globals
[ disk
  piston
  rod
  old-diam
  
]

to startup
   setup
end

to resize
   if drive-diam != old-diam
   [ set old-diam drive-diam
     ask disk [ set size .001 + drive-diam setxy (min-pxcor + size * .5 + 1) 0 ]
     ask rod  [ set size .001 + max-pxcor - min-pxcor - ( [xcor] of disk - min-pxcor ) - .5 * [size] of disk - [size] of piston - 2 ] 
   ]
end
   
to setup
   ca
   
   ask patches [ set pcolor white ]
   
   crt 1 [ set disk self set size drive-diam set old-diam drive-diam ]
   crt 1 [ set piston self set size 10]
   crt 1 [ set rod self ]
      
   ask disk
   [ set shape "disk"
     setxy (min-pxcor + size * .5 + 1) 0
     set color brown
     set heading 90
   ]
   ask rod 
   [ ; set shape "linkage"
      set shape "rod"
      __set-line-thickness 1
     set size max-pxcor - min-pxcor - ( [xcor] of disk - min-pxcor ) - .5 * [size] of disk - [size] of piston - 2
     snap-to-tail disk
     set color blue
     set rod self
     set heading 90
   ]
   ask piston
   [ set shape "piston"
     snap-to-tail-x rod
     set color green
     set piston self 
     face disk
   ]
   
   ask rod
   [ face piston ]
   
  ;;  __tie rod disk
   
end


to go
   ;; rotate the drive wheel
   
   resize
   every (1 / 30 )
   [ 
     ask disk
     [ rt speed + .1
     ]
     ;; snap the end of the rod to the drive wheel
     ;; point the rod at the piston
     ask rod
     [  snap-to-tail disk
        set heading towards piston
     ]
     ;; push the piston to the location of the end of the rod
     ask piston 
     [ snap-to-tail-x rod
     ]
     tick
   ]   
end       

to snap-to-tail [ agent ]
   setxy ( [ xcor + dx * size * .5 ] of agent ) ( [ ycor + dy * size * .5] of agent )   
end  

to snap-to-tail-x [ agent ]
   set xcor ( [ xcor + dx * size  ] of agent )
end 
    
   
@#$#@#$#@
GRAPHICS-WINDOW
183
15
743
296
27
12
10.0
1
10
1
1
1
0
0
0
1
-27
27
-12
12
1
1
1
ticks

CC-WINDOW
5
310
752
405
Command Center
0

BUTTON
13
15
76
48
NIL
setup
NIL
1
T
OBSERVER
NIL
NIL
NIL
NIL

BUTTON
13
56
76
89
NIL
go
T
1
T
OBSERVER
NIL
NIL
NIL
NIL

SLIDER
84
56
176
89
speed
speed
1
20
5
1
1
NIL
HORIZONTAL

SLIDER
84
15
176
48
drive-diam
drive-diam
10
18
12
1
1
NIL
HORIZONTAL

@#$#@#$#@
WHAT IS IT?
-----------

A simulation of a simple crank and piston.

Inspired by a diagram from "507 Mechanical Movements" by Henry T. Brown, originally published in 1896.

I was thinking about making a mechanical movement construction set, with drag-and-drop features... but then "crayon physics" happened, and I thought, "why bother?"


@#$#@#$#@
default
true
0
Polygon -7500403 true true 150 5 40 250 150 205 260 250

disk
true
6
Circle -13840069 true true -1 -1 301
Circle -1 true false 29 29 242
Rectangle -13840069 true true 135 15 165 285
Rectangle -13840069 true true 15 135 285 165
Circle -13840069 true true 120 -30 60

line
true
0
Line -7500403 true 150 0 150 300

line half
true
0
Line -7500403 true 150 0 150 150

link
true
0
Line -7500403 true 150 0 150 300

link direction
true
0
Line -7500403 true 150 150 30 225
Line -7500403 true 150 150 270 225

linkage
true
6
Polygon -13840069 true true 135 120 120 135 120 180 180 180 180 135 165 120 165 165 135 165 135 135 165 135 165 -120 180 -135 180 -180 120 -180 120 -135 135 -120 135 -165 165 -165 165 -135 135 -135

piston
true
6
Rectangle -13840069 true true 75 150 225 195
Rectangle -13840069 true true 75 210 225 450
Circle -13840069 true true 105 105 90

rod
true
6
Line -13840069 true 150 150 150 -150

@#$#@#$#@
NetLogo 4.0.4
@#$#@#$#@
@#$#@#$#@
@#$#@#$#@
@#$#@#$#@
@#$#@#$#@
default
0.0
-0.2 0 0.0 1.0
0.0 1 1.0 0.0
0.2 0 0.0 1.0
link direction
true
0
Line -7500403 true 150 150 90 180
Line -7500403 true 150 150 210 180

@#$#@#$#@