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Steam tractor

Steam tractor
Steam tractor
Steam traction engines at the Central North Dakota Steam Threshers Reunion, September 2007. Photo: TRBUFF, public domain, via Wikimedia Commons.
Also calledTraction engine
Road speed4 to 6 miles an hour
RelatedPortable engine, road roller, ploughing engine, showman's engine

A steam tractor, also called a traction engine, is a steam engine on wheels that moves under its own power, as opposed to portable steam engines, which cannot move themselves and are moved by animals or by some mechanical device.[1][2] A fire boils water in its boiler, and the steam works an engine that turns the wheels.[1] Standing still, it drives other machines by a belt from its flywheel.[3][4] On American farms it threshed grain, pulled plows, drove belt machines and hauled loads, beside the horses and mules.[4][5][6]

Working parts

The working parts of a Port Huron 19-65 traction engine, seen from the cylinder side and numbered as in the table. Drawn from a CAD model of the engine. The boiler is cut open down the middle, and the cylinders are cut open to show a piston and the slide valve. The near drive wheel and its gears are drawn in outline; the gears hidden behind the boiler are outlined in brown. No. 9, the feed pump, is not shown. CC BY-NC 4.0.
The working parts of a Port Huron 19-65 traction engine, seen from the cylinder side and numbered as in the table. Drawn from a CAD model of the engine. The boiler is cut open down the middle, and the cylinders are cut open to show a piston and the slide valve. The near drive wheel and its gears are drawn in outline; the gears hidden behind the boiler are outlined in brown. No. 9, the feed pump, is not shown. CC BY-NC 4.0.
No.PartWhat it does
1Firebox and grateHolds the fire. Water fills the space between the firebox's double walls.[7]
2Fire doorWhere the fireman puts in the fuel: coal, wood or straw, and on some engines crude oil.[8]
3Boiler tubesCarry the hot gases forward through the water. They are 2 to 4 inches across.[7]
4SmokeboxGathers the smoke at the front of the boiler.[9]
5SmokestackTakes the smoke away.[9]
6Exhaust nozzleBlows the used steam up the stack, which draws air through the fire. Before the engine runs, a blower pipe does the same with steam from the boiler.[10][11]
7Water tankCarries the water.[12]
8InjectorForces water into the boiler with a jet of the boiler's own steam.[13]
9Feed pumpPumps water into the boiler. It is worked by the crosshead, so it feeds only while the engine runs.[14][13]
10Check valveLets water into the boiler and shuts if the water tries to come back.[14]
11Water glass and try cocksShow the water level. A try cock below the water level blows white mist; one above it blows blue steam.[15]
12Fusible plugA plug of soft metal in the top of the firebox, the crown sheet. If the water gets too low, it melts, and the steam puts out the fire.[16]
13Steam domeThe highest point of the boiler. The engine takes its steam from the top of the dome, where it carries the least water.[9]
14Safety valveLets steam out before the pressure gets too high. On traction engines it was usually set at 110 to 130 pounds per square inch.[17]
15WhistleSignals to the crew.[18] One short blast meant stop; two short blasts meant the engine was about to begin work.[19]
16Steam gaugeShows the pressure.[12]
17ThrottleA valve in the steam pipe from the dome, usually opened and closed by a lever.[20]
18GovernorHolds the engine's speed steady as the load changes. Two spinning balls fly outward as the engine speeds up and close a valve in the steam pipe.[21][22]
19Steam chest and slide valveThe slide valve lets steam into one end of the cylinder while the used steam leaves the other end, then swaps.[20][23]
20Cylinder and pistonThe steam pushes the piston first one way, then the other.[24]
21Crosshead and guidesThe piston rod is fixed to the crosshead, which slides between the guides.[25]
22Connecting rodJoins the crosshead to the crank.[25]
23Crank and crankshaftTurn the piston's push into the turning of a shaft.[20]
24Eccentric and reverse gearThe eccentric is a disc fixed off-centre on the crankshaft. Its rod moves the slide valve in time with the piston.[26]
25Reverse leverSets which way the engine turns, and how long steam is let in on each stroke.[27][28]
26Flywheel and friction clutchThe flywheel evens out the piston's push and carries the crank past the two dead points.[24] The clutch inside it connects the engine to the gears; released, it lets the engine drive a belt while the wheels stand still.[3][8]
27GearingThe engine generally runs at 200 to 225 revolutions a minute. Spur gears bring this down to the speed of the wheels.[29][3]
28DifferentialLets the outside drive wheel turn faster than the inside one on a turn.[30]
29Bull gear and drive wheelA pinion drives the large bull gear on each rear wheel. The wheels' broad rims carry lugs to grip the ground.[30][31][32]
30SteeringThe hand wheel turns a roller through a worm gear. Chains from the roller swing the front axle. Large engines steered by engine power.[33][8]
31Front wheelCarries the front of the engine. The front axle pivots on a ball-and-socket joint.[8]

On nearly all traction engines the engine was mounted on the boiler. The exceptions were undermounted engines, set beneath the boiler.[1] Frick built the engine on a frame on the wheels, separate from the boiler.[34]

Valve gear

Most traction engines had a reverse gear with one eccentric. The rest used the Stephenson link, which has two.[35]

GearEccentricsUsed by
Woolf reverseOneCase, Huber, Buffalo Pitts, Port Huron, Minneapolis[36]
Stephenson linkTwoNichols & Shepard,[37] Gaar-Scott,[38] Aultman Co., Colean[39]
GrimeOneAvery[40]
MarshAdvance[41]
Arnold shifting eccentricOneRumely[42]
Frick single eccentricOneFrick[34]

Use

Threshing

Steam traction engines drove most of the larger threshing machines. Horse powers and small gasoline engines drove the smaller ones.[43] An average steam outfit threshed 500 to 1,000 bushels of wheat a day, or twice as many bushels of oats.[43] The engine was set in line with the threshing machine and backed into the belt with the clutch.[44]

Plowing

Engines of 40 to 60 horsepower at the drawbar pulled 10 to 14 plows at once, where farms were large and labor scarce, as in the Northwest.[5] Steam plowing was used only on large farms and on level land.[45] A wagon of water and fuel had to follow the engine.[46] See engine gang plow.

Belt work

Standing still, the engine drove hay balers, corn shellers, water pumps, feed grinders, ensilage cutters and wood saws by belt.[4] See portable sawmill.

Hauling

Engines hauled grain to the station or market and fertilizer, and moved houses and barns. They pulled road graders, scrapers and road plows.[4][47] On the road a traction engine usually made 4 to 6 miles an hour.[2]

With horses and mules

In 1917 American farms still had about 25 million horses and mules.[6] In 1911 the horse sweep power was still widely used for threshing, because it cost less than a steam outfit.[48] A team hitched in front could often pull an engine out of a soft plowed field.[49]

History

YearEvent
1842Ransomes shows a farmer's road locomotive at the Royal Show at Bristol, driven by chain to one wheel.[50]
1857The first self-moving ploughing engine, built by Ransomes for Messrs. Fowler, is shown at the Royal Show at Salisbury.[50]
1858Thomas Aveling patents a chain drive that makes a portable engine move itself. Many portables are converted.[51]
1861, 1865, 1878Britain passes the Road Locomotive Acts.[52]
1870Aveling's engine at the Oxford show is driven wholly by gearing and steered from the footplate.[53]
1878In America, portable engines are sometimes built to drive themselves.[54]
1891Under those Acts, road engines are held to 4 miles an hour in the country, with a man at least 20 yards ahead.[52]
1911Tractors driven by internal-combustion engines, on petrol, kerosene, distillate or alcohol, are coming into use in the United States.[55]

See also

Notes

  1. ^ a b c dDavidson and Chase 1908, p. 436.
  2. ^ a b cEncyclopaedia Britannica 1911, "Traction", p. 119.
  3. ^ a b cPotter 1917, p. 177.
  4. ^ a b c dPotter 1917, p. 200.
  5. ^ a bPotter 1917, p. 201.
  6. ^ a bPotter 1917, p. 4.
  7. ^ a bStephenson 1910, p. 13.
  8. ^ a b c dPotter 1917, p. 169.
  9. ^ a b cStephenson 1910, p. 18.
  10. ^Stephenson 1910, p. 30.
  11. ^MacGregor 1911, p. 110.
  12. ^ a bPotter 1917, p. 168.
  13. ^ a bStephenson 1910, pp. 28-29.
  14. ^ a bStephenson 1910, pp. 25-26.
  15. ^Stephenson 1910, pp. 20-21.
  16. ^Stephenson 1910, pp. 48-49.
  17. ^Stephenson 1910, p. 23.
  18. ^MacGregor 1911, p. 107.
  19. ^Stephenson 1910, p. 219.
  20. ^ a b cStephenson 1910, p. 34.
  21. ^Stephenson 1910, pp. 40-41.
  22. ^Potter 1917, pp. 51-52.
  23. ^Stephenson 1910, pp. 34-35.
  24. ^ a bPotter 1917, p. 43.
  25. ^ a bStephenson 1910, p. 33.
  26. ^Stephenson 1910, p. 36.
  27. ^Potter 1917, p. 175.
  28. ^Potter 1917, p. 205.
  29. ^Davidson and Chase 1908, p. 449.
  30. ^ a bPotter 1917, pp. 177-179.
  31. ^MacGregor 1911, p. 121.
  32. ^Stephenson 1910, pp. 47-48.
  33. ^Potter 1917, p. 176.
  34. ^ a bStephenson 1910, p. 223.
  35. ^Potter 1917, pp. 171, 174.
  36. ^Stephenson 1910, pp. 221-240.
  37. ^Stephenson 1910, p. 228.
  38. ^Stephenson 1910, pp. 224-225.
  39. ^Maggard 1905, pp. 141, 151.
  40. ^Stephenson 1910, p. 232.
  41. ^Traction Engine Catechism 1906, p. 96.
  42. ^Stephenson 1910, p. 237.
  43. ^ a bDavidson and Chase 1908, p. 218.
  44. ^Davidson and Chase 1908, p. 456.
  45. ^Davidson and Chase 1908, p. 68.
  46. ^Potter 1917, pp. 181-182.
  47. ^Potter 1917, pp. 200-201.
  48. ^MacGregor 1911, p. 131.
  49. ^Davidson and Chase 1908, p. 455.
  50. ^ a bFletcher 1891, p. 193.
  51. ^Fletcher 1891, pp. 211-212.
  52. ^ a bFletcher 1891, p. 279.
  53. ^Fletcher 1891, p. 213.
  54. ^Thurston 1878, pp. 355-356.
  55. ^ a bThe Engineer, 31 March 1911, p. 333.
  56. ^Davidson and Chase 1908, p. 453.
  57. ^Encyclopaedia Britannica 1911, "Plough and Ploughing", p. 852.
  58. ^Thurston 1878, p. 359.
  59. ^The Engineer, 26 June 1896, p. 639.

References