The Heisler has been in operation for several years with no whistle ---- just no fun. On the prototype, the whistle is a warning signal like a auto horn and is also often useful for the same purpose on model tracks. It can also be used as a form of greeting -- like tooting your horn at a friend. (Several years ago I took a ride on the Nevada Northern Railroad. The train stopped at the edge of town and the engineer blew the whistle for a while until some woman came out on a porch and waved. I later learned that the house was a brothel (legal in Nevada) and greeting the girls from the train is historic from the mining days.)
The whistle on the Shay (Shay Whistle) was a success so I decided to duplicate it. The Shay whistle was designed to resemble an air tank and was mounted on the right running board. The air tanks on the Heisler are hidden under the boiler and mounting the whistle on the running boards would be out of place. Instead, it was decided to mount it under the right side of the cab, beside the fire pan.
The design is identical to that of the Shay Whistle except the tube OD was reduced to 1.5" to better fit under the cab. The whistle is secured with a couple 1.75" ID hoops cut from tubing. The whistle must be free to rotate for adjustment. Once the whistle is adjusted properly it is tightened down with setscrews through the hoops.
Photo above shows the whistle mounted beside the fire pan ---- the rusty piece behind and above the whistle. The spark plug prevents mounting the whistle higher. Note that the whistle is mounted on a slight slope so that condensate will drain. The hoop mounts are connected to the frame with short lengths of 1/8" X 1/2" bar stock. The rear piece of bar stock has several bends to get the whistle positioned properly. The whistle can be dropped down out of the way by removing one screw per mount and disconnecting the steam feed compression nut. Easy removable is necessary to access the spark plug and the fire pan-burner nozzle apparatus.
The whistle from a slightly different angle. It is not noticeable from above.
This photo shows the whistle valve mounted below the gauges for the air brake system. The valve input and output pipes are 1/4" OD tubes threaded MTP. The top of the whistle valve is threaded 1/8" NPT. The input pipe uses a 1/4" MTP elbow into a 1/4" MTP nipple into a 1/4" MTP to 1/8" NPT bushing. The 1/4" MTP output pipe connects to the whistle via a compression fitting to facilitate easy removal.
The whistle valve steam supply pipe connects to the main steam feed to the turret via a 1/4" NPT tee, a 1/4" NPT to 1/8" NPT bushing, a 1/8" NPT ball valve, a 1/8" NPT elbow and 1/8" NPT to 1/4" OD tube compression elbow. The compression fitting serves as a union.
Whistle Tone: Recently I got an inquiry asking if I had any recordings of the whistle sound. I didn't and its too cold to fire up the locomotive. However, I was able to make the following video with the whistle operating on air. I'll make and post another video in the spring with the whistle operating on steam. It will be interesting to compare the two.
After building the whistle and valve I realized that since there is 12 volt battery, a more economical solution likely would have been an electronic sound system.