steam cylinder oil winker mounted on the dash below and between the steam pressure gauge (left) and the fuel pressure gauge (right).  The dash light is just above the winker.

A steam engine does not have a crankcase similar to an internal combustion engine. Lubricating oil contained in the crankcase of the internal combustion engine is pumped and splashed onto the cylinder walls as the engine runs and lubricates the sliding interface between the moving piston and the stationary cylinder wall.

In order to lubricate the piston and cylinder wall of a steam engine the oil is injected into the steam supply. While the oil quantity in a crankcase can be checked with a dipstick, a winker is used on a Stanley Steam Car to visibly indicate lubricating oil is flowing to the engine. 

Mounted within a nickel plated disk between the steam and fuel pressure gauges on the dash, the dark eye of the winker is easy to observe as it "winks". The winker alternately turns silvery to dark brown and back to silvery with each stroke of the power oil pump indicating proper oil flow to the engine for lubrication.



The winker assembly (shown at left) provides an indication that steam cylinder oil is flowing to the engine to lubricate the slide valves and pistons.  Invented and patented (patent number 694,406) on March 4, 1902 by Benjamin T. McCanna and Thomas A. Delaney of Chicago, the device was assigned to and manufactured by Hills-McCanna Company of Chicago.  The origins of Hills-McCanna still exist today as the McCanna Division of Worcester Controls manufacturing a wide selection of industrial ball valves.

Operation of the winker is simple.  When no oil is flowing the "eye" of the winker is clear showing the "iris" as shown in the photo.  When oil is passing through the winker the eye turns dark as depicted in the photo to the right.

Oil flow from the power steam cylinder oil pump is piped to the right leg of the winker.  The left leg of the winker is the discharge and which includes a standard ball and spring check valve (shown in the disassembled view of the winker below).  The discharge from the winker is piped to a fitting tapped into the side of the steam line which runs back to the engine.

The power steam oil pump is a piston pump and thus pumps oil in pulses.  It is this pulsing action of pumping oil that causes the winker sight glass to alternate between fully dark with oil and back to silvery again when no oil is present.  As the power steam oil pump's plunger is pushed into the pump by the pump drive oil is discharged from the pump.  That oil flows through tubing between the pump and the winker and ends up flowing out a small port in the top surface of the winker (the port is indicated by arrow 1 in the photo).  That oil fills a cavity between the glass and the body of the winker.

Pressed up against the glass is a spring loaded plunger assembly that includes a small hole in the cap (indicated by arrow 2 in the photo).  As the oil fills the cavity the pressure of the oil as exerted by the pump causes the plunger to compress the spring and thus the plunger is pushed away from the back side of the glass and the winker eye appears totally dark.  Once the pump reaches the end of its stroke no more oil is being pumped and the spring attempts to push the plunger back against the glass.  The small hole in the top center of the plunger allows the oil to run past the plunger and into the cavity below the plunger (indicated by arrow 3 in the photo).  Once in the cavity below the plunger the oil passes the check valve and runs to the engine's steam supply pipe.

In the event that the throttle is open the steam supply pipe to the engine will be under some level of steam pressure.  The check valve at the discharge of the winker prevents the steam pressure from flowing back through the winker.  In this case as the oil passes through the hole in the plunger it builds pressure.  With each stroke of the power steam oil pump the pressure in the oil line between the pump and the winker discharge check valve is increased.  The plunger continues its winking action but now only to equalize the pressure between the pump and the plunger and the plunger and the check valve.  The discharge check valve in the power steam oil pump keeps the oil pressure from leaking back through the steam oil pump.  When the pressure between the power steam oil pump and the winker check valve becomes greater than the steam pressure in the steam line to the engine, the winker discharge check valve opens and allows oil to pass through to the steam pipe.  Now with each successive pump of the power steam oil pump's piston oil is delivered to the engine's steam supply line and the steam oil system operates at the nominal pressure of the steam line to the engine.  As this pressure can be near the maximum boiler pressure of 600 PSIG, the glass on the winker is 1/4" thick.  When the throttle is closed and the steam pressure in the engine's steam supply line decreases, the higher pressure of the steam cylinder oil supply system is is equalized by the action of the winker discharge check valve. 

The winker pictured is from a non-condensing Stanley were the check valve is located right at the discharge of the winker.  From the discharge of the check valve the oil line went through the firewall and was attached to a fitting on the steam line to the engine.  For condensing Stanleys the check valve was located near the connection of the steam cylinder oil line to the steam loop and was not installed under the dash attached to the winker.  See the discussion on the steam cylinder oil check valve for additional information.

Winker drawing ~ patent 694,406

  •   7 - Supply Line

  • 10 - Winker Casting

  • 11 - Plunger Cavity

  • 12 - Plunger

  • 13 - Spring

  • 14 - Sight Glass

  • 15 - Winker Cap

  • 16 - In-feed Oil Passage

  • 17 - Out-feed Oil Passage

  • 18 - Plunger Orifice

  • 19 - Orifice Flare