knowledge. Unmarked keys may be attributed to a railroad through comparison with documented examples, catalog records, or archival photographs.
B
- Barrel Bit
- The hollow cylindrical tip of a barrel key, which fits over a post in the keyway and engages the lock mechanism via a bit projecting from the side of the barrel. A characteristic feature of hollow barrel switch keys — the most common type used by American railroads from the 1870s through the early 20th century. See also: Hollow Barrel Key, Bit
- Barrel Key
- A key with a hollow cylindrical shank that fits over a post inside the lock. On railroad switch keys, the barrel design was nearly universal — the cylindrical shank slides over a center post in the switch lock, and the bit at the base engages the tumblers or wards. Barrel keys are distinguished from solid-shank (bit) keys by this hollow construction. See also: Hollow Barrel Key, Bit Key
- Bit
- The projecting blade, wing, or flat profile at the tip of a key that engages the tumblers, wards, or locking mechanism inside the lock. On railroad switch keys, the shape and cut of the bit is one of the primary identifying characteristics, along with the bow shape and any stamped markings. Also refers to the pattern cut into the flat face of the key tip. See also: Bit Pattern, Barrel Bit
- Bit Key
- A solid-shank key with a projecting bit, as distinguished from a hollow barrel key. Bit keys were more common on early American locks and on padlocks; hollow barrel keys dominated the switch lock application. Some railroad padlock keys are solid-bit design. See also: Barrel Key
- Bit Pattern
- The profile of cuts, steps, or recesses on the bit of a switch key that determine which specific lock it can operate. Bit pattern is a primary identification characteristic. Common pattern descriptions include single-step, double-step, three-step, and single-ward. Different railroads and manufacturers used proprietary patterns to prevent unauthorized key use. See also: Bit, Ward
- Blank
- An uncut key — a raw key form before the bit pattern has been machined. Railroad switch key blanks were maintained by station agents and section foremen for cutting to specific locks. Finding a blank in a railroad context is uncommon and typically indicates a depot or maintenance-of-way supply cache.
- Bow
- The looped head of a key, used as a grip for turning. On railroad switch keys, the bow is typically round or oval, though heart, coffin, oblong, and occasional decorative bows are encountered. Bow shape was often specific to a manufacturer or railroad purchasing preference, and is a primary identification characteristic alongside the bit pattern and marking. See also: Bow Shape
- Bow Shape
- The physical form of the bow (looped head) of a switch key. Standard bow shapes in the railroad key collector vocabulary include: Round, Oval, Heart, Coffin (tapered oval), Oblong (elongated round), and Teardrop. Bow shape is one of the three primary identification characteristics of a switch key, alongside the bit pattern and stamped marking. See also: Bow
- Brass
- The dominant metal used for American railroad switch keys from the 1870s through the early 20th century. Brass (an alloy of copper and zinc) is corrosion-resistant, relatively easy to machine, and develops a characteristic patina with age. The warm golden-brown patina of an aged brass key is a hallmark of pre-1920s production. Later keys were increasingly made of steel. See also: Steel, Nickel Plated
- Broad Gauge
- A railroad track width (gauge) wider than the standard 4 ft 8½ in. Switch keys from broad gauge railroads — notably the early Erie Railroad (6 ft gauge) and various narrow gauge lines — can sometimes be identified by construction details or direct railroad markings. Gauge changes often triggered wholesale key replacement, making transitional examples rare.
C
- Caboose Key
- A key used to access the doors, lockers, or storage compartments of a caboose (the crew car at the rear of a freight train). Caboose keys were held by conductors and trainmen. Marked examples typically carry the railroad's initials and may indicate a specific caboose number or division. See also: Car Key
- Car Door Key
- A key used to operate the locking mechanisms on freight car doors — boxcars, refrigerator cars, and express cars. Car door locks secured lading against theft in transit. Car door keys are typically heavier and more robust than switch keys, and were held by conductors, agents, and car inspectors. See also: Car Key, Car Seal Key
- Car Key
- A general term for any key used to operate locks on railroad rolling stock — including car doors, caboose locks, tank car hatches, and hopper car gates. Car keys are distinguished from switch keys by their function: they secure freight and passenger cars rather than track switches. See also: Car Door Key, Car Seal Key, Caboose Key
- Car Seal
- A device applied to freight car doors to indicate that a car has not been opened since loading and sealing. Railroad padlocks used as car seals are a specific collecting category — typically lightweight and stamped with the sealing railroad's marks. The lock (and its key) establishes chain of custody for the shipment. See also: Car Seal Key
- Car Seal Key
- A key used to operate car seal padlocks. Car seal locks were applied to freight cars to evidence unauthorized opening; the key was held by the recipient or authorized agent. Keys in this category are often lightweight and marked with the railroad's abbreviated initials. See also: Car Seal, Car Door Key
- Case Hardened
- A heat treatment applied to the outer surface of a padlock shackle or body, creating a hardened exterior while the interior remains tough and resistant to fracture. Railroad switch lock shackles were frequently case hardened to resist cutting. The hardened layer is typically 1–2 mm deep.
- Coal Bin Key
- A key used to access coal storage facilities along the railroad right-of-way — typically at section houses, engine houses, and maintenance depots. Coal was the primary fuel for steam locomotives and heating of railroad buildings through the steam era. Coal bin keys are relatively scarce compared to switch keys.
- Conductor
- The railroad employee in charge of a train's operation and its passengers or freight. Conductors held keys to car locks, caboose compartments, and sometimes emergency switch access. Conductor's keys are a specific collecting category; some examples are marked "Conductor" or with a division number.
- Crossing Gate Key
- A key used to operate the locking mechanism of a grade crossing gate — the barrier lowered across a road when a train approaches. Crossing gate locks were maintained by the crossing watchman or section gang responsible for that portion of the right-of-way.
D
- Dead Key
- Collector slang for a switch key that has been identified as non-functional — either because its bit pattern does not match any documented lock type, or because it has been significantly altered. Also used informally to describe a key that is known not to open any currently serviceable lock.
- Depot Key
- A key used to access a railroad depot (station building) — including agent's offices, waiting rooms, baggage rooms, and freight areas. Depot keys were held by the station agent and may be marked with the station name, initials, or a numbered key tag. Finding a depot key with an associated tag or chain is uncommon. See also: Agent (Station Agent), Freight House Key
- Division
- An administrative subdivision of a railroad, typically defined by geography or operational unit. Railroads organized their maintenance and operations by division, and keys were often procured, distributed, and tracked at the division level. Some marked keys include a division number or divisional abbreviation alongside the railroad initials.
- Drop Forged
- A manufacturing method in which metal is shaped by pressing or hammering it between dies under high force. Drop forged keys are denser and stronger than die-cast keys. The majority of quality railroad switch keys from the 1880s onward were produced by drop forging, then finish machined.
E
- Engine House Key
- A key used to access a locomotive roundhouse or engine house — the facility where locomotives were serviced, stored, and repaired. Engine house keys were held by the roundhouse foreman and select mechanical department employees. They are less common than switch keys and often unmarked.
- Era
- In this archive, the historical period during which a key was manufactured or used, assigned in 20-year segments from 1850 to the present. Era classification is based on construction materials (brass vs. steel), manufacturing method, known railroad history, key style, and physical evidence of age. Assigning era with confidence typically requires multiple corroborating factors.
- Express Car Key
- A key used to access an express car — the dedicated freight car operated by an express company (Adams, American, United States, Wells Fargo, etc.) for the transport of valuables, mail, and high-value shipments. Express car locks were high-security by the standards of their era. Express keys are marked with the carrier's initials and are a significant collecting category. See also: Express Company
- Express Company
- A private freight carrier that operated over railroad lines under contract, transporting valuables, mail, and expedited freight. Major express companies include Adams Express, American Express, Southern Express, and Wells Fargo. Express company keys and padlocks are among the most widely collected railroad-related hardware, due to the large number of companies and the diversity of marked examples. See also: Express Car Key
F
- Fantasy Key
- A key produced after the fact to represent a railroad or marking that did not issue keys with that specific marking during regular service — or produced in a design inconsistent with the railroad's known key procurement. Fantasy keys are distinct from reproductions in that they may not copy a specific original, but are fabricated to appear collectible. Important to identify before purchase. See also: Reproduction
- Freight House Key
- A key used to access a freight house — the building at a depot where incoming and outgoing freight was received, sorted, and held for pickup. Freight house keys were held by the freight agent and authorized employees. Marked examples typically carry the railroad's initials and sometimes the station name. See also: Depot Key
G
- Gauge
- The distance between the inner faces of the two running rails of a railroad track. Standard gauge is 4 ft 8½ in (1,435 mm). Switch locks and keys were not typically gauge-specific, but narrow gauge railroad keys are a documented collecting category, as many narrow gauge lines had distinctive marking conventions. See also: Broad Gauge, Narrow Gauge
H
- Hollow Barrel Key
- The most common type of American railroad switch key — characterized by a hollow cylindrical shank that fits over a center post in the switch lock. The hollow barrel design became standard in the 1870s–1880s and remained so through the steam and early diesel eras. The interior diameter of the barrel and the bit profile at its base are key identification characteristics. See also: Barrel Key, Barrel Bit
- Hopper Car Key
- A key used to operate the locking gates on coal or ore hopper cars — the open-top cars used for bulk commodity transport. Hopper keys operated the bottom-discharge or side-gate mechanisms that released the load at the destination. A relatively uncommon category.
I
- Initials (Railroad Initials)
- The abbreviated form of a railroad's name stamped on a key — typically 2–6 letters representing the railroad's corporate name. For example, "UP" for Union Pacific, "B&O" for Baltimore and Ohio, "LVRR" for Ligonier Valley Railroad. Railroad initials are the primary identification marking on the majority of switch keys and the single most important field in attribution. See also: Marking, Attribution
K
- Key Chain
- A chain or ring used to keep a set of railroad keys together and attached to a beltloop, ring, or lanyard. Finding a switch key on its original railroad-issue chain significantly increases its provenance value. Chain styles varied by railroad and era.
- Key Tag
- A metal or celluloid tag attached to a key identifying its specific lock location, station, or use. Key tags with legible information are highly desirable to collectors as they provide direct provenance. Tags may be numbered, lettered, or bear descriptive text.
- Keyway
- The opening in a lock body through which the key is inserted. On switch locks, the keyway profile accepts the barrel of the switch key. Restricted or proprietary keyway profiles were used by some railroads to prevent unauthorized key duplication.
L
- Lever Tumbler
- A locking mechanism using flat pivoting plates (levers), each of which must be lifted to a precise height by the key before the bolt can move. Lever tumblers were common in earlier railroad padlocks before the widespread adoption of pin tumbler cylinders. High-security lever locks with six or eight levers were specified for some railroad applications. See also: Pin Tumbler
- Locking Dog
- A hardened steel component inside a switch lock or padlock body that physically engages the shackle leg to hold it locked. When the correct key is used, the locking dog retracts to release the shackle. In ball-locking designs, a steel ball serves this function.
M
- Maintenance of Way
- The department responsible for maintaining railroad track, structures, and right-of-way. Abbreviated MOW. Section gangs under the direction of section foremen were the frontline maintenance of way employees who operated and maintained track switches. MOW employees held the switch keys used in daily operations and were responsible for their custody. See also: Section Gang, Section Foreman
- Marking
- Any text, abbreviation, number, or symbol stamped, cast, or engraved on a key. The most important marking is typically the railroad's initials, but markings may also include the manufacturer's name, a patent date, a key number, a station name, or a department identifier. The location of the marking on the key (bow face, bow ring, shank, or bit) can also be diagnostic. See also: Initials (Railroad Initials), Attribution
- Master Key
- A key cut to operate multiple locks within a keyed system, in addition to each lock's individual key. Railroad master keys allowed supervisory personnel (roadmasters, division superintendents, railroad police) to access any lock in their district. Master keys for significant railroads are highly collectible and relatively scarce.
N
- Narrow Gauge
- A railroad track width narrower than standard gauge (4 ft 8½ in). Common narrow gauge widths in North America were 3 ft and 2 ft. Narrow gauge railroads — particularly mountain mining and logging lines — issued their own distinctive keys and locks. Nevada County Narrow Gauge, Rio Grande, and East Tennessee & Western North Carolina are notable narrow gauge collecting categories. See also: Gauge
- Nickel Plated
- A surface finish applied to some railroad keys in which a thin layer of nickel is electrodeposited over the base metal (typically brass or steel). Nickel plating resists corrosion and provides a bright, silver-toned appearance. Original nickel plating intact on an antique key is a desirable condition indicator. See also: Brass, Steel
- NOS (New Old Stock)
- A key or lock that has never been placed in service — retaining original finish, sharp stamping, and often found in original packaging or tied in a group. New old stock railroad keys surface occasionally from estate sales, depot closures, and railroad property auctions. NOS examples command a significant premium.
O
- Original Key
- The key made by the original manufacturer for a specific lock, as opposed to a duplicate, replacement, or copy made later. On collector padlocks, the presence of an original key substantially increases value. On switch locks, confirming originality requires matching the manufacturer and typically the bit profile to the lock.
P
- Pancake Lock
- A flat, disc-profile padlock used extensively on railroad applications including switch locks, section house locks, and car seals. The pancake form factor was produced by Adlake, Yale, Slaymaker, and others. Railroad pancake locks are frequently marked with the railroad's initials and are a major collecting category.
- Patina
- The surface coloration and texture that develops on a metal object through age, oxidation, and use. On brass railroad keys, genuine patina ranges from golden-yellow through amber, dark brown, and near-black, depending on age and storage conditions. Authentic patina is a key indicator of age; artificially induced or cleaned patina is a significant condition concern for collectors.
- Phantom Key
- A switch key marked with the initials of a railroad that is not documented as having issued keys with that specific marking — often the result of a very small road, a very brief operational period, or a non-standard abbreviation. Phantom keys require careful authentication; some represent legitimate rarities, while others are fantasy pieces. See also: Fantasy Key, Attribution
- Pin Tumbler
- A locking mechanism using spring-loaded pin stacks — each consisting of a key pin and a driver pin. The correct key lifts each pin stack to the precise height where the gap between key pin and driver pin aligns with the shear line, allowing the plug to rotate. Pin tumbler mechanisms became common in railroad padlocks by the early 20th century. See also: Lever Tumbler
- Predecessor Line
- A railroad that was absorbed, merged into, or reorganized to form a successor line. Keys from predecessor lines are often more scarce than keys from the larger successor, and can document the history of railroad consolidation. Predecessor markings may continue in use for years after a merger. See also: Amalgamated
- Provenance
- The documented or verifiable history of a key's origin, ownership, and location — establishing its authenticity and historical significance. Provenance for a railroad key might include a known origin point (estate of a railroad employee, a specific depot), a key tag, or archival records. Strong provenance significantly increases both historical and monetary value.
- Push Key
- A key that operates a spring-loaded lock by pressing the key directly into the keyway without rotating — the key compresses internal springs to release the shackle. Push key locks (also called Scandinavian or Polhem-type) were used for some railroad padlock applications where rapid one-handed operation was desired.
R
- Railroad Police Key
- A key issued to railroad police officers (also called special agents or railroad detectives) granting access to rail facilities, cars, or switches in their jurisdiction. Railroad police keys may be marked with a badge number, "Special Agent," "Police," or the railroad's initials. A scarce and historically interesting collecting category.
- Rarity
- In this archive, rarity is rated on a five-level scale: Common (regularly available), Uncommon (appears occasionally), Scarce (rarely seen for sale), Rare (few known examples), and Extreme (1–3 known to exist). Rarity is determined by documented examples in collections, historical production records, and the frequency of appearance at auction and in the collector market.
- Refrigerator Car Key
- A key used to access the ice bunkers, load compartments, or mechanical refrigeration equipment of refrigerator cars. Refrigerator car keys were held by the railroad or the refrigerator car company (Pacific Fruit Express, Santa Fe Refrigerator Despatch, etc.) and may carry the car company's initials rather than the railroad's.
- Reproduction
- A key made as a copy of an original, after the fact, without being produced during the railroad's operational period. Reproductions range from honest reference copies to deceptive fakes intended to deceive collectors. Signs of reproduction include sharp, uniform stamping on a blank with no service wear, incorrect metal alloy, and bit patterns that don't match any documented original. See also: Fantasy Key
- Right-of-Way
- The strip of land owned or controlled by a railroad over which its tracks and infrastructure run. Switch keys and locks secured the physical infrastructure of the right-of-way — track switches, signal boxes, section houses, and tool storage. Keys are tangible artifacts of the daily operational life along the right-of-way.
- Roadmaster
- The supervisory employee responsible for the physical condition of the track, structures, and right-of-way within a defined district. Roadmasters oversaw section gangs, authorized maintenance work, and were responsible for the security of track hardware including switches and their locks. A roadmaster's master key is a significant find. See also: Section Foreman, Maintenance of Way
- Round Bow
- A circular loop at the head of a key — the most common bow shape on American railroad switch keys. The round bow was easy to manufacture, comfortable to grip with gloved hands, and allowed rapid identification by touch in low-light conditions. Manufacturers including Adlake, Slaymaker, and Yale all produced round-bow switch keys. See also: Bow Shape
S
- Section Foreman
- The employee responsible for maintaining a specific section of railroad track, typically 6–8 miles in length. Section foremen supervised a small crew (the section gang) and were responsible for track inspection, repair, and the security of switches on their section. The section foreman held the switch keys for all switches in his territory. See also: Section Gang, Roadmaster
- Section Gang
- The crew of laborers responsible for maintaining a section of railroad track under the direction of a section foreman. Section gang members performed track inspection, spike driving, tie replacement, and switch maintenance. They operated switches using keys issued by the section foreman. See also: Section Foreman, Maintenance of Way
- Section House
- A building provided by the railroad for the housing of the section foreman and his crew, typically located at the midpoint of the track section. Section houses also served as tool storage facilities. A section house key accessed the building and its storage rooms; finding a key marked "Section House" is uncommon. See also: Section House Key
- Section House Key
- A key used to access a section house — the railroad-provided residence and tool storage facility for the section foreman and crew. Section house keys are less common in the collector market than switch keys and are often unmarked or marked only with the railroad's initials. See also: Section House
- Signal Box Key
- A key used to access a signal box or interlocking tower — the facility housing the mechanical levers and electrical controls that operated signals and switches in a complex track area. Signal boxes were supervised by operators or levermen who held specific keys. Signal box keys are an uncommon and historically significant collecting category.
- Slaymaker
- Henry Slaymaker & Sons (later Slaymaker Lock Company), Lancaster, Pennsylvania — a major manufacturer of padlocks and hardware for the American market from the mid-19th century. Slaymaker produced significant quantities of railroad switch locks and padlocks. Examples marked "Slaymaker" or "H. Slaymaker" are commonly encountered in railroad collections.
- Steel
- Beginning in the early 20th century, steel increasingly replaced brass as the primary metal for railroad switch keys, particularly as manufacturing costs and procurement practices changed. Steel keys are generally less attractive to collectors than brass examples, though the transition period produced some mixed-metal and plated variants of interest. See also: Brass, Drop Forged
- Switch
- A movable section of track (also called a turnout or points) that allows a locomotive or car to be diverted from one track to another. The switch is operated by a lever or handle, and the switch lock secures it in the correct position to prevent unauthorized movement. Switch keys were the daily-use tools of the section gang and train crew. See also: Switch Lock, Switch Key
- Switch Key
- A key used to operate a switch lock — the padlock or locking mechanism that secures a track switch (turnout) in position. Switch keys are the primary collecting category on this archive. They are characterized by a hollow barrel shank, a bow at the head for grip, and a bit at the tip that engages the lock mechanism. The term is sometimes used informally to describe any key associated with railroad operations. See also: Switch, Switch Lock, Hollow Barrel Key
- Switch Lock
- A padlock or locking device used to secure a track switch (turnout) in the correct position, preventing unauthorized manipulation that could cause a derailment. Switch locks were standardized in design across a given railroad's system, with all locks on a division or system keyed alike so that any authorized employee with the system key could operate any switch. See also: Switch, Switch Key
T
- Tank Car Key
- A key used to access the dome valves, sample hatches, or loading/unloading connections on a tank car. Tank car keys were held by the railroad, the shipper, or the tank car lessor depending on the specific application. Marked examples may carry the tank car company's initials rather than the railroad's.
- Tie
- The cross-member (also called a sleeper outside North America) that supports the rails and maintains track gauge. Railroad ties are part of the track structure maintained by the section gang. While ties themselves are not collected, "tie plug" keys — used to access tie tamping equipment — are occasionally encountered.
- Tumbler
- The internal security component of a lock mechanism — typically a lever, pin, or disc — that must be moved to a specific position by the correct key before the lock can be opened. The number and type of tumblers determines both the security level and the key profile required. See also: Lever Tumbler, Pin Tumbler
- Turnout
- An alternate term for a track switch — the movable rail assembly that diverts rolling stock from one track to another. A turnout consists of a switch point (movable rails), closure rails, frog, and guard rails. The switch lock secures the switch point in the correct position. See also: Switch
U
- Unmarked
- A switch key or lock bearing no railroad markings, manufacturer marks, or other identifying stamps. Unmarked keys are common and may represent generic procurement, keys from very small railroads, or keys from which markings have been removed. Attribution of unmarked keys is possible through bit pattern, bow shape, and construction details, but is inherently uncertain. See also: Attribution, Marking
V
- Variation
- A distinct version of a key or lock within a collecting category — distinguished by a different bow shape, bit pattern, marking style, manufacturer, or material. Documenting variations within a railroad's key history is a significant area of advanced collecting. Some railroads show only one or two known key variations; others show dozens across their operational history.
W
- Ward
- A fixed obstruction inside a keyway or lock mechanism that blocks all but the correctly shaped key from operating the lock. Warded locks are among the oldest lock types; the key's bit must have recesses that clear the wards to allow rotation. Warded switch locks were common in the 19th century before lever and pin tumbler mechanisms became standard. See also: Bit, Keyway
- Water Tower Key
- A key used to access a railroad water tower — the structure providing water for steam locomotive boilers at watering stops along the line. Water tower keys were held by the section foreman or tower maintenance crew and operated the access hatch, fill valve, or equipment room. Water tower keys are relatively uncommon as many towers were unmanned.
- Wilson Bohannan
- Wilson Bohannan Company, Mount Vernon, New York — a manufacturer of high-quality padlocks for industrial, railroad, and institutional use. Wilson Bohannan padlocks are recognized for their quality and are found in railroad applications including switch lock and facility security. The "WB" mark on a padlock indicates this maker.
Y
- Yale
- Yale & Towne Manufacturing Company (later Yale Security), Stamford, Connecticut — one of the largest American lock manufacturers and a major supplier to railroads. Linus Yale Jr.'s 1861 pin tumbler cylinder patent formed the basis of the Yale padlock line. Railroad switch locks and padlocks bearing the Yale name are among the most commonly encountered, with examples ranging from the 1870s through the 20th century. See also: Pin Tumbler