(146) The “Big Four” Tractor.
The Big Four tractor differs from the majority of tractors in having a four cylinder vertical type motor of 30 tractive and 60 brake horse-power capacity. The cylinders have a bore of 6½ inches and a stroke of 8 inches. The engine runs at the comparatively high speed of 450 revolutions per minute. Gasoline is used for fuel, and is vaporized in a conventional type of jet carburetor.
Both the inlet and the exhaust valves are placed in a pocket at one side of the cylinder making what is known as an “L” engine. The cylinders and the heads are cast in one piece, doing away with points between the cylinders and heads. The pistons and connecting rods may be removed without disturbing the cylinders or their connections by pulling them out through hand holes in the base of the crank case.
The four throw crank shaft is provided with five bearings, these intermediate bearings between the throws and two end bearings in the case. The interior working parts of the motor are lubricated by the splash system with a positive forced feed oiler. The splash pools can be adjusted at a minute’s notice so that any desired oil level can be obtained. Grease cups provide the lubrication for all bearings outside of the motor.
Water is circulated by a direct driven centrifugal pump, and as the cooling water is in a closed system the same water is used over and over again without much loss, a bucketful or so a day being an ample supply. The tubular radiator situated in the front of the tractor is provided with a cooling fan that is driven from the engine in a manner similar to automobile practice. A high tension magneto is gear driven from the cam shaft, and is mounted on a rocking bracket so that the armature is advanced and retarded as well as the circuit breaker.
Fig. 131. Views of the Four Cylinder Motor of the “Big Four” Tractor. Note the Massive Construction Compared with Automobile Practice.
An internal expanding clutch connects the motor with the driving gear by operating on the inner run of the fly-wheel. The motion of the engine is transmitted to an intermediate reversing device through bevel gears, this being necessary for the reason that the crank-shaft runs “fore and aft,” or parallel to the length of the tractor. A double acting jaw clutch engages with either one or the other of a pair of bevel pinions that run in opposite directions. Motion from the reverse gear is transmitted directly to the different shaft, and from there it is transmitted to the master gears on the bull wheels. The differential shaft is in one piece.
“Big Four,” Four Cylinder Tractor Motor.
Showing the Position of Engine on “Big Four” Tractor.
The main driving wheels are very large when compared with the wheels of an ordinary tractor, for they are eight feet in diameter and are proportionately broad. This no doubt gives splendid tractive effect in soft and uneven fields and must save the machine from “stalling” under adverse conditions. Another unusual feature is the automatic steering device used in plowing. This device consists of a long tubular boom that is fastened to the swiveled front axle of the tractor and a small wheel fastened to the outer end of the boom. The small wheel rolls in the next furrow and compels the tractor to plow in a line parallel to it. This steers the tractor more accurately than would be possible by hand and at the same time enables one man to operate both the engine and the plows.
The “Case” Gas Tractor.
| Cost of Gas Engine Operation (American). | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| GAS PRODUCER PLANT. | NATURAL-GAS ENGINE. | LOW-PRESSURE OIL ENGINE. | DIESEL ENGINE. | ||||||||||
| Load. | Three-quarter Load. | Half Load. | Load. | Three-quarter Load. | Half Load. | Load. | Three-quarter Load. | Half Load. | Load. | Three-quarter Load. | Half Load. | ||
| 1 | Fuel per hp-hour | 1.25 lb. | 1.5 | 1.8 lb. | 10 cu. ft. | 12 cu. ft. | 15 cu ft. | 1 lb. | 1.25 lb. | 1.60 lb. | 0.50 lb. | 0.55 lb. | 0.60 lb. |
| 2 | Fuel per hp-year (4,500 hours) | 2.5 tons | 3 tons | 3.6 tons | 45,000 cu. ft. | 54,000 cu. ft. | 67,500 cu. ft. | 643 gals. | 803.5 gals. | 1028.5 gals. | 321.5 gals. | 353.5 gals. | 386 gals. |
| 3 | Cost of fuel | $4.00 per ton | 30 cents per 1,000 cu. ft. | 3 cents per gallon | 3 cents per gallon | ||||||||
| 4 | Cost of fuel per year | $10.00 | $12.00 | $14.40 | $13.50 | $16.26 | $20.25 | $19.30 | $24.10 | $30.85 | $9.65 | $10.60 | $11.58 |
| 5 | Cost of attendance per hp-hour | 0.40 cent | 0.25 cent | 0.25 cent | 0.30 cent | ||||||||
| 6 | Cost of attendance per year | $18.00 | $11.25 | $11.25 | $13.50 | ||||||||
| 7 | Lubricating oil per hp-hour | 0.006 pint | 0.006 pint | 0.006 pint | 0.007 pint | ||||||||
| 8 | Cost of oil per year at 25 cents per gal. | $0.84 | $0.84 | $0.84 | $0.98 | ||||||||
| 9 | Scrubber and cooling water per hp-hour | 8 gals. | 5 gals. | 5 gals. | 4 gals. | ||||||||
| 10 | Cost of water per year at 30 cents per 1,000 cubic feet | $1.44 | 0.90 | 0.90 | 0.72 | ||||||||
| 11 | Operating expenses; items, 4, 6, 8 and 10 | $30.28 | $32.28 | $34.68 | $26.49 | $29.19 | $34.24 | $32.29 | $37.09 | $43.84 | $24.85 | $25.80 | $26.78 |
| 12 | Saving by Diesel engine | 5.43 | 6.47 | 7.90 | 1.64 | 3.39 | 6.56 | 7.44 | 11.29 | 17.06 | ... | ... | ... |
| 13 | Interest, depreciation and maintenance respectively in per cent of investment | 6 + 7 + 2 = 15% | 6 + 7 + 2 = 15% | 6 + 7 + 2 = 15% | 6 + 10 + 3 = 19% | ||||||||
| 14 | Assuming $80 initial cost per hp. the yearly fixed charges will be | $12.00 | $12.00 | $12.00 | $15.00 | ||||||||
| From a Paper Read Before the American Institute of Electrical Engineers. | |||||||||||||