附 录AThe Analysis of Fuller Twin Countershafts Transmission Structure SharacteristicsFulham (Fuller) because American Eaton is twin countershafts transmission Eaton company of the 60s original products, in 1965 patent application, and then put into production, supply market. It is aimed at the condition of design: when the U.S. has gradually built highway system, in order to improve the economic benefit to freight cars, trucks, and fast pace to large, specialty direction. In the United States more prevalent mode of transportation is by the saddle type tractor trailer and car pulled the tractor is the train, the main road with heavy car models, its characteristic is short wheelbase, in addition to the U.S. highway law caps the car before hanging must not be more than 800, and consequently make twin countershafts transmission shaft to size is very limited. The needs of the development of surface but repeated requests to improve the car engine power, and corresponding enlarges the bearing capacity of the transmission, this to the traditional single axis twin countershafts transmission for, its axial dimensions must increase thus had a contradiction, double the axis is that the twin countershafts transmission in such a situation of The Times looks unfamiliar. It greatly improve the twin countershafts transmission torque capacity (Fuller products has reached 2240), largest and decreases the axial dimensions. It supply market in the United States, after the heavy car gradually replaced the traditional single axis transmission. Eighty s it almost exclusive American heavy vehicle twin countershafts transmission market (including Eaton company products accounted for about 75%). Since the mid seventy s, Eaton products in reducing noise and improve life and reliability have increased significantly. And in the twin countershafts transmission basic structure under the condition of invariable, and has successfully developed series presentation of a new generation transmission. At the same time, adjusted the original, redesign the product series and realize standardization. Eighty s has the new series production. This paper is based on the original 900 series (namely the new series 11600, both the same basic structure of RT-915) type group structure of the desktop twin countershafts transmission for an example cent fold.Figure A1 Fuller Twin Countershafts Transmission-The first shaft -Lord box box axial -The second Lord box in the axisR-Lord box in reverse Thaft axis -vice Box-vice box output shaft-Bhift joints set -Vice box high low synchronizer joints sets-Vice box super cheap synchronizer joints set ofZR2-Lord box in reverse presence wheelAttached A1 RT-915 type the basic structure of transmission Figure A1 shows is the RT-915 type twin countershafts transmission structure diagram, it consists of a main five gear box and a rear times of three gear shift combination to vice box, it has 15 forward gears and three in reverse. The Lord box and vice gearbox which is 148.43center distance they each have two sets of intermediate bearing assembly, all the gear for spur gear, often meshing type transmission , both on the output shaft gear are floating, Lord box output shaft also float. The box without the file synchronizer, vice box with high cheap locking pin type synchronizer, ultra low inertia by outer profile of mating type shift device. The box for each file mechanical hand manipulation, vice box every file adopted the pneumatic control shift. When vice box synchronizer joints set with mating set of () are moved to the mating position when the left and the twin countershafts transmission were at high speed area, low speed area, super-low speed area, equipped with five ratio for selection.Attached A2 Structure analysisAttached A2.1 Dual axis power diversionFigure A1 shows twin countershafts transmission box and vice box the Lord had two sets of the axis assembly, input power points to two road axis assembly, again by the output shaft assembly will be two road after mixing power output. Input and output shaft of the gear has at the same time two teeth on the axis of the two respectively with gear, work by load per tooth structure is concerned, because the relative single reduced 1/2, in fact, in theory, the tooth shape error, the tooth thickness error, the center distance, the error on the axis gear and corresponding mesh loading not even, make the actual reduce the value of less than 1/2. This situation than single axis transmission double the axis has obvious advantages.Attached A2.1.1 Dual axis gears lifeIn view of the fatigue life of gear with its load of three times about square of inverse ratio, the formula is as follows: (constant) type (A1)Type: P-Gear load;N-Fatigue damage of gear tooth cycles.The type that a single tooth, A1 power twin countershafts transmission cases, gear load, the corresponding fatigue damage cycle times. When dou