HIGH VOLTAGE VERTICAL BREAK DISCONNECT SWITCH WITH PLANETARY GEAR REDUCTION SWITCH DRIVE MECHANISM

Abstract

A high voltage vertical break disconnect switch with a planetary gear reduction drive assembly including at least one stage operatively attached to a perpendicular rotatable insulator of the high voltage vertical break disconnect switch. The planetary gear reduction drive assembly includes a lower crankshaft part and a cooperating upper crankshaft part. The lower crankshaft part is solidly connected to the perpendicular rotatable insulator. The planetary gear reduction drive assembly includes an output that drives the upper crankshaft part. The upper crankshaft part drives a movable link assembly that causes a switch blade of the vertical break switch to open and close.

Claims

1. A high voltage vertical break disconnect switch comprising: three perpendicular cylindrically-shaped insulators mounted in operative arrangement on a longitudinal beam, one of the perpendicular cylindrically-shaped insulators being rotatable axially and the other of the perpendicular cylindrically-shaped insulators being stationary, a prime mover including a drive shaft in operative rotational drive arrangement with the one rotatable perpendicular cylindrically-shaped insulator, an elongated movable switch-blade assembly in operative arrangement with the prime mover drive shaft, the elongated movable switch-blade assembly including an elongated switch blade for electrically opening and closing the high voltage vertical break disconnect switch, the elongated movable switch-blade assembly including a hinge assembly configured to movably support a proximal end of the elongated switch blade, the hinge assembly in electrically conductive relationship with the elongated switch blade, a movable link assembly in operative arrangement with the hinge assembly for rotating the elongated switch blade from a closed electrically conductive position to an open electrically non-conductive position, a planetary gear reduction drive assembly including a planetary gear reduction switch drive mechanism having at least one stage, the planetary gear reduction switch drive mechanism including at least a two-piece crank shaft assembly mounted coaxially and in operative rotational relationship with the rotatable perpendicular cylindrically-shaped insulator, the planetary gear reduction switch drive mechanism in operative rotational drive arrangement with the movable link assembly, the planetary gear reduction switch drive assembly operatively supported by and housed within a live base assembly having oppositely disposed side plates a first of the stationary perpendicular cylindrically-shaped insulators in operative supportive relationship with the base assembly, the movable link assembly mounted in operative arrangement between the two-piece crank shaft assembly and the hinge assembly, whereby loads to be transmitted between the prime mover drive shaft and the movable link assembly are reduced by the planetary gear reduction drive assembly.

2. The high voltage vertical break disconnect switch of claim 1, wherein the two-piece crank shaft comprises a lower crankshaft part and an upper crankshaft part, the upper crankshaft part coaxially aligned with the lower crankshaft part and in operative arrangement therewith.

3. The high voltage vertical break disconnect switch of claim 2, wherein the planetary gear reduction switch drive assembly is a two-stage planetary gear reduction switch drive mechanism.

4. The high voltage vertical break disconnect switch of claim 2, wherein the planetary gear reduction switch drive assembly is a single-stage planetary gear reduction switch drive mechanism.

5. The high voltage disconnect switch of claim 1, wherein the prime mover comprises a motor or a geared hand crank assembly.

6. The high voltage vertical break disconnect switch of claim 2, wherein the lower crankshaft part is in direct drive solid connection with the top of the rotatable perpendicular cylindrically-shaped insulator.

7. The high voltage vertical break disconnect switch of claim 3, wherein the two-stage planetary gear reduction switch drive mechanism includes a second stage planetary gear set in operative rotational drive arrangement with the upper crankshaft part with respect to the rotation of the lower crankshaft part.

8. The high voltage vertical break disconnect switch of claim 7, wherein the two-stage planetary gear reduction switch drive mechanism further includes a first stage sun gear in operative connection with a top of the lower crankshaft part, the first stage sun gear configured as an input gear to a first stage planetary gear set.

9. The high voltage vertical break disconnect switch of claim 8, wherein the two-stage planetary gear reduction switch drive mechanism further includes a stationary first stage ring gear in operative connection with the live base assembly oppositely disposed side plates, a first stage planet carrier assembly configured to rotate by the interaction of the first stage sun gear, the first stage planetary gear set and the stationary first stage ring gear.

10. The high voltage vertical break disconnect switch of claim 9, wherein the two-stage planetary gear reduction switch drive mechanism further includes a second stage sun gear configured in rigid connection with the first stage planet carrier, the second stage sun gear configured as an input gear to a second stage planetary gear set of the two-stage planetary gear reduction switch drive mechanism.

11. The high voltage vertical break disconnect switch of claim 10, wherein the two-stage planetary gear reduction switch drive mechanism further includes a stationary second stage ring gear in operative connection with the live base assembly oppositely disposed side plates, a second stage planet carrier assembly is configured to rotate by the interaction of the second stage sun gear, the second stage planetary gear set and the stationary second stage ring gear.

12. The high voltage vertical break disconnect switch of claim 11, further comprising a second stage planet carrier assembly configured in solid connection with the upper crankshaft part as an output of the two-stage planetary gear reduction switch drive mechanism and in operative rotational drive arrangement with the movable link assembly.

13. The high voltage vertical break disconnect switch of claim 12, wherein the first stage planetary gear set and the second stage planetary gear set each comprise a plurality of planet gears.

14. The high voltage vertical break disconnect switch of claim 2, wherein the lower crankshaft part has a central recess proximate a top of the lower crankshaft part for operatively receiving and rotatably supporting a bottom portion of the upper crankshaft part.

15. The high voltage vertical break disconnect switch of claim 14, wherein the upper crankshaft part has a lower crankshaft engagement portion configured to operatively engage the central recess of the lower crankshaft part.

16. The high voltage vertical break disconnect switch of claim 15, further comprising an upper crankshaft part support bearing configured in operative arrangement in the central recess of the lower crankshaft part.

17. The high voltage vertical break disconnect switch of claim 4, wherein the single-stage planetary reduction switch drive mechanism includes a single-stage planetary gear set comprising a plurality of planet gears in operative rotational drive arrangement the upper crankshaft part with respect to the lower crankshaft part.

18. The high voltage vertical break disconnect switch of claim 17, wherein the single-stage planetary gear reduction switch drive mechanism further includes a single stage sun gear in operative connection with a top of the lower crankshaft part, the single stage sun gear configured as an input gear to the single-stage planetary gear set.

19. The high voltage vertical break disconnect switch of claim 18, wherein the single-stage planetary gear reduction switch drive mechanism further includes a stationary single stage ring gear in operative connection with the base assembly oppositely disposed side plates, a single stage planet carrier assembly configured to rotate by the interaction of the single stage sun gear, the single stage planetary gear set and the stationary single stage ring gear.

20. The high voltage vertical break disconnect switch of claim 19, wherein the single stage planet carrier assembly configured in solid connection with the upper crankshaft part as an output of the single-stage planetary gear reduction switch drive mechanism and in operative rotational drive arrangement with the movable link assembly.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] For a better understanding of the invention reference may be made to the accompanying drawings exemplary of the invention, in which:

[0013] FIG. 1 is a schematic partially cut away side-elevation view of an extra high voltage vertical break switch of the prior art shown in both the closed position and open position;

[0014] FIG. 2 is a schematic perspective view of the live base assembly in the configuration of the invention;

[0015] FIG. 3 is a schematic sectional elevation view of the live base assembly of the invention with a two-stage planetary gear reduction assembly mounted on the rotating perpendicular cylindrically-shaped insulator taken along the line ‘3’-‘3’ of FIG. 2;

[0016] FIG. 4 is an exploded view of FIG. 3.

[0017] FIG. 5 is a schematic sectional elevation view of a single-stage planetary gear reduction assembly version of the invention; and,

[0018] FIG. 6 is an exploded view of FIG. 5.

DETAILED DESCRIPTION OF THE INVENTION

[0019] With reference to FIG. 1 showing the prior art, a high voltage vertical air break disconnect switch 10 in the electrically closed position and also in the electrically opened position, indicated by the curved arrow and dashed lines, is shown. The switch 10 includes a longitudinal beam 12 having a top 12a with three perpendicularly mounted post-type cylindrically-shaped insulators 13a, 13b and 14. A first post insulator 13a and a second post insulator 13b are stationary and are mounted as shown in FIG. 1. The third post insulator 14 is rotatable and can be driven by a prime mover 36, such as an electric motor with controls or a manual geared hand crank assembly having a prime mover drive shaft 16, as well known in the art, operatively attached to the bottom 18 of the third post insulator 14.

[0020] A line-terminal connection 20 and a stationary break-jaw contact assembly 22 are attached to the top 15 of the stationary first post perpendicular cylindrically-shaped insulator 13a. The break-jaw contact assembly 22 may have U-shaped break-jaws, not shown in the drawings. An elongated movable switch-blade assembly 24 makes electrical contact with the stationary break-jaw contact assembly 22, when the switch 10 is closed. The elongated movable switch-blade assembly 24 includes an elongated switch blade 26 which is pivotally mounted at its proximal end 30 to a hinge assembly 28, for electrically opening and closing the high voltage vertical break disconnect switch 10. The general details of this arrangement are apparent by reference to FIG. 1. The elongated switch blade 26 may be tubular for example. A switch blade contact portion, is arranged at a distal end 32 of the switch blade 26, such as a relatively flat switch blade tip 34, for contacting the U-shaped stationary break-jaw contact assembly 22, when the switch 10 is in the electrically closed position, as shown in FIG. 1.

[0021] As shown in FIG. 1, the rotatable third post perpendicular cylindrically-shaped insulator 14 is capable of rotary operative motion about its longitudinal axis 23 for driving the switch-blade assembly 24 to mechanically interconnect the operation of the elongated movable switch-blade assembly 24 with the rotation of the rotatable third post insulator 14. As mentioned, the switch 10 includes a prime mover, such as an electric motor or geared hand crank assembly 36, shown in FIG. 1 schematically as a box, for three phase group operation, for rotating the prime mover drive shaft 16 to cause the rotation of the third post perpendicular cylindrically-shaped insulator 14 to open and close the switch 10, as is well known in the art. A drive shaft support bearing 25 is provided for supporting the prime mover drive shaft 16 and the rotatable third post insulator 14, as shown in FIG. 1.

[0022] The hinge assembly 28 is provided with a blade hinge pivot point, which may be hinge shaft 38; the hinge assembly 28 in electrically conductive relationship with the elongated switch blade 26. The switch-blade 26 is operatively attached at its proximal end 30 to the hinge shaft 38 which blade hinge pivot point is used for rotating the blade 26 to the open position as shown in FIG. 1. A crank assembly 40 at one end 40a operatively engages a movable link assembly 42 through pin 46, which is rotated by the operating motion of the rotatable third post perpendicular cylindrically-shaped insulator 14. The movable link assembly 42 is in operative arrangement with the hinge assembly 28 for rotating the elongated switch blade 26 from a closed electrically conductive position to an open electrically non-conductive position. The crank assembly 40 is connected at the other end 40b to a one piece crank shaft 50 supported by and substantially housed in a live base assembly 52, as shown in FIG. 1, which is the prior art. The live base assembly 52 is mounted on and supported by stationary first post perpendicular cylindrically-shaped insulator 13b, which as can be seen in FIG. 1, adjoins rotatable third post perpendicular cylindrically-shaped insulator 14. The live base assembly 52 includes a straight unbent first side plate 54 and an oppositely disposed straight unbent second side plate 56, not shown in FIG. 1. The crank assembly 40 is attached to the one piece crank shaft 50 as shown in FIG. 1. A spring counter balance tube assembly 48 is connected at one end 66 to a fixed pin 67 through the live base assembly 52 and at the other end 68 to spring counterbalance arm assembly 69. The spring counter balance tube assembly 48 acts to counter balance the weight of the switch-blade assembly 24.

[0023] Regarding the operation of the switch 10 during closing, the movement of the rotatable third post perpendicular cylindrically-shaped insulator 14 initially causes the one piece crank shaft 50 and the elongated movable switch-blade assembly 24 to rotate about the hinge axis 44, through a predetermined angle ‘A’—from a vertical orientation to a horizontal orientation as shown in FIG. 1. During this movement, the switch 10 goes from the open electrically non-conductive position to an almost fully closed position, as indicated by the solid curved line with double arrows in FIG. 1, which is designated as angle CA′ of about 90°. This initial rotation results in the switch 10 being in a so-called intermediate closed position, not shown in the drawings, with the switch blade tip 34 entering the U-shaped stationary break-jaw contact assembly 22—but the tip is at a non-horizontal orientation between the jaw stationary contacts—and thus is not yet in the fully electrically closed position with the jaw stationary contacts, not shown. In the second switch closing operation, instead of the switch-blade assembly 24 rotating about the hinge axis 44, the switch-blade assembly 24 rotates about its own longitudinal axis 27 to the fully closed position as shown in FIG. 1.

[0024] The horizontal vertical break switch 10 of prior art as described thus far is conventional and well known in the industry. As shown in FIG. 2, the live base assembly 52 of the present invention includes a first side plate 54 and an oppositely disposed parallel second side plate 56, that have been modified from the side plates of the prior art live base assembly which are straight and not bent. This modified form of the side plates of the prior art live base assembly results in the live base assembly 52 of the present invention having a wide section 52a and a narrow section 52b, as shown in FIG. 2, instead of the side plates having a uniform width of separation like the prior art live base assembly, not shown in the drawings. The modified live base assembly 52 also includes a top plate 58 and a bottom plate 62 which are positioned between the first and second side plates 54, 56 in the wide section 52a as shown in FIG. 2. As shown in FIG. 3, the bottom plate 62 is provided with a bottom plate crank shaft aperture 64. The top plate 58 is provided with a top plate crank shaft aperture 60. The narrow section 52b of live base assembly 52 is configured to carry a switch blade proximal end contact assembly 33 proximate the hinge assembly 28, for provided electrical connection to the proximal end 30 of the switch blade 26 as shown in FIG. 1. Also, as shown in FIG. 3, the improvement of the present invention provides a planetary gear reduction assembly 65 housed within the wide section 52a of the modified live base assembly 52. The planetary gear reduction assembly 65 includes a planetary gear reduction switch drive mechanism having at least one stage. A stage may include a stationary ring gear and a rotatable carrier assembly with planet gears. As shown in FIGS. 3 and 4, an embodiment for a high voltage vertical break disconnect switch of the extra high voltage (EHV) type, having a two-stage planetary gear reduction switch drive mechanism 70 in place of the prior art one piece crank shaft 50 is provided. This embodiment of the invention can be seen in FIG. 3 showing the components of the two-stage planetary gear reduction switch drive mechanism 70 with an associated two-piece crank shaft assembly 72, which are mounted between a plate 19 of rotatable third post insulator 14 and the crank assembly 40. The two-piece crank shaft assembly 72 is coaxially aligned with and in operational rotational relationship with the rotatable perpendicular cylindrically-shaped insulator 13a. The linkage beyond the crank assembly 40, that moves the switch blade 26 between the open and closed positions is the same as the prior art arrangement already described. As can be seen in FIGS. 3 and 4, the two-stage planetary gear reduction switch drive mechanism 70 circumferentially surrounds a substantial portion of the two-piece crank shaft assembly 72. The two-piece crank shaft assembly 72 includes a lower shaft part 74 which is solidly connected to plate 19 of the rotatable third post perpendicular cylindrically-shaped insulator 14. The lower crankshaft part 74 has a central recess 75, as can be seen in FIG. 3, for receiving a lower crankshaft part engagement portion 77 of the upper crankshaft part 76. An upper crankshaft part support bearing 79 is operatively arranged proximate the central recess 75, as shown in FIG. 3, for rotatably supporting the lower crankshaft part engagement portion 77. The lower crankshaft part engagement portion 77 is rotatable within the central recess 75. An upper shaft part 76 of the two-piece crank shaft assembly 72 is turned by means of a second planetary gear set 78 of the two-stage planetary gear reduction switch drive mechanism 70. The lower shaft part 74 of the two-piece crank shaft assembly 72 has a first stage sun gear 80 connected to it as the input gear which engages with a first stage planetary gear set 82 as shown in FIG. 4. The first stage planetary gear set 82 and the second stage planetary gear set 78, each include eight planet gears 84, for example. The first stage planetary gear set 82 is turned by the interaction or engagement with the first sun gear 80, i.e., the input gear, and a stationary first stage ring gear 86. The stationary first stage ring gear 86 is held fixed relative to plates 58 and 62 by bolting. Plates 58 and 62 are held from turning by stationary insulator oppositely disposed side plates 56 and 54 of the live base assembly 52, as can be discerned from FIGS. 2 and 3. The first stage planetary gear set 82 is nested within the stationary first stage ring gear 86 as can be seen by reference to FIGS. 3 and 4. Within the center of the first stage planetary gear set 82 is a first stage planet carrier 90 configured to carry the first stage planetary gear set 82 shown on FIG. 4.

[0025] In this embodiment, a second stage sun gear 92 is rigidly connected to the first stage planet carrier 90 and is driven by the first stage planetary gear set 82. The second stage sun gear 92 is the input gear for the second stage planetary gear set 78. The second stage planetary gear set 78 is turned by the interaction or engagement of the second stage sun gear 92, i.e., the input gear, and a stationary second stage ring gear 96 which is held stationary in the same manner as the first stage ring gear 86. Within the center of the second stage planetary gear set 78 is a second stage planet carrier 94 configured to carry the second stage planetary gear set 78. The upper shaft part 76 of the two-piece crank shaft assembly 72 is solidly connected to the second stage planet carrier 94 and is the output of the two-stage planetary gear reduction switch drive mechanism 70. The upper shaft part 76 is part of the second stage planetary gear set 78 and is the gear reduction output.

[0026] The lower shaft part 74 of the two-piece crank shaft assembly 72 is operably connected to the first stage sun gear 80 by cross pin 100. As the lower shaft part 74 of the two-piece crank shaft assembly 72 is caused to rotate by perpendicular cylindrically-shaped insulator 14 connected to the prime mover 36 the first stage sun gear 80 actuates first stage planetary gear set 82 of the two-stage planetary gear reduction switch drive mechanism 70.

[0027] This embodiment of the two-stage planetary gear reduction switch drive mechanism 70 with an associated two-piece crank shaft assembly 72 provides for the rotatable third post insulator 14 and the lower shaft part 74 of the two-piece crank shaft assembly 72 to rotate multiple times while the upper shaft part 76 of the two-piece crank shaft assembly 72 rotates about 180 degrees. This particular arrangement has a 9:1 gear reduction. The rotatable third post insulator 14 rotates about 4.5 times to rotate the crank assembly 40 through 0.5 rotations, thus providing reduced stress on the rotating perpendicular cylindrically-shaped insulator 14 and power transmitting components between prime mover 36 and the switch crank component compared to prior art switches, particularly under heavy thick ice conditions when opening or closing.

[0028] In a second embodiment of the invention, applicable to the case of a high voltage vertical break disconnect switch 10 rated for voltages of 345 kV and lower, a single-stage planetary gear reduction switch drive mechanism 98 of the present invention may be utilized as shown in FIGS. 5 and 6, instead of a two-stage mechanism. Like reference numerals are used for the present embodiment as were used for the first embodiment and represent the same or similar elements for this embodiment. This embodiment of the invention as can be seen in FIG. 6 shows the components of the single-stage planetary gear reduction switch drive mechanism 98 with an associated two-piece crank shaft assembly 72. As can be seen in FIGS. 5 and 6, the single-stage planetary gear reduction switch drive mechanism 98 circumferentially surrounds a substantial portion of the two-piece crank shaft assembly 72. The two-piece crank shaft assembly 72 includes a lower shaft part 74 which is solidly connected to the plate 19 of the rotatable third post perpendicular cylindrically-shaped insulator 14. The lower crankshaft part 74 has a central recess 75, as can be seen in FIG. 5, for receiving a lower crankshaft part engagement portion 77 of the upper crankshaft part 76. An upper crankshaft part support bearing 79 is operatively arranged proximate the central recess 75, as shown in FIG. 5, for rotatably supporting the lower crankshaft part engagement portion 77. The lower crankshaft part engagement portion 77 is rotatable within the central recess 75. An upper shaft part 76 of the two-piece crank shaft assembly 72 is connected to the single-stage planetary gear set 78 of the single-stage planetary gear reduction switch drive mechanism 98. As shown in FIG. 6, the lower shaft part 74 of the two-piece crank shaft assembly 72 has a single stage sun gear 80 connected to it by cross pin 100 and is the input gear which engages with the single-stage planetary gear set 78. The single-stage planetary gear set 78 includes eight planet gears 84, for example. The single-stage planetary gear set 78 is turned by the interaction or engagement with the single-stage sun gear 80, i.e., the input gear, and a stationary single stage ring gear 86. The stationary single stage ring gear 86 is held fixed relative to plates 58 and 62 by bolting. Plates 58 and 62 are held from turning by stationary insulator oppositely disposed side plates 56 and 54 of the live base assembly 52, as can be discerned from FIGS. 2 and 5. The single-stage planetary gear set 78 is nested within the stationary single stage ring gear 86 as can be seen by reference to FIGS. 5 and 6.

[0029] Within the center of the single stage planetary gear set 78 is a single stage planet carrier 90 configured to carry the single stage planetary gear set 78. The upper shaft part 76 of the two-piece crank shaft assembly 72 is solidly connected to the single stage planet carrier 90 and is the output of the single-stage planetary gear reduction switch drive mechanism 98. The upper shaft part 76 is part of the single stage planetary gear set 78 and is the gear reduction output.

[0030] As the lower shaft part 74 of the two-piece crank shaft assembly 72 is caused to rotate by insulator 14 connected to the prime mover 36, the single stage sun gear 80 actuates the single stage planetary gear set 78 of the single-stage planetary gear reduction switch drive mechanism 98.

[0031] This embodiment of the single-stage planetary gear reduction switch drive mechanism 98 with an associated two-piece crank shaft assembly 72 provides for the rotatable third post insulator 14 and the lower shaft part 74 of the two piece crank shaft assembly 72 to rotate multiple times while the upper shaft part 76 of the two piece crank shaft assembly 72 rotates about 180 degrees. This particular arrangement has a 3:1 gear reduction. The rotatable third post insulator 14 rotates about 1.5 times to rotate the crank assembly 40 through 0.5 rotations, thus providing reduced stress on the rotating insulator 14 and power transmitting components between prime mover 36 and the switch crank component compared to prior art switches, particularly under heavy thick ice conditions when opening or closing.

LIST OF REFERENCE NUMERALS

[0032] 10 high voltage air break disconnect switch [0033] 12 longitudinal beam [0034] 12a top of 12 [0035] 13a stationary 1.sup.st post perpendicular cylindrically-shaped insulator [0036] 13b stationary 2.sup.nd post perpendicular cylindrically-shaped insulator [0037] 14 rotatable 3rd post perpendicular cylindrically-shaped insulator [0038] 15 top of 13a [0039] 16 motor drive shaft [0040] 18 bottom of 14 [0041] 19 plate of 14 [0042] 20 line-terminal connection [0043] 22 U-shaped stationary break-jaw contact assembly [0044] 23 longitudinal axis of 14 [0045] 24 elongated movable switch-blade assembly [0046] 25 drive shaft support bearing assembly [0047] 26 elongated switch blade [0048] 27 longitudinal axis of 24 [0049] 28 hinge assembly [0050] 30 proximal end of 26 [0051] 32 distal end of 26 [0052] 33 switch blade proximal end contact assembly [0053] 34 switch blade tip [0054] 36 prime mover, motor or geared hand crank assembly [0055] 38 hinge shaft [0056] 40 crank assembly [0057] 40a one end of 40 [0058] 40b other end of 40 [0059] 42 movable link assembly [0060] 44 hinge axis [0061] 46 pin [0062] 48 spring counter balance tube assembly [0063] 50 one piece crank shaft of prior art [0064] 52 live base assembly [0065] 52a wide section of 52 [0066] 52b narrow section of 52 [0067] 54 first live base assembly side plate [0068] 56 second live base assembly side plate [0069] 58 top plate of live base assembly [0070] 60 top plate crank shaft aperture [0071] 62 bottom plate of live base assembly [0072] 64 bottom plate crank shaft aperture [0073] 65 planetary gear reduction assembly [0074] 66 one end of 48 [0075] 67 fixed pin [0076] 68 the other end of 48 [0077] 69 counterbalance arm assembly [0078] 70 two-stage planetary gear reduction switch drive mechanism [0079] 72 two piece crank shaft assembly [0080] 74 lower shaft part of 72 [0081] 75 central recess [0082] 76 upper shaft part of 72 [0083] 77 lower crankshaft part engagement portion [0084] 78 2.sup.nd stage or single stage planetary gear set [0085] 79 upper crankshaft part engagement portion [0086] 80 first stage or single stage sun gear [0087] 82 first stage planetary gear set [0088] 84 planet gears [0089] 86 stationary first stage or single stage ring gear [0090] 90 first stage planet carrier or single stage planet carrier [0091] 92 second stage sun gear [0092] 94 second stage planet carrier [0093] 96 stationary second stage ring gear [0094] 98 single-stage planetary gear reduction switch drive mechanism [0095] 100 cross pin

[0096] Of course variations from the foregoing embodiments are possible without departing from the scope of the invention.