Krausch Engine Indicator Patent Model
date: label: date made
content: 1862
label: patent date
content: 1862-09-09
name: label: inventor
content: Krausch, C. W. T.
notes: label: Description
content: This model was submitted to the U.S. Patent Office with the application for the patent issued to C. W. T. Krausch, of Chicago, Illinois, September 9, 1862, no. 36411.
label: Description
content: The model represents an instrument designed to indicate and record speeds, draw-bar loads, boiler water levels, boiler pressures, steam-chest pressures, cylinder pressures, and conditions of the track connected with the operation of a locomotive engine and to plot these on a paper belt driven from a truck axle with a motion corresponding to the progress of the engine.
label: Description
content: A series of levers and markers corresponding to the number of the above operations to be recorded works transversely on the paper record as the paper is advanced by the progress of the engine. The marker indicating speed is actuated by a spring-balanced bellows, the motion of which is determined by the volume of air delivered to it by small air-pump cylinders actuated by any convenient part of the engine. The other markers are actuated mechanically by a series of levers to various indicating instruments on the engine, not described.*
label: Description
content: An engine indicator is an instrument for graphically recording the pressure versus piston displacement through an engine stroke cycle. Engineers use the resulting diagram to check the design and performance of the engine.
label: Description
content: A mechanical indicator consists of a piston, spring, stylus, and recording system. The gas pressure of the cylinder deflects the piston and pushes against the spring, creating a linear relationship between the gas pressure and the deflection of the piston against the spring. The deflection is recorded by the stylus on a rotating drum that is connected to the piston. Most indicators incorporate a mechanical linkage to amplify the movement of the piston to increase the scale of the record.
label: Description
content: When the ratio of the frequency of the pressure variation to the natural frequency of the system is small, then the dynamic deflection is equal to the static deflection. To design a system with a high natural frequency, the mass of the piston, spring, stylus, and mechanical linkage must be small, but the stiffness of the spring must be high. The indicator is subjected to high temperatures and pressures and rapid oscillations, imposing a limitation on the reduction in mass. Too stiff a spring will result in a small displacement of the indicator piston and a record too small to measure with accuracy. Multiplication of the displacement will introduce mechanical ad dynamic errors.
label: Description
content: The parameters of the problem for designing an accurate and trouble free recorder are such that there is no easy or simple solution. Studying the variety of indicators in the collection shows how different inventors made different compromises in their designs.
label: Description
content: *Reference:
label: Description
content: This description comes from the 1939 Catalog of the Mechanical Collections of the Division of Engineering United States Museum Bulletin 173 by Frank A. Taylor.
label: Location
content: Currently not on view
place: label: place made
content: United States: Illinois, Chicago
label: associated place
content: United States: Illinois, Chicago
setName: label: See more items in
content: Work and Industry: Mechanical and Civil Engineering
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content: Bulletin 173
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content: Engineering, Building, and Architecture
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content: Work
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content: Industry & Manufacturing
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content: Indicators
publisher: label: Related Publication
content: Frank A. Taylor. Catalog of the Mechanical Collections of the Division of Engineering United States National Museum, Bulletin 173
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: MC.308664
label: catalog number
content: 308664
label: patent number
content: 36,411
label: accession number
content: 89797
objectType: label: Object Name
content: indicator, steam engine. model
label: Object Name
content: patent model, engine indicator
label: Object Type
content: Patent Model
physicalDescription: label: Physical Description
content: brass, iron, wood, paper (overall material)
label: Measurements
content: overall: 8 7/8 in x 11 7/8 in x 11 3/4 in; 22.5425 cm x 30.1625 cm x 29.845 cm