WO2016124071A1

WO2016124071A1 - Outer shuttle frame, rotating shuttle, and rotating shuttle lubrication method

Info

Publication number: WO2016124071A1
Application number: PCT/CN2016/070854
Authority: WO
Inventors: 张旭生
Original assignee: 中山市旋霸缝纫设备有限公司
Priority date: 2014-11-17
Filing date: 2016-01-14
Publication date: 2016-08-11
Also published as: CN104358039B; CN104358039A; JP3214070U

Abstract

The present invention relates to the field of sewing machine apparatuses, and provides an outer shuttle frame, a rotating shuttle, and a rotating shuttle lubrication method. The outer shuttle frame comprises a drive force reception part for receiving a rotating drive force and an inner shuttle frame housing cavity. The surrounding wall of the inner shuttle frame housing cavity is provided with a groove for slidingly matching an inner shuttle frame. The drive force reception part is provided with an essentially sealed oil storage cavity. The oil storage cavity is in communication with the groove via an oil path. Also disclosed are a rotating shuttle having the outer shuttle frame and a lubrication method using the rotating shuttle.

Description

Outer shuttle frame, hook and hook lubrication method

Technical field

The present invention relates to the field of sewing machine equipment, and more particularly to an outer shuttle frame for a sewing machine, a hook with an outer shuttle frame, and a lubrication method for the hook. The present application is based on a Chinese patent application filed on Nov. 17, 2014, the entire disclosure of which is hereby incorporated by reference.

Background technique

The sewing machine is provided with a hook on the lower side of the needle plate. The hook includes an outer shuttle and an inner shuttle. The outer shuttle rotates integrally with the shaft as the needle moves up and down, and rotatably supports the inner shuttle. The inner shuttle can rotate independently of the outer shuttle and includes a shuttle at its outer peripheral portion. The shuttle portion is engaged with the stop shuttle included in the sewing machine for stopping the rotation of the inner shuttle frame so that the inner shuttle frame does not rotate synchronously with the outer shuttle frame. The needle thread of the needle thread is inserted into the needle. The outer shuttle of the sewing machine captures the upper thread of the needle passing through the fabric, and the upper thread is interlaced with the bottom thread held by the inner shuttle in the stopped state to perform sewing.

Referring to Fig. 1, there is shown a cross-sectional view of a conventional rotary hook 1 having a lubrication system. The rotary hook 1 comprises an outer shuttle frame 11, an inner shuttle frame 12 and a pressing piece 15, the outer shuttle frame 11 is provided with an inner shuttle frame receiving cavity, the inner shuttle frame receiving cavity is provided with an inner shuttle frame 12, and the outer shuttle frame 11 is provided with an inner shuttle frame A groove portion 16 is circumferentially opened on the inner wall of the accommodating cavity, and an outer wall of the inner shuttle frame 12 is circumferentially provided with an edge portion 17, and the edge portion 17 cooperates with the groove portion 16 so that the inner shuttle frame 12 can be along the groove portion and the outer portion The shuttle frame 11 rotates independently. The pressing piece 15 includes a radially extending buckle, and the pressing piece is fixedly mounted on the outer wall of the outer shuttle frame 11, and the buckle cooperates with the groove portion 16 of the inner shuttle frame to restrict the axial movement of the edge portion 17, that is, at the buckle edge and The inner shuttle frame 12 cannot be disengaged from the outer shuttle frame 11 by the groove portion 16. When the hook 1 rotates during normal operation, since the inner shuttle 12 is relatively fixed and does not rotate, the outer shuttle 11 needs to rotate about its axis, so that the groove portion 16 and the edge portion 17 need to be coated with lubrication. Oil, and the lubricating oil will wear out after a long time of use, and in order to achieve rotation for a long time, it is necessary to set up a continuous oil supply system. Specifically, an oil supply pipe 13 is provided in the driving force receiving portion of the outer shuttle frame 11, and an oil passage 14 is opened in the outer shuttle frame 11, and the oil passage 14 communicates between the groove portion 16 and the oil supply pipe 13 in the oil supply pipe. The distal end of the 13 is applied with a positive pressure by the oil pump so that the lubricating oil is ejected from the opening at the groove portion 16 through the oil passage under the force of the positive pressure, thereby achieving continuous oil supply.

Then, because the pressure of the oil pump is not easy to achieve precise control, if the oil pressure is too large, there will be external spray or leakage of the lubricating oil, which will cause serious pollution to the textile fabric. If the oil pressure is too small, the lubrication will be caused. The oil supply is insufficient, that is, the friction between the outer shuttle frame 11 and the inner shuttle frame 12 will be abruptly increased, thereby causing great wear on the groove portion of the outer shuttle frame 11 and the edge portion of the inner shuttle frame 12, thereby seriously affecting the rotation. The service life of the shuttle.

technical problem

In order to solve the above problems, it is a first object of the present invention to provide an outer shuttle that can accurately supply oil and avoid oil leakage.

A second object of the present invention is to provide a hook that can accurately supply oil and avoid oil leakage.

A third object of the present invention is to provide a hook lubrication method that can accurately supply oil and avoid oil leakage.

Technical solution

In order to achieve the first object of the present invention, the present invention provides an outer shuttle frame including a driving force receiving portion that receives a rotational driving force and an inner shuttle housing receiving chamber, and a peripheral wall of the inner shuttle housing receiving chamber is provided for sliding with the inner shuttle frame The groove portion to be engaged, wherein the driving force receiving portion is provided with a substantially sealed oil storage chamber, and the oil storage chamber communicates with the groove portion of the oil passage.

In a further aspect, the oil passage is a hole that opens the inner wall of the inner shuttle accommodating chamber.

In a further aspect, the oil reservoir is provided with an opening, and the opening is provided with a seal.

A further solution is that the oil reservoir extends in the circumferential direction.

A further solution is that the oil reservoir is offset from the central axis of rotation of the outer shuttle.

In order to achieve the second object of the present invention, the present invention provides a rotary hook including an outer shuttle frame, an inner shuttle frame and a pressing piece, and the outer shuttle frame includes a driving force receiving portion for receiving a transmission force and an inner shuttle frame accommodating chamber. The peripheral wall of the shuttle accommodating cavity is provided with a groove portion in the circumferential direction, and the inner shuttle frame is installed in the inner shuttle accommodating cavity, and the inner shuttle frame is disposed on the groove portion and can rotate independently along the groove portion and the outer shuttle frame, and the pressing piece includes a peripheral wall and a buckle edge at an axial end of the peripheral wall, the pressing piece is mounted on the outer wall of the outer shuttle frame, and the buckle is engaged with the inner shuttle frame, wherein the outer shuttle frame is provided with a substantially closed oil storage cavity in the driving force receiving portion, and the outer shuttle The frame also includes an oil passage that communicates between the groove portion and the oil reservoir.

In order to achieve the third object of the present invention, the present invention provides a method of lubricating a rotary hook, wherein the rotary hook includes a relatively rotatable outer shuttle frame and an inner shuttle frame, and the outer shuttle frame is provided with a driving force receiving portion and for the inner portion The sliding portion of the shuttle frame is matched with a substantially sealed oil storage chamber storing lubricating oil at the driving force receiving portion, and the oil storage chamber is communicated with the groove portion through the oil passage, and the lubrication method of the rotary hook includes: following the outer shuttle frame Rotating, the lubricating oil is output to the groove portion through the oil passage under the action of centrifugal force.

Beneficial effect

The outer shuttle frame, the rotary hook and the rotary hook lubrication method provided by the invention provide a closed oil storage chamber in the driving force receiving portion of the outer shuttle frame, and pass through the oil passage connecting groove portion and the oil storage chamber which are the only lubricant outlets. During the rotation of the outer shuttle frame, the liquid lubricating oil inside the oil storage chamber is also accompanied by the rotation, and the rotation of the lubricating oil generates centrifugal force, so that a positive pressure in the radial direction is applied to the lubricating oil, which in turn The lubricating oil can be output to the groove portion through the oil passage under the force of the positive pressure, and adhered to the surface of the groove portion or the inner shuttle frame portion to provide lubrication for the rotation of the outer shuttle frame. Since the oil pressure provided by the oil pump commonly used in the prior art is no longer used, the present invention uses the lubricating oil in the substantially closed oil storage chamber, the positive pressure generated by the centrifugal force of the lubricating oil, and the outer shuttle frame high speed. During operation, more lubricating oil is needed. At this time, the centrifugal force generated by the faster rotation speed also increases, so the positive pressure applied to the lubricating oil also increases, and then more lubricating oil will be oiled. The road is output at the slot opening to lubricate the rotation of the outer shuttle. When the outer shuttle frame is running at a low speed, less lubricating oil is required, and the centrifugal force generated by the slower rotation speed is also reduced, so that less lubricating oil will seep out from the oil passage at the slot opening, while the outer shuttle When the frame stops rotating, since there is no centrifugal force, and since the lubricating oil is disposed in the closed cavity, the lubricating oil will not leak out under the action of the air pressure. By automatically adjusting the oil pressure by using different rotational speeds, the precise supply of oil to the groove portion of the outer shuttle frame is realized, thereby avoiding excessive lubricating oil contaminating the clothes or too little lubricating oil affecting the normal use of the outer shuttle frame. In addition, since the hook or the outer shuttle frame will wear out after a certain period of time or after rotating to a certain number of turns, and the overall replacement is required, the hook or the outer shuttle frame are both lossy parts and receive at the driving force. The oil storage chamber is opened in the department, and the lubricating oil in the oil storage chamber is matched with the service life of the outer shuttle frame, so that the existing complicated oil supply pipeline and the oil supply system are no longer needed, thereby reducing the later period. The maintenance cost and the simple structure of the outer shuttle frame of the present invention are more conducive to improving production efficiency.

In addition, by providing the oil passage of the inner wall as the oil passage of the lubricating oil, it is no longer necessary to add other components to the outer shuttle frame, and the lubricating oil can be accurately conveyed to the groove portion through the internal oil passage, and at the same time, since the inner wall is longer than the axis by the length of the axis The length of the force receiving portion from the axis makes the lubricating oil have a larger radius of rotation when it rotates, which is beneficial to increase the centrifugal force, that is, to improve the oil pressure of the lubricating oil.

Moreover, when the oil storage chamber is filled with lubricating oil, it can be injected from the opening, and the oil storage chamber is sealed by the sealing member, which is convenient for facilitating the filling process and improving the production efficiency.

In addition, since the outer shuttle frame is a common part of the sewing machine, its size and shape are greatly limited. Therefore, it is quite difficult to store an oil storage chamber with sufficient space inside the outer shuttle frame for storing lubricating oil, so it is driven. The annular receiving groove extending in the circumferential direction is provided in the force receiving portion, and the use of the excess space in the driving force receiving portion is skillfully utilized, which not only solves the problem of the oil storage cavity space, but also the annular oil storage cavity solves the uneven distribution of the lubricating oil. The problem that the outer shuttle is not rotated smoothly. At the same time, it is advantageous to increase the rotation radius of the lubricating oil by setting the oil storage chamber away from the central axis of rotation, thereby increasing the oil pressure by increasing the centrifugal force.

DRAWINGS

1 is a cross-sectional view of a conventional hook.

Figure 2 is a structural view of an embodiment of the hook of the present invention.

Figure 3 is a structural view of the hook embodiment of the present invention at different viewing angles.

Figure 4 is an exploded perspective view of the embodiment of the hook of the present invention.

Figure 5 is an exploded perspective view of the outer shuttle frame of the hook embodiment of the present invention.

Figure 6 is a cross-sectional view of an embodiment of the hook of the present invention.

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Embodiments of the invention

First embodiment:

2 and 3, FIG. 2 and FIG. 3 are structural views of the hook 2 at different viewing angles, and the hook 2 includes an outer shuttle frame 3, an inner shuttle frame 4, and a pressing piece 5. Referring to Figure 4 in conjunction with Figures 2 and 3, Figure 4 is an exploded view of the structure of the hook 2. The shape of the inner shuttle frame 4 is a bottomed cylindrical inner shuttle frame, and a cylindrical portion is formed in the middle portion of the inner shuttle frame 4, and the inner shuttle frame 4 is formed on the peripheral wall of the outer peripheral side thereof substantially circumferentially around the circumference. Along the 42, the inner shuttle frame 4 is formed with a stop portion 41 at its open end.

The pressing piece 50 includes a curved peripheral wall 53 and a buckle 51 on an axial end of the curved peripheral wall 53. The buckle 51 is disposed perpendicular to the peripheral wall 53, and is evenly distributed along the radial direction of the pressing piece 50 on the curved peripheral wall 53. Three positioning holes 52 are opened, and the pressing piece 5 is mounted and fixed on the outer wall of the outer shuttle frame 3 through the positioning hole 52 and rotates integrally with the outer shuttle frame 3.

Referring to Fig. 5 in conjunction with Figs. 3 and 4, Fig. 5 is an exploded view of the outer shuttle frame 3, the outer shuttle frame 3 is provided in a bottomed cylindrical shape, and an inner shuttle frame receiving cavity is provided in the middle of the outer shuttle frame 3. 31. The inner wall of the inner bobbin accommodating chamber 31 has a groove portion 32 which is circumferentially wound. The groove portion 32 has a two-part composition, wherein a part of the groove portion is a circumferential groove formed by the inner wall of the outer shuttle frame 3, and the other portion is a circumferential groove formed by the combination of the step formed by the inner wall of the outer shuttle frame 3 and the buckle edge 51. A driving force receiving portion 34 is provided on a side of the outer shuttle frame with respect to the inner shuttle housing accommodating chamber 31. The driving force receiving portion 34 is for receiving an external rotational force and driving the outer shuttle frame 3 to rotate, specifically, the driving force receiving portion 34. A boss extending in the axial direction of the back side surface of the bottom 311 of the outer shuttle frame is provided with a positioning hole 35 extending in the middle of the driving force receiving portion 34 along the axis, along the side wall of the driving force receiving portion 34. A transmission hole 36 and a transmission hole 37 are opened through the through hole, and the transmission hole 36 and the transmission hole 37 are symmetrically disposed on both sides of the positioning hole 35. A shuttle shaft (not shown) is inserted into the positioning hole 35, and is engaged with the shuttle shaft through the screw through the transmission hole 36 and the transmission hole 37, and then the outer shuttle 3 can be received with the driving force of the shuttle shaft as a central axis of rotation. The portion 34 rotates integrally with the axis.

An oil reservoir 6 is formed inwardly on the bottom 311 of the outer shuttle frame 3. The oil reservoir 6 is located in the driving force receiving portion 34, and the oil reservoir chamber 6 is a sealed annular groove extending in an annular shape. The groove is disposed away from the axis of the driving force receiving portion 34, and a connecting groove 63 is formed in the radial direction on the circumferential end portion of the annularly disposed oil reservoir, and the oil reservoir chamber 6 and the connecting groove 63 have a direction toward the inner shuttle housing chamber 31. a continuous opening, a sealing member 61 is mounted on the continuous opening, and the sealing member 61, the oil reservoir 6 and the connecting groove 63 enclose a substantially closed space for storing lubricating oil, and the substantially sealed oil storage chamber 6 only serves as a lubricating oil The outlet of the output port, that is, the substantially closed oil reservoir 6 does not have an external input of lubricating oil into the reservoir.

Referring to Figure 6, Figure 6 is a cross-sectional view of the hook 2. The oil passage 62 will be described below with reference to Figs. 5 and 6. An oil passage 62 is provided at an end of the connecting groove 63 facing the inner wall of the outer shuttle frame 3. Specifically, the oil passage 62 is a hole formed in the inner wall of the outer shuttle frame 3, and the hole is composed of a first through hole opened in the radial direction and a second through hole opened in the axial direction, and the first through hole and the second through hole are connected in communication. And a sealing member 622 is disposed on the outer end of the first through hole, and a sealing member 621 is disposed on the outer end of the second through hole, so that the oil passage 62 is a communicating hole that is bent at a right angle. The first end opening of the oil passage 62 is disposed on the connecting groove 63, and the second end opening of the oil passage 62 is disposed on the groove portion 32. Since the connecting groove 63 is disposed in communication with the oil reservoir 6, the oil passage 62 communicates with the groove. Between the portion 32 and the oil reservoir 6, the lubricating oil located in the oil reservoir 6 can be output to the groove portion 32 through the oil passage 62.

Since the inner shuttle frame 4 is disposed in the inner shuttle accommodating chamber 31 of the outer shuttle frame 3, and the edge portion 41 of the inner shuttle frame 4 is disposed in the groove portion 32, and is sandwiched along the portion 41 at a partial position of the outer shuttle frame 3 The buckle is between the 51 and the groove portion 32. Therefore, when the hook 2 is in operation, the inner shuttle frame 4 is fixed and does not rotate, and when the outer shuttle frame 3 and the pressing piece 5 rotate together, the lubricating oil placed in the oil storage chamber 6 is centrifugally driven. Under the action of the connection groove 63 into the oil passage 62, the force generated by the centrifugal force is applied to the lubricating oil located in the connecting groove 63, so that the lubricating oil has a positive pressure toward the outside, and finally the lubricating oil is under the action of the positive pressure. The oil passage 62 is discharged from the groove portion 32 to be attached to the surfaces of the buckle edge 51, the edge portion 41, and the groove portion 32.

Second embodiment:

The opening of the oil reservoir 6 and the connecting groove 63 of the first embodiment is opened toward the inner shuttle, and on the basis of the first embodiment, the hook of the second embodiment can also connect the oil reservoir and the connecting groove. The opening is disposed away from the inner shuttle frame, and a sealing member is mounted on the opening disposed away from the rear, and when the lubricating oil of the oil storage chamber is exhausted, the setting can be performed without disassembling the pressing piece and the inner shuttle frame. Fill the lubricant. In addition, an oil filling hole may be formed in the sealing member so that the sealing member is not required to be disassembled when filling the lubricating oil, and the lubricating oil is poured through the oil filling hole, which can also achieve the object of the present invention.

Third embodiment:

The oil passage 62 of the first embodiment is a hole provided in the inner wall of the outer shuttle frame. On the basis of the first embodiment, the oil passage of the rotary hook of the third embodiment may also be a cotton thread disposed in the hole, and the cotton thread may be used. The transfer of lubricating oil from the oil reservoir to the trough portion, in turn, achieves the objectives of the present invention.

Fourth embodiment:

On the basis of the first embodiment, the fourth embodiment can set the oil passage 62 of the first embodiment as an oil guiding tube, and place the oil guiding tube in the outer shuttle frame, and communicate the oil storage chamber and the groove portion through the oil guiding tube. The present invention can also be realized by transferring lubricating oil to the groove portion through the oil guiding tube when the outer shuttle frame is rotated.

Fifth embodiment:

On the basis of the first embodiment, the fifth embodiment can provide the oil passage 62 of the first embodiment as a plurality of holes disposed in the outer shuttle frame, and the plurality of holes are evenly distributed in the circumferential direction of the oil reservoir, so that The lubricating oil in the oil reservoir can be input to the groove portion through a plurality of holes respectively under the action of centrifugal force, and the object of the present invention is achieved. Further, the tunnel in the fifth embodiment may be disposed obliquely or curvedly in the inner wall of the outer shuttle.

Sixth embodiment:

On the basis of the first embodiment, the sixth embodiment can set the annular oil storage chamber 6 of the first embodiment to be located in a rectangular or triangular oil storage chamber in the driving force receiving portion, and set the oil storage chamber to be offset. At the position of the central axis of the shuttle rotation, the object of the present invention can also be achieved by injecting lubricating oil into the oil reservoir and transporting the lubricating oil to the groove portion through the oil passage.

Seventh embodiment:

On the basis of the first embodiment, the seventh embodiment is a lubrication method applied to the hook of the first embodiment, and the lubrication method of the hook is: since the inner shuttle is fixed without rotation, and the hook is working, first The outer shuttle frame and the pressing piece will rotate together, and then the lubricating oil placed in the oil storage chamber will rotate with the rotation of the outer shuttle frame, and the centrifugal force will act on the lubricating oil while the lubricating oil rotates, and then under the action of centrifugal force The lubricating oil will enter the oil passage through the connecting groove. The force generated by the centrifugal force is applied to the lubricating oil located in the connecting groove, so that the lubricating oil has a positive pressure facing outward, and finally the lubricating oil is discharged from the groove portion through the oil passage under the action of the positive pressure to be attached to the buckle edge and the edge portion. And on the surface of the groove.

It can be seen that a closed oil storage chamber is arranged in the driving force receiving portion of the outer shuttle frame, and the liquid lubricating oil inside the oil storage chamber is also made between the oil passage connecting groove portion and the oil storage chamber when the outer shuttle frame rotates. Along with the rotation, the rotation of the lubricating oil generates centrifugal force, so that a positive pressure in the radial direction is applied to the lubricating oil, and then the lubricating oil can be output to the groove portion through the oil passage under the force of the positive pressure. At the same time, it is attached to the surface of the groove portion or the inner shuttle frame to provide lubrication for the rotation of the outer shuttle frame. By automatically adjusting the oil pressure by using different rotational speeds, the precise supply of oil to the groove portion of the outer shuttle frame is realized, thereby avoiding excessive lubricating oil contaminating the clothes or too little lubricating oil affecting the normal use of the outer shuttle frame. In addition, since the hook or the outer shuttle frame will wear out after a certain period of time or after rotating to a certain number of turns, and the overall replacement is required, the hook or the outer shuttle frame are both lossy parts and receive at the driving force. The oil storage chamber is opened in the department, and the lubricating oil in the oil storage chamber is matched with the service life of the outer shuttle frame, so that the existing complicated oil supply pipeline and the oil supply system are no longer needed, thereby reducing the later period. Maintenance cost, while the simple structure of the outer shuttle frame and the rotary hook of the present invention is more advantageous for improving production efficiency.

Industrial applicability

The outer shuttle frame, the rotary hook and the rotary hook lubrication method of the invention are suitable for the sewing airport in the garment manufacturing field, and the product and the method of the invention are applied, the simple structure thereof is more favorable for improving the production efficiency, and the oil is realized by using different rotation speeds. The automatic adjustment of the pressure enables precise oil supply to the groove portion of the outer shuttle frame, thereby avoiding excessive lubricating oil contaminating the laundry or too little lubricating oil affecting the normal use of the outer shuttle frame.

Claims

The outer shuttle frame includes a driving force receiving portion for receiving a rotational driving force and an inner shuttle accommodating cavity, and a peripheral wall of the inner shuttle accommodating cavity is provided with a groove portion for slidingly engaging the inner shuttle frame,

It is characterized by:

The driving force receiving portion is provided with a substantially sealed oil storage chamber, and the oil storage chamber communicates with the groove portion through an oil passage.
The outer shuttle according to claim 1, wherein:

The oil passage is a bore opened in an inner wall of the inner shuttle accommodating chamber.
The outer shuttle according to claim 1, wherein:

The oil reservoir is provided with an opening, and the opening is provided with a seal.
The outer shuttle according to claim 1, wherein:

The oil reservoir extends in a circumferential direction.
An outer shuttle according to any one of claims 1 to 4, characterized in that:

The oil reservoir is disposed away from the central axis of rotation of the outer shuttle.
The rotary hook includes an outer shuttle frame, an inner shuttle frame and a pressing piece, and the outer shuttle frame includes a driving force receiving portion and an inner shuttle frame receiving cavity for receiving a driving force, and a circumferential wall of the inner shuttle frame receiving cavity is circumferentially opened a grooved portion, the inner shuttle frame being mounted in the inner shuttle frame accommodating cavity, the inner shuttle frame being disposed on the groove portion and rotatable independently of the outer shuttle frame along the groove portion The pressing piece comprises a peripheral wall and a buckle edge at an axial end of the peripheral wall, the pressing piece is mounted on an outer wall of the outer shuttle frame, and the buckle edge is engaged with the inner shuttle frame;

It is characterized by:

The outer shuttle frame is provided with a substantially closed oil storage chamber in the driving force receiving portion, and the outer shuttle frame further includes an oil passage communicating between the groove portion and the oil reservoir.
The hook according to claim 6, wherein:

The oil passage is a bore opened in an inner wall of the inner shuttle accommodating chamber.
The hook according to claim 6, wherein:

The oil reservoir is provided with an opening, and the opening is provided with a seal.
A hook according to any one of claims 6 to 8, characterized in that:

The oil reservoir extends in a circumferential direction.
A method for lubricating a rotary hook, characterized in that:

The rotary hook includes a relatively rotatable outer shuttle frame and an inner shuttle frame, and the outer shuttle frame is provided with a driving force receiving portion and a groove portion for slidingly engaging with the inner shuttle frame, and the driving force receiving portion is provided with a storage portion a substantially sealed oil reservoir for lubricating oil, The oil storage chamber is in communication with the groove portion through an oil passage;

The lubrication method of the hook includes:

The lubricating oil is output to the groove portion through the oil passage by the centrifugal force as the outer shuttle frame rotates.