Abstract: In a high-loaded, light-weight, compact, multi-stage gear transmission unit with at least one stage with non-parallel shafts, and a transmission ratio between approximately 70 and 150, like a helicopter transmission, said angle transmission generally forms the weakest link. By adoption of a face gear/cylindrical pinion-stage instead of the commonly used bevelled-stage, not only a more reliable drive is possible, but its efficiency is higher, due to less friction, its size is smaller, its adjustment is simpler such that straight forward replacement becomes possible, and - not in the least - the transmission ratio of said angle drive tends to high ratios in contrast to known bevelled-drives which tend to low ratios. In many cases one or even more stages less become possible, providing a further important reduction in weight and size.

Abstract: In a high-loaded, light-weight, compact, multi-stage gear transmission unit with at least one stage with non-parallel shafts, and a transmission ratio between approximately 70 and 150, like a helicopter transmission, said angle transmission generally forms the weakest link. By adoption of a face gear/cylindrical pinion-stage instead of the commonly used bevelled-stage, not only a more reliable drive is possible, but its efficiency is higher, due to less friction, its size is smaller, its adjustment is simpler such that straight forward replacement becomes possible, and--not in the least--the transmission ratio of said angle drive tends to high ratios in contrast to known bevelled-drives which tend to low ratios. In many cases one or even more stages less become possible, providing a further important reduction in weight and size.

Abstract: The invention relates to a high-vacuum molecular pump of the kind comprising at least two coaxial elements (1 and 2) mounted rotatably with respect to each other and at a small distance from each other, wherein a side of one of the elements (1) positioned opposite a side of another element (2) is provided with at least one helical groove (5), and wherein a pump space (6) is present between these two sides of the elements, which pump space (6) is in communication with a gas supply (7) and a gas discharge (10, 8). Between the gas supply (7) and the pump space (6) a substantially annular gas supply chamber (9) is present, which is bounded by the elements (1 and 2) and which is relatively wide near the gas supply (7) but narrows downstream towards the pumpspace (6). The helical groove (5) extends into the annular gas supply chamber (9).