Specifications of the John Deere 7720 Combineby Tim McQuade
The John Deere 7720 is part of the John Deere Titan II combine series. It is a high-powered combine used to harvest large grain fields. A combine amalgamates the reaping, binding and threshing process into a single operation. Because of its efficiency, comfort and performance capabilities, the 7720 was John Deere's top-selling grain harvester.
The John Deere 7720 Titan II comes standard with a turbocharged diesel engine with six cylinders and Posi-Torq belt drive. The standard horsepower is 145 at 2,200 RPM, but the engine can be upgraded to 165 horsepower with the optional hydrostatic ground drive. The total engine displacement is 466 cubic inches. The transmission has four speeds. The cylinder type is a Rasp bar, and the diameter of each cylinder is 22 inches, while the cylinder width is 55 inches. The cylinder speed range is 350 to 1,240 RPM, and the cylinder drive is dual range. The two-cylinder drive range allows for 620 to 1,240 RPM in direct drive high, and 350 to 700 RPM in the low-drive gear.
Dimensions and Features
Without a header, the John Deere 7720 combine is 26 feet long, 13.25 feet wide and 13.3 inches high. The 7720 weighs approximately 20,000 pounds. Total fuel capacity of the 7720 is 100 gallons. The grain tank can hold 190 bushels, and has an unloading rate of 1.9 bushels per second. The 7720 has five straw walkers with a length of 150 inches. The straw walker has a total of six steps, and the crankshaft-throw is six inches. Total walker area is 8,222 square inches. The cleaning chaffer unit has a length of 66.7 inches and a width of 52.8 inches. The sieve length is 52 inches and the width is 66.7 inches. The cleaning fan speed is 370 to 1,170 RPM, while the max cleaning area is 6,179 square inches.
Design and Equipment
The 7720 combine comes standard with a regular-length feeder house that has variable speeds and a reverser. The bar-type concave has deep crossbars that are built strongly to deliver an even, smooth crop and complete threshing. To match the cylinder speed, the beater on the 7720 adjusts its speed automatically when cylinder speed is changed. The gearbox-drive fountain-type loading auger offers a simple loading design. To engage four-wheel drive, the optional hydraulic rear-wheel drive is available with a switch on the operator's console. The straw chopper uses knives and wide-vane deflectors to chop material and then spread it in a 35-foot-wide wake behind the combine. The 7720 comes in the John Deere standard green body with yellow decals.
Tim McQuade began writing in 1999. He has worked for two newspapers, including "The Ithaca Times," and has had a short story published. McQuade received a Bachelor of Arts in writing from Ithaca College.