The effort have been many and extensive to arrive at transmission units or gears that are able to accommodate the varying demands for torque or rotational speed under various situations, e.g. at start and operation and otherwise different operational conditions.

There are already in existence several publications describing such constructions, e.g. NO 300 834, NO 177 807 and WE 97/23315.

Great efforts are being made to arrive at transmissions with minimized energy losses, length and diameter within the area of self adjusting transmissions.

The device according to the present invention provides a solution that will give the above-mentioned advantages, plus others, that will be apparent from the following description.

This is achieved with the device according to the invention as it is defined with the features said forth in the claims.

The drawing shows in fig. 1 a longitudinal section through an embodiment of the device according to the invention, used as a transmission to a boat propeller, fig. 2 shows a first embodiment of a pulling tool in longitudinal section, and fig.

3 shows, also in longitudinal section, a pulling tool similar to fig. 2, but in a different embodiment.

The device according to the invention comprises in principal an input shaft 1 that is connected to an output shaft 2 through a planetary gear. A housing 3 provides a connection between the two planetary gears, and would such rotate with those, however limited by possible resistance the housing might encounter.

Planetary gear may in principal be formed in various manners.

Both the planetary gears may be formed as toothed gears as shown on figure 2. On the other hand, one or both the planetary gears may be formed as friction gears with balls as shown in figure 1 and 3, where one planetary gear is embodied as a toothed wheel connection. In one embodiment with adjustable gear ratio in one of the planetary gears, for example according to figure 1, one can achieve the adjusting of the torque both with the resistance

against turning of the housing 3 and altering of the planetary gear gear ratio by means of balls in an outer ball path on the sliding sleeve 5 and an inner ball path in the housing 3. This ball path will move the sliding sleeve 5 on figure 1 axially with respect to the input shaft 1 and the output shaft 2. Thereby the first planetary gear will give a changed gear ratio which is self balancing against the rotational resistance on the housing 3.

With the device according to the invention it is achieved that the output shaft 2 rotates with the torque that is demanded at a given time. This means that the transmission for example from the start ensures a continuous transfer from rest to full rotational speed.

The invention is described in the following on the basis of three practical embodiments, one, shown in figure 1, as a differential for a boat propeller, the following two comprise to variants of a pulling machine or actuator. Figure 2 shows an embodiment where one planetary gear consists of a tooth wheel, while figure 3 shows an embodiment where one planetary gear consists of balls.

The device in figure 1 comprises a differential for a boat propeller where the differential is connected with a motor with input shaft 1 and with the a propeller with output shaft 2.

Attached to the housing 3 are fins 4 that stay in the water and run axially with respect to the shafts 1 and 2. The fins 4 are axially positioned consecutively with spaces along the circum- ference of the housing 3. Rotation of the housing 3 will be damped or hindered by the resistance that the fins 4 encounter in water. This means that the input shaft 1 by means of ram slide sleeve 5 will press the gear balls 6 to the right on figure 1, that is against the smaller running diameter with the input shaft 1. When the balls 6, which are free running within the ring being held by an axially movable rod 7, are pressed by the ram slide sleeve 5, the rod 7 will be pressed against a piston which by means of a spring 9 keeps the rods 7 under load.

With the device according to figure 1 the rotational speed of the propeller will be adjusted with respect to the resistance encountered by the fins 4, until the fins, when the speed is reached, are held in a position such that also the housing 3 will be held, and the propeller on the output shaft 2

has reached the desired rotational speed.

The movement of the slide sleeve 5 is achieved by balls 11 in ball paths 12. This motion will in turn depend on the rotational speed of the housing 3.

The surfaces against which the balls 6 move can be shaped as shown on the figure. If the rolling surface of the input shaft 1 is extended sufficiently to the left so that the center of the ball 6 turn on circles with the same diameter as the axis of the planetary wheels 13, the output shaft 2 will stand still, and if the motion of the balls 6 continue beyond this point, the output shaft 2 will reverse. Further, the gear ratio may be varied from a undergear to a overgear.

Figure 2 shows an embodiment of the pulling tool especially adapted for carrying out a blind riveting process. An input shaft 1 has an inside annular wheel 16 in the housing 3.

In the other end of the housing is formed an inside ball path 12 with a left hand thread and a great pitch. A sun sleeve 18 rotates freely on the center axis 8. In the center axis 19 is provided a return spring 20 that loads a return shaft 21 against the input axis 1. The sun sleeve 18 is constantly meshed with the planetary wheels 14 and 13. The blind riveting tool pulling rod 23 runs axially free through a sleeve 24. Needles 25 are fastened between the sleeve 24 and a needle case 26. Behind the sleeve 24 the rod 23 is connected to the center axis. The planetary housing 27 is fitted with preferably three planetary wheels 13 and includes a contact surface for contact against the housing 3. The planetary house 27 has ball bearing threads corresponding to the housing 3 grooves or ball path 12. Conveniently the planetary house 27 forward part can be equipped with a free coupling to permit free rotation to the left and blocked rotation to the right of the nose housing 28 which internally has a groove to obtain the same function as a ratchet. The forward part of the nose house 28 is shaped as screw bit 29 and the outside of the nose house 28 has threads for an adjusting nut 30 for adjusting of the rod 23 desired depths in the rivet at the start of the expansion or extension of the rivet wall. A bearing 31 assures free friction under the pulling operation.

When the rod 23 is moved over the rivet, the planetary house 27 will be pressed to the right on the figure by balls in

the ball paths 12. The needles 25 will then be pressed against the rod 23 and squeezed against the output shaft 2 so that the rivet will be pulled to the left on the figure because the planetary house 27 will be displaced to the left on the figure by the balls in the ball path 12.

Figure 3 shows another embodiment of the pulling tool in figure 2. Against the conical surface of the input shaft 1, rest planetary balls 6 held by rods 7 that are adjustable with an adjustment nut 17. The balls 6 rest against an annular path 22. The annular path 22 rotates freely against housing 3 by means of a bearing.

The forward end of the input axis constitutes a sun wheel 10 on which a planetary wheel 13 rotates, as the planetary wheels 13 are fastened to the planetary housing 2. The planetary housing 2 has an outer ball path 12 and similarly the housing 3 has inside wheel path, so that balls 11 make connection between the two.

When the housing 3 has rotated one turn, the planetary wheels 13 will not yet have reached full turn, since their distance from the axel is greater. Therefore the balls 11 will be somewhat displaced for each turn. In front of the housing 3 of the planetary housing 2 there is provided a bearing with a running ring 32 that locks and pulls with it the housing 3 in the rotation towards the right. During the pulling operation itself, this bearing will run freely by means of a housing 3 rotating faster than the planetary housing 2. After the pulling operation is completed, the housing 3 and the planetary housing 2 will have the same rotational speed, which means that the planetary housing 2 will be brought back to the starting position on figure 3, with axial contact between the planetary housing 2 and the housing 3.

Thereby the one way bearing running ring 32 will be locked so that the housing 3 will be brought forward to a new pulling operation.

For the embodiments according to figure 2 and 3, the difference in rotational speed between the housing 3 and the planetary housing 2 constitutes the effect that is utilized for the pulling of rivets.

The adjustment nut 17 can be adjusted so that the planetary balls 6 will be placed in greater or smaller distance from the axis of rotation, which will provide changed gear ratio due the fact that the two contact surfaces have different cone angles.