Four-pole Gramme-type demonstration dynamo
date: label: date made
content: ca 1890
notes: label: Description (Brief)
content: This unit is a mystery found in an attic at Princeton but staff there had no information about the piece. It appears to be laboratory demonstration device having a Gramme-type armature with a ordinary commutator on one side. A double-section pulley wheel (with a 1/8" air gap between the wheels) is attached to the opposite side of the armature shaft. A heavy brass balancing arm affixed to the top of the field-pole frame (directly above the armature) has adjustable steel rods at either end. One rod has a pointed tip, the other has a chiseled tip. Contact plates below each rod show a corresponding point and slot, respectively. There is a thin rod set to the front that appears to be a handle, but it is unclear what the handle might actuate. The frame is loose on the base plate, but cannot be adjusted in any dimension. The balancing arm is firmly fixed in place and cannot pivot in any direction. The only adjustments that can be made are the tension of the brushes on the commutator, and the rods which can be raised away from their contact plates about 1/2 inch. The entire unit is mounted on wooden base. The only extant marking is "84" in white chalk on the wooden base.
label: Location
content: Currently not on view
setName: label: See more items in
content: Work and Industry: Electricity
creditLine: label: Credit Line
content: from Palmer Physical Laboratory, Princeton University, thru A. G. Shenstone
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: EM.322765
label: catalog number
content: 322765
label: accession number
content: 248683
objectType: label: Object Name
content: electrical generator
label: Other Terms
content: Generator; Motors and Generators
physicalDescription: label: Measurements
content: overall: 11 1/2 in x 24 1/2 in x 18 1/2 in; 29.21 cm x 62.23 cm x 46.99 cm