| 摘要 |
<p num="1"><br/><br/> Abstract<br/><br/> A power unit of the type varying its length comprises<br/>three members movable in relation to each other. The<br/>power unit is used for transferring load from a first<br/>load carrier to a second one. In order to make this<br/>transfer possible in a satisfying manner, the power<br/>unit has to be constructed so that it can be extended<br/>to at least two times its length in the contracted<br/>state. For this reason it is a necessity that trans-<br/>missions comprising wheels (13) and a loop (15) laid<br/>around these are so arranged, that when the third<br/>member (3) is displaced with respect to the first member<br/>(1) fixed in the room, at the same time the second<br/>member (2) is displaced in the same direction and the<br/>same distance with respect to the third member (3).<br/>In order to solve this problem in an appropriate manner<br/>the invention proposes to design the first member (1)<br/>with at least partly the character of a housing for<br/>the power unit, with an elongated shape in cross section.<br/>The power device (6, 7, 8, 9, 10, 11) for displacement<br/>of the members (1, 2, 3) is disposed generally in the<br/>central region (22) of this housing. The transmissions<br/>are two in number and they are generally symmetrical<br/>in a mirror image relation to each other with respect<br/>to a plane comprising the longitudinal axis of the<br/>power device and being perpendicular to the greater<br/>dimension of the cross sectional shape of the housing<br/>(S-S plane). (Fig 1, 2 and 3).<br/> |
