Example, compound motion variable expansion slide valve
- Made:
- c.1882
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Example, compound motion variable expansion slide valve
This is an example of the slide valve for variable expansion, patented by Mr. Halpin in 1882. The valve is formed with a cylindrical bearing surface and slides on a similar valve face. The central exhaust port has its edges at right angles to the axis, while the steam ports are triangular, having their outer edges inclined to it. The valve is of corresponding shape, and, besides being reciprocated longitudinally by one eccentric, it receives a rocking motion in its seat from another eccentric, by means of an external lever attached to the valve spindle which is provided with a swivel joint. Varying the amplitude of the rocking motion, which may be performed by the governor, alters the cut-off without affecting the lead or exhaust. The steam ports and the edges of the valve are formed in two parts, so as to reduce the angular motion required.
