The present invention relates to a sun gear transmission system for a planetary strander.

It is advantageous to be able to switch from planetary to fixed motion in a planetary strander and vice-versa. The purpose of the transmission system of the invention is to enable this to be done.

According to the present invention there is provided a transmission system for a planetary strander comprising a plurality of cradles disposed for rotation about a mandrel, said system comprising first means for transmitting a drive from drive means to the mandrel and second means for transmitting drive from the drive means to the cradles, said second drive means having two operative positions, a first in which the orientation of the cradles is fixed as they rotate about the mandrel and a second in which the cradles perform a planetary motion about the mandrel.

In a preferred embodiment of the invention, the first means for transmitting a drive comprises a drive pulley on the mandrel and a pulley keyed to an output drive shaft from an electric motor, the two pulleys being drivably connected by means of a drive belt. The second

means comprises a pulley rotatably mounted on the output drive shaft and a clutch keyed to the shaft which enables that pulley to be locked to the shaft. A brake which may be bolted to the frame of the strander is provided for " locking the pulley to prevent it rotating with the shaft when the clutch is inoperative. The brake and clutch may be electromagnetic. Drive from the pulley is transmitted via a drive belt to a sun gear which is rotatably mounted on the mandrel. Each cradle of the strander may be driven through planetary gears by this sun gear. When the sun gear is rotated with the mandrel . at the same speed, the cradles rotate at a fixed orientation about the mandrel. When the sun gear is stationary relative to the mandrel, the cradles rotate about their own axes as they rotate about the mandrel thus performing a planetary motion. If desired means may be provided for altering the speed ratio of the sun gear and the mandrel enabling the degree and direction of planetary motion to be altered. These means comprise a belt and pulley arrangement and speed variator for transmitting drive from the output shaft of the electric motor to the pulley which is rotatably mounted on this output shaft.

In order that the invention may be more clearly understood, embodiments of the invention will now be described, by way of example, with reference to the acompanying drawings in which:-

Figure 1 shows a diagrammatic perspective view of one form of transmission system according to the invention and

Figure 2 shows a diagrammatic perspective view of a modified form of the transmission system shown in Figure 1.

Referring to Figure 1, a transmission system is shown according to the invention. This system forms part of a planetary strander which is otherwise of conventional construction. The strander therefor comprises a pair of discs between which a plurality of bobbin accommodating cradles are supported. In Figure 1 for simplicity only, a part of one of these discs 1, and a part of one cradle 2 are shown. The discs 1 are keyed to a mandrel 3 to rotate with the mandrel and one of the discs 1 houses planetary gearing having a 1 to 1 drive ratio for driving the cradles 2. In some forms, if the ratio between pulleys 17 and 21 is different to the ratio between pulleys 16 and 18, then a ratio of other than 1:1 is required. One set of gearing 4 is shown for the one cradle 2 shown. Each set of planetary gearing 4 comprises a planetary gear 5 drivably connected to its corresponding cradle 2, an intermediate gear 6 and a sun gear 7 which is common to each gearset 4. The common sun gear 7 is free to rotate on the mandrel 3.

The mandrel is supported for rotation in bearings located on opposite sides respectively of the disc and cradle assembly. One bearing only is shown in Figure 1. The mandrel 3 is driven through a drive arrangement comprising an electric drive motor 10 , pulleys and drive belts. The output shaft 11 from the motor 10 is drivably connected via a drive belt 12 and pulleys 13 and 14 to an intermediate shaft 15. This shaft supports two other pulleys 16 and 17. Pulley 16 is keyed to the shaft and is drivably connected via a drive belt 19 to a drive pulley 18 which is keyed to the mandrel 3. Pulley 17 is free to rotate on shaft 15 and is drivably connected via a drive belt 20 to a pulley 21 which is rotatably mounted on the mandrel and is keyed to the sun gear 7. The pairs of pulleys connected by the two drive belts 19 and 20 both have the same drive ratio, although as indicated earlier this may be different.

An electromagnetic brake 22 and clutch 23 are also disposed on the intermediate shaft 15 on opposite sides respectively of the pulley 17. The brake 22 is bolted to the frame (not shown) of the strander and enables the pulley 17 to be braked so that drive is not transmitted to the sun gear. The clutch 23 is keyed to the shaft 15 and enables the pulley 17 to be driven by the shaft 15.

The above described transmission arrangement has two operating modes depending upon whether the stranders desired operation is fixed or planetary. In the fixed operating mode, the clutch 23 is engaged and the brake 22 released. With the clutch 23 engaged, the pulley 17 is driven by shaft 15 and drive is transmitted via belt 20 to sun gear 7. The sun gear 7 is therefor rotated at the same speed as the mandrel 3 as a result of which the cradles 2 adopt fixed positions relative to the discs 1. In the planetary operating mode, the clutch 23 is disengaged and the brake 22 is engaged. The pulley 17 is fixed relative to the rotating shaft 15 and no drive is transmitted via belt 20 to the pulley 21. The sun gear 7, which is keyed to pulley 21, is therefor held stationary and does not rotate with mandrel 3. As a result each cradle 2 is rotated via its planetary gears 5, 6 relative to the discs 1 as the mandrel and discs rotate, each cradle thereby performing a planetary motion. Changing between these two operating modes may be achieved by a simple changeover switch (not shown) which switches current to the clutch 23 or brake 22 as required.

Figure 2 shows a modification of the arrangement of Figure 1.

In this modification, a speed differential unit is provided attached to the clutch 23 which enables the

SUBSTITUTE SHEET

speed of the sun gear to be varied relative to the speed of the mandrel and therefor the disc 2. In this way, the degree of planetary motion may be varied in both a positive and a negative direction. The speed differential unit comprises a pulley 30 keyed to the clutch 23 and free to rotate on the shaft 15. This pulley 30 is drivably connected to a further pulley 31 by means of a drive belt 32. Pulley 31 is keyed to an output shaft from a differential 35. Pulley 33 is- drivably connected via a drive belt 36 to a further pulley 37 which is keyed to shaft 15. Pulley 33 is drivably connected to one of the two input shafts to the differential 35.

Another pulley 38 is also keyed to shaft 15 and drives the speed variator via a drive belt 39 and drive pulley 40. In other respects the arrangement is the same as the arrangement of Figure 1, equivalent parts bearing the same reference numerals. By altering the speed variator, which may be a P.I.V. box, the relative speeds between pulley 17 and pulley 16 may be varied thus altering the relative speeds of the mandrel 3 and sun gear 7 and thereby the degree and direction of planetary movement of the cradles 2.

It will be appreciated that the above embodiments have been described by way of example only and that many

variations are possible without departing from the scope of the invention.