HIGH SPEED STEAM ENGINE._Scientific American Supplement, No. 481, March 21, 1885

The use of rapidly rotating machinery in electric lighting has created a

demand for engines running from 400 to 1,200 revolutions per minute, and

capable of being coupled directly to a dynamo machine. We have already

illustrated several forms of these engines, and now publish engravings of

another in which the most noticeable feature is the employment of separate

expansion valves and very short steam passages. Many high-speed engines

labor under the well-grounded suspicion of being heavy steam users, and

their want of economy often precludes their employment. Mr. Chandler, the

inventor of the engine illustrated above, has therefore adopted a more

elaborate arrangement of valves than ordinarily obtains in engines of this

class, and claims that he gains thereby an additional economy of 33 per

cent. in steam. The valves are cylindrical, and are driven by independent

eccentrics, the spindle of the cut-off valve passing through the center of

the main valve. The upper valve is exposed to the steam on its top face,

and works in a cylinder with a groove cut around its inner surface. As

soon as the lower edge of the valve passes below the bottom lip of the

groove, the steam is cut off from the space between it and the main valve,

which is fitted with packing rings and works over a latticed port. This

port opens directly into the cylinder. The exhaust takes place chiefly

through a port uncovered when the piston is approaching the end of its

stroke. The remaining vapor left in the cylinder is exhausted under the

lower edge of the main valve, until cushioning commences, and the steam

from both upper and lower ports is discharged into the exhaust box shown

in Fig. 2. The speed of the engine is controlled by a centrifugal governor

and an equilibrium valve. This is a "dead face" valve, and when the engine

is running empty it opens and closes many times per minute. The spindle

on which the valve is mounted revolves with the governor pulley, and

consequently never sticks. To prevent the small gland being jammed by

unequal screwing up, the pressure is applied by a loose flange which is

rounded at the part which presses against the gland. The governor is

adjustable while the engine is running.

[Illustration: IMPROVED HIGH SPEED STEAM ENGINE.]

Another economy claimed for this engine is in the use of oil. The cranks

and connecting rods work in a closed chamber, the lower part of which is

filled with oil and water. The oil floats in a layer on the surface of the

water, and at every revolution is splashed all over the working parts,

including the interior of the cylinder, which it reaches through holes in

the piston. The oil is maintained exactly at one level by a very ingenious

arrangement. The bottom of the crank chamber communicates through a hole,

C, with an outer box, which receives the water deposited by the exhaust

steam. The level of this water is exactly determined by an overflow hole,

B, which allows all excess above that level to pass into an elbow of the

exhaust pipe, out of which it is licked by the passing steam and carried

away. Thus, as the oil is gradually used the pressure of the water in the

other leg of the hydrostatic balance raises the level of the remaining

portion. When a fresh supply of oil is poured into the box, it forces out

some of the water and descends very nearly to the level of the hole, B.

The engine is made with either one or two cylinders, and is, of course,

single-acting. The pistons and connecting rods are of forged steel and

phosphor-bronze. The following is a list of their sizes:

_Single Engines_.

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| in. | | in. | in. in. |

2¼ | 4 | 1,100 | 26 | 14 by 14 |

3½ | 5 | 1,000 | 28 | 14 " 15 |

6 | 6½ | 800 | 30 | 16 " 16 |

10 | 8 | 700 | 32 | 18 " 18 |

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_Double Engines_.

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----------|-----------|------------|---------|-------------

| in. | | in. | in. in. |

4½ | 4 | 1,100 | 26 | 14 by 20 |

7¼ | 5 | 1,000 | 28 | 14 " 20 |

12 | 6½ | 800 | 30 | 16 " 26 |

20 | 8 | 700 | 32 | 18 " 32 |

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The manufacturer is Mr. F.D. Bumstead, Hednesford,

Staffordshire.--_Engineering_.

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