Combination lever: Difference between revisions
(Created page with "Category:Steam Locomotive Parts Combination levers by Charles A. Purinton <i>The Live Steamer</i>, July-August 1950 "Dead Centers" and "Valve-Terms", havin...") |
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[[Category:Steam Locomotive Parts]] | [[Category:Steam Locomotive Parts]] | ||
[[Category:Definitions]] | |||
[[Combination | [[Combination lever]] | ||
by [[Charles A. Purinton]] | by [[Charles A. Purinton]] | ||
<i>[[The Live Steamer]]</i>, July-August 1950 | <i>[[The Live Steamer]]</i>, July-August 1950 | ||
[[File:CarlPurinton ValveDiagrams 1950.jpg|thumb|right|300px|Outside admission valves]] | |||
"Dead Centers" and "Valve-Terms", having been briefly touched on in the first two articles in [[The Live Steamer]], [[Combination levers]] perhaps should be next. They are used with both [[Baker valve gear|Baker]] and [[Walschaert valve gear|Walschaert]] valve gears. | "Dead Centers" and "Valve-Terms", having been briefly touched on in the first two articles in [[The Live Steamer]], [[Combination levers]] perhaps should be next. They are used with both [[Baker valve gear|Baker]] and [[Walschaert valve gear|Walschaert]] valve gears. | ||
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The same method of figuring out their sizes applies to either valve gear. The only difference in the [[Combination levers|combination level]] layout is that which is due to inside or outside admission valves. | The same method of figuring out their sizes applies to either valve gear. The only difference in the [[Combination levers|combination level]] layout is that which is due to inside or outside admission valves. | ||
As the valve sketches in Volume #1, Number 2 of [[The Live Steamer]] show an outside admission slide valve, the sketch herewith will deal only with the proportions for outside admission. | As the valve sketches in [[Valves|Volume #1, Number 2]] of [[The Live Steamer]] show an outside admission slide valve, the sketch herewith will deal only with the proportions for outside admission. | ||
The [[Combination lever]] gives a movement to the valve of one lap plus one lead, times two. This motion is constant, as it derives its movement from the crosshead, whose travel is always the same. With the reverse lever in mid-gear, the valve will receive no movement from the valve gear, but will get the lap and lead motion from the crosshead. | The [[Combination levers|Combination lever]] gives a movement to the valve of one lap plus one lead, times two. This motion is constant, as it derives its movement from the crosshead, whose travel is always the same. With the reverse lever in mid-gear, the valve will receive no movement from the valve gear, but will get the lap and lead motion from the crosshead. | ||
When laying out the [[Combination lever]], it is desireable to keep the distance "B" as great as possible, say 5/16 inch to 9/32 inch. If made much less than this, there will not be much room for the pins, they would have to be small and would war out rather fast. The other dimensions can be applied in the formula in their proper places and the whole is easily worked out by arithmetic. | When laying out the [[Combination levers|Combination lever]], it is desireable to keep the distance "B" as great as possible, say 5/16 inch to 9/32 inch. If made much less than this, there will not be much room for the pins, they would have to be small and would war out rather fast. The other dimensions can be applied in the formula in their proper places and the whole is easily worked out by arithmetic. | ||
[[File:CombinationLevers CharlesAPurinton1950.jpg|thumb|center|500px]] | [[File:CombinationLevers CharlesAPurinton1950.jpg|thumb|center|500px]] | ||
Latest revision as of 18:27, 13 February 2020
The Live Steamer, July-August 1950
"Dead Centers" and "Valve-Terms", having been briefly touched on in the first two articles in The Live Steamer, Combination levers perhaps should be next. They are used with both Baker and Walschaert valve gears.
The same method of figuring out their sizes applies to either valve gear. The only difference in the combination level layout is that which is due to inside or outside admission valves.
As the valve sketches in Volume #1, Number 2 of The Live Steamer show an outside admission slide valve, the sketch herewith will deal only with the proportions for outside admission.
The Combination lever gives a movement to the valve of one lap plus one lead, times two. This motion is constant, as it derives its movement from the crosshead, whose travel is always the same. With the reverse lever in mid-gear, the valve will receive no movement from the valve gear, but will get the lap and lead motion from the crosshead.
When laying out the Combination lever, it is desireable to keep the distance "B" as great as possible, say 5/16 inch to 9/32 inch. If made much less than this, there will not be much room for the pins, they would have to be small and would war out rather fast. The other dimensions can be applied in the formula in their proper places and the whole is easily worked out by arithmetic.
