1862 London Exhibition: Catalogue: Class V.: Alexander Allan
1228. ALLAN, ALEXANDER, Perth.
- Improvements in the expansion valve gear of steam-engines. Straight-link valve motion.
By this arrangement simultaneous movement is given to the eccentric rods and link, and to the valve rod, in opposite directions, by short levers placed on opposite sides of the reversing shaft, thereby obtaining a straight link. This valve motion is easier of reversal, balance weights are dispensed with, and the sliding movement of the block is reduced. The only fixings required are the reversing shaft brackets. Most accurate results as regards an equal distribution of the steam, can be obtained; while from the simplicity of the motion and from the link being straight (in place of curved), repairs are more economically executed.
- Pressure gauges: indications by water rising in the gauge, compressing air within it.
Pressure, by this gauge, is indicated by the more or less compressed or expanded condition of an accurately measured quantity of atmospheric air contained within the body of the gauge, which is acted upon by cold water contained within a bent tube.
The pressure, acting on the water, forces it up the glass tube, and is indicated by the height to which the water rises, a graduated index being marked on the body of the gauge.
The principal features of this gauge are its simplicity, the durability of its parts, and facility of re-adjustment.
The air, which is the elastic spring, can be renewed at pleasure by simply turning the cocks to the positions shown (at A, B) and when the new atmosphere is thus admitted, the cocks must be reversed.
These gauges are capable of being made to suit any pressure from 1 to 5 lbs. for blast furnaces, and from 1 to 15, or up to 300 lbs. per square inch, for steam boilers or other purposes.
- Compound buffer, springs with independent action, giving double resisting power in small space.
The improvement in this buffer consists in obtaining increased resistance within a given space.
The springs used may be of steel or india rubber, as preferred, provided the principles of the arrangement be followed.
For the purpose of showing the action, the buffer is illustrated with its plunger at half stroke; the dotted lines show the position of the plunger when at rest.
It will be observed that while the first spring (A) is acting between the bottom of the cylinder (D) and the inner end of the plunger (C), the second spring (B) is acting between the front of the plunger (C) and the washer (E) fixed on the pillar (F).
There is thus a compound action; and it will be seen the resistance is exactly equal to the united power of the two springs, or, double that of an ordinary buffer.
See Also
Sources of Information