Slide Valve Animation

 

Steam Engine : Slide Valve Animation

This example shows the relationship between the position of the slide valve and the piston for three cases, namely:

  • Slide valve with no lap or lead
  • Slide valve with lap but no lead
  • Slide valve with both lap and lead

Note that in the latter two cases the slide valve has the same dimensions.

The user may control the animation by means of the buttons at the bottom of the form. Two modes of operation are possible, namely “Loop : Continuous Play” or “Manual Control”. Particular attention should be given to the ingress of live steam and the egress of exhaust steam in relation to the cylinder, as well as to the positions of expansion, compression and lead steam.

To understand what is going on it will be found instructive to use the “Manual” and “All three models” options and step through the positions one at a time, having positioned the three model images so that they are all visible on the screen at the same time. The following table shows the principal features in the left and right parts of the given cylinder:

 

No lap or lead

Lap but no lead

With both lap and lead

Position

Left

Right

Left

Right

Left

Right

1

Exhaust

Steam

Exhaust

Steam

Exhaust

Steam

2

Exhaust

Steam

Exhaust

Steam

Exhaust

Steam

3

Exhaust

Steam

Exhaust

Steam

Exhaust

Steam

4

Exhaust

Steam

Exhaust

Steam

Exhaust

Steam

5

Exhaust

Steam

Exhaust

Expansion

Exhaust

Expansion

6

Exhaust

Steam

Compression

Exhaust

Compression

Exhaust

7

Neither

Neither

Compression

Exhaust

Lead steam

Exhaust

8

Steam

Exhaust

Steam

Exhaust

Steam

Exhaust

9

Steam

Exhaust

Steam

Exhaust

Steam

Exhaust

10

Steam

Exhaust

Steam

Exhaust

Steam

Exhaust

11

Steam

Exhaust

Steam

Exhaust

Steam

Exhaust

12

Steam

Exhaust

Steam

Exhaust

Steam

Exhaust

13

Steam

Exhaust

Steam

Exhaust

Steam

Exhaust

14

Steam

Exhaust

Steam

Exhaust

Steam

Exhaust

15

Steam

Exhaust

Steam

Exhaust

Steam

Exhaust

16

Steam

Exhaust

Steam

Exhaust

Steam

Exhaust

17

Steam

Exhaust

Expansion

Exhaust

Expansion

Exhaust

18

Steam

Exhaust

Exhaust

Compression

Exhaust

Compression

19

Neither

Neither

Exhaust

Compression

Exhaust

Lead Steam

20

Exhaust

Steam

Exhaust

Steam

Exhaust

Steam

21

Exhaust

Steam

Exhaust

Steam

Exhaust

Steam

22

Exhaust

Steam

Exhaust

Steam

Exhaust

Steam

23

Exhaust

Steam

Exhaust

Steam

Exhaust

Steam

24

Exhaust

Steam

Exhaust

Steam

Exhaust

Steam


Note:

  • Position 6 shows the right areas with lap to be open to exhaust before the end of the stroke
  • Position 7 shows the left area with lap and lead to be open to steam at the end of the stroke
  • Position 18 shows the left areas with lap to be open to exhaust before the end of the stroke
  • Position 19 shows the right area with lap and lead to be open to steam at the end of the stroke
     

Select Model:

 

 

 

 

Play Mode:

 

 

 

 

Speed:

 

 

 

 

Controls:

 

 

 

 

Upper Image #:

Middle Image #:

Lower Image #:

(1)
No Lap or Lead

Key:

Steam

 

Expansion

 

Exhaust

 

Compression

 

Lead

(2) Lap but no Lead

(3)
Lap and Lead


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