hine and robertson new york steam engine arc indicator

I found this link above via Google search. Looks like vintage tool - something to do with steam engines, either trains or boats. Did your dad have either work or hobby in field of steam enginges? I think I’d make sure of what this was and potential value before offering for sale.

Thanks much, KW. My Dad and his Dad were both into such things. My Dad didn't really know but I'll go back to him with your info. He is 96 years old. This might jog his memory.

D.

@HU-419333994 Maybe this tool belonged to your grandpa, not your dad? The bits I found suggest it’s from early 1900’s.

Yes, quite likely. Edit - quite possible, I should say.

Is this yours? Or someone else?

https://www.ebay.com/itm/255603295107

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.

It is a steam Locomotive diagnostic instrument.

https://www.youtube.com/watch?v=gvo9Ve40Q8U

Thanks for that detailed info and the links, Michael. No, that eBay ad is not mine. I will definitely look at those resources.