Conventional changeover, transmission, distributor or axle gears generally comprise a cast metal case, which contains bearings, transmission shafts, couplings and gear wheels. Normally an oil bath is provided for lubricating the gear wheels and bearings, the gear wheels being immersed therein and whirled around. This system is appropriate for normal uses and vehicles. However, for large, modern special vehicles where ever higher engine performances are required, this gear technology is no longer adequate. Such high engine performances make it necessary to have much larger gears and therefore, apart from the disadvantage of the much greater space requirement, also lead to a significant weight increase. In particular, the increased space requirement is unacceptable, because the loading surface would then have to be higher, which would in turn lead to important disadvantages, such as e.g. unstable travelling behavior. The conventional gear lubrication method and the conventional construction procedure do not make it possible to reduce gear dimensions, even when using modern materials, which permit higher loading of the shafts, gear wheels and bearings. The reason for this is that if higher loads and pressures occur in the bearings and tooth profiles, there is a much greater heat evolution, because both on the bearing and on the gear transmissions losses occur, to which must be added the drag losses on friction tooth clutches and synchronous rings. A considerable amount of space is still required for the so-called oil sump, which can contain 30 to 60 and more liters of oil. The performance or power losses, which are all converted into heat, amount to 5 to 10% of the engine performance for changeover gears and 5 to 10% thereof for transmission and axle gears. For engines performing in the area of 500 kW, the undesired thermal output is approximately 50 to 80 kW. With such a heat loss 80 liters of oil are quickly heated to 150.degree. C. and therefore a critical point is reached at which the gear is damaged. The vehicle must be stopped and cooling must take place for a considerable time before travelling on, during which time the vehicle constitutes a traffic obstacle. At higher pressures the cooling or lubrication power are no longer sufficient, even when several gear wheels are immersed in the lubricating oil. A higher filling of the gear box with oil does not remedy this, because then the gear wheels circulate the oil too strongly leading to additional power losses and additional heat production, so that the gear would be subject to even greater heating.
USPTO Backgrounds
USPTO Backgrounds