Davenport Contact-Plate Electric Motor
US 132Revolving Galvanic Magnets, Fixed Copper Contact Plates, and Stationary Field Magnets
Listen to the narrated mechanical breakdown and civilizational context
How It Works: Step-by-Step Mechanical & Physical Breakdown
Davenport places galvanic magnets M, N, O, and P on a wooden wheel attached to vertical shaft R. Their copper wires contact detached copper plates K and L on the lower platform, while stationary artificial magnets S and T face the shaft from the upper platform. In the stated starting condition, battery connections make one rotating magnet north and another south; the stationary poles attract them through a quarter-circle. After the arms pass the pole centers, the moving wires reach different contact plates, changing the rotating poles so that the same stationary poles repel them. Repetition produces rotary shaft motion.
Interactive Real-Time Physical Simulation
Drag to rotate · Pinch to zoom · Shared controls update the displayed modelDetailed Component Architecture
1Platforms and supporting frame
The source gives the frame's role as structural support but deliberately permits its form to vary. It identifies upper and lower platforms instead of specifying a modern chassis material, dimension, or air gap.
2Galvanic battery and fixed contact plates
The patent places K and L on the lower platform, detached from the shaft and from each other. The moving coil wires touch different plates as the shaft turns; the source describes that contact sequence, not a rotating split-cylinder commutator, brush material, or contact force.
3Revolving galvanic magnets
The arms may be straight bars, horseshoes, or another form. Their wires run beside the shaft to the contact plates, and wheel V fixes the magnets to the shaft. That arrangement makes the rotating field responsive to rotor position without asserting a modern winding count or magnetic-flux value.
4Artificial magnets
Davenport permits ordinary steel magnets or stationary galvanic magnets, with a number and strength chosen for the apparatus. Their poles point toward the shaft; the specification's crucial distinction is that they remain fixed while the galvanic magnets rotate.
5Position-dependent pole change
In the source's illustrative state, magnet 2 becomes north from the copper-side battery path and magnet 4 becomes south from the zinc-side path. Attraction carries them past poles 5 and 6; their wires then touch different plates and the former attraction becomes repulsion. This describes a contact-controlled reversal, not a specified switch timing or rotation rate.
Governing Equations & Engineering Principles
Commutated Magnetic Torque & Electromagnetic Pole Attraction
Electromagnetics & DC MachinesClaim 1Instantaneous Electromagnetic Torque
Produced by magnetic attraction and repulsion between rotating electromagnets and fixed permanent magnets.
Thomas Davenport built the first patented practical DC electric motor in America. His key invention was the split-ring rotary commutator, which automatically reversed rotor magnetic polarity every half-turn just as the poles aligned, producing continuous rotary motion.
Historical Context: US 132 was the first patent granted for an electric motor, demonstrating that electricity could propel rotary machinery, printing presses, and model electric railways.
Electromagnetic Commutator Polarity Switching & Rotary Armature Torque
Electrical Engineering & Motive PowerClaim 1Electromagnetic Motor Torque
Produced by continuous magnetic attraction and repulsion between the revolving electromagnets and the fixed curved stator poles.
Thomas Davenport, a blacksmith from Brandon, Vermont, sold his wife's wedding dress to buy an electromagnet from Joseph Henry. He realized that if he split the copper contact ring so that current flipped polarity every half-turn, magnetic repulsion would spin the shaft continuously. In 1837, he received US Patent 132—the first patent for an electric motor in history.
Historical Context: US 132 proved that electricity could produce continuous rotary mechanical motion, establishing the electrical machine industry that powers all modern vehicles, appliances, and industrial drives.
reversing coil current reverses the electromagnet's poles
contact change → pole change → continued shaft torque
Interactive Schematic Sheet (Unnumbered drawing sheet)
The grant prints three unnumbered views: a perspective apparatus view, a rotor-and-field plan, and a lower contact-plate plan. The letters below follow the source rather than imposing a modern figure number.
Select Any Numbered Pin
Click pins on the schematic or select from the list below to inspect historical specifications.
Why It Still Matters
The facsimile gives a compact, inspectable account of a position-dependent contact system that changes rotating electromagnet poles to sustain shaft motion. It is most useful as an early primary-source example of the control problem behind continuous electromagnetic rotation, rather than as evidence for any particular modern motor design or performance figure.
Legal Claims Decoder (1 Numbered Claims)
The Historical Bottleneck
Why Prior Art Failed
- •The facsimile does not provide a comparative prior-art survey or numerical performance limits.
- •It instead distinguishes stationary artificial magnets from the revolving galvanic magnets and describes the contact sequence that changes the latter's poles.
- The first PDF page is an unnumbered drawing sheet; the specification spans the two remaining pages.
- The grant prints one unnumbered claim, represented as reader anchor Claim 1 without changing its wording.
The Polyphase Electric Grid
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The electrical revolution that replaced localized chemical galvanic cells and direct current with universal polyphase induction motors and high-voltage transmission.
Davenport Contact-Plate Electric Motor
Commutator-switched electromagnets creating continuous rotary motive torque.
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