The use of an insulated outside rail to control train accessories has a history that starts with a 1915 patent. Lionel introduced its first product operated by an insulated outside rail in 1921.

By electrically isolating one outside rail from metal track ties, three rail toy train track allows engines or rolling stock to activate a trackside accessory. The wheels and axles of engines and rolling stock can be used to close an electrical connection across track outside rails.

By insulating one outside track rail from the other, a train's wheels and axles will provide a useful electrical action that can be used for operating accessories when trains enter a designated track area.

The first track-actuated accessory made by Lionel was the 69/O69 Electric Warning Signal (a ringing bell), introduced in 1921. The track section with an insulated outside rail that came with the accessory was a Lionel innovation. By attaching a lock-on to the isolated outside rail and the center rail and connecting the accessory to the lock-on, the accessory was operated from train power when any engine or rolling stock passed over the isolated rail track section.

The O69 version came with an O-gauge track section, the 69 came with a standard gauge track section. Otherwise, the accessories were the same.

A cardboard insert packed with the track section read:

"Use this special section of OSS track with O68 Warning signal, O76 Block Signal, O77 Crossing Gate, O80 Electric Semaphore and O99 Position Signal Light. Do not connect other accessories to this section or make current connections to it. The red fiber pins in the envelope packed with this track must be inserted in the ends of the insulated outside rail. Patented. Manufactured exclusively by the Lionel Corporation, New York."

Lionel used the terms OSS for a straight section and OCS for a curved section of "special" track, that is, with an insulated outside rail. The instruction sheet OSS and OCS Track shows how to operate accessories with an insulated outside rail using track voltage or a separate transformer connection.

The 76/O76 Block Signal came with two insulated rail track sections. Lock-ons connected each insulated outside rail to a light in the signal. The light would be on whenever a train was over the connected track section.

A brass plate on Lionel's 77/O77 Automatic Crossing Gate (1923 vintage) includes the text "PATENTED SEPT. 21, 1915 / THE LIONEL CORPORATION, N.Y." Patent number 1,153,922 was issued to Frank J. Hummel, Pittsburgh, Pennsylvania, on Sept. 21, 1915 for a "Toy Railroad." This patent teaches using an isolated outside rail to control a semaphore signal or a crossing gate. (Click to open Patent 1,153,922 images in a new window. Return to this page while they load.)

Lionel's name does not appear on the patent, but corporate assignments are not prevalent on patents of this vintage. Lionel could have acquired the patent from Frank Hummel before its introduction of the 69/O69 Electric Warning Signal.

Some versions of the 78/O78 Block signal are embossed with the word "PATENTED," and others carry the text "MADE BY THE LIONEL CORPORATION / NEW YORK / PATENTED / AUG. 21, 1917." Patent number 1,237,287 was issued to Willie J. Boemper, New York City, for a "Toy Railroad." (Click to open Patent 1,237,287 images in a new window. Return to this page while they load.)

This patent teaches using a pressure switch to activate a block signal light and to stop a train as it enters a station. A thermostat near the light heats up and, after a delay, causes the train to start again. Lionel is not mentioned in the patent, but Willie, being from New York, may have been an employee of Lionel.

Lionel offered the same train controlled trackside accessories in two versions, one for O-gauge and another for standard gauge. Which is why, even today, O-gauge block signals and other accessories are about twice as tall as a 1/4-inch-to-the-foot scale would suggest.

In 1936, Lionel introduced the 41 Track Contactor which could be used with O-gauge or standard gauge track. The 41 contactor replaced the special O-gauge and standard gauge track sections and train controlled accessories then needed to be offered in only one version, introducing the "N" (e.g. 69N) model designations. Insulated track sections could still be used to operate the accessory, but did not come with the accessory.

The 154C (circa 1940) and 1045C (circa 1938) contactors clamp onto rail sections so that a spring-loaded metal plate rests on top of an outside rail. The contactor plate is insulated from the outside rail. When a train wheel rides over the contactor plate, an electrical connection is made to the other outside rail, and a connected accessory is activated. This operation is similar to a track section with an insulated outside rail, except the insulated part is supplied by the contactor plate. A center-rail contact can be used to supply train power to the accessory.

The 1045C contactor is used to operate accessories such as the 1045 Watchman. The 154C contactor has two metal plates that rest on the outside rail, providing a "alternate flashing" capability for the Lionel 154 Automatic Highway Signal (sort of).

O22 switches use the insulated-rail technique to provide a non-derailing feature. Insulated outside rail sections in each track path are connected to the switch motor. A train approaching the switch activates the switch motor to throw the switch in the appropriate direction. The instruction sheet for O22 switches includes a section "Special Uses of the Non-Derailing Feature" which shows how to connect a 45N Gateman to the switch so it will operate when a train passes over one of the insulated outside rail sections of the switch.

John's first experience with an insulated outside rail was on his childhood layout. A Marx crossing gate came with a formed copper "over-rail" that fit over an outside rail and was insulated from it. An attached wire connected to the crossing gate. A lock-on was used to supply track voltage. A Marx highway crossbuck came with two short sections of over-rail. (Click the image.) They could be moved around to change the way the crossbuck lights flashed.

Unfortunately (or fortunately) the over-rail sections would loosen up and get snagged by the train. John solved the problem by loosening a track rail, wrapping the rail with friction tape, putting the rail back, and trimming the friction tape. Kitchen matches served as isolating pins.

This discovery led to all sorts of tricks, including connecting some salvaged pin-ball machine relays to insulated track sections and using them to run two trains on the same track.