Automatic Cylinder Cocks

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Automatic Cylinder Cocks

Steve Adler design

by Steve Adler, Vancouver Island Model Engineers

Retrieved from

These cylinder cocks cost practically nothing and can be easily made in an evening. They vent condensate and snap shut on stream. Additionally, they become snifting valves when drifting. Water moves slowly in these cocks and steam more quickly. The stainless steel ball is pushed against the lower "A" outlet. After fabrication, take a mouthful of water and blow into the upper "A" inlet. The water will exit and the following air will snap the cylinder cocks shut. Dimensions are not critical.

SteveAlder AutomaticCylinderCocks.jpg
1 inch Scale 1-1/2 inch Scale
A: 0.0785 inch No. 47 drill 2 places A: 0.120 inch No. 31 drill 2 places
B: 0.159 inch No. 21 drill B: 0.213 inch No. 3 drill
C: 10-32 C: 1/4-28
D: 1/8 inch stainless steel ball D: 5/32 inch stainless steel ball
E: 5/16 inch round or hex E: 9/16 inch round or hex
F: 7/16 inch F: 5/8 inch

Van Brocklin design

George Hoke wrote:

Attached is a drawing of automatic cylinder cocks as designed by Van Brocklin. I have used them on my Fitchburg Northern for several years and find them satisfactory. They are easy to make. Don't use them in a locomotive with piston valves or where you cannot orient them horizontal.
George Hoke
Bellevue, WA
Automatic cylinder cocks designed by Bill Van Brocklin, drawn by George Hoke.

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