Examples of Emerson Electric Motors

(Photograph courtesy of Art Reblitz)

Emerson Electric “pancake” motor (named because of its thin, flat shape) installed in a 1920s Nelson-Wiggen Style 8. Other Emerson motors frequently had a series of round holes in the end bells instead of the triangular holes shown here.

(Photograph courtesy of Art Reblitz)

Nameplate on the above pictured Nelson-Wiggen Emerson motor.

(Photograph courtesy of Art Reblitz)

Emerson used several types of starting switches in their piano motors in the ‘teens and ‘twenties. At least two styles of switch incorporated the split cylindrical stator as pointed out in the above picture. The stator is made in two halves, separated by slots, and the two parts are wired in series with the starting winding. The rotating part of the switch, mounted on the armature (see following image pane), electrically connects the two parts of the stator when the motor is at rest, connecting the starting winding to the circuit when the motor is first turned on. When the armature reaches a certain speed, the contact pieces fly away from the stator and turn off the circuit to the starting winding.

(Photograph courtesy of Art Reblitz)

One type of Emerson switch utilizing the above stator has three brass fingers electrically connected to each other through their mounting plate, but insulated from the armature with fiber washers and standoffs. These three spring-loaded fingers rest against the stator, bridging across its two halves and connecting the starting circuit until a certain speed is attained, when centrifugal force causes them to fly apart, opening the starting circuit.

(Photograph courtesy of Art Reblitz)

This is the nameplate on the motor containing the three-arm switch in the two pictures above. We encourage readers to submit information for other motors, to determine whether or not the “DD” following the Type number represents the type of starting switch.

(Photograph courtesy of Art Reblitz)

The second type of starting switch using the split cylindrical stator has two crescent shaped pieces that are held against the switch stator by a pair of springs, and electrically connected with a small flexible wire at each end. When the rotor happens to stop with its gaps aligned with the gaps in the stator, the wires conduct across the gap and make the circuit. When the rotor attains running speed, centrifugal force pulls the switch parts away from each other, breaking the starting circuit. We believe this switch is earlier than the type with three spring-loaded pivot arms, but we need more information to confirm this. We are currently in the process of getting the nameplate information for the motor housing this armature.

(Photograph courtesy of Art Reblitz)

A third type of Emerson starting switch, pictured immediately above, has two parallel copper strips forming the stator, connected in series with the starting winding, instead of the split cylindrical copper stator. Also clearly visible in this photograph are the six large pole windings that make up the motor's running magnetic field. Between the larger windings are the much smaller starting current windings, which cause the motor to begin spinning in the desired direction and give it more starting torque. Once the motor nears its normal rated speed the starting windings are automatically disconnected by means of a centrifugally operated switch mounted within the rotating armature.

(Photograph courtesy of Art Reblitz)

In this third type of Emerson switch, the armature has a copper ring fitted over a fiber insulating disc that is free to spin separately from the armature. At rest, a coil spring presses the ring against the two copper strips in the previous picture, closing the starting circuit. The contact disc remains stationary as the rotor comes up to speed. At running speed, centrifugal force causes two spring-loaded weight arms to fly apart, diagonally pressing on the angled steel piece that supports the contact disc, pulling it back from the strips, and breaking the starting circuit. The fact that the ring doesn’t rotate while it is touching the stationary strips was thought to reduce the perennial sparking problem common with other Emerson motors, but this type of switch sparks like the others once it is contaminated with a film of old motor oil and dirt.

(Photograph courtesy of Art Reblitz)

Nameplate on the motor with the slip ring starting switch immediately above. The number M16524 indicates this motor might be newer than the example with three spring-loaded pivot arms above (M12024).

(Photograph courtesy of Art Reblitz)

A more streamlined Emerson motor installed in a 1924 Seeburg KT Special Orchestrion, one of the first of that model orchestrion ever made.

(Photograph courtesy of Art Reblitz)

Nameplate on the above pictured Seeburg 1924 KT Special Orchestrion motor.

(Photograph courtesy of Rusty King)

Emerson Electric Mfg. Co., motor No. 949828, Type 422DW, compound wound, 110V direct current, 1/12 H.P., and 900 RPM. This motor was reportedly once installed in a coin piano. It only has two field coils, which are large because of the compound winding. It is thought that the pulley for 5/16" round leather belting is original to the motor.

(Photograph courtesy of Rusty King)

Nameplate for Emerson Electric Mfg. Co. direct current motor No. 949828. This motor was reportedly once installed in a coin piano.