Flagstaff Hill Maritime Museum and Village
Engine Dynamometer, c.1890’s
The steam engine indicator, or dynamometer, is an instrument used on a steam engine (such as that of a vessel or train) to measure and record the change in the pressures of the engine’s cylinders during their operating cycle. The engineer would use it to identify problems or defects such as bad valve settings or constricted steam pipes. It could indicate the difference in efficiency caused by adjustments made to the engine, being able to instantly measure the variation of pressure from the engine stroke at any given time. This force of power would be registered by a pencil, fitted to the adjustable arm, which would trace a line on paper wound around the cylinder.
The recorded information could be used in conjunction with mathematical tables.
This particular instrument was made by T.S. Mc Innes, one of the better manufacturers of engine indicators. Mc Innes engine indicators were still being used in the mid 1900’s.
This specific instrument was used by Mark Forsythe of North Berwial, Scotland and late of Ararat, Victoria when he was chief engineer on the “SS Talawena” in 1892.
The Port of Warrnambool, in Victoria, harboured steam ships that carried both passengers and cargo along the south west coast in the late 1800’s and into the 1900’s. The engineer of a steam ship was responsible for reaching and maintaining the optimum level of steam energy to serve the locomotion and efficiency of the steam ship. The engineer would use a steam engine indicator to measure and record information to achieve this purpose. Engine Dynamometer or Steam Engine Indicator in square, fitted oak case. This brass instrument is used to measure and record steam pressure for setting up and adjusting valves on a steam engine.
It has an oscillating recording drum with vertical, silver clip attached for holding paper in place around the drum. The drum oscillates left to right. There is a pulley attached to a length of cord, which is attached to the drum. Beside the drum is a fine metal arm, vertically adjustable, small hole in the end to hold a pencil. Inscription stamped into bracket of the arm.
The engine indicator is mounted on a hinged side of the case that swings out ready for use. Attached chains prevent the side from opening past vertical. There is storage for other accessories and an empty compartment in the base (where a scale or ruler may have been located).
The case has a collapsible wooden handle, brass hinges and two brass, hook-shaped catches. There is a code stamped inside the lid. It contains a brass, ‘T’ shaped steam-cock (or stop cock) with two open ends made of metal pipe with different sized threads. (Turning the handle on top opens and closes the space in the pipe and would close off the flow of steam from one end to the other.)
Also inside the case are three different spiral springs, each with a threaded nut on the end that has a threaded hole inside it. Used by Mr Mark Forsythe when chief engineer on the SS Talawena in 1892
“T.S. MC INNES PATENT” and “522 _ _” (last 2 digits are unreadable) pressed into the arm of the brass indicator.
“[ ] X ’ stamped inside the lid of the case.
The 3 springs all have a number stamped into them: (1) “32” and “12” (2) “12” and “16” [above] “12” (3) “64” and “150”
Card that came with instrument “This instrument was used by Mark Forsythe of North Berwial Scotland and late of Ararat, Victoria when chief engineer on the SS Talawena in 1892"
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