Copyright Goodheart-Willcox Co., Inc. Heavy Equipment Power Trains and Systems 582 can be held by applying its two hydraulically actuated service brake calipers. The parking brake is not directly attached to the transmission’s output shaft, but is attached to the transmission’s countershaft. The trans- mission output shafts deliver power to the final drive through the couplers and driveshafts. Harvester Bull-and-Pinion Final Drives Bull-and-pinion final drives and planetary final drives are found in combines, cotton pickers, cotton strippers, and self-propelled forage harvesters. The combine bull- and-pinion final drive shown in Figure 17-15 consists of a nine-toothed pinion that drives a 95-toothed bull gear for a 10.55:1 speed reduction, torque multiplication ratio. It is found in large frame S series John Deere combines and 7760 cotton pickers. Some CNH combines also have bull-and-pinion final drives. They are the only final drives offered on midrange 2016 Case IH combines, such as the 5140, 6140, and 7140. Bull-and-pinion final drives are also used in different gen- erations of flagship combines, including Case IH 7240, 8240, and 9240, and New Holland’s CR 9.90 and CR 10.90. Harvester Planetary Final Drives Other harvesters use planetary final drives. A combine planetary final drive normally inte- grates a bull-and-pinion, which serves as the first reduction and a planetary gear set as the second reduction. In the final drive shown in Figure 17-16, a 16-toothed pinion drives a 73-toothed bull gear for a 4.56:1 ratio. Case IH labels the large bull gear a reducer gear. This final drive is the heavy-duty final drive used in class 8, 9, and 10 combines. The plan- etary ring has 75 teeth, and its sun gear has 33 teeth, for a 3.27:1 ratio. Case IH combines Goodheart-Willcox Publisher Figure 17-15. This bull-and-pinion final drive is used in John Deere S-series combines and 60-series cotton pickers. Upper left service brake caliper Left service brake rotor Electric shift motor Axle housing Right final drive Right driveshaft Spring-applied parking brake caliper Left driveshaft Hydrostatic motor Transmission case Bull gear (95 teeth) Pinion gear (9 teeth) Output drive hub (splined to bull gear) Goodheart-Willcox Publisher Figure 17-14. On Case IH flagship 10, 20, 30, and 240 series combines, the final drives are mounted to the rigid axle housing. The transmission sends power through the output shafts to the final drive assemblies.