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Solenoid: Iron-Clad Valve Magnet with Two Coils, 1860 and 1765 Turns (Nachod 1905, in Underhill 1910)
A short-stroke solenoid that opens an air valve. One coil pulls the iron armature down; a second, weaker coil holds it there against the air pressure once the first is switched off. A cast-iron shell closes the magnetic circuit around both.
Result: an iron-clad plunger solenoid driving a brass valve rod through its hollow core.
Source: C. P. Nachod's test (Electrical World, 1905) in Underhill, Solenoids, Electromagnets and Electromagnetic Windings (1910), pp. 125-129. Unknown: the wire insulation; the test does not give it. Not given: shell and armature sizes, voltage. Picture drawn by Youblob.
Advanced
2 days
Instructions
1
1
Turn the core and armature
Turn the core and armature
Turn the core from Norway iron to 3.17 cm outside diameter and bore a 0.95 cm hole through it for the valve rod. Turn the armature from the same iron. Ours: wrought iron bar; the armature size is not given.
Materials for this step:
Wrought Iron Bar1 as requiredTools needed:
Lathe Tool Set (HSS)2
2
Cast the shell and top
Cast the shell and top
Cast the shell and top in cast iron so they close the magnetic circuit round the coils, leaving a round clearance gap for the armature in the top. Sizes: not given (Underhill's Fig. 92 shows the layout).
Materials for this step:
Pig Iron Ingots1 as requiredTools needed:
Cupola Furnace
Moulding Flask
Casting Sand3
3
Wind coil A: 1860 turns of No. 25
Wind coil A: 1860 turns of No. 25
Wind the operating coil, 1860 turns of No. 25 wire, and place it where it encircles the working air gap between armature and core. Copper, as Underhill gives for magnet windings. Unknown: the insulation; the test does not give it.
Materials for this step:
Copper Wire1 as required
Unknown Insulating Material1 as requiredTools needed:
Lathe Tool Set (HSS)4
4
Wind coil B: 1765 turns of No. 26
Wind coil B: 1765 turns of No. 26
Wind the retaining coil, 1765 turns of No. 26 wire, and place it below coil A on the core. Being away from the gap, it pulls only 0.4-0.8 as hard as A, enough to hold the armature down.
Materials for this step:
Copper Wire1 as requiredTools needed:
Lathe Tool Set (HSS)5
5
Assemble with the brass valve rod
Assemble with the brass valve rod
Fit core, coils and armature in the shell and pass the brass rod through the core to the valve. Nachod set test gaps of 0.41 and 2.05 mm with brass washers.
Materials for this step:
Brass Rod1 as requiredTools needed:
Lathe Tool Set (HSS)Materials
5- 1 as requiredPlaceholder
- 1 as requiredPlaceholder
- 2 as requiredPlaceholder
- 1 as requiredPlaceholder
- 1 as requiredPlaceholder
Tools Required
4- Placeholder
- Placeholder
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