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Bachelder Steam Engine Indicator

view Bachelder Steam Engine Indicator digital asset: Bachelder Steam Engine Indicator
Physical Description:
wood (case material)
Measurements:
overall: 4 3/4 in x 8 1/2 in x 8 3/4 in; 12.065 cm x 21.59 cm x 22.225 cm
in oak case - from catalog card: 8 1/4 in x 5 in x 8 3/4 in; 20.955 cm x 12.7 cm x 22.225 cm
Object Name:
indicator, steam engine
Date made:
1887
Description:
Thomas and Bushnell manufactured this steam engine indicator, serial number 482, based on a design by Joseph Bachelder, who received patent number 360644 on April 5, 1887. It consists of a brass piston, a brass cylinder, and a large drum with a coil spring and a single record. The cantilever spring is enclosed in the tube; an adjustable fulcrum renders one spring usable over a range of values. Two springs are included: one low pressure 10-25 (20-50 pounds) and one high pressure 30-90 (60-175 pounds).
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.
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.
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.
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.
Location:
Currently not on view
Subject:
Engineering, Building, and Architecture
Work
Industry & Manufacturing
Indicators
Credit Line:
Gift of Department of Mechanical Engineering, University of Illinois, Urbana, Illinois
ID Number:
MC*316789
Catalog number:
316789
Accession number:
228496
See more items in:
Work and Industry: Mechanical and Civil Engineering
Indicators
Data Source:
National Museum of American History, Kenneth E. Behring Center
Additional Online Media:

Tabor Steam Engine Indicator

view Tabor Steam Engine Indicator digital asset: Tabor Steam Engine Indicator, Patented on December 10, 1878
Maker:
Ashcroft Mfg. Co.
Physical Description:
wood (case material)
Measurements:
walnut case-from catalog card: 8 1/2 in x 6 in x 10 in; 21.59 cm x 15.24 cm x 25.4 cm
overall: 5 7/8 in x 9 3/4 in x 8 in; 14.9225 cm x 24.765 cm x 20.32 cm
Object Name:
indicator, steam engine
Place made:
United States: Connecticut
Description:
Ashcroft Mfg. Co. of Bridgeport, Connecticut, manufactured this Tabor steam engine indicator, serial number 2418. It consists of a steel piston with three grooves and a guide below the spring; a vented brass cylinder; an internal, single wound spring, which can be changed; a large drum with a coil spring and a single record. There is a Houghtaling worm gear reduction apparatus and a conical brass stylus. The piston, spring, and parts of the linkage are missing. Accompanying the indicator is a box with extra springs, piston, and worm reduction gear.
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.
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.
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.
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.
Location:
Currently not on view
Subject:
Engineering, Building, and Architecture
Work
Industry & Manufacturing
Indicators
Credit Line:
Gift of Department of Mechanical Engineering, University of Illinois, Urbana, Illinois
ID Number:
MC*316790
Catalog number:
316790
Accession number:
228496
See more items in:
Work and Industry: Mechanical and Civil Engineering
Indicators
Data Source:
National Museum of American History, Kenneth E. Behring Center

Tabor Steam Engine Indicator

view Tabor Steam Engine Indicator digital asset: Tabor Steam Engine Indicator
Maker:
Ashcroft Mfg. Co.
Physical Description:
wood (case material)
Measurements:
overall: 6 1/4 in x 9 7/8 in x 8 5/8 in; 15.875 cm x 25.0825 cm x 21.9075 cm
walnut case - from catalog card: 6 1/2 in x 8 1/2 in x 10 in; 16.51 cm x 21.59 cm x 25.4 cm
Object Name:
indicator, steam engine
Place made:
United States: Connecticut
Description:
Ashcroft Mfg. Co. of Bridgeport, Connecticut, manufactured this Tabor steam engine indicator, serial number 2325. It consists of a brass piston with three grooves; a vented brass cylinder; an internal, single wound spring, which can be changed; a large drum with a coil spring and a single record. The end of the linkage that holds the stylus is missing, as is the pulley. Accompanying the indicator is a box with several springs.
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.
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.
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.
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.
Location:
Currently not on view
Subject:
Engineering, Building, and Architecture
Work
Industry & Manufacturing
Indicators
Credit Line:
Gift of Department of Mechanical Engineering, University of Illinois, Urbana, Illinois
ID Number:
MC*316791
Catalog number:
316791
Accession number:
228496
See more items in:
Work and Industry: Mechanical and Civil Engineering
Indicators
Data Source:
National Museum of American History, Kenneth E. Behring Center
Additional Online Media:

Tabor Steam Engine Indicator

view Tabor Steam Engine Indicator digital asset: Tabor Steam Engine Indicator,  Patented on  December  10, 1878 and April 3, 1900
Maker:
Ashcroft Mfg. Co.
Physical Description:
wood (case material)
Measurements:
walnut case-from catalog card: 8 in x 8 1/2 in x 10 in; 20.32 cm x 21.59 cm x 25.4 cm
overall: 7 1/2 in x 9 3/4 in x 8 1/4 in; 19.05 cm x 24.765 cm x 20.955 cm
Object Name:
indicator, steam engine
Place made:
United States: Connecticut
Description:
Ashcroft Mfg. Co. of Bridgeport, Connecticut, manufactured this Tabor steam engine indicator, serial number 7171. It consists of a brass piston with three grooves; a vented brass cylinder; an external, single wound spring, which can be changed; a large drum with a coil spring and a single record. The small knob to adjust the stylus pressure is missing. Accompanying the indicator is a box with several springs and reduction gear.
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.
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.
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.
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.
Location:
Currently not on view
Subject:
Engineering, Building, and Architecture
Work
Industry & Manufacturing
Indicators
Credit Line:
Gift of Department of Mechanical Engineering, University of Illinois, Urbana, Illinois
ID Number:
MC*316792
Catalog number:
316792
Accession number:
228496
See more items in:
Work and Industry: Mechanical and Civil Engineering
Indicators
Data Source:
National Museum of American History, Kenneth E. Behring Center

Integrating Steam Engine Indicator

view Integrating Steam Engine Indicator digital asset: Integrating Steam Engine Indicator
Physical Description:
wood (case material)
Measurements:
overall: 4 7/8 in x 9 3/4 in x 10 in; 12.3825 cm x 24.765 cm x 25.4 cm
overall - from catalog card: 4 in x 7 in x 7 in; 10.16 cm x 17.78 cm x 17.78 cm
Object Name:
indicator, steam engine
Description:
This device is designed to integrate the area under the indicator diagram and will total the work for several strokes of the piston. A small metal cylinder about one inch by three-quarters is geared to a counter. The cylinder turns about its horizontal axis, and a small metal disc bears against the cylinder. The plane of the disc coincides with the axis of the cylinder and is turned by the motion of the indicator piston. The motion of the engine piston moves the cylinder horizontally. This combined action results in the rotation of the cylinder. The increment to rotation is proportional to the angle of the disc.
The manufacturer of this indicator is unknown. The spring is missing, although Thompson indicator springs will fit it. Similar instruments are described in William Robinson’s book Gas and Petroleum Engines: A Manual for Students and Engineers (Spon & Chamberlain, New York: 1902).
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.
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.
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.
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.
Location:
Currently not on view
Subject:
Engineering, Building, and Architecture
Work
Industry & Manufacturing
Indicators
Credit Line:
Gift of Department of Mechanical Engineering, University of Illlinois, Urbana, Illinois
ID Number:
MC*316793
Catalog number:
316793
Accession number:
228496
See more items in:
Work and Industry: Mechanical and Civil Engineering
Indicators
Data Source:
National Museum of American History, Kenneth E. Behring Center
Additional Online Media:

Tabor Steam Engine Indicator

view Tabor Steam Engine Indicator digital asset: Tabor Steam Engine Indicator
Maker:
Ashcroft Mfg. Co.
Physical Description:
wood (case material)
Measurements:
overall: 5 1/4 in x 9 1/4 in x 8 3/8 in; 13.335 cm x 23.495 cm x 21.2725 cm
walnut case - from catalog card: 5 1/4 in x 7 1/2 in x 9 1/4 in; 13.335 cm x 19.05 cm x 23.495 cm
Object Name:
indicator, steam engine
Place made:
United States: Connecticut
Description:
Ashcroft Mfg. Co. of Bridgeport, Connecticut, manufactured this Tabor steam engine indicator, serial number 2329. It consists of a steel piston with a guide below the spring; a vented brass cylinder; an internal, single wound spring, which can be changed; a large drum with a coil spring and a single record. The piston, spring, and parts of the linkage are missing.
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.
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.
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.
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.
Location:
Currently not on view
Subject:
Engineering, Building, and Architecture
Work
Industry & Manufacturing
Indicators
Credit Line:
Gift of Department of Mechanical Engineering, University of Illinois, Urbana, Illinois
ID Number:
MC*316794
Catalog number:
316794
Accession number:
228496
See more items in:
Work and Industry: Mechanical and Civil Engineering
Indicators
Data Source:
National Museum of American History, Kenneth E. Behring Center
Additional Online Media:

Crosby Steam Engine Indicator

view Crosby Steam Engine Indicator digital asset: Crosby Steam Engine Indicator
Maker:
Crosby Steam Gage & Valve Company
Physical Description:
wood (case material)
Measurements:
overall: 4 5/8 in x 7 3/4 in x 7 1/8 in; 11.7475 cm x 19.685 cm x 18.0975 cm
walnut case - from catalog card: 4 3/4 in x 6 3/4 in x 7 3/4 in; 12.065 cm x 17.145 cm x 19.685 cm
Object Name:
indicator, steam engine
Place made:
United States: Massachusetts
Description:
Crosby Steam Gauge & Valve Co. of Boston, Massachusetts, manufactured this steam engine indicator, serial number 3309. It consists of a piston, which is stuck inside the cylinder. A brass stylus can record onto a large small drum with a spiral spring and a single record. Accompanying the indicator is a box with twelve springs and a spring wrench.
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.
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.
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.
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.
Location:
Currently not on view
Subject:
Engineering, Building, and Architecture
Work
Industry & Manufacturing
Indicators
Credit Line:
Gift of Department of Mechanical Engineering, University of Illinois, Urbana, Illinois
ID Number:
MC*316795
Catalog number:
316795
Accession number:
228496
See more items in:
Work and Industry: Mechanical and Civil Engineering
Indicators
Data Source:
National Museum of American History, Kenneth E. Behring Center
Additional Online Media:

Crosby Steam Engine Indicator

view Crosby Steam Engine Indicator digital asset: Crosby Steam Engine Indicator
Physical Description:
wood (case material)
Measurements:
overall: 5 1/2 in x 10 in x 8 1/8 in; 13.97 cm x 25.4 cm x 20.6375 cm
Object Name:
indicator, steam engine
Place made:
United States: Massachusetts
Description:
Crosby Steam Gauge & Valve Co. of Boston, Massachusetts, manufactured this steam engine indicator, serial number 10021. It consists of a steel piston with four grooves, a vented brass cylinder, an internal spring (which is missing), a small drum with a spiral spring and a single record, and a brass stylus. Accompanying the indicator is a box with twelve springs, double wound.
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.
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.
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.
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.
Location:
Currently not on view
Subject:
Engineering, Building, and Architecture
Industry & Manufacturing
Work
Indicators
Credit Line:
Gift of Department of Mechanical Engineering, University of Illinois, Urbana, Illinois
ID Number:
MC*316796
Catalog number:
316796
Accession number:
228496
Patent number:
10021
See more items in:
Work and Industry: Mechanical and Civil Engineering
Indicators
Data Source:
National Museum of American History, Kenneth E. Behring Center
Additional Online Media:

Crosby Steam Engine Indicator

view Crosby Steam Engine Indicator digital asset: Crosby Steam Engine Indicator
Maker:
Crosby Steam Gage & Valve Company
Physical Description:
wood (container material)
Measurements:
overall: 5 3/4 in x 10 in x 8 1/2 in; 14.605 cm x 25.4 cm x 21.59 cm
walnut case - from catalog card: 5 3/4 in x 7 3/4 in x 10 in; 14.605 cm x 19.685 cm x 25.4 cm
Object Name:
indicator, steam engine
Place made:
United States: Massachusetts
Description:
Crosby Steam Gauge & Valve Co. of Boston, Massachusetts, manufactured this steam engine indicator, serial number 1074D. It consists of a steel piston; a vented brass cylinder; an external, double wound spring, which can be changed; a large drum with a spiral spring and a single record; and a brass stylus. Accompanying the indicator is a box with twelve springs and some small tools.
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.
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.
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.
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.
Location:
Currently not on view
Subject:
Engineering, Building, and Architecture
Work
Industry & Manufacturing
Indicators
Credit Line:
Gift of Department of Mechanical Engineering, University of Illinois, Urbana, Illinois
ID Number:
MC*316797
Catalog number:
316797
Accession number:
228496
Patent number:
1074D
See more items in:
Work and Industry: Mechanical and Civil Engineering
Indicators
Data Source:
National Museum of American History, Kenneth E. Behring Center
Additional Online Media:

Crosby Gas Engine Indicator

view Crosby Gas Engine Indicator digital asset: Crosby Gas Engine Indicator
Maker:
Crosby Steam Gage & Valve Company
Physical Description:
wood (case material)
Measurements:
overall: 5 3/8 in x 8 1/2 in x 8 in; 13.6525 cm x 21.59 cm x 20.32 cm
walnut case - from catalog card: 5 1/2 in x 7 in x 8 1/2 in; 13.97 cm x 17.78 cm x 21.59 cm
Object Name:
indicator, gas engine
Place made:
United States: Massachusetts
Description:
Crosby Steam Gauge & Valve Co. of Boston, Massachusetts, manufactured this steam engine indicator, serial number 8619. It consists of a steel piston with four grooves, a vented brass cylinder, an internal spring (which is missing), a small drum with a spiral spring and a single record, and a brass stylus. Accompanying the indicator is a box with twelve springs, double wound, and some small tools.
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.
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.
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.
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.
Location:
Currently not on view
Subject:
Engineering, Building, and Architecture
Industry & Manufacturing
Work
Indicators
Credit Line:
Gift of Department of Mechanical Engineering, University of Illinois, Urbana, Illinois
ID Number:
MC*316798
Catalog number:
316798
Accession number:
228496
Patent number:
8619
See more items in:
Work and Industry: Mechanical and Civil Engineering
Indicators
Data Source:
National Museum of American History, Kenneth E. Behring Center
Additional Online Media:

Crosby Gas Engine Indicator

view Crosby Gas Engine Indicator digital asset: Crosby Gas Engine Indicator
Maker:
Crosby Steam Gage & Valve Company
Physical Description:
wood (case material)
Measurements:
overall: 4 3/8 in x 8 in x 6 3/4 in; 11.1125 cm x 20.32 cm x 17.145 cm
walnut case - from catalog card: 4 1/2 in x 6 1/2 in x 8 in; 11.43 cm x 16.51 cm x 20.32 cm
Object Name:
indicator, gas engine
Place made:
United States: Massachusetts
Description:
Crosby Steam Gauge & Valve Co. of Boston, Massachusetts, manufactured this steam engine indicator, serial number 6163. It consists of a small steel piston (1/8 inch); a vented brass cylinder; an internal, double wound spring, which can be changed; a small drum with a spiral spring and a single record; and a brass stylus. Accompanying the indicator is a box with fourteen springs, small tools, and an extra piston with top stem.
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.
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.
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.
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.
Location:
Currently not on view
Subject:
Engineering, Building, and Architecture
Industry & Manufacturing
Work
Indicators
Credit Line:
Gift of Department of Mechanical Engineering, University of Illinois, Urbana, Illinois.
ID Number:
MC*316799
Catalog number:
316799
Accession number:
228496
Patent number:
6163
See more items in:
Work and Industry: Mechanical and Civil Engineering
Indicators
Data Source:
National Museum of American History, Kenneth E. Behring Center
Additional Online Media:

Lippincott Steam Engine Indicator

view Lippincott Steam Engine Indicator digital asset: Lippincott Steam Engine Indicator
Physical Description:
oak (container material)
Measurements:
overall: 5 1/2 in x 9 1/2 in x 9 7/8 in; 13.97 cm x 24.13 cm x 25.0825 cm
oak case - from catalog card: 6 in x 9 1/2 in x 9 1/2 in; 15.24 cm x 24.13 cm x 24.13 cm
Object Name:
indicator, steam engine
Place made:
United States: New Jersey
Description:
The Lippincott Steam Specialty and Supply Co. manufactured this steam engine indicator, serial number 1380. It consists of a steel piston with two grooves and a bottom guide; a brass cylinder; an internal spring, which is missing; a small drum with a spiral spring and single record. The stylus is missing, but assumed to be a lead pencil point. Accompanying the indicator is a box with four springs, and extra piston, a wrench, reduction pulleys, record cards, and scales.
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.
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.
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.
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.
Location:
Currently not on view
Subject:
Engineering, Building, and Architecture
Industry & Manufacturing
Work
Indicators
Credit Line:
Gift of Department of Mechanical Engineering, University of Illinois, Urbana, Illinois
ID Number:
MC*316800
Catalog number:
316800
Accession number:
228496
Patent number:
1380
See more items in:
Work and Industry: Mechanical and Civil Engineering
Indicators
Data Source:
National Museum of American History, Kenneth E. Behring Center
Additional Online Media:

Thompson Steam Engine Indicator

view Thompson Steam Engine Indicator digital asset: Thompson Steam Engine Indicator
Physical Description:
wood (case material)
Measurements:
overall: 4 5/8 in x 8 5/8 in x 7 in; 11.7475 cm x 21.9075 cm x 17.78 cm
walnut case-from catalog card: 4 1/2 in x 7 1/4 in x 9 in; 11.43 cm x 18.415 cm x 22.86 cm
Object Name:
indicator, steam engine
Place made:
United States: Massachusetts
Description:
The American Steam Gauge Co. of Boston, Massachusetts, manufactured this steam engine indicator, serial number 1875. J.W. Thompson patented this style of indicator on August 31, 1875, patent number 167,364.
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.
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.
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.
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.
Location:
Currently not on view
Subject:
Engineering, Building, and Architecture
Industry & Manufacturing
Work
Indicators
Credit Line:
Gift of Department of Mechanical Engineering, University of Illinois, Urbana, IIlinois
ID Number:
MC*316801
Catalog number:
316801
Accession number:
228496
Patent number:
2547
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Work and Industry: Mechanical and Civil Engineering
Indicators
Data Source:
National Museum of American History, Kenneth E. Behring Center
Additional Online Media:

Star Steam Engine Indicator

view Star Steam Engine Indicator digital asset: Star Steam Engine Indicator,  Patented on  February 16, 1904
Physical Description:
wood (container material)
Measurements:
walnut case-from catalog card: 6 in x 9 in x 10 in; 15.24 cm x 22.86 cm x 25.4 cm
overall: 5 5/8 in x 9 3/4 in x 8 5/8 in; 14.2875 cm x 24.765 cm x 21.9075 cm
Object Name:
indicator, steam engine
Place made:
United States: Massachusetts
Description:
The Star Brass Mfg. Co. manufactured this steam engine indicator, serial number 485. It consists of a steel piston; a steel cylinder; an external spring, which is missing; a small drum with a spiral spring and a single record. The stylus is missing, but is likely a pencil point. The accompanying box has five double wound springs.
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.
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.
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.
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.
Location:
Currently not on view
Subject:
Engineering, Building, and Architecture
Work
Industry & Manufacturing
Indicators
Credit Line:
Gift of Department of Mechanical Engineering, University of Illinois, Urbana, Illinois.
ID Number:
MC*316802
Catalog number:
316802
Accession number:
228496
See more items in:
Work and Industry: Mechanical and Civil Engineering
Indicators
Data Source:
National Museum of American History, Kenneth E. Behring Center

Robertson-Thompson Steam Engine Indicator

view Robertson-Thompson Steam Engine Indicator digital asset: Robertson-Thompson Improved Steam Engine Indicator
Measurements:
box - from catalog card: 7 in x 9 1/2 in x 10 1/2 in; 17.78 cm x 24.13 cm x 26.67 cm
overall: 7 1/4 in x 6 in x 2 in; 18.415 cm x 15.24 cm x 5.08 cm
Object Name:
indicator, steam engine
Place made:
United States: New York
Date made:
ca 1900
Description:
This Robertson-Thompson steam engine indicator, serial number 7735, consists of a brass piston with two grooves; a brass cylinder; an internal, single wound spring, which can be changed; a medium sized drum with a coil spring and a single record; and a short pencil lead for the stylus. Accompanying the indicator is a box with two extra springs, drum springs, seven wooden pulleys for the reducer, two scales, and two extra pistons.
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.
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.
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.
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.
Location:
Currently not on view
Subject:
Engineering, Building, and Architecture
Work
Industry & Manufacturing
Indicators
Credit Line:
Gift of Mr. William Slater Allen, Providence 7, Rhode Island.
ID Number:
MC*318483
Catalog number:
318483
Accession number:
234643
See more items in:
Work and Industry: Mechanical and Civil Engineering
Indicators
Data Source:
National Museum of American History, Kenneth E. Behring Center

Crosby Steam Engine Indicator

view Crosby Steam Engine Indicator digital asset: Crosby Steam Engine Indicator
Maker:
Crosby Steam Gage & Valve Company
Physical Description:
wood (case material)
Measurements:
in case-from catalog card: 8 in x 6 1/2 in x 4 1/2 in; 20.32 cm x 16.51 cm x 11.43 cm
overall: 4 3/8 in x 8 in x 6 3/8 in; 11.1125 cm x 20.32 cm x 16.1925 cm
Object Name:
indicator, steam engine
Place made:
United States: Massachusetts, Boston
Date made:
ca 1885
Description:
Crosby Steam Gauge & Valve Co. of Boston, Massachusetts, manufactured this steam engine indicator, serial number 330. It consists of a brass piston with one groove, a vented brass cylinder, an internal, double wound spring which can be changed, and a small drum with a spiral spring and single record. The stylus is missing. Accompanying the indicator is a box with two springs, two turn cocks, a scale, and small tools.
This indicator was made for W. J. Hammer, Chief Inspector of Edison Light Co. There is a nickel-plated name plate on the front marked: “Property of W. J. Hammer, 65 Fifth Ave, New York.”
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.
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.
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.
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.
Location:
Currently not on view
Subject:
Engineering, Building, and Architecture
Work
Industry & Manufacturing
Indicators
Credit Line:
Gift of International Business Machines Corp., New York
ID Number:
MC*320555
Catalog number:
320555
Accession number:
241402
See more items in:
Work and Industry: Mechanical and Civil Engineering
Indicators
Data Source:
National Museum of American History, Kenneth E. Behring Center
Additional Online Media:

Bacharach Steam Engine Indicator

view Bacharach Steam Engine Indicator digital asset: Bacharach Steam Engine Indicator
Maker:
Bacharach Industrial Instrument Co.
Physical Description:
wood (case material)
metal (case material)
nickel plated brass (overall material)
aluminum (overall material)
Measurements:
overall: 5 7/8 in x 8 3/4 in x 9 in; 14.9225 cm x 22.225 cm x 22.86 cm
Object Name:
indicator, steam engine
Place made:
United States: Pennsylvania, Pittsburgh
Date made:
early 20th century
Description:
Bacharach Industrial Instrument Co. manufactured this steam engine indicator. It consists of a large steel piston with three grooves; a vented brass cylinder; an external, double wound spring, which can be changed; an aluminum drum with a small spiral spring and single record; and a small brass stylus. Accompanying the indicator is a box with three springs and some small tools. The pulley and bracket are missing.
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.
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.
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.
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.
Location:
Currently not on view
Subject:
Engineering, Building, and Architecture
Work
Industry & Manufacturing
Indicators
ID Number:
MC*325992
Catalog number:
325992
Accession number:
308486
Serial number:
50597
See more items in:
Work and Industry: Mechanical and Civil Engineering
Indicators
Data Source:
National Museum of American History, Kenneth E. Behring Center
Additional Online Media:

De Juhasz Gas Engine Indicator

view De Juhasz Gas Engine Indicator digital asset: Dejuhasz Gas Engine Indicator
Measurements:
overall: 6 in x 9 1/8 in x 7 in; 15.24 cm x 23.1775 cm x 17.78 cm
Object Name:
indicator, gas engine
Description:
This gas engine indicator, manufactured by Kalman J. De Juhasz, is very similar to another one in the collection (catalog number 311.621). It is a modification of the steam engine indicator to adapt it for use on diesel engines. The improvements consist of cooling fins, reduced masses of piston and pencil movement, light Bakelite drum, ball bearings for drum and roller, and a built-in indicator.
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.
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.
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.
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.
Location:
Currently not on view
Subject:
Engineering, Building, and Architecture
Work
Industry & Manufacturing
Indicators
Credit Line:
Gift of Estate of Kalman J. Dejuhasz, State College, Pennsylvania
ID Number:
1981.0217.02
Accession number:
1981.0217
Catalog number:
1981.0217.02
See more items in:
Work and Industry: Mechanical and Civil Engineering
Indicators
Data Source:
National Museum of American History, Kenneth E. Behring Center

Schaeffer & Budenberg Steam Engine Indicator

view Schaeffer & Budenberg Steam Engine Indicator digital asset: Schaeffer & Budenberg Steam Engine Indicator
Maker:
Schaeffer and Bundenberg Manufacturing Company
Physical Description:
wood (case material)
brass (overall material)
Measurements:
overall: 4 1/2 in x 16 7/8 in x 11 1/4 in; 11.43 cm x 42.8625 cm x 28.575 cm
Object Name:
indicator, steam engine
Description:
Shaeffer & Budenberg manufactured this steam engine indicator. It consists of a large brass piston with a single groove; a vented brass cylinder; an internal, single wound spring, which can be changed; a large drum with a spiral spring and single record; and a heavy brass stylus. Accompanying the indicator is a wooden box with three scales and a wooden ram rod.
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.
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.
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.
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.
Location:
Currently not on view
Subject:
Engineering, Building, and Architecture
Work
Industry & Manufacturing
Indicators
Credit Line:
Gift from Estate of Kalman J. Dejuhasz, State College, Pennsylvania
ID Number:
1981.0217.03
Accession number:
1981.0217
Catalog number:
1981.0217.03
See more items in:
Work and Industry: Mechanical and Civil Engineering
Indicators
Data Source:
National Museum of American History, Kenneth E. Behring Center
Additional Online Media:

Ashcroft Tabor Steam Engine Indicator

view Ashcroft Tabor Steam Engine Indicator digital asset: Ashcroft-Tabor Steam Engine Indicator
Physical Description:
brass (overall material)
wood (container material)
Measurements:
overall: 5 in x 9 1/2 in x 7 3/4 in; 12.7 cm x 24.13 cm x 19.685 cm
Object Name:
indicator, steam engine
Description:
Ashcroft Mfg. Co. of Bridgeport, Connecticut, manufactured this Tabor steam engine indicator, serial number 2604. It consists of a brass piston with three grooves; a vented brass cylinder; an internal, single wound spring, which can be changed; a large drum with a coil spring and a single record; and a short pencil lead for the stylus. Accompanying the indicator is a box with eight springs, two turn cocks, a coil spring for the drum, and a small wooden knob. The internal spring is missing.
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.
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.
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.
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.
Location:
Currently not on view
Subject:
Engineering, Building, and Architecture
Work
Industry & Manufacturing
Indicators
Credit Line:
Gift of Estate of Kalman J. Dejuhasz, State College, Pennsylvania
ID Number:
1981.0217.06
Accession number:
1981.0217
Catalog number:
1981.0217.06
See more items in:
Work and Industry: Mechanical and Civil Engineering
Indicators
Data Source:
National Museum of American History, Kenneth E. Behring Center

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