[1502]. Tredgold’s trap. The valve is opened by a simple float.
[1503]. Wilson’s trap, like [1501], is dependent on the different expansion of a spring under the difference of temperature of the steam and condensed water. In this case the spring is formed of a steel and brass plate riveted together.
There are many other forms upon similar principles to the foregoing.
Section 83.—STARTING VALVES.
The valves used for starting steam and other engines are usually merely of the ordinary screw down or sliding types. See [Section 89].
For starting and controlling all other forms of reciprocating cylinder motors, such as hydraulic lifting cylinders and presses for all purposes, the ordinary slide valve with either two or three ports is the common device; also the ordinary three or four way cock. See [Section 89].
[1504]. Locke’s 3-way balanced valve, which is balanced in all positions. A is the supply, B the cylinder branch, and C exhaust.
[1505]. Fenby’s 3-way equilibrium starting valve. A supply, B cylinder branch, C exhaust.
[1506]. Auxiliary valve and pistons to start large slide valves too heavy for direct hand power. A 3-way cock is shown as the auxiliary valve, but a small slide valve or piston valve may be substituted. See [note] at foot of [Section 93], also [Nos. 1740] and [1741].