History of the Erector Motor

The history of the Erector Electric Motor is a long and convoluted one. A.C. Gilbert, being the visionary that he was, recognized from the beginning that providing a means of animating models built with his new Erector sets would give them an added realism that would elevate them beyond the level of mere toys. So, in 1913, the first year of Erector production, he began a practice that would last until the end of traditional Erector production in 1962: at least one Erector set in each model year included an electric motor.

The first Erector motor was an interesting one, consisting of 31 separate parts which had to be assembled to create the final product. It was battery powered, as many subsequent Erector motors would be, and was designated the "Model 56", as noted in the 1913 Erector manual (not to be confused with the P56G, a 110-volt motor which first appeared in 1922). The Model 56 lasted only one year, being replaced in 1914 by a completely new, much improved (and fully assembled!) motor. Examples of the Model 56 are extremely rare today, no doubt due as much to the tendency of the individual parts to become lost or destroyed over time as to its limited production run.

P58 Electric MotorIn 1914, the P51 motor appeared as a replacement for the Model 56. Like its predecessor, it was battery powered, and also like its predecessor, it lasted only a single year, being replaced in 1915 by the motor which would serve as the main powerplant for Erector models for the next 24 years, the P58. While the P51 had been a significant improvement in both function and design over the Model 56, the P58 represented more of a "fine tuning" of the P51 which it replaced. The P58 was small, compact, and elegantly designed, measuring 2¼" h. x 2½" w. x 2¼" d. It was also quite sturdy, having a steel frame and all metal components, which accounted for its 10½ oz. weight.

The P58 was designed to operate over a range of voltages, lower voltage producing lower speeds, and vice versa. While this much is clear, there does seem to be some confusion as to the actual voltage range. The description of the P58 appears in the Separate Parts Prices listing for various years as "Motor, 6 to 14 volts" and "Motor, 6 to 24 volts." Whether this discrepancy was due to modifications in the motor's electrical components over time, or simply to typos in the manuals, is not clear. Further complicating the picture were the instructions for the motor in the Erector manuals. According to those instructions, "It [the P58] requires from one to four dry cells, according to the power desired. If used on storage batteries, one or two cells of two volts each, or a four volt battery will do nicely."

P59 Reversing BaseAccompanying the P58 motor into larger Erector sets in 1915 was another new electrical component, the P59 "Reversing Base." When wired into a motor-battery circuit, moving a lever on the P59 would reverse the direction of current flowing through the motor, thereby reversing the direction of motion (this simple yet clever device would, in effect, be replaced in later years by the reversing lever on the electrical engine gearbox). Four screws near the corners of the base could be used for mounting the P58 motor, or the base and motor could remain separate if necessary. This mounting feature came into play years later when the motor and base were offered as a combined unit (more on this later).

P56G Electric MotorIn 1920, a new battery-powered motor, the P73-B, joined the P58 in the Erector line. Like the Model 56 before it, it came unassembed. It was replaced two years later in 1922 by the 110-volt P56G, the first Erector motor to run on standard "house" current. The P56G was a bit larger and heavier than most of its predecessors, measuring 3½" h. x 2¾" w. x 3½" d. and weighing in at a hefty 18 oz. It was also more streamlined in design, but more utilitarian at the same time, with its simple, almost spherical black-painted housing. It had a black four-footed base which was attached to the bottom of the housing with two screws. In many sets, this base hung from the motor cord, separate from the housing, in order for the motor to fit properly into the box. The P56G appeared in Erector sets again in 1923, before disappearing for a year.


In this narrative, and in the pictorial timeline which accompanies it, dates are used exclusively to indicate the year(s) that a specific motor or other component was included in the inventory of at least one Erector set. However, during any given year, additional motors or electrical components may have appeared on the Extra Parts Price listing, and so were available for purchase.

For example, in 1935 two motors, the A52 "Induction Motor" and the P51 "Electric Engine", were part of the inventory of selected sets in the Erector line. However, in that same year four additional electrical items were shown on the Extra Parts listing: the P54 motor, P58 motor, P56G motor, and the P59 reversing base.

In 1924, the P56G motor was gone, but another new electrical component was added to the Erector line, the P60C transformer. Using the P60C, the P58 motor could now be powered by the same 110-volt AC "house" current that powered the P56G motor. In addition, the P60C was equipped with a rheostat which served, in effect, as a speed control for the motor by allowing the current to be increased or decreased incrementely over the entire voltage range.

The number of options for powering Erector models tripled in 1928 with the return of the P56G motor and the appearance of a new 110-volt motor, the P57, which was larger and more powerful than P56G. Despite this, the P57 was dropped from Erector sets by 1930. Also appearing in 1928 was an interesting but short-lived experiment in marketing which Gilbert dubbed the P54. This item was not really new, but instead represented a factory "mating" of the P58 motor and the now discontinued P59 reversing base.

By 1931, Erector motive power had been pared back to two options, the P58 and the P56G, which held sway through the end of the Classic Period of Erector sets and into the early years of the Transition Period. Then, in 1935, as Erector sets were undergoing major changes, so did the electric motors that they contained. After a nearly continuous 20-year run, the battery-powered P58 motor was replaced by a similar-looking 110-volt motor, the A52 "induction motor". In addition, the venerable P56G motor gave way to the new P51 "electric engine" (not to be confused with the 1914 P51 electric motor). This marked the first time battery powered motors were completely absent from Erector sets. Perhaps more significantly, 1935 marked the beginning of a new era in Erector power, that of the Electric Engine. Gilbert applied this term to the new P51, which included an integrated gearbox. He further refined this concept in the motor which eventually replaced the P51: the A49 Electric Engine. In the A49, the gearbox provided multiple speeds, as well as the ability to reverse motor direction (mechanically this time, rather than electrically as in the past with the P59), all by simply moving a lever. With the exception of a four-year period in the early 1950s, the A49, which first appeared in 1938, would remain the primary Erector power source until the demise of traditional Erector sets in 1962.

In 1936, the P58 returned for a last hurrah, joining the A52 which had replaced it, and the P51. Two years later, in 1938, another major change in Erector motive power took place. In that year, the P58 disappeared from Erector sets once and for all, to be replaced by the first and only mechanical motor ever to appear in an Erector set, the A48. This motor contained a large clockwork spring which was wound tight using a special key. The A48 remained in Erector sets until 1956, disappearing for only two years at the end of the 1940s.

As noted earlier, the A49 Electrical Engine also appeared for the first time in 1938. It measured 2¾" h. x 3" w. x 5½" l. and weighed a whopping 2 pounds 2 oz. During its long tenure as the most famous of all Erector motors, it underwent many minor engineering and cosmetic changes, while still retaining its well-known shape and general appearance. By 1940, the A49 was the only electric motor included in Erector sets. This was true until 1948, when a new electric motor, the P55 Remote Control Motor, joined it. The P55 was a low-voltage motor (7-15 volts) which originated in American Flyer trains, as did the transformer which powered it. The P55 was somewhat smaller than the A49, and was used to power models which could not accommodate the A49. By 1951, these models had been redesigned for the A49, and the P55 was gone after a short three-year run.

During this same period, a new electric engine temporarily replaced the A49 in Erector sets: the A47. The A47 differed from the A49 in several areas: the motor housing was formed from sheet metal rather than being cast; the integrated gearbox was sturdier than its A49 counterpart, and it also contained mounting holes in flanges along its lower edges. But, like many another of Gilbert's experiments with Erector motors, the A47 gave way after only four years to the motor it had originally replaced, the A49.

The new version of the A49 which appeared in 1954 differed from its previous incarnations in several ways: paint color was now blue-grey, there were minor cosmetic changes to the motor housing, and most significantly, it used the A47's improved gearbox. It continued to change over the next few years: in 1955, the Erector name was moved from the motor core to a yellow paper label glued to the motor guard; in addition, the gearbox side plates were painted red. Between 1956 and 1962, Erector's final year, changes to the A49 included: plated gearbox side plates (1956), engraved lettering on motor guard (1958), one-piece gearbox (1959), and raised lettering on the motor housing (1960), as well as several motor housing paint color changes.

The final Erector motor replacement came in 1957 when the A48 mechanical motor made way for the first new battery powered motor in many years, the DC3. This 3-volt motor along with the A49 remained in Erector sets until the end of Erector production in 1962. Unfortunately, the DC3 was inferior to the battery powered motors that had preceded it. It was underpowered, and its plastic case broke easily, which makes it difficult to find an intact example today. The DC3 was representative of the cost-cutting measures and subsequent decrease in quality that marked the decline of Erector during its final years.

P59 Reversing Base P56G 110 Volt motor P56G 110 Volt Motor P56G 110 Volt motor P56G 110 Volt Motor P54 Reversing Motor P54 Reversing Motor P57 110 Volt Motor P57 110 Volt Motor P58 P58 A48 Mechanical Motor P56G 110 Volt Motor A49 Electric Engine P58 P58 A48 Mechanical Motor A48 Mechanical Motor A48 Mechanical Motor A49 Electric Engine A47 Electric Engine A48 Mechanical Motor A48 Mechanical Motor P55 7-15 Volt Motor P55 7-15 Volt Motor A48 Mechanical Motor DC3 3 Volt Motor DC3 3 Volt Motor A47 Electric Engine A49 Electric Engine A49 Electric Engine A49 Electric Engine A48 Mechanical Motor DC3 3 Volt Motor DC3 3 Volt Motor Model 56 P51 P58 P59 Reversing Base P56G 110 Volt Motor Model 56 P51 P58 P58