Lippincott Steam Engine Indicator

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.
Currently not on view
Object Name
indicator, steam engine
Physical Description
oak (container material)
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
place made
United States: New Jersey
ID Number
catalog number
accession number
patent number
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Work and Industry: Mechanical and Civil Engineering
Industry & Manufacturing
Engineering, Building, and Architecture
Data Source
National Museum of American History, Kenneth E. Behring Center


"I have one of these that belonged to my father who was fascinated with steam engines. As a child he was constantly encouraging me to build a model steam engine and regretfully I never did. He was a auto mechanic by trade and I did however follow in his footsteps.Back to the Indicator. It appears to be fairly compete and in the original wooden case. The stylus is there however the main spring is broken.I assume the serial number is 2314 but not certain. There are still test sheets in the box along with with a book entitled The Steam-Engine Indicator, and its uses by W.B. Le Van. Book #78. Any additional information would be appreciated. Thank you!"

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